The Physics of Sailing - KQED QUEST

Northern California has a storied, 500-year history of sailing. But despite this rich heritage, scientists and boat designers continue to learn more each day about what makes a sail boat move. Contrary to what you might expect, the physics of sailing still present some mysteries to modern sailors.

The Physics of Sailing - KQED QUEST sentiment_very_dissatisfied 322

Sailing 13 years ago 1,516,385 views

Northern California has a storied, 500-year history of sailing. But despite this rich heritage, scientists and boat designers continue to learn more each day about what makes a sail boat move. Contrary to what you might expect, the physics of sailing still present some mysteries to modern sailors.

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for The Physics of Sailing - KQED QUEST

Ernoskij
Ernoskij - 3 years ago
4:03 and here I thought it was the midi-chlorians that leads to the force
Taylor Moore
Taylor Moore - 3 years ago
Remember that time when wind was like, "Bruh, the ships changed. Guess we gotta change the way we work too."
Tom Hunter
Tom Hunter - 3 years ago
This is an insult to the subject of physics. If you simplify some thing too much, you loose the meaning.
Comanche Don bushcraft
Comanche Don bushcraft - 3 years ago
Why did ghe wind shift, just cause? I couldnt help but laugh when she asked that. Just goes to show, you dont have to be smart to be successful.
J3AN P3T3R
J3AN P3T3R - 3 years ago
1:34 is confusing. he said the boat can also go into the wind but then says except for directly into the wind.
Atlas Stories
Atlas Stories - 3 years ago
Bali Yacht Services
Bali Yacht Services - 3 years ago
Excellent
nexusgroupnxt
nexusgroupnxt - 3 years ago
alleen echte nederlanders kunnen zo goed op zee varen. Ik ben trots!
apic165
apic165 - 3 years ago
high definition ?

10. comment for The Physics of Sailing - KQED QUEST

João Bento
João Bento - 3 years ago
Modern sailing and old sailing !? Wtf !??
Lucian schwartz-croft
Lucian schwartz-croft - 3 years ago
Ugh noob
Leafdroid
Leafdroid - 3 years ago
2:12 Fluid Mechanics Laboratory

aka F.M.L.
Andre Rovigatti
Andre Rovigatti - 3 years ago
Ouch ! Let´s start over again, first reading about Coanda Effect , not Bernoulli. " Square-rigged ships can not sail into the wind." . Ouch ! I am guessing , how could Columbus go back to his harbour in Europe ?
treefiddy
treefiddy - 3 years ago
That's too much damn work, on my motor boat I just need one hand on the throttle to go forward and on the other hand I can hold a beer
Herobrine Dust Team Hero
Herobrine Dust Team Hero - 3 years ago
That BAM at the 5:51 at the video is hilarious
Lawathe M. Eid لاوَذ ميثَم عيد
Lawathe M. Eid لاوَذ ميثَم عيد - 3 years ago
5:48 the vertical component (on the path line) of both forces (on keel and sails) not the component of force on sails with the path line, the force on keel has on component that canceled with the component of sails force.
ban jomi
ban jomi - 3 years ago
This is a very confused expanation of how a sailboat works, using terms like 'lift' and 'suck', does not help. By the way square riggers could sail to windward but not very well as they were primarily designed to sail downwind.
Robert Applegate
Robert Applegate - 3 years ago
Not sure what "produced in high definition" means exactly....I didn't see a single high def shot unless it was of people talking....
Richard Bedard
Richard Bedard - 3 years ago
You may not have to know physics to sail but the more I know about how and why things do what they do the better prepared I feel.

20. comment for The Physics of Sailing - KQED QUEST

King David
King David - 3 years ago
I miss Raccoon Straits, too much fun. That 27 foot sailboat came out of the water.
Vilo Conshmillo
Vilo Conshmillo - 3 years ago
I am not sure how this supposed to clear things up.
james moylan
james moylan - 3 years ago
take a landsurfer,the wheels stop the thing from sliding sideways as a boat does without a keel?
The wheels do not generate lift?
james rudolph
james rudolph - 3 years ago
if god had wanted men to sail he would not have invented engines.
terrapin
terrapin - 3 years ago
Flying fish
Anton
Anton - 4 years ago
So, how does NASA create lift in space with a space rocket when there is nothing to push against?
Jack Lewis
Jack Lewis - 4 years ago
High definition potato?
Lee Weisbecker
Lee Weisbecker - 4 years ago
who says a square rigger only goes down wind?
Tyler Hill
Tyler Hill - 4 years ago
L
Christopher Darley
Christopher Darley - 4 years ago
duus sailing is EZ im 11 lol

30. comment for The Physics of Sailing - KQED QUEST

Gio
Gio - 4 years ago
As someone already pointed out, the physics explanation of the lift is WRONG ! There is no reason why the air should hurry around the curved area (there is no law saying that the transit time must be the same on the two sides of the sail/wing). It's just the curved geometry of the sail that leaves a side with less air, hence a lower pressure that causes the lift in that direction. Google "how wings really work" and you'll find a nice explanation from a Cambridge professor
Richardo Frankie
Richardo Frankie - 4 years ago
With the Wind! Yes!
LinuxUser119
LinuxUser119 - 4 years ago
Nice simple physics anyone can understand.
Guruprasad Shetti
Guruprasad Shetti - 4 years ago
Wow!! Its like Re-Visiting "Principles of Bernulli" - Governing the dynamics of fluid movements.

Here, Explaining the physics behind the world of Sailing!

I should say - A Very nicely illustrated video piece - As compared to any of the boring lecturers speeches/ the books on college library shelf racks!

Reflecting on the new times.

Well I call it "An Era Of Real Thought Sharing"!!

Thanks for sharing.
Lorrin Barth
Lorrin Barth - 4 years ago
Being a sailor I'd very much love to delve into the detailed physics of sailing. I watched this video and didn't learn anything.
Flight Sim Joe
Flight Sim Joe - 4 years ago
I like how they say that they're getting into "the nitty gritty" with lift and then they explain it wrong with that explanation you could any the with a flat bottom and a curved top produce lift, instead of using Bernoulli's law wings use Newton's third law. The airfoil shape forces the fluid down which makes the the object go in the opposite direction. (Every action had an equal and opposite reaction)
Matthew Holevinski
Matthew Holevinski - 4 years ago
dynamical my new favorite word
Noli's Art
Noli's Art - 4 years ago
Bernuili principle declares:
Increase in velocity results in decrease in pressure and temperature.
Erlend Dalheim
Erlend Dalheim - 4 years ago
Produced in highj definition!. oooh 360p!
Wade Patton
Wade Patton - 4 years ago
And THIS my fellow sailors, is WHY we NEVER confuse facts with Television.
Just Wow
Just Wow - 4 years ago
Before the Europeans arrived to America. Pacific Islanders had had already been sailed there and gone.
Frank Gibson
Frank Gibson - 4 years ago
I am amazed that a video about the physics of sailing spends so much time implying that it is just to difficult for most people to understand. Is this what science education is all about in the US?. I was also impressed by the incorrectness of much of what was said. Sucking is NOT a force. If you have higher pressure on one side of a wing or sail than the other then it is excess pressure giving the resultant force not the lack of pressure on one side.
nadorf75
nadorf75 - 4 years ago
Bah...Bernoulli holds for closed conduct
s. Giustino
s. Giustino - 4 years ago
So many false statements made on this broadcast, but then again, it is PUBLIC BROADCASTING.
Borat Sagdyev
Borat Sagdyev - 4 years ago
7:46 watch the white sailboat at the bottom of the screen.
Odival Quaresma
Odival Quaresma - 4 years ago
Theres nothing quite like master boat all day long
Fran Linden
Fran Linden - 4 years ago
nice and informational
J Podolski
J Podolski - 4 years ago
That video just took all fun out of sailing!! What a bunch of crap!!
Lee Riley
Lee Riley - 4 years ago
In high 360p definition!
Max Blinkhorn
Max Blinkhorn - 4 years ago
Early sailboat did MUCH more than drag across the water. They were limited by materials but they knew how sail these amazing craft round the world.

50. comment for The Physics of Sailing - KQED QUEST

algaetodiesel
algaetodiesel - 4 years ago
360p: High definition in 2008
Account New
Account New - 4 years ago
I don't understand this... he said at 3:34 that the place where it was curved and where the color accelerated it created a "lower pressure". If the pressure is there lower, the object would normally move towards that point instead of being lifted away from that point. Am I missing something here?
Account New
Account New - 4 years ago
hahah omg he actually said it 5 seconds after that hahah but they are simply horrible at explaining things! Typical American physicist. So here is the thing, sail is this cloth thing material on the mast. Mast is like this metal dick on the ship. Okay? so far so good... Wind blows into sail from a 45% angle (NOT HORIZONTALLY NOT VERTICALL), then sail is curved on one side. Why is it curved? Well YOU MAKE IT. You tie the center of it on the side of the ship so it is curved! On that side air has to travel longer distance, okay, it is curved okay? >>>>> Air moves faster >>> pressure falls on that side >>> on the other side pressure is high>>> ship moves to the side with lower pressure (side where sail is curved). Keel is this thing you have in the water... it makes the ship go forward and not completely to that side so yeah. Mkay? Okay...
Ariel ben Yochanan
Ariel ben Yochanan - 4 years ago
The title of this video is Physics of Sailing and so people come here to learn more about just that. To say that experienced sailors don't need to know more about the physics of sailing is just not good enough, sorry! I flag this video for misleading title.
Awesome Bent
Awesome Bent - 4 years ago
That's awesome. Thanks for making it clear to me!
ex0duzz
ex0duzz - 4 years ago
Pretty confusing video.. i thought that it would explain it in a non technical, easy to understand manner..

The only part i really got much form was the bit at @4:16 where he blew on the paper, and demonstrated how 'lift' works, same as aeroplane wings etc.

Other than that, i want to know how one sails INTO the wind(IIRC, they said it was not directly, so yeah. As close to the direction of the wind as possible). I want to see what kind of mechanical system they have to harness that energy which allows it to move into the wind..
Landell N
Landell N - 4 years ago
This video is totally wrong. Bernoulli's principle only applies to enclosed systems, such as oil pipelines, or water in pipes (plumbing).
Zeph Orac
Zeph Orac - 4 years ago
It's not a damn airplane wing. The pressure of the wind from the side pushes the sail both forward and to the side. (If the wind is behind it pushes the board forward. The keel and rudder combination limits the sideways movement and transfers most of the forces forward. It is unstable which is why there needs to be constant rudder adjustment. In this manner the wind causes the sail to push the boat forward like a wedge with it constantly being wedged by the wind.
The Great of Beam
The Great of Beam - 4 years ago
It works the same way. The force acted on the sail is perpendicular to the direction of the wind - just like an airplane wing. However, the sail is slightly angled forwards so there is a "forward" force component.

http://1.bp.blogspot.com/-bkRxU2KQ2fM/VVESGlmwyUI/AAAAAAAAFCo/F7yqcCywU1I/s1600/Slide2%2Bcopy.jpg
Landell N
Landell N - 4 years ago
a sail is not an airplane wing !! A wing pushes a plane up; not forward. A sail pushes a boat forward.
Zeph Orac
Zeph Orac - 4 years ago
I said something similar. On the other hand it's as much the angle of attack of an airplane wing (as in the air pushing up from below and back as a result of the airplane moving forward) that keeps an airplane aloft hence the word plane. A sheet of paper (plane) will float through the air when propelled forward as well.
reaktor55
reaktor55 - 4 years ago
this was produced in high definition you guys
Zeph Orac
Zeph Orac - 4 years ago
so what happened?
RisingPhoenix
RisingPhoenix - 4 years ago
I don't think they've heard of a schooner.
Ryan Mcbride
Ryan Mcbride - 4 years ago
me to dude cool. see you on the sea
carlos1750777
carlos1750777 - 4 years ago
Gonna go and practice this activity... looks fun . Thank you.
Antarctican
Antarctican - 4 years ago
360p = high definition
HerrHolz Paul
HerrHolz Paul - 4 years ago
Do you have an explanation as to why the air wants to rush round the outside of the sail? I guess it is something like - as the air reaches an oblique sail and passes the leading edge, low pressure is created as this air has to turn a corner. ie the very act of putting an obstacle against the wind will tend to cause a vacuum in the lee.
W. Scott Womer
W. Scott Womer - 3 years ago
The air on the top (side) curve has to cover a longer distance than the air on bottom flat side. The air on the top side has to go faster to meet the air on the bottom side. See Bernoulli's Law. Good video, I just now learned this about sailing.
Jack Lewis
Jack Lewis - 4 years ago
Yeah, I guess that hitting something head on like that redirects the energy and creates an inward spiral that follows the curve. It's a fight of the higher pressure vs low pressure, so the side with least resistance will take the hit.
Romano
Romano - 5 years ago
Its a Stitchup
Steven Bryant
Steven Bryant - 5 years ago
The big Clipper ships held oceanic route records from the mid 1800's until the 1990's. Much of the speed was born of the hull designs, very much ballast balanced by as much sail as they could put up. They also plied the trade winds and ocean streams as much as possible. The ships often paid for their construction after a one way trip, like to S.F., Cal.
Sometimes they were even broken up for their valuable lumber. This preferable to losing the ships to Teredo worms. This was inevitable as copper plating wasn't mounted on the bottom of the hulls to save money, speed construction, keep the cargo weight high and keep the the hull speed high. If someone reads a script that is pertaining to a subject that they don't know well, is it fair to ridicule the orator? It depends on how well they were paid!
Steven Bryant
Steven Bryant - 5 years ago
Man, I thought this was dumbed down for the girls, until I read some of the comments here. LOL
Everything Cool
Everything Cool - 5 years ago
lol i been sailing a lean all this years a go but i forgot lol so all these ships in old films in the real world only dose forward how do they go back
This name is either restricted, too long, or contains too many invalid characters.
This name is either restricted, too long, or contains too many invalid characters. - 5 years ago
"produced in high definition" = 360p

LOL
James
James - 5 years ago
fucken white people
James
James - 5 years ago
fuck off
Ft Lauderdale Swing & Shag Beach Bash
Ft Lauderdale Swing & Shag Beach Bash - 5 years ago
great video... join our Sailing Facebook Group https://www.facebook.com/groups/886157941490965/
Matt Stacey
Matt Stacey - 5 years ago
4:15 is an incorrect demonstration of Bernoulli's Law. Try hanging the paper vertically and blowing on it...it will not move in the direction of the blown air.

Correctly analyzed, lift is caused by streamline curvature, which is not taken into account for by Bernoulli's equation, which only analyzes velocity and pressure gradients ALONG the streamline (from mouth to far end of paper), not PERPENDICULAR to it (from paper surface outward).
Henry Merrilees
Henry Merrilees - 4 years ago
You are right, it's actually the Conandă effect. (The same thing that makes ping pong balls float in hair dryers.)
Steven Bryant
Steven Bryant - 5 years ago
It did move in the direction of the blown wind for me, from the vertical. The paper will not move into compression on the blown side very much; and past a flat plane shape you are, as they mentioned correctly, are introducing a concave shape to the former low pressure side, thus equalising the system. Maybe you just don't blow as hard as you think! LOL Quote real evidence from a reliable source to counter me.
James Dillenbeck
James Dillenbeck - 5 years ago
It's a good way to teach it. Bernoulli's law works even if it isn't in use in this situation.
Shahana Perveen
Shahana Perveen - 5 years ago
when you absolutely HAVE to spam the word modern trying to catch the attention of audience (-_-) how irritating
RaZ3 Storm
RaZ3 Storm - 5 years ago
Story: You were fishing peacefully, but suduntly, a shark sunk your boat! All you have on you boat is doughnuts with deadly sprinkles to kill the deadly lopsters! If you train a shark, you can ride him or her and kill the lopsters easy! Good luck, Sailer! :)
Mojo522
Mojo522 - 5 years ago
I have 3 years of studies left then I'm buying a used sailboat and taken sometime off. For me it's the best thing in the world.
MrLoadedHog
MrLoadedHog - 3 years ago
Lol Steve Bryant!  If you actually grasped how ignorant you sound right now, you would drive to your mama's house and slap her..........wait....you still live with her don't you?....well, just go into the kitchen and do it then!!!
mark paweena
mark paweena - 4 years ago
Steven Bryant back to school for you
Mojo522
Mojo522 - 4 years ago
+Zeph Orac No way I'll be buying a used sailboat this year, I'm already looking and I also have to friends saving to help outfit the boat and go with me. I can't wait. I hate being a tax cattle for our government, I want sometime away from that. I need to go live life the way it was meant to be...FREE.
Zeph Orac
Zeph Orac - 4 years ago
Won't be able to afford it with your loans. You'll have to work for 10 more years and then hope for the best.
Raidi Ray
Raidi Ray - 4 years ago
Mojo522 guddJggckh nbgh
James Potter
James Potter - 4 years ago
What you just said barely made any sense, I think you need some extra lessons as well.
Steven Bryant
Steven Bryant - 5 years ago
+Mojo522 I read what have written. I believe that if you take the time to read what I have written that it I can take the time to look at it also. Like the difference between then and than.... It isn't that hard!
Mojo522
Mojo522 - 5 years ago
+Audfile that sounds wicked fun
Audfile
Audfile - 5 years ago
I'm buying a Hobie Mirage sailing kayak and going to spend my days off exploring and camping puget sound where I live. and night fishing!
Mojo522
Mojo522 - 5 years ago
+Steven Bryant Haven't you ever made a typo. Not sure why you need to be ignorant about it, web warrior.
Steven Bryant
Steven Bryant - 5 years ago
taken is past tense, study harder!
Mineav
Mineav - 5 years ago
What's your vector, Victor?
movieklump
movieklump - 5 years ago
The lateen sail has been around for thousands of years. They could go to windward. It is just that England and Spain were to dumb to see it's potential.
movieklump
movieklump - 5 years ago
+James Dillenbeck
Well there goes my "theory" up in smoke.
James Dillenbeck
James Dillenbeck - 5 years ago
Lateen rigs were used extensively by the Spanish in the Mediterranean but because they don't hold up well in higher winds and waves square sails had to be used on the Atlantic. Many Spanish boats used lateen rigs in the Med but re-rigged them to square when they went out on the ocean. Same applies to gaff-rig. The reason Bermuda sails weren't used was because there wasn't material strong enough.
Harry Akira Eaton
Harry Akira Eaton - 5 years ago
That's because England has had Gaff rig for ages, which is similar to Lateen rig but uses a more squarish sail and a boom, just as effective if not more than Lateen.
axr1766
axr1766 - 5 years ago
I think it would be more helpful if there were diagram showing wind direction and airflow around the sail. Thanks for the effort.
Raidi Ray
Raidi Ray - 4 years ago
Black Ninja149 cf
Blackninja149
Blackninja149 - 5 years ago
There is, its called points of sail
Rick Pelland
Rick Pelland - 5 years ago
sailing seems like it would be fun to do but it looks uncomfortable when the boat is leaned right over
William Donahue
William Donahue - 5 years ago
that's when it gets really exciting! but remember guys- a flat boat is a fast boat lol
archiew
archiew - 5 years ago
That's the best part!!! So much fun!
Blackninja149
Blackninja149 - 5 years ago
+Carter Busby "Not really" What?
Carter Busby
Carter Busby - 5 years ago
Not really
Harry Akira Eaton
Harry Akira Eaton - 5 years ago
Same, you get a feel for what the wind is doing so although it makes you nervous the first time it happens, you enjoy it from then on out.

Best thing if you're nervous is to try sailing a little dinghy with the simplest kind of sail, then you're directly holding the main sheet and can feel the power of the wind, you can let out the sail to reduce heel but soon get a rate for getting as much speed as possible and at the same time learn all the important basics of how the wind interacts with the sail.
Blackninja149
Blackninja149 - 5 years ago
Dude heeling when you are in a sailboat is one of the most amazing feelings ever. It might look uncomfortable but it is so fun especially when you are in the side closest to the water.
Harry Akira Eaton
Harry Akira Eaton - 5 years ago
It depends what kind of sailboat you're on.
I've sailed Norfolk Broads yachts and they're pretty stable, quite wide so don't lean much and the rig is optimised for that style of sailing.
Modern racing yachts are designed for high speed over comfort so lean, unless you sail a catamaran for stability.
movieklump
movieklump - 5 years ago
That is why I sold my mono and bought a catamaran.
Michael Etzel
Michael Etzel - 5 years ago
+Rick Pelland It is fun, especially when the boat is leaning to one side! :D
RyanORourkelol
RyanORourkelol - 5 years ago
Square rigged boats have WAAAY more sailing ability than just downwind. Such ignorance.
bethells86
bethells86 - 5 years ago
Best analogy about how a boat sails when wind is forward of the beam is "squeezing the seed". The person in this video did mention this, not many know this, most think its only the lift, like aeroplane wings that move the boat.
bethells86
bethells86 - 5 years ago
The web has made many lazy :) Watch a movie called idiocracy, shows what happens to human race in a few decades from now, all dumbed down, its all part of A21 :)
All sailing boats use same principles to sail, Older ones would have used lots of ballast instead of deep keels.
fidan2fast
fidan2fast - 5 years ago
+bethells86 but small sport sail boats have large keels, but what about large sail ships with square sails? how do they keep balance and move forward? ...a stupid question because I'm lazy to do some research
Typh Vam
Typh Vam - 5 years ago
Correct me if I'm wrong, but I'm quite sure sailing against the wind with triangular sails is nothing new, been used for Millenia. Viking ships, and several mediterranian ones used those principles, albeit without a keel so I'm not entirely sure how those particular sails worked, but they did not work like the square sails where its merely pushed by the wind.

Also those square sails are needed in such huge ships, you cant quite easily correct weight by shifting passengers in a boat of that size.
ban jomi
ban jomi - 3 years ago
You don't have to have a keel to sail upwind, you just need a hull where the submerged part is capable of inducing the water to flow around it rathher than under it, ie. any reasonably deep hull.
PatDaBunnyLego
PatDaBunnyLego - 4 years ago
Vikings didnt use triangular sails, however in the mediterainian these did exist. Also vikings have been around for (a) millenia.
Colonel Barboskin
Colonel Barboskin - 5 years ago
You MUST have a keel to sail upwind. So those triangular sails didn't do any good (regarding sailing upwind) and in principle the same as square sails.
Harry Akira Eaton
Harry Akira Eaton - 5 years ago
Large sailing ships had a large amount of ballast in their lowest deck, acting the same as a yacht's keel.

Square sails do in fact work fine for going to windward, they're just a little less efficient at it than a small sailing yacht with Bermuda rig.
Gene Vickers
Gene Vickers - 5 years ago
It would be nice if they tried to teach something that actually has got to do with sailing. Im pretty sure i learned this in the second grade.
arbonac
arbonac - 5 years ago
Bernoulli's principle holds no water. If it did, then why can an airplane fly upside down.
arbonac
arbonac - 5 years ago
Have you never seen a small remote control on a paper airplane, they've been out for years.
fidan2fast
fidan2fast - 5 years ago
+arbonac a paper airplane glides, it doesnt fly, it just falls down with style
Jared Bryan
Jared Bryan - 5 years ago
+arbonac The same reason I mentioned before, they just increase the angle of attack of the wing. That will cause a larger area of low air pressure on the top of the wing, and high air pressure under... which creates lift. The typical aircraft wing shape does the same thing, but requires a lower angle of attack and has less drag... making it more efficient.
arbonac
arbonac - 5 years ago
Then why can a flat winged paper airplane fly?
fidan2fast
fidan2fast - 5 years ago
+arbonac because when you're upside down in an airplane, you move down with your elevator, which is up when upside down... if you fly upside down for too long, your plane will either move downwards in a loop like matter, or will stall if you apply the elevator too much... a plane can't fly upside down, it can only loop and roll which evolves a lot of inertia and air speed
Jared Bryan
Jared Bryan - 5 years ago
+arbonac they just change the pitch of the aircraft to create lift... using the same principle
storybored
storybored - 5 years ago
I live near the water in Florida. While watching sloops, I notice that when one sail in play, some favor the jib, others the mainsail, often in the same conditions. Why?
Donald Merrell
Donald Merrell - 5 years ago
+storybored The mainsail will try to push the stern around whereas the jib does not. Kind of like rear wheel drive vs front wheel drive.
Mattshu
Mattshu - 5 years ago
3:12 was he trying to make it look like his lightswitch was voice activated?
Mattshu
Mattshu - 5 years ago
+Mohamed Saleh not much of a warning haha but makes sense. thanks
Mohamed Saleh
Mohamed Saleh - 5 years ago
He was letting everyone in the lab know that the lights were about to go out. Its like when a chef calls out "hot pan" as they walk from one side of the kitchen to another with a hot pan. Its just warning so no one gets hurt.
Yo Shi
Yo Shi - 5 years ago
I expected it to be a sailboat flying and moving underwater like a submarine.
Science Cat
Science Cat - 5 years ago
Haven't seen it in the comments yet, but square riggers were NOT parachutes. Using the braces, they caught the wind just like the Bermuda rig. The ship was "square rigged" to build a much larger virtual wing. SV Peking's mast stood 170 feet. It wouldn't be until the advent of carbon fiber that triangular masts would approach that size.
Rusty Shackleford
Rusty Shackleford - 5 years ago
The laws of physics are so perfect... almost like they were... designed by someone...
DO U KNOW DA WAE?
DO U KNOW DA WAE? - 3 years ago
God.
ANDREW SCOTT
ANDREW SCOTT - 3 years ago
The laws of physics can not be perfect. However! Sails, which use physics to move, can be perfected. There is no god you imbecile.
Stu Rocks
Stu Rocks - 3 years ago
Marketing guys
Dangerous Don
Dangerous Don - 3 years ago
god was designed by the same people that put a talking donkey in the bible.
Vilo Conshmillo
Vilo Conshmillo - 3 years ago
Yeah. Maybe it was designed by a stick on a dick. Isn't that amazing.
Tomato Lemon
Tomato Lemon - 3 years ago
Almost as if... human design is based on and dependent on practical function thus causing people to project their view of design on the naturally occurring, original phenomena?
Jack Lewis
Jack Lewis - 4 years ago
@Matthew Holevinski This is what people who believe in the God of the Bible have always understood. That there's a perfect, infallible, driving force behind all forces that always was and will be.

'I am that I am'.

Existing out of necessity.

We always try to image a chicken/egg scenario because that's our experience of life. But what if rather than there originally being nothing, there was originally something - originally life rather than non-existence?
It had to be one of the two, and we're here! Which makes more sense?

Put nothing in a vacuum and leave nothing there for 100 quadragintillion**999 years - What will you find when you open it?
A universe??
If you do, something was put in there.

Now imagine existence in the abstract sense. Why would that need to come from anything? That's an oxymoron.
If there's existence; there was always existence.
Jack Lewis
Jack Lewis - 4 years ago
Andrew McKay 'Science designed physics, derp'.
Matthew Holevinski
Matthew Holevinski - 4 years ago
all physics no matter their forces, no matter their values, no matter their interactions, will always be perfect, because they just fucking are.
EpicFishFingers
EpicFishFingers - 4 years ago
So who designed that someone? something even more perfect?
Alex A
Alex A - 4 years ago
Please do not ever comment something as stupid as this ever again
PrimalMiltos
PrimalMiltos - 4 years ago
Rusty Shackleford - And who designed that someone?
nicougrikify Pelletier
nicougrikify Pelletier - 4 years ago
Nothing ever designed by someone has ever been as perfect as the laws of nature/physics. So no, its almost impossible for someone to have designed something so "perfect".
J W
J W - 5 years ago
how subtly religious.
Vasto Lorde
Vasto Lorde - 5 years ago
+bethells86 hahaha well, whatever floats your boat XD
bethells86
bethells86 - 5 years ago
Sorry bud, when you trimming sails to get that fraction of a knot you have to over think this :)
Vasto Lorde
Vasto Lorde - 5 years ago
Don't over think it.... just go with it.
Policarp
Policarp - 5 years ago
+bethells86 yep, it's funny when people see something amazing in creation and then say "wow Science is amazing", but it's incredible that they don't think about the fact that science isn't a creative force but a discovering process. If I discover a good song that really moves me, I don't say " Wow, I'm amazing" because I merely discovered what wasn't crested by me.
bethells86
bethells86 - 5 years ago
+Policarp Exactly!!
Policarp
Policarp - 5 years ago
+bethells86 Science is "how humans interpret" things around them. :)
bethells86
bethells86 - 5 years ago
+Rusty Shackleford Science and laws of physics is how humans interpret things that happen naturally. Sailing has been around for thousands of years in South of India and the Pacific, no science or physics developed it. It was discovered and then explained through physics by curious beings called humans :)
Policarp
Policarp - 5 years ago
they are perfect. kind of like DNA...
Policarp
Policarp - 5 years ago
+Andrew McKay science discovers not designs.
Andrew McKay
Andrew McKay - 5 years ago
Yeah bro science
no coat
no coat - 5 years ago
8:12 Spoiled brat has time to sail when most of us are trying to stay off the street and get the rent paid. I hate these extreme sailors. Technology has changed. Go help someone with your free time
filterz on
filterz on - 5 years ago
cool spinnaker pants 1:32
Sailing Miss Lone Star
Sailing Miss Lone Star - 5 years ago
Great video! We are selling our power boat and switching to sail later next year. We are currently cruising the Caribbean and I always love catching up with your channel! https://youtu.be/-QpAMvKhFzU
Nicholas Littlejohn
Nicholas Littlejohn - 4 years ago
Sailing Miss Lone Star sailing is a lot cooler indeed
John Rogan
John Rogan - 5 years ago
blowing over the top of a sheet of paper lifted it up...good demo.
Ramesh Buch
Ramesh Buch - 5 years ago
the film perpetuates an error about how sails work. They are NOTHING like airplane wings. It is the thickness of the leading edge of a wing, curved on top and flat below that gives rise to pressure differentials and therefore lift. Sails are uniform and essentially thin sheets. Don't be fooled by the curve of the sail. Any sailor knows a sail has ticklers (or tell-tales) set a few inches in from the leading edge. A sail trimmer looks though a clear window in the sail at the lee tickler and at the windward tickler facing him and trims the sail till both lay flat and streaming aft. This means the wind travels the same speed and distance from front to back. So no pressure differential. What makes a modern sail work is that the sail forces the wind to change direction from the angle over the bow, to along the boom to astern. A change in directions results in two force vectors at 90 degrees to each other: one forward over the bow, and the other over the lee side. The resultant vector moves between them depending on the trim of the sail. The forward force drives the boat forward, the side force heals it over, and makes the boat move slightly sideways (both are counteracted by the heavy and board keel).
James Romano
James Romano - 6 years ago
BOLTH
Moon Sims
Moon Sims - 6 years ago
This documentary completely misses the mark:  It's the KEEL, not the sail, that allows "modern" sailboats (invented at least as early as the 14th century AD) to sail into the wind.  Square riggers' best performance is when the window is off the beam or a little forward of it, not off the stern, so the idea that they could sail only downwind again shows a lack of understanding of the physics they are supposedly talking about as well as the history of sailing.The deep keel is made possible by two key factors:  (1) smaller boats with smaller cargoes after the introduction of steam, and (2) stronger materials for masts, spars, and hulls.  The key advantage of the triangular "modern" sail is that it can be handled by a much smaller crew.
John Rogan
John Rogan - 5 years ago
+Moon Sims centerboards are useless when sailing with the wind.
Dan DCC91
Dan DCC91 - 6 years ago
I'm kind of baffled by the intro, "before there were airplanes, before there were trains, there were sailboats." I mean, yeah, it is not wrong, but why not "before there were internal combustion ships, before there were steamboats?" This is like saying, "before there were pencils, before there were teapots, there were shoes." Yeah, you are not wrong, but I still question your thought process.
Jamie B
Jamie B - 3 years ago
It's to show how old and historic they are...
John Paterson
John Paterson - 3 years ago
it all falls under the category of transportation maybe you fucking weirdo
Tyler Hill
Tyler Hill - 4 years ago
Dan DCC91 yea I agree that's so true
Austin
Austin - 4 years ago
+Dan DCC91 HAHAHAHAH this comment is absolutely fucking brilliant.
Daniel Lame
Daniel Lame - 4 years ago
Really disappointed to see nobody got why there was a plane to sail comparison although this comment was made a year ago. They both ran on aerodynamics, and the physics behind the airflow is supposedly similar. Combustion ships don't need to care about aerodynamics. She kept repeating terms like "wing" and "sail" just so that the reference could be seen, but nobody understood. Nothing to do with popularity of travel.
Dan DCC91
Dan DCC91 - 4 years ago
+Ross Olinger In a nutshell anyway.
Dan DCC91
Dan DCC91 - 4 years ago
+Ross Olinger Except, nothing on that list replaced another thing on the list. Airplanes replaced sailing(I am talking about shipping in general, not just sailboats) as the fastest means of travel, but it's hardly the most efficient. Why do you think express packages are so expensive? Most of world's goods are transported by ships, trains and cargo trucks. They each have advantages and disadvantages, and none on the list replaced another on the list.

As far as the modern world goes:
Airplanes: Quickest without equal. Can only land in aiports. Logistics heavy mode of transportation and therefore, most expensive.
Trains: Inexpensive and fast, but limited to where the rails go.
Cars: Relatively fast and can go anywhere the roads are(or in extreme cases, are not), but heavily affected by traffic and weather conditions and is more expensive than trains.
Ships: Most inexpensive for intercontinental transportation of lots of goods, can go anywhere the water is deep enough. Limited to the waters, slowest transportation on the list.
Ross Olinger
Ross Olinger - 4 years ago
Hey man, they are highly correlated because they are methods of popular travel. Airplanes replace sailing as the most effecient, effective, fastest means of travel. Before any of that, the most effecient, effective, fastest means of travel was sailing. They were faster than any going land vessel at that time on average.
Dan DCC91
Dan DCC91 - 4 years ago
+Carlos T Both sailboats and tea pots are things. Checkmate. King me.
John Rogan
John Rogan - 4 years ago
well said carlos!
Carlos T
Carlos T - 4 years ago
Dan DCC91 sailboats and tea pots are completely different things. Atleast trains and planes are transportation devices..long before them sailboats were the means of crossing larges distances.. even inland depending on region.
John Rogan
John Rogan - 5 years ago
Here's a cough drop, sniffles!
Liarra Sniffles
Liarra Sniffles - 5 years ago
+Dan DCC91 I straight up blocked them; they are some old crazy american dude going on about NASA-NAZI's.

No clue what he is on.
Dan DCC91
Dan DCC91 - 5 years ago
+John Rogan what the hell are you talking about?
John Rogan
John Rogan - 5 years ago
The candle was right for 1840...the rocket engine was right for 1970...we need to move on to nuclear or electro magnetic...the metal ships might not work in high radiation areas....the human race will never leave Earth with the current NASANAZI administration...they are anachronisms!
Liarra Sniffles
Liarra Sniffles - 5 years ago
+Dan DCC91 It's related more than your examples because they were all mass transit methods.
John Rogan
John Rogan - 5 years ago
+Dan DCC91 ...your dealing with nasanazi...like talking to a group of bankers about baseball.
kevlar20
kevlar20 - 6 years ago
Someone please explain: how the heck is it anything like "squeezing a watermelon seed between your fingers" and it shoots out. with the water melon seed the reason it shoots out is because of the wedge shape on each side. How is that anything like a sailboat? The way i picture the sailboat sail v.s keel (two opposite forces) would be like pushing down on both bicycle pedals at the same time. the force just balances out....the boat should just sit there. where does the forward force come from?
John Rogan
John Rogan - 5 years ago
the wind provides an equal and opposite force to the sails...the keel provides stability...geez louise.....all NASANAZI candidates!
Fwq Kaw
Fwq Kaw - 5 years ago
+kevlar20 You're right, the force of the water is sideways and back and the force of the sails is sideways and forwards relative to the centre line of the boat. At a steady speed all those forces cancel out. Unfortunately the vectors of buoyancy and gravity and the pitch, roll and yaw couples never seem to agree with each other or most peoples stomachs. Now the physics of projectile vomiting, the rainbow ellipse, well, that's something else. Go, Isaac.
John Rogan
John Rogan - 5 years ago
+kevlar20 the wind!
spathr
spathr - 5 years ago
+kevlar20 The keel really only wants to go straight. The rudder however must exert what can be thought of as a forward force because it must counter the force of the sail but in the opposite direction across a sagital plane bisecting the boat. Without this counter-steer a sail boat rotates itself into the wind and goes nowhere. That is why when things get too hairy or a dangerous wind gust hits, you can just let go of the rudder and the boat will "turn and stall". Just watch out for the boom whpiping back and forth!
kevlar20
kevlar20 - 5 years ago
what component is in the forward direction? The air being scooped and shot off the back edge of the sail? that would explain the sail. how is the force of the keel in a forward direction?
spathr
spathr - 5 years ago
+kevlar20 A vector component of each of the two forces is in the forward direction. These two add while the remaining vectors (sideways components) act against each other and therefore subtract. A physicist would actually say they add but with a positive and negative magnitude.

100. comment for The Physics of Sailing - KQED QUEST

Juan Pablo Ramirez
Juan Pablo Ramirez - 6 years ago
ytff
Ako si Wokkawokka
Ako si Wokkawokka - 6 years ago
plus their explanation of "Keel Force" is wrong ... keel simply keeps gravity going down to stabilize the vessel. The Keel does not provide any moving 'Force' whatsoever,... its simply a stabilizing vertical force to the vessel .....
Ako si Wokkawokka
Ako si Wokkawokka - 6 years ago
new generation has lost all common sense ... this all is simplistic physics that should be understood by anyone past 5th grade...
T Smtih
T Smtih - 6 years ago
Me mom
TitanConceptss
TitanConceptss - 6 years ago
I learned nothing from this
Observ45er
Observ45er - 6 years ago
+TitanConceptss   If you are into the physics of things...For those interested, much more detail, An EXCELLENT sail boat explanation site:
http://www.real-world-physics-problems.com/physics-of-sailing.html
trisailor33
trisailor33 - 6 years ago
Sailing into the wind can be demonstrated with a slippery wedge on a table top. No elaborate lift theory necessary. And my first sailboat had a "keel" (a daggerboard) made of a sheet of plywood. No lift there either. A 12 year old can learn to sail very efficiently without knowing anything about fluid dynamics or even physics. Sailing is fun and pretty easy (Though winning races is not). Just start on a very small boat so that you can instantly feel the effects of your adjustments and you'll have loads of fun while learning.
Observ45er
Observ45er - 6 years ago
+trisailor33   Yup.  There are good analogies and the wedge is one.  As the NASA guys said in the video, the sailor doesn't need the physics detail (just as a airplane pilot doesn't).  You only need the practical knowledge of how to trim the boat, but some folks like tha kind of detail stuff....And BTW, a flat plate does generate lift.  That's how paper, or small balsa toy airplanes fly.   We fly them just fine with no thought of physics.  The problem is that the rtur physics has some detail that takes more to explain and many don't care about that detail.  Unfortunately, many who *do* try their best to explain it with a limited background in the physics don't get it correct.  The true detailed physics of a flat plate is actually the same basic phenomenon as any other wing, sail, daggerboard, or keel....that is, the true physics not the common misconceptions. ...Even if you have the wrong understanding of the physics you can still sail (and fly) well knowing the practical stuff.
MyTube6444
MyTube6444 - 6 years ago
Lol high definition is 360p!
Martin Hatchuel
Martin Hatchuel - 6 years ago
Nice! Thank you
Jon
Jon - 6 years ago
That's all very interesting except that it's wrong. The paper blowing trick has nothing to do with the forces you're dealing with. It is the same thing they use to show us when describing how airplane wings generate lift, which is also wrong.
The wing and the sail simply divert air in the opposite direction and then Newton's third law takes over.
AK FOX
AK FOX - 6 years ago
+Jon Blake
Jon, you need to read more carefully, I didn't say I believe Bernoulli accounts for all the lift, I said I believe it's a combination of that and Newtons, meaning the air is also flowing down and being pushed down depending on the angle of the wing or sail and that also contributes. That is why an airplane can fly upside down and also have symmetrical wings (Newtons Law).  Symmetrical wings would obviously just take advantage of the downward force of the air and have no advantage of the pressure differential of Bernoulli. But if you look it up, wings that are cambered have advantages such as lower stall speeds etc.
Jon
Jon - 6 years ago
+AK FOX
Bernoulli is not strong enough to produce the lift, besides, how do you account for the fact that some airplanes have symmetrical wings? Shouldn't the curved surfaces cancel each other out and produce no lift at all?
AK FOX
AK FOX - 6 years ago
+Jon Blake John, you're looking at only one side of the entire piece. It has been debated for yeas how much of the lift is from Newtons Third law (equal and opposite) and how much is from Bernoulli and pressure differential. In the end, depending on the situation both seem to contribute. Not sure where you got your information.
Jeff Wulf
Jeff Wulf - 6 years ago
Dynamical?
Norm Rubin
Norm Rubin - 6 years ago
I'm disappointed by the fuzzy physics and the perpetuation of a series of myths kept alive by High School teachers who feel the need to oversimplify Bernoulli to explain lift. And total confusion between a sail that STALLS and a sail that LUFFS! They are not the same, they are essentially opposites. A sail presented to the wind at too close an angle becomes like a flag. That's call LUFFing. A sail presented to the wind at too great an angle loses the laminar flow of air around both sides (especially the "outside"), loses its lift, and STALLS.
It's funny to see the "water tunnel" demonstration of High School Bernoulli, because it demonstrates that the simplified theory is nonsense! The simplified theory says that the two flows -- over the straight side and the curved side of the old-fashioned asymmetrical airfoil -- arrive at the trailing edge simultaneously, predicting the higher speed over the curved side. In real life -- and in the underwater demo in the video -- that doesn't happen. And in real life, symmetrical airfoils work just fine, thanks, and airplanes fly upside-down pretty well, too! Disappointing presentation of "science"!
Fortunately, Newton's laws of motion facilitate a simple AND accurate explanation of lift, including symmetrical foils and inverted flight. Why not find some physicists who can talk about THAT on camera?
And finally, the famous curved piece of paper has NO flow over its bottom side, so it only proves that there is a pressure drop with increased flow, not that we need asymmetrically curved wings to get airborne.
Shame on KQED for this! Fortunately, the Internet has a number of accurate explanations of BOTH how airplines REALLY fly AND how sailboats sail. But not here.
Agent00F
Agent00F - 3 years ago
Simplifying the theory down to Bernoulli explains the less intuitive component of aero forces. The other more straightforward component is the drag force mentioned in the first part of the video. Planes and sails work via the addition of both forces. For example, an upside down plane still works because the upward angle of attack (ie upwards drag) overcomes the downward Bernoulli. Not terribly efficient in that configuration, which is why plane wings aren't designed that way.

As such, the video is perfectly fine for an intro to the topic. It would help when criticizing these pop sci videos to have some basic understanding of the subject yourself.
Robert Brandywine
Robert Brandywine - 3 years ago
How do airplanes fly upside down without falling all the time?
Wade Patton
Wade Patton - 4 years ago
I basically taught myself on a 23' sloop (many years back). So much for theories...point A-B getter dunn! But I don't recommend that method.
Fwq Kaw
Fwq Kaw - 5 years ago
+Dan Alex good read here if you like that sort of thing http://www.av8n.com/how/
Dan Alex
Dan Alex - 5 years ago
+Observ45er Thank you . You have provided me some really great information and it has given me a great deal of insight in the subject .
John Rogan
John Rogan - 5 years ago
+Norm Rubin NASANAZI uses water tanks to explain and demonstrate "space walking"....you can see the level of intelligence at Ames would never get man to the moon or mars...fuzzy math and fuzzy physics!
AK FOX
AK FOX - 6 years ago
+Observ45er What I meant is in the grand scheme of things sometimes even the best explanations of what causes something or explains something can change over time. For example the beginning of the universe being explained by so many different theories over the years, each one being then disproved by another down the road. I know that overall Bernoulli's principle and Newtons law have been thoroughly tested and have held up over time. Either way what we come up with to explain the naturally occurring phenomenon around us are just ways for us to better understand them.
Observ45er
Observ45er - 6 years ago
+AK FOX  AK,
This is simply not corrrect: "best scientists in the world never nail it down perfectly." 
...
Many amateurs debate it.  The pros I have consulted with and read only differ on small details and sometimes on emphasis, but the major phenomena are similarly very well understood by the folks in the business.

... See my other lengthy post to you and Jon
AK FOX
AK FOX - 6 years ago
+Norm Rubin You guys are taking the explanations way too seriously. I don't mean that to sound rude or diminishing of the effort you've both obviously put into researching the subjects, but you do realize that even the best scientists in the world never nail it down perfectly. They may claim they do, but then a few years later something is updated or changed or disproved. The bottom line is that to most people Bernoulli principle makes sense as a an accelerated fluid (air, water) resulting in a lower pressure area. This is how it was taught to me in College Physics and how I was taught it when learning to fly. Also, Newtons THIRD LAW also makes sense to go along with and work with the accelerated airflow by causing an equal and opposite reaction to the air being pushed down (airplane wing) or the air pushing the sail (drag) , contributing to the "lift" portion of the sail. Yes, this a semi simple explanation but it's the practical one that can be seen and demonstrated.
Observ45er
Observ45er - 6 years ago
+Norm Rubin     Hi Norm,
The 61 lines I see is what I posted.  There was a glitch and I re posted it, then deleted a short portion that was the error.
...
I understand and I see you have fallen prey to the many amateur discussions.
 No, the pressure difference on the wing or sail IS the lift and causes the heel.  Think carefully about it.  In air (or any fluid) the only thing you have at your disposal to create a force is the fluid itself and the only way to get a force is by pressure differences. This must be understood first.  There can be no other cause for forces (except for more detail when explaining just how that pressure difference comes about). 
...
People (pros) who have actually MEASURED the pressures have proved this is lift.  People who tried to CALCULATE the pressure difference using long-standing bad assumptions got the wrong answer.   This proved their assumptions were in error, not the correct concept of lift.
...
   What Bernoulli revealed to us is that in a classical flow, say along a pipe (where no energy is either added or extracted), there is a relationship between velocity and pressure.  This is easily understood if you realize that a higher pressure region will push (accelerate) fluid toward a lower pressure region.   Fast air doesn't create the lower pressure; it is being pushed toward it by a higher pressure elsewhere.
...
Bernoulli's EQUATION only applies in a single stream, called a streamline.  He revealed that as a bit of air moves along A PATH, pressure differences ALONG THAT PATH affect its speed (velocity) IN THAT PATH as you would expect.  
...
The error comes when you extend that to the two DIFFERENT paths AND also assume that the air on both sides of the foil arrive at the trailing edge at the same time (the equal transit-time theory).  Using those two incorrect assumptions gives the wrong result  --  EVEN THOUGH there are videos on-line showing this method today! Sigh! Two wrong assumptions don't make a right.  In addition, the wing is indeed doing work on the fluid and, therefore adding energy...bad assumption abound.
...
IF you use the Bernoulli concepts correctly in CALCULATIONS you do get the correct result, but the math is complex and completely unnecessary for understanding the phenomena happening.
...
For sail boats, this is a darn good reference, though it doesn't get into the nitty-gritty of how pressures are changed:
http://www.real-world-physics-problems.com/physics-of-sailing.html 
...
.  If you want authoritative sources, try any one, or all of these for a good understanding.  While each author will emphasize different things or use slightly different ways to describe some things, the basic story is the same:
...
An example of someone who started by doing his homework:
Peter Eastwell - teacher 
 http://www.scienceeducationreview.com/open_access/eastwell-bernoulli.pdf 
...
Weltner in PDF - "Misinterpretations of Bernoulli's Law":
 http://user.uni-frankfurt.de/~weltner/Misinterpretations%20of%20Bernoullis%20Law%202011%20internet.pdf    
Weltner as a web page:
http://www-stud.rbi.informatik.uni-frankfurt.de/~plass/MIS/mis6.html  
...
Anderson & Eberhardt AAPT paper: The Newtonian Description of Lift of a Wing-Revised 2009:
  http://home.comcast.net/~clipper-108/Lift_AAPT.pdf   
...
NASA Glenn Research Center.  This is a series of pages you move through:
 http://www.grc.nasa.gov/WWW/k-12/airplane/wrong1.html  
...
Or, AllStar is another good source:
    http://www.allstar.fiu.edu/aero/airflylvl3.htm    
... 
If you prefer videos...
Video lecture explaining the Bernoulli Principle. If you understand Newton, you'll clearly understand Bernoiulli after this video.
Dr Holger Babinsky, Cambridge University Engineering Department
https://www.youtube.com/watch?v=XWdNEGr53Gw   
His missing slides HERE (Click the Download Icon for the complete set of slides):  
https://docs.google.com/file/d/0B0JABuFvb_G_MkpBZHJmRGo3UkU/edit?usp=sharing  
This is the 2003 article he mentions in the video:
http://www3.eng.cam.ac.uk/outreach/Project-resources/Senior-glider/howwingswork.pdf   
...
Doug McLean Boeing Technical Fellow, retired; gets rather esoteric later in the video, but starts simply for the most part. (I've talked with him):  Common Misconceptions in Aerodynamics.
https://www.youtube.com/watch?v=QKCK4lJLQHU   
For the "Newton" part of lift, watch the result of the pressure difference, in the GREEN VIDEO:
...  http://amasci.com/wing/lasrWing.gif     Quite impressive!
For the setup used to get that green video, watch part this 2 of 5  from 10:20 to 12:59
https://www.youtube.com/watch?v=H-qyrqxuH4Y 
...
David Bentley Australian Air Force Cadets:
  http://219sqn.aafc.org.au/Flight/Principles%20of%20Flight%20-%20web.pdf  
Dave Bentley shows slowing of upper air & other misconseptions:
  http://219sqn.aafc.org.au/Flight/Simple%20Aerodynamics-How%20planes%20fly.pdf  
Dave Bentley Wings Don't Suck
  http://219sqn.aafc.org.au/Flight/Wings%20don't%20suck-How%20planes%20really%20fly.pdf   
--
Cheers, ScienceAdvisorSteve
http://www.challengerillinois.org/
Norm Rubin
Norm Rubin - 6 years ago
+Observ45er Sorry if I went too far, but maybe it'll be useful for somebody else. You had a much longer response here, then deleted most of it?


In that response, you attributed all the lift effect (and presumably the heeling effect, too) to the difference in pressure between the two sides of the sail. I've read that people who've measured those pressures found them significantly inadequate to explain the lift that's experienced -- e.g., the pressure difference between top and bottom of a plane's wing wouldn't suffice to keep the plane in the air. I haven't worked hard to reconcile every conflicting statement, and I've also taken "the Coanda effect" on faith.
Observ45er
Observ45er - 6 years ago
+Norm Rubin  OK Norm.  US Public Broadcasting is ok, but it also talks to a more general audience.   Wisconsin Public Radio does an even better job.
...
Now, I appologize.  You went much further after your Newton summary than I intended.  I wasn't looking for sailing instructions.
...
I was holding back the way I asked about your Newton explanation.  I understand lift well, but wanted to see how you framed it.
What you say is correct, but doesn't explain the pressure difference that causes the "lift" force in the first place, which, then causes the air to be "thrown" rearward.  That explanation is sort of backwards --- or "If "A" always causes "B" and we can see "B" happening, then "A" must be happening even though we can't see or explain why it is happening".  See what I mean?
 It says that since air is thrust rearward, there must be an equal and opposite force forward that is accompanying it, but doesn't explain what causes what (or even talks about the forward force in reality).  This, "what" is, of cource, the pressure difference that actually is the "lift" force that is transferred to the mast and movers the boat --- not the reward moving air as you know. 
That version of the "Newton Explanation" is only half the complete story of "HOW".
...
Your reference to Coanda is technically incorrect.  Many mistakenly call the effect Coanda for normal airflow over the convex side of a sail/wing, but Coanda Effect is reserved for the narrowly  defined effect seen by a high velocity jet, or sheet of air directed (forced) along one side of a curved surface (it is not defined [by Coanda himself] as any air moving past due to the ordinary motion of the surface through the air).  The normal airflow around a moving sail or wing is not the Coanda Effect proper, although it obviously occurs for similar reasons.  This is a common misconception, though I admit perhaps a bit of a nit to pick.
...
BTW it's Newton's THIRD Law (equal and opposite) that you refer to.
...
The web site posted in another comment
http://www.real-world-physics-problems.com/physics-of-sailing.html 
is excelent at describing all the sailboat forces, though it glosses over the fine detail of the cause of the pressure differences resulting in lift.  That's ok with me.  The vast majority of discussions/disagreements about what causes lift is only among amateurs...
I also have my own set of authoritative on-line sources and wanted to see if you have any others.
--
Cheers, ScienceAdvisorSteve
http://www.challengerillinois.org/
Norm Rubin
Norm Rubin - 6 years ago
+Observ45er US Public Broadcasting is often impressive. The only website I recall offhand that explains lift accurately is called something like How Airplanes REALLY Fly. But I have seen some that get lift right in the context of sailboats. There was a Q&A on one of the Q&A sites (Quora?) that asked something like "How could I explain upwind sailing to a scientifically literate friend?" A bunch of us responded and engaged in a useful discussion too. (That was my first introduction to the fact that a wind-turbine-driven-propeller boat can sail straight upwind!)
The simple Newtonian explanation of lift involves his 2nd Law of Motion: For every action there's an equal and opposite reaction. So, in order to push a sailboat forwards, the sails have to "throw" an equivalent amount of air backwards. Specifically (and way more complex than necessarily), the forward momentum (mv) imparted to the boat equals the net (resultant) momentum (mv) imparted to the air that's deflected "aft".
And an airplane wing has to deflect enough air DOWN to hold the airplane UP. And a centerboard or keel has to deflect enough water to leeward (downwind) to hold the boat on track, pushing to windward (upwind).
There is one semi-complex part of what a sail does, which invokes the Coanda effect. Basically, through that effect, a sail can not only deflect or "curve" the airflow that HITS the sail (on the INside of the sail's curvature), but it can also deflect or "curve" the airflow that MISSES the sail and curves around the OUTside of the curve.
When the sail is too in-line with the wind, we first lose the force from the inside of the curve as the sail transforms into a flag. That's luffing. When the sail is too perpendicular to the wind, we first lose the force from deflecting the wind along the OUTside of the curve, because the Coanda effect has limits, and the wind will not curve around a sail that's perpendicular to the wind. That's stalling, and it happens similarly with airplane wings, keels, centerboards, and rudders.
Both of those airflows leave the leach (TE) of the sail at a much more "aft" or "rearwards" angle than they come at the luff (LE) of the sail. The resultant of that change in direction is partly sideways (downwind) and partly forward, and the keel or centerboard resolves that force into an effective forward force, and a sideways force that's mostly converted to heel (tipping). The forward force is conceptually identical (to Newton) to the forward force we'd get from throwing sandbags overboard, over the back of the boat. Except instead of throwing sand aft, we're throwing air aft.
The ratio of sideways force to forward force is not constant, but changes with the angle of the boat to the wind -- the Point of Sail. When cutting across the wind (Beam Reach), the sails are quite far out, so the sideways force is modest compared to the forward force.
When we sail upwind, we do several things that create bad effects (more heel and slower speed), in return for being able to point higher, i.e., closer to the wind. It's a compromise, trying to maximize our Velocity Made Good to Windward. E.g., we have to use a flatter sail shape than the high-power shape we use on a reach, and we trim in tight, with the boom more-or-less on the centerline. None of that is fast, but it lets most boats sail at a decent speed around 45 degrees off the true wind, which we couldn't do without those adjustments. And when we sail that way, the sails are probably pushing us sideways around 10 times harder than they're pushing us forwards -- but it's worth it.
Observ45er
Observ45er - 6 years ago
+Norm Rubin   Norm,   I agree it's quite weak and poor, but, hey!  It's US TV after all.   I'd be interested in a summary of how you use Newton.  I've probably heard them all, so a summary of the salient phenomena is enough.   
Also, which internet  sources you recommend.
--
Cheers
Sam Dandashli
Sam Dandashli - 6 years ago
This video is helpful. My understanding of sailing is much better now .Thankyou.
John Rogan
John Rogan - 5 years ago
+Sam Dandashli still look confused to me, sam.
Lachlan Dowell
Lachlan Dowell - 6 years ago
square rigged ships were perfectly capable of making headway against wind direction, sure they could not achieve an angle of attack anything like some modern yachts but to say that they could only travel in the direction of the wind is completely false, such a ship would be impossible to navigate
Andreas sUND
Andreas sUND - 6 years ago
6:46 - start by hoisting your sail properly...
Юрий Вихляев
Юрий Вихляев - 6 years ago
Ames scientists give wrong explanation of how lifting force works :)

Current accelerates because of low pressure on one side of the airfoil compared to other side, not vice versa. Pressure is set up by viscous force in a boundary layer. There is no lifting force in superfluids.
Observ45er
Observ45er - 6 years ago
+Юрий Вихляев Air accelerates because of pressure differences in the stream, not from one side of the sail to the other.
Pepe Tora
Pepe Tora - 6 years ago
Great Video! Sailing Fans should also watch the video "33 sailing tips & tricks" that contains a free sailing membership
hoshino
hoshino - 6 years ago
@ 5:51 "And bam..!" stfu. Use actual words.
ACAhmann
ACAhmann - 6 years ago
The emphasis that that's how "modern" sailing works is a bit stupid. Fore-and-aft rigs have been around for hundreds of years. Old vessels, even square riggers, could be fast and sail upwind. Replica tall ships have been know to outrun modern yachts fairly often.
ban jomi
ban jomi - 3 years ago
The Cornish lugger(twin lugsails, ie elongated square sails) could sail the keel of just about any other boat in its day.
ACAhmann
ACAhmann - 6 years ago
+GrandOldPuba

 +jolllyroger1 is correct. Now go find some real evidence to refute that, or even better spend a few hundred hours on both square rigger and a modern yacht and actually find out for yourself.
jolllyroger1
jolllyroger1 - 6 years ago
+GrandOldPuba lol obviously you know nothing of sailing and sailing ships .....
generally a modern sail boats main sail can be let out to approximately 45 degrees give or take a few....
a square rigger can generally turn it's sails 45 degrees give or take .... now back when the Nina pinta and Santa Maria came to America those had round tub like hulls and we're literally some of the worst ships available. ..... viking ships were long canoe like ships with square sails
in posting here a link to viking replica square sailers and if you have ender addled you will know that these are sailing up wind ... yes they are beating into the wind and are capable of what a fore aft rig is. ....
just imagine a Lug Sail..... it's square and it can point into the wind. .... any good sailor knows how to point with any rig.....
ACAhmann
ACAhmann - 6 years ago
+Tommy "Johny" Wiseau What, can't read more than four sentences? Words too long? I can give you a dumbed down version if you're interested.
Tommy
Tommy "Johny" Wiseau - 6 years ago
+ACAhmann r u high
ACAhmann
ACAhmann - 6 years ago
And I should mention, no need to distinguish between modern sailing and historic sailing in that context. On a fore-and-aft rigged vessel from 2015 (excluding solid wing sails) the sails still work literally exactly the same as the sails on a fore-and-aft rigged vessel from 1890. Or 1800. The only thing that's changed is the equipment, material, and the loss of the gaff in some cases. Again, I'm experienced sailing modern and traditional craft.
ACAhmann
ACAhmann - 6 years ago
+GrandOldPuba I'm sorry but you're relying on trite misconceptions. I've been on a square rigger making headway upwind many dozens of times. Not as much headway as something fore-and-aft rigged but it's enough to make it upwind. The quoted number is about 66 degrees off the wind, but a good tops'l schooner or virginia-built brig or hermaphrodite brig (or something of the sort) could probably make more like 50-55 degrees if well-handled. The hulls on most of these vessels were deep enough to provide plenty of resistance to leeway. A squares'l will create an aerofoil, but not as efficiently as a fore-and-aft sail cut for the purpose of creating an efficient aerofoil.

 If you want verifiable examples of tall ships outrunning modern yachts, Pride of Baltimore I outran several racing yachts the first time she went out according to the crew that was onboard. It's very easy to believe given her hull, rig, and size if you're familiar with sailing vessels. The crew in the documentary Pride: Legacy of the Baltimore Clipper talk about that briefly. Another example is HMS Rose sailing into Boston shortly after her construction. That's mentioned in detail in an article written for a publication of the San Diego maritime museum written by her designer who was on board at the time. You''re welcome to go find it if you like, that's the verifiable stuff that comes to mind.

But it's quite easy to see how an authentic replica of a fast sailing tall ship like a Baltimore clipper can outrun a modern yacht in many conditions. Vessels like this were very sharp with massively powerful hulls and huge rigs. They're also over twice the size of your average modern sailing yacht. Add a decent breeze and you can outstrip an average yacht, even an average racing yacht, in a variety of conditions, especially when you have stronger breezes and rougher seas which favor bigger heavier boats. This stops applying, of course, with hardcore racing yachts like volvo 70s or anything that's on foils. This is coming from a student of naval architecture who races yachts inshore and offshore and an experienced tall ship sailor.
fukthegoog
fukthegoog - 6 years ago
500 years? I thought the Chinese were sailing 800 years or more?
RealityIsTheNow
RealityIsTheNow - 5 years ago
+fukthegoog its more like 5000 years. The egyptians were the first real sailors, I believe.
T Smtih
T Smtih - 6 years ago
+jakobion I made that comment did they really care about the markets about the poor?
jakobion
jakobion - 6 years ago
+fukthegoog This was released in 2008, then it was probably only 500 years. Inflation's a bitch
Henbot
Henbot - 6 years ago
really awesome vid had no idea
Hans Zarkov
Hans Zarkov - 6 years ago
I was confused as to why a keel would generate lift, but I think I understand now. The keel typically has a teardrop shape but the shape is symmetrical and the keel does not seem to be upturned into the oncoming water like an airplane wing needs to be. You have to have one or other. Either you have to have an asymmetrical wing so that fluid travels faster over one surface, or you have to upturn the wing. A keel leans in the water but its leading edge is not upturned. However, the reason the keel does generate lateral lift is due to the 'angle of attack' of the boat. A sailboat does not travel 'head on' through the water. It travels at a slightly skewed angle off center (think moving forward while the hull is turned slightly to port or starboard). It's this skewing that 'upturns' the keel wing and causes lift.
ZX Spectrum
ZX Spectrum - 6 years ago
+Cessna5296Q the bet force from the sail isnt forward its forward and off to one side. the keel prevents this crabbing motion and instead the boat leans over
Hans Zarkov
Hans Zarkov - 6 years ago
+Cessna5296Q I'm not sure which comment you are referring to.
Jason Knight
Jason Knight - 6 years ago
+Hans Zarkov that cant make sense. that means a boat would have to travel in one direction only and to turn around the keels airfoil would have to also be flipped.
ZX Spectrum
ZX Spectrum - 6 years ago
+decidiousrex "It doesn't add another vector, it simply cancels out anything but the desired one so that the only motion is in the forward/backward direction."

in order to cancel a force, and equal and opposite force must be applied. it does add another vector, which like you say is equal and opposite to any that arnt directly inline with its thin ends
jolllyroger1
jolllyroger1 - 6 years ago
Best explanation of a keel and rudder I can give you is this... Take an airplane slice the fuselage in half cutting vertically top to bottom split.... One wing in left one on right

Now let's take the left side turn it so the wing points straight down .... Now you will see the wing is the keel and the elevator is the rudder ..... Turn the rudder the keel changes angle making lift
Observ45er
Observ45er - 6 years ago
Warwick Wells
Warwick Wells - 6 years ago
Yes. I know all about it anyway as I sail my self :)
Ray Rothermel
Ray Rothermel - 6 years ago
+Warwick Wells Well of course. If you aren't moving you don't need a keel. 
Warwick Wells
Warwick Wells - 6 years ago
Depends on what your doing
Ray Rothermel
Ray Rothermel - 6 years ago
+Warwick Wells Without a keel, the boat would capsize.
Observ45er
Observ45er - 6 years ago
+Warwick Wells As NASA's Kurt Long and Steve Smith  say  in the video, most sailors don't need all the intricate details. They need the practical understanding of how to trim the boat.
...
However, some people want to understand just how "a keel keeps the boat moving the way the boat is going. and keeps the boat up right", that is, the detailed physics.
...
 Hans has the correct idea.
...
For those interested, much more detail, An EXCELLENT sail boat explanation site:
http://www.real-world-physics-problems.com/physics-of-sailing.html
--
Cheers
Warwick Wells
Warwick Wells - 6 years ago
basically forget all that and just think a keel keeps the boat moving the way the boat is going. and keeps the boat up right. with out a keel you would have no stearing.
Observ45er
Observ45er - 6 years ago
+Hans Zarkov Hans,
That Web Page has an excellent explanation of both the sail and keel, the drag components, the sideways motion of the keel *and* pointing out that the keel and sail forces are offset and produce the unavoidable torque-moment causing the tilt. 
I give it a A+  (;-) --
Cheers
Hopefully decidiousrex read it also.
decidiousrex
decidiousrex - 6 years ago
+Hans Zarkov Yeah, I guess it's a kind of weird thing to call lift, though yes it technically is, but it's still just the keel resisting sideways motion.
Hans Zarkov
Hans Zarkov - 6 years ago
+decidiousrex Nearly all keels, dagger boards and centerboards do generate lateral lift, not because they have exotic designs but because a sailboat's hull travels though the water at a slight angle off center. See: Physics of Sailing
http://www.real-world-physics-problems.com/physics-of-sailing.html
decidiousrex
decidiousrex - 6 years ago
+Hans Zarkov Well, of course based on their design they might, but they don't need to. I'm sure there's benefits to it, but generally any design which would incorporate lift will inevitably have some degree of drag, which in water is BAD. Very bad. Hence most keels are as thin and simple as possible.
Hans Zarkov
Hans Zarkov - 6 years ago
+decidiousrex  Keels, dagger boards and centerboards actually do generate lift. But I agree that the lift they generate is fairly insignificant and their main purpose is to stop the boat from sliding laterally. I've sailed dagger board boats without the dagger board. It can be a bit squirrely but it's still doable.
decidiousrex
decidiousrex - 6 years ago
No. Not really.
But it's not you misunderstanding, it's that their description of the keel is very misleading. A keel's purpose is less to generate force and more to ensure unidirectional movement. Think of it this way, go grab a credit card, driver's license, library card, etc, and fill up a sink with water. Slide the card through it so that the skinny part is "cutting" through the water. Moves pretty easy right? Now try to move it side-to-side. Doesn't work so well. It takes a much greater force to do it. That's the principle of a keel. It doesn't add another vector, it simply cancels out anything but the desired one so that the only motion is in the forward/backward direction.
Without a keel a sailboat would still go forward, only you will notice the boat will also shift and hop sideways, which is bad for navigation and the boat and also is incredibly dangerous.
quest 34470
quest 34470 - 6 years ago
EPIC....THANKS.
jjn 123
jjn 123 - 6 years ago
Square riggers can go at about 210-240 degrees from the wind (but couldn't as fast at that angle) and can tack over it, however a square rigged ship in the form of a frigate could sometimes outrun sloops 1/50 of the size due to square rig being better at holding air at 0-60 degrees of the winds direction...

... lets put it this way, modern sails would never give enough wind to a Man O War...
Kars Keizer
Kars Keizer - 6 years ago
modern sailboats have it only? look at the old Dutch boats, we use it already for age's
Zane Gifford
Zane Gifford - 6 years ago
"produced in high definition" only plays in 360p
KJ Aitken
KJ Aitken - 6 years ago
I'm a major sailor. I know a lot about sailing and have been doing it for some time... when I first watched this video it made me laugh.
SuburbAllied
SuburbAllied - 7 years ago
7:47 watch the two sailboats and the motorboat, above the sailboat with the red sail - almost a bonus clip with a sail disaster, and a lesion by itself; How to NOT maneuver a boat in crowded situations.  
SuburbAllied
SuburbAllied - 6 years ago
+Gregory Simmons
yea, thats probably it
Tommy
Tommy "Johny" Wiseau - 6 years ago
+SuburbAllied


was likely a race committee motor boat, a start line, and boats starting. when there's racing, boats easily come within a foot of one another.
Sugarsail1
Sugarsail1 - 7 years ago
a luffing sail and a stall on an airplane wing are not aerodynamically equivalent.
Sergio.J.V.
Sergio.J.V. - 7 years ago
Lift (in sails as in wings) is generated according to Newton's 3rd: http://www.grc.nasa.gov/WWW/k-12/airplane/lift1.html
Levi Partridge
Levi Partridge - 7 years ago
lol lucky you're doing it somewhere warm and not somewhere freezing like Hamworthy (Poole, UK)
SirLobsterman
SirLobsterman - 7 years ago
it's simpler to just figure out a workable route and let the sail dictate the angle of approach, turn away from the wind until the sail starts catching and let the wind push/pull you along. always look to your sail for information, it'll tell you how it wants to work.
David Galamov
David Galamov - 7 years ago
the most idiotic video ive ever seen!(from the eyes of a sailor).
Kronstadt Sailor
Kronstadt Sailor - 7 years ago
SQUARE RIGGERS CAN SAIL TO 90 DEGREEZ FROM FROM DA WIND
Robert
Robert - 7 years ago
Or you can just say that the shape of the haul and centerboard keeps it from drifting sideways...
Ali Nazari
Ali Nazari - 7 years ago
Fantastic
Gilbert Pilz
Gilbert Pilz - 7 years ago
Hard to take this seriously when the first thing they say is completely wrong. Square-rigged ships can most certainly sail into the wind. It's true that they can't lie as close to the wind as a fore-and-aft rigged ship, but they can tack.There's no way Magellan, Drake etc. could have made it around the world in ships that only sailed with the wind. Getting around Cape Horn from east to west is impossible if you can't sail your ship into the wind.
ppplll000999
ppplll000999 - 6 years ago
I think the reason is , under the force of wind, a square shape sail would attain a small degree of FOIL FORM. The wind hitting the leading edge of the square sail would be decelerated along the sail & exit the sail at a lesser force, & hence creating a foil form, I think.
Disabler
Disabler - 7 years ago
Scientists are terrible at explaining things lol
Truth Teller
Truth Teller - 6 years ago
+ppplll000999
That is an excellent point.  It's all the more reason why good tech writers are important. 

Engineers and most programmers DO understand how things work.  So much so that it is nearly incomprehensible to them that there are people who do not.   
Truth Teller
Truth Teller - 7 years ago
That's why technical writing is such an important profession (I did that for 30 years)  Tech writers translate the things scientists, engineer, and programmers write into something the intended reader can understand.

Nothing at all wrong with being a scientist, engineer, or programmer.  Some of my best friends are.  Of course, I wouldn't want my sister to marry one  ;)
Truth Teller
Truth Teller - 7 years ago
That's why there are professional technical writers.  They translate what engineers and scientists say to language most people can understand.

Yes, I was a tech writer for 30 years when I wasn't teaching sailing.
animatem
animatem - 7 years ago
Anyone ever notice the "models" in these videos never use a "wing" shape that is only a few millimeters in thickness from front to back like real sails?  These demos use sails that are apparently made of cloth several feet thick on the luff.  The models also show the wing directly facing the wind, instead of properly trimmed.  The sail would be luffing horribly if it was trimmed like this video shows.  SERIOUSLY, watch this video again at 3:26 seconds.  The wind would push the sail cloth flat from front to back since it is only sail cloth!  There would be nothing to hold the curved shape against the forward wind.  
Ian Edmonds
Ian Edmonds - 7 years ago
That was fun.
Thanks
Antipodean33
Antipodean33 - 7 years ago
Checkout the wing sails on the America Cup cats, those are something else again
quosmo1
quosmo1 - 7 years ago
what about when a boat loses its keel (on a reef or some such), they still sail ... forwards! albeit less efficiently and somewhat dangerously, they still 'work' from a momentum perspective. their forward moment is still greater than the leeway, even without a keel.

this kind of 'lift' theory of aerodynamics has (in the past decade) been quite disputed in the field of aerodynamics anyway, as many experiments with airfoil (wing) designs which should not create any lift according to this theory - do!

so this is not the whole story. it may play a part (maybe even a large part) but its not a complete explanation of whats going on.
Mostly Vertical
Mostly Vertical - 7 years ago
Ian, lots of good comments here. you are correct - it depends a great deal on the boat design, and more particularly, the keel design. but let me make two somewhat specific and hopefully useful comments.
Comment One: if the keel of the boat in the video fell off, and the sailors wanted to move forward in any direction other than downwind, the more they tried to head in away direction other than downwind, the more trouble they would have in making in real forward progress. and that is because of something the video makers did not even talk about, which is that one of the main purposes of the keel is to counter act the force of the wind pushing the boat over. when you are headed up wind, as the wind meets the sails, the wind tends to push to boat over on its side (heeling), and that prevents two real problems. Problem 1: the keel keeps the wind from successfully knocking the boat over. sailboats do not move well if at all when knocked over. If you lost the keel, the wind would knock the boat over if you tried to go upwind. The wind would not knock the boat over if the boat only wanted to go downwind; the wind would just drag the boat downwind. Problem 2: the sail is most effective when the sail is perpendicular to face of the water, and less effective as the sail moves to a parallel position relative to the water. The keel helps to keep the mast vertical and the sails perpendicular to the face of the water. If the sails where parallel to the face of the water, the wind would tend to pull the mast down into the water, effectively pushing the boat over. So, both of these problems are avoided with the boat in this video having a keel, and if the keel was lost, the boat would instantly face these two problems, if they tried to go anywhere but downwind.

Comment Two: if the keel on the boat in this video was lost, the sailors still have a tool they can use to address the two problems pointed out in comment one: they can (try to) use the rudder. So, let's say the wind is blowing from the north, to the south, and the sailors are headed west. they are on what's called a "port tack", headed northwest, the wind is coming over the port (left) side of the boat. Suddenly, the bolts that hold the keel to the bottom of the boat fail, and the keel finds its way to the bottom of the bay. In a manner of seconds, the boat would first lean over to the right a great deal. This would make the rudder useless, and the design of this particular boat (and most modern sloopes) would make the bow of the boat going directly into the wind almost immediately, which would stop all forward motion of the boat at the same time. The rudder continues to be useless. The sails would instantly start flapping like they were possessed. Then the wind would start to push the boat backwards, and not too long after that the boat would start to "fall off" probably to the right (because it was previously on a port tack). As the boat continued to turn right, at some point, the sails would fill with air, stop flapping and the boat would move some combination of forward and to the right. As soon as water starts to flow over the rudder again, the rudder now can be used to steer the boat to the left and counteract the force of the wind pushing the boat to the right. Not very effectively, mind you, but it will work somewhat. Instead of heading northwest like the boat was doing with the keel, the boat could probably head somewhere between west and southwest without the keel. Tricky business here, because if you try to head back to the north, the excessive force on the rudder would tend to break its linkage. The sailors would be wise to forgo "tacking" (turning the front of the boat through the eye of the wind) and stick to "gybes" (turning the back of the boat through the eye of the wind).

If you want to have some real fun seeing how this works, take out a windsurfer (which does not have a rudder) and leave the dagger board up, and see how much you really can control the direction of a board just by altering the sail position relative to the wind. Before long you'll be saying, "Keels? Rudders? I don't need no stinking Keels and Rudders!" 

btw, my favorite boat to sail is my Prindle catamaran, that has no keel whatsoever, of any kind. on my boat, the rudders force the hulls to carve a track in the water in the direction I point them, which is most often at odds with the direction the sails want to push the boat. The only exception to this is when the boat is headed downwind; then the sails are dragging (not lifting) the boat and this whole vector thing becomes moot (I think). A concession here - I am pretty sure the hulls take on the role of producing these vector things that the keels produce, but that is physics beyond me.

Fair winds, and following seas!
Truth Teller
Truth Teller - 7 years ago
+Ian Edmonds
In those days, the central timber laid down to which all of the ribs and other parts were attached was called the keel.  It is from the term that the more modern wing-shaped keep got it's name.

The Dutch, having to sail very shallow waters, built boats with very broad and shallow hulls with a system of lee boards on each side that could be lowered and raised to fit conditions.  As these boats often had to travel through canals, often by towing, this worked very well for them. 
Ian Edmonds
Ian Edmonds - 7 years ago
+Truth Teller I guess that makes sense. You do see some of these older shaped keelboats where the hull and keel sort of blend in to each other so I guess in that case it's the hull providing the lateral resistance. 
Truth Teller
Truth Teller - 7 years ago
+Ian Edmonds
As a sailing instructor using lasers, I can verify what you say is true, especially with shallow hull boats like the laser. 

Larger boats with more  hull in the water, they can still be sailed although not as efficiently.  Keep in mind that , in the age of sail, very few boats had deep keels or dagger boards.  When they had 14 or 15 feet of hull in the water, they didn't need them.  No, they did not point as well as modern boats, but they still were sailed around the world.
quosmo1
quosmo1 - 7 years ago
+Ian Edmonds hi Ian, sure that may happen maybe it depends on the other characteristics of the boat design. Here is a discussion about a particular story of people who sailed (unbelievably without even knowing it!) without a keel for long journeys : http://www.sailnet.com/forums/general-discussion-sailing-related/70857-boat-lost-keel-no-one-noticed.html

not saying its the rule rather than the exception, just interesting how that would relate to the theory in this video.
Ian Edmonds
Ian Edmonds - 7 years ago
If you lose your keel you will either broach or just start slipping sideways.
We see this all the time when we land at the beach in our Laser 4000. The moment the daggerboard is taken out to land the boat only has the momentum to carry it where the bow is pointing. all further force from the sails is in the direction of the force of the wind. We almost always end up crabbing in for the last few meters. Without a dagger board or keel you can't balance the lift provided by the sails with the drag required to cancel out the sideforce and the boat goes sideways.
Luv and Peace.
welshpete12
welshpete12 - 7 years ago
As a sailor for a long time one thing I never understood . When beating to windward in a good blow . Why does the centre of effort more aft ?   
detonatorJE
detonatorJE - 7 years ago
Hey guys, just a note about why lift happens, this guy is chatting bull. Bernoullis law doesnt apply in the case of a wing (or sail). For his law to apply, certain assumptions must be made. firstly that the fluid has zero viscosity, but as we can see, the fluid 'sticks' to the shape of the wing, which is a viscous effect. secondly, that it is a steady flow. which as said in the video, it is not. Finally, Bernoullis theorem only applies to a single flow, once you talk about flows above and below a wing, its moot.

While Bernoullis can describe some of what is happening, the fundamental law behind lift is newtons 3rd. watch the flow as it comes off the wing, its at a different angle, meaning a force was imparted on the air by the wing, and thus vice versa

(im an aerospace engineering student and even people in the aero business get this wrong (including the most of the internet), and this isnt coming from me, this is coming from Dr Iain Dupere at Manchester University)
Iain Dupere
Iain Dupere - 7 years ago
+Kronstadt Sailor Wow that is a strong response.  Unfortunately it is also completely wrong.  Bernoulli himself would not subscribe to this. A few things to note:
1)  Bernoulli's equation is a description of the momentum equation under three very specific conditions: inviscid (all viscous forces are ignored), steady (i.e. time invariant) and incompressible (actually not too bad here although interestingly +Kronstadt Sailor  also comments that fluids are all slightly compressible).  In fact it is easily understood, if the only two forces acting on a fluid are pressure-area and gravity, then for the flow to accelerate it must either see a drop in pressure (i.e. it accelerates from high to low pressure) or a drop in height or both.  Far from causing low pressure with high speed, in fact the low pressure creates the high speed.

2)  Bernoulli's equation comes from consideration of a stream tube and so only applies along a streamline and not to more than one streamline.

Bernoulli then, definitely falls down in this application, on two counts (inviscid and more than one streamline (the flow either side of the sail is on two different streamlines).

Someone else refers to Potential flow and, in particular, the Kutta condition.  This is a common approximation, in which the flow is assumed inviscid apart from the generation of vorticity.  This is a fudge since Kelvin's law shows that vorticity cannot be created in inviscid, incompressible flow.  To have the same constant on either side of the sail requires uniform horizontal flow which has no vorticity.

All this leads to the well documented result that, in the event that Bernoull's equation is correctly applied to a wing (or sail) the actual lift will be zero!!

The Kutta condition does give a crude estimate of the lift (and was used before the days of CFD) and does give some indication of why the viscous effects are important in this case, however, Bernoulli does not strictly apply (the flow violates one of the conditions) and certainly is a poor explanation without some reference to the Kutta condition.  As pointed out, it is better to say that the flow leaving the sail follows the path of the sail due to a subtle but important viscous effect (this could also be described crudely Mathematically as Kutta's condition) and the turning of the flow gives rise to the lift force through Newton's second law (force causing a rate of change of momentum) and third law (equal and opposite reaction - flow is pushed in one direction by the sail causing a force on the sail in the opposite direction).

If +Kronstadt Sailor wishes to come along to the University of Manchester I will happily not only teach him this, but show him how this works.

PS Application of Multivariable calculus leads to zero lift! precisely because Bernoulli does not apply in the strict sense of the term to this case.
Sergio.J.V.
Kronstadt Sailor
Kronstadt Sailor - 7 years ago
Fluids are compressible to a slight extent.  
Sergio.J.V.
Sergio.J.V. - 7 years ago
+Kronstadt Sailor Don't be precipitated. The guy there above is half right. Newton's 3rd law actually explains the main forces in wings and sails (look at NASA's recent researchs). Bernoulli's principle "does" exist, but it's too weak; thats why in close-hauled the speed is very slow; much less if compared to air speed in plane's wings. There is more: https://en.wikipedia.org/wiki/Kutta%E2%80%93Joukowski_theorem. Also, one cannot test Bernoulli in fluids, because it supposes gas flow and pressure; in fluids (thus not compressible (not as much as air to this case)), you will be actually testing only Newton's 3rd. Even scientists have some outdated beliefs.
Kronstadt Sailor
Kronstadt Sailor - 7 years ago
Your professor is a fucking idiot. Do you understand the difference between engineering and science boy? Real physical phenomena don't look like your fucking textbooks. That's why you need a copy of Perry's Chemical Engineer's Handbook. The job of the engineer is to provide a best guess model. Of course Benoulli's principle applies here. You need to learn multivariable calculus and differential equations, and to break down a complex system into parts. It's just some egghead academic trying to be a smartass and impress the kids. When you pantywastes instituted the gun ban everything went to hell. With each successive generation you Brits get more and more feminized.
Ryan Rodgers
Ryan Rodgers - 7 years ago
Your model desperately l lacks sail trim.  Move your jib cars back and for the love of god, tighten your outhaul!
Mike Collins
Mike Collins - 7 years ago
"Square rigged ships only went in one basic direction - with the wind"  PARDON?!  Clearly, this statement is false.  What did they do if the wind changed, or if they had to return home against the trade winds?
In fact, square riggers, while not as efficient to wind as a modern sailing boat, could sail at a reasonably close angle to the wind.
Kyle Blank
Kyle Blank - 6 years ago
+Mike Collins Thank you for the information. An old-fashioned yacht I know of is called the Libava, just Google it.  
Mike Collins
Mike Collins - 6 years ago
+Kyle Blank
I know that they were building a galleon from authentic materials and techniques about 15 years ago in Rochefort on the French West coast.  It was quite well under way when I saw it, and all the frames were in place, with the bottom planking of the hull completed, and planking was progressing up the sides.  I would expect it to be finished by now, although I know they were having financial difficulties which may have slowed it down.
Oh - it is finished.  I just found ...
http://discover-poitou-charentes.com/what-to-see/visit-the-hermione-at-rochefort/

I think most "ancient" ships built these days are for film props, such as the bounty.
http://en.wikipedia.org/wiki/Bounty_%281960_ship%29
Kyle Blank
Kyle Blank - 6 years ago
+Alex Newman Was not trying to insult square-rigged ships if that is the impression you got. From my understanding though, the Mayflower was a ship that even for its time was slower because of the wind resistance the back part generated, which made it difficult to sail.  

As a side question, do you know of any good places to learn wooden shipbuilding (shipwright skills)? I am very interested in replicas of the classic sailing ships and wooden ships/yachts/boats based off of the old sailing vessels.
Alex Newman
Alex Newman - 6 years ago
Sorry, pilgrims have traveled on a square riggers but would you call your modern seafarer a pilgrim? Square rigged sailing vessels are, with the exception of oil tankers the most influential thing to the development to modern seafaring. As only the loss of masts, larger scale, different cargo and the introduction of engineers are really the only difference between them. Square rigs only ended their days as trading vessels after world war 2. After hundreds of years of development so saying that an aft castle (the high back part) makes them not very aerodynamic is comparing a cars speed to its wheel size when you were neglecting it's date and model. If I were to say that a carrack was not a vessel made for speed as it was beamy (wide) and made to haul the most amount amount of cargo across an ocean. So took a long time to cross the ocean. Not because they went into the wind but as with seafaring today we go the best way, while accounting for prevailing winds and currents at all times of year etc etc. which is all calculated and published for todays use. So back to the carrack they made use of the different latitudes as the Trade winds are Nor or Sou Easterly and the Westerlies are obvious enough. So they went to the necessary latitude and sailed across at that latitude as the wind prevailed in the direction they were going.

Moving on to a discussion I had recently about sailing yachts to sail trading vessels. Sailing yachts are efficient at using the wind available to a point but then you are comparing a sport car to a house mover the power to weight ratio is showing us that the sports car is as fast as possible and the house mover is moving as much as possible. When the house mover has more power so is less efficient. But again compare the date, the difference of technology, the difference of purpose of sailing vessels. As I have already stated, there are vessels, clippers being the favorite that are the high speed, high valve product carrier and sailing record holders for speed.
Modern naval architecture is a compromise of speed, stability, cost and how well it completes its purpose as well as exploiting every chance to make a vessel as efficient as possible through new technology. Today ships are slowing down and are carrying unthinkable masses of cargo.
To be honest the modern cargo ship and yacht should be able to look at a flying P-Liner and see that it is the pinnacle of human exploitation of modern physics and design. To move multi thousand tonne vessels at comparable speed to modern monohulls. Which is even more impressive when you think of the much greater winds they handled out at sea, a later period square rigged vessel will trump the top speed in the monohull class.
And if there is to be a mass scale of sailing cargo vessels again they well bear more resemblance to a Fly P than a yacht or cargo ship of today.

Not that any of this reply is necessary to this particular comment on this video as well as any offensive I might of given in expressing myself so righteously but I am proud of my career and its origins which I have as my hobby.
Kyle Blank
Kyle Blank - 6 years ago
The Pilgrims sailed on a ship into the wind which took them a long time to cross the ocean, as their ship had a high back part which made it not very aerodynamic either. It was a very difficult ship to sail into the wind. But nonetheless, they did it. On the return voyage of the ship, it was able to sail back far more quickly.

My understanding is that sailboats and ships of the Age of Sail were able to sail into the wind, but they were not efficient at it in the same way as modern sailboats designed with computers and modern physics can be.
Mike Collins
Mike Collins - 6 years ago
+Don Adamms
Well, I've contemplated my reply, and my assertion is still the same.  The exact wording in the video clip that I objected to was this ; "Square riggers [... did various things ...].  But these ships of old had their limitations.  They were slow, and they only went in one basic direction - with the wind"

These ships went to other countries, and came back again, not always by taking a different route home to make the best of the wind patterns, but frequently in both directions along the same route, such as from Europe around the Cape of Good Hope to Australia, then back the same way, so the statement that "they only went one way" is counter-intuitive.  More than that, however, it's wrong.  See the explanation by Alex Newman, who has first hand experience and knowledge of these boats, below.

BTW, you might care to reconsider your own assertion that I make you wish you had cancer.  Be careful what you wish for.  As one who does, I can tell you that it's no matter for glib comment.
Truth Teller
Truth Teller - 6 years ago
+Alex Newman
Exactly right and well explained, too.  :)
Alex Newman
Alex Newman - 7 years ago
Calling on my experience as a tophand on a tallship, squares are set in two ways, baggy and perpendicular to the wind when the wind is aft the beam this is the best time to sail these vessels, and on the slowness that the video states champion of the seas set a 130 year record of an average of 19 knot over 24 hours in 1854 that is just under the speed of the faster range of cargo ship today.
The second way to set squares is to achieve the airfoil like a modern sloop does but instead of haveing the mast as the leading edge of the sail they are projected out by the yards and then the luff (leading edge) is twerked (actual term for over tensioning a line) then the trailing edge is slacked a touch, this makes your wing shape. The major problem to going high upwind is the fact of the shrouds prevent the yards from achieving the same angle you can apply to a boom when closed hauled. 
On the 60' Brigintine I sail in we have got 8 knots at 35º off the wind in under 20 knots of wind
And 9 knots with 12 knot of wind while running, and for a cargo style sailing ship of it's size and at about 30 ton with less than 1000 sq. ft of sail.
Modern sailing is just using a simpler rig and boats designed for sailing not trading 
Jonathon Cowley
Jonathon Cowley - 7 years ago
Despite Don Adamms obnoxious response, square rigged ships were quite capable of sailing on a beam reach, and smaller brig rigged ships could even manage a close reach.  
Truth Teller
Truth Teller - 7 years ago
If you consider 70 degrees "close to the wind" they could.
Gilbert Pilz
Gilbert Pilz - 7 years ago
+Don Adamms I guess I wouldn't be as offended by the sheer ignorance of your comment if you didn't make it such a wildly offensive manner. Yes, a square-rigged ship's best point of sail is downwind. This made the trade winds useful for quickly crossing oceans. But people have been sailing into the wind in square rigged ships since at least the 12th century and probably well before that. Don't be such a putz.
Don Adamms
Don Adamms - 7 years ago
Ugh. Its people like you that make me wish I had cancer. I want you to think about your question, think about the phrase "trade winds", contemplate your question. Then get back to me
Christopher Koffel
Christopher Koffel - 7 years ago
1:52 I was dying that that jib sheet wasn't being pulled!
Ben Hamrick
Ben Hamrick - 4 years ago
OMG IK
Truth Teller
Truth Teller - 7 years ago
Me, too!   :)
John Wilson
John Wilson - 7 years ago
"A luffing sail is not the equivalent of stall on an aircraft", per minute 7:40, it would be an over-trimmed sail.
Tisc Sailing
Tisc Sailing - 7 years ago
And when I criticize an over-trimmed sail, I say it is STALLing (because it is). As John Wilson says, it is most definitely NOT LUFFing, quite the opposite. That statement is just embarrassing.
aidtry182
aidtry182 - 7 years ago
I've always been so fascinated on how sailing ship works!!
José Eric Estrada Rodríguez
José Eric Estrada Rodríguez - 7 years ago
Was produced in high definition "360" max...
Dobre Octavian
Dobre Octavian - 7 years ago
this video keeled me
ageliki moulos
ageliki moulos - 7 years ago
How do you guys (the sailing school) get away with completely inadequate safety equipment for students? And then comically prodcast it to the whole world via youtube. You should be closed down by the US authorities. Boyancy aids. are not suitable life savers for offshore yacht sailing!! Inshore dinghysailing with supervision maybe..........
Kronstadt Sailor
Kronstadt Sailor - 7 years ago
go back in the kitchen you sissy
Truth Teller
Truth Teller - 7 years ago
I saw students wearing USCG approved PFDs (personal flotation devices)  There are legal and good to wear in all conditions.  I personally have a USCG approved automatically inflating PFD the doubles as a safety harness.  ( SOSpenders) When doing deliveries, I would wear it any time I was on deck and stayed clipped in with a safety lanyard attached at all times.

When teaching sailing, the #1 rule I teach is "Stay on the boat."   That applies to everyone.  You cannot sail the boat, help others, or do much if you are not on the boat.

A piece if the book I wrote for students (So You Wanna Be A Sailor?)  is at:
http://www.boatsafe.com/nauticalknowhow/overboar.htm
Gilbert Pilz
Gilbert Pilz - 7 years ago
What "offshore" are you talking about? Looks like they are in the S.F. Bay to me. That's hardly "offshore sailing".
quosmo1
quosmo1 - 7 years ago
isnt it the usual to wear a boyancy aid until shit hits the fan (like getting into bad weather etc) then you change it up ? cause a boyancy aid typically gives you better mobility around the boat ?
where i learnt to sail (Mediterranean) that was how they did it. there must be a life preserver for each person, but they dont need to wear that the whole time unless your in (or it becomes) bad or dangerous conditions.
Maciek Ostrowski
Maciek Ostrowski - 7 years ago
California is not 500 yrs old... Don't play unfair! :-)
Kirk R
Kirk R - 7 years ago
I always thought that if I were to travel back thru time, this would be one of the most valuable bits of knowledge to have.
tarklot
tarklot - 7 years ago
Or how to make penicillin
SUPERNOVA
SUPERNOVA - 7 years ago
Ya this and the next weeks lotto numbers
sergio assumpção
sergio assumpção - 7 years ago
which one is better and safer catamaran ou monolhull  ?
Jonathon Cowley
Jonathon Cowley - 7 years ago
Boats will naturally try to gravitate towards their most stable position. A  catamarans most stable position is upside down on the surface.  However, a monohull's most stable position is on the sea bottom. A capsized catamaran floats.  A capsized monohull doesn't.  Catamarans win.
steve cooper
steve cooper - 7 years ago
Cat,,,,,, until it tips :-(.
Saraleah Sands
Saraleah Sands - 7 years ago
When you blow on that piece of paper, does the Coanda effect help create that lift ?
Richard Tarr
Richard Tarr - 7 years ago
No. It's the Bernoulli principle
quosmo1
quosmo1 - 7 years ago
+1 romanians! :)
Lorenzo Quarta
Lorenzo Quarta - 7 years ago
Nnnn nn bbjn . Platz rf cY vvhbbn
ThreeeAngles
ThreeeAngles - 8 years ago
They were not designed to go crosswind anyways, going with the wind a sideways was the way to go...
Anthony Ferreira
Anthony Ferreira - 8 years ago
And also square sail ships can rotate the sails 90º to each side, so they can sail like triangular sailboat!
Domenica Ascatigno
Domenica Ascatigno - 8 years ago
thanks a lot for this very useful video !!! greetings from italy !!!!!!!!!!!
Gariel2007
Gariel2007 - 8 years ago
the following KQED blaw blaw was produced in HI definition.. (360 P)
SamuelRiv
SamuelRiv - 8 years ago
The narrator speaks as if the physics behind sailing is some magical mystery enclosed in impenetrable jargon. Once she says "resultant vector" at 6:16 it's obvious that she's assuming the audience will be turned off by any hint of diagrams, math, or basically any useful explanation at all. KQED makes some great videos; this is insulting to your audience, and, apparently in particular, the sailors and scientists among them.
scythedd7
scythedd7 - 8 years ago
what person involved in sailing thinks that at all? all cat and sloop rigs can sail upwind, and half the classes I've ever sailed (Lightning, E-Scow, Y Flyer, Star) where originally from the 1930s or before!
scythedd7
scythedd7 - 8 years ago
Square-rig boats where exceptionally bad at it though, as they had to real problems tacking and they really can't come up to the wind all that much. /watch?v=zlRbcTsm2rc&list=TLgbgn6cNwmrQ You don't have to wait around, there are prevailing winds in the ocean (closer to the equator tend to blow west, father north to the east). That's why trips across the Atlantic go in a circular pattern, and also why they was a triangle shape to the trade routes between Europe, Africa and America.
drphosferrous
drphosferrous - 8 years ago
the transcontinental tallships usually had long, shallow keels to help keep courses. A High aspect ratio keel can help ya point higher (also depends on sail design), but it wouldn't have made sense for the kind of sailing those merchant vessels normally did.
drphosferrous
drphosferrous - 8 years ago
That's a misunderstanding that I here a lot: that before 1950 or so, all boats were downwinders exclusively. This transparently idiotic idea is part of a big con job that is aimed at making us all believe that technology is linear and progressive. If we believe it, it makes us easier to market products to.
Charles Carlberg
Charles Carlberg - 8 years ago
Hey Fred the key word is keel those square rigged ships did not have them.
Edward Burke
Edward Burke - 8 years ago
I took catamaran classes with Stan
sam monet
sam monet - 8 years ago
The 2,000 year old Hawaiian crab claw sail, still used on Hawaiian sailing canoes can still beat almost any modern mono hull, no keel, just a lot of lift component generated by a very efficient sail
Argus Brown
Argus Brown - 8 years ago
There lift generated by the keel is mostly perpendicular to the keel however with proper fairing you can move that lift forward. The "airfoil" is not as efficient as a wing since the surface is symmetrical. So what you have is a bit of stalling towards the trailing edge of the keel but you still get lift.
subductionzone
subductionzone - 8 years ago
No, the long answer is even directly downwind, if you are clever enough.
subductionzone
subductionzone - 8 years ago
Of course. Even directly downwind if you are clever enough.
Nilguiri
Nilguiri - 8 years ago
You may have understood it perfectly but it isn't Bernoulli's principle as the air passing over the top is in a different flow field from the air passing underneath. Bernoulli's principle only applies within a single flow field like the illustration at 3:55. They did not explain it perfectly at all.
Steve Meadows
Steve Meadows - 8 years ago
Yes, is the short answer. The long answer is: fuck yes!
Tobias
Tobias - 8 years ago
I don't think it was the sail technology that was the major limiting factor in holding ships back from sailing upwind. They had jibs and spankers even on the old ships. It was rather the heavy, bulky hulls that created the limitation: too much water-resistance going forward compared to the side-ways resistance. Also, the sail area per weight was much higher (and weight translates to more forward water resistance).
Tobias
Tobias - 8 years ago
There's no forward component in the force originating from the keel as claimed by this video. There's obviously a side-way component, but the fore-aft component is in the very opposite direction - water resistance on the keel.
c6rocks
c6rocks - 8 years ago
Is it possible for a sailboat to travel faster than the wind that's blowing it?
SirLobsterman
SirLobsterman - 8 years ago
you know most historians consider the modern era as after the italian renaissance, since it marks the end of the middle ages. the egyptians and romans existed 2000-4000 years ago, 500 years from the present doesn't seem all that old anymore....
SirLobsterman
SirLobsterman - 8 years ago
well, yes, but you need to remember that humans have been sailing for millenia and the advent of upwind sail designs weren't developed until the 13th-15th century and most more efficient designs were developed even later, so compared to square sails and possible head sails of the egyptians, greeks and romans, the up wind designs are pretty modern.
SirLobsterman
SirLobsterman - 8 years ago
they could, but they didn't understand it fully until bernoulli figured out why it happens, then it made it a lot simpler to travel against the wind. it lead to different sail types being preferred when traveling in a particular direction, instead of having to follow trade winds, they could instead measure what angle they needed to travel to get to a destination and get the most out of the sails and the wind with that particular angle.
SirLobsterman
SirLobsterman - 8 years ago
the downward curvature of the paper prevents it from being pulled down and instead the wind catches into the curvature, with the wind pushing the paper up when you blow under the paper. the downward curve on top is what creates the lift by attracting the paper to the lower pressure, I see that they explained it perfectly, you're just bullheadedly making claims when they already explained it....
GaskellleoCinema
GaskellleoCinema - 8 years ago
I may not have a physics doctorate, but a luffing sail is not analogous to a stalled airplane wing... A stalled airplane wing is analogous to a stalled sail. There's a heck of a lot of misinformation in this video!
yfx2
yfx2 - 8 years ago
4:42 "actually sucked" ..... No it's being pushed by the area of high pressure moving to the area of low pressure. The only thing being sucked... is me.
Tony Glaude
Tony Glaude - 8 years ago
Are you related to Sergio Garcia???
Fred Young
Fred Young - 8 years ago
First of all, from the beginning, the misnomer is that square rigged sailing ships could only sail with the wind. Is she serious? As long as a ship has a keel and a rudder it doesn't matter what the shape of the sails are, the ships could tack into the wind. They probably teach that Columbus had to wait until the winds blew from the east to sail to America then wait again until it blew from the west to get back to Spain for example. She should have conferred with "big bird" first!.
TheYachtskipper
TheYachtskipper - 8 years ago
Dig the guy said stalled sail will luff??? gee... What this video demonstrates really - lack of physics education in US primary school...
frankleofonic
frankleofonic - 8 years ago
You can do that with an airplane, because wind speeds are much higher on an airplane wing. Airplaines use this method because zero angle means less air resistance. But try with a windsurfing sail, which is always curved, and you will see that zero angle leads to zero force. Almost all the force of a sail is generated by angle of attack.
Ventosa Makari
Ventosa Makari - 8 years ago
OMFG.
VeS Com
VeS Com - 8 years ago
See more in: ventoesom.blogspot.com - Tks!
Brian Palmer
Brian Palmer - 8 years ago
actually, if your sails are balanced well, you can sail upwind with the rudder unattended. That's how fast racers inch ahead of the competition... you can literally steer the boat with fine trimming changes.
Nicholas Littlejohn
Nicholas Littlejohn - 8 years ago
carried the..slaves : )
Dacino Hoihe
Dacino Hoihe - 8 years ago
Both explanations are right.
salman000
salman000 - 8 years ago
5:50, boat has sails and keel, so resulting force moves the boat forward, REALLY, what happened to the rudder? piss off.
salman000
salman000 - 8 years ago
full of shit, acceleration requires force, where does the force come from on air that goes around the curved surface? so it does not go faster, due to angle of attack, you are slowing the air on the flat side and you are dreaming the air on the curved side is accelerating, wake up!
Scott Shirey
Scott Shirey - 8 years ago
How to sail: 1) point boat into the wind. 2) raise the sail. 3) turn boat sideways. Congratulations, you're a sailor!
ricsudukai1
ricsudukai1 - 8 years ago
Don't shout, listen. Inverted flight is possible due to the mostly symetrical wing section of planes with that capability. Wings not designed to work in 3D flight don't work at all well when inverted. Try flying a parachute or hang glider upside down. Some wings are designed to work in only one attitude. Square rigged vessels may not work to windward as well as a modern for and aft system, but they are unmatched for downwind work. Now take an aspirin and have a lie down before you get ill.
leneanderthalien
leneanderthalien - 8 years ago
Not possible with a so basic square sail from the Drakkar or Snekkar.In that times, the only efficient sails to gain to the wind was the latin sail ... 16 knots was the top speed from a 30m Drakkar , only with wind from the rear/side...and 10 knots at rudder...
Nader Ameeruddin
Nader Ameeruddin - 8 years ago
Sail has nothing 2 do with lift! Sail & wing work differently. A surfing kite is similar to a wing, not a sail.
Peter. Winckler-Krog.
Peter. Winckler-Krog. - 8 years ago
A Viking ship can sail 60 degrees to the wind.with a speed up to 16 kn.
Eloquence
Eloquence - 8 years ago
Produced in high definition, posted in 360p?
ephesus
ephesus - 8 years ago
THEN WHY CAN AN AIRPLANE FLY UPSIDE DOWN, MOTHERFUCKERS??!
blinginlike3p0
blinginlike3p0 - 8 years ago
the blowing over the paper is the Coanda effect, not bernoulli's.
Johnchuk
Johnchuk - 8 years ago
awesome video
Johnchuk
Johnchuk - 8 years ago
pretty sure ancient mariners figured out how to tack
Jonbeee
Jonbeee - 8 years ago
"Produced in high definition" - shown in 360... Jolly good!
Craig Dymock
Craig Dymock - 8 years ago
Now I know why it goes! Thank you Quest.
Scott
Scott - 8 years ago
This is pretty cool. However the way people sail today was invented a couple thousand years ago. So in the begining where they try and say that modern sailing is much different, or more technological, is basically wrong. Anyone who has studied or sailed on a square rigged ship knows that those vessels are anything but technically backward. What modern sailing has over the past is the reduction of crew.
ForLincolnandLibertyToo
ForLincolnandLibertyToo - 8 years ago
But the air will never move faster in the underside...
NauticEd International Sailing School
NauticEd International Sailing School - 8 years ago
So here is an animation of how the paper lifts nauticed.org/freesailingcourse-m1-31
sabresforthecup
sabresforthecup - 8 years ago
The two are closely related. The reason that the angle of attack causes lift to generate is that, by keeping the foil/wing/sail at an angle to the flow, you are in fact forcing the air to accelerate around the suction side (leeward side) of the foil, reducing the pressure on that side and sucking the foil in that direction. The angle of attack is essentially another means of controlling the shape of the air foil as seen by the air flow. Too large an angle = too much curvature = stall = drag.
Paolo Alto
Paolo Alto - 8 years ago
Sorry, but you can have zero angle of attack and still generate lift. Ask any aerospace engineer, ask any pilot.
aj981981
aj981981 - 8 years ago
It's all about the forces. If he had blown under the paper, then there ABSOLUTELY would be a pressure drop and a force from pressure acting downward. However, there would be a much LARGER force from the wind hitting the paper at that large "angle of attack." Bernoulli has not been abused. Also, Bernoulli's equation involves many many MANY assumptions and simplifications. It is in itself abusive in many cases.
sailorgeer
sailorgeer - 8 years ago
7:45 close but no smokin' roll of tobacco. Separated flow on an airfoil (e.g. stall on an aircraft wing) is when the angle of attack is too HIGH, analogous to the sail being over sheeted, or pulled in too tight for the boat's course. Luffing is when the angle of attack is too LOW and there is insufficient pressure differential across the sail for it to maintain its nice curved shape. That's when it just flaps uselessly in the breeze (much like people who comments on Youtube videos! :)
Brent O'Dell
Brent O'Dell - 8 years ago
So what DOES make the paper lift, if not a drop in pressure?
Brent O'Dell
Brent O'Dell - 8 years ago
But when you blow over a piece of paper, you're not moving any air across the other side, so you aren't raising the pressure there. Also, you know... these guys are scientists who study this for a living, so...
SOLARIS-boat
SOLARIS-boat - 8 years ago
Закон Бернули полная глупость, особенно в случае с парусами. Жаль, что люди тратят такие ресурсы и остаются в полном неведеньи процессов которые изучают, ставят бредовые опыты. А зеленые, не окрепшие, умы воспринимают это как должное.
woodwind314
woodwind314 - 8 years ago
Heed your own advice. Bernoulli's law simply states a relationship between speed and pressure (under certain restrictions). Nowhere does it state anything to causality. In this video, as so often, it was stated that the fluid's speed differences between both sides of the sail would create pressure differences (lift). That is plain wrong.
woodwind314
woodwind314 - 8 years ago
However, *anything* (barn door, sail, wing, or your ignorant head), when exposed to a moving fluid, creates pressure differences. And these pressure differences in turn increase or decrease local fluid speeds.
launchsquid
launchsquid - 8 years ago
dumbass! faster air has lower pressure. FACT! when lower pressure exists, higher pressure air moves to reach equilibrium. if ANYTHING is inbetween the two pressure cells it will be moved in that direction aswell. It is why a balloon will fly around a room when it's tail isn't tied, the air coming out the tail reaches equibrium and has no force but the air at the top can't get to the otherside of the membrain so it pushes the balloon untill it is at the same pressure on both sides.
launchsquid
launchsquid - 8 years ago
dumbass!! :) the air, even when its blowing along, has pressure. when it reaches a sail the same volume of air still has to travel past. either less air goes past the sail (in which case the sail would behave like a dam) or it has to blow faster to move all the air in the same time. both sides of the sail have a different shape, and restrict airflow by different amounts. the difference between the two creates a higher reletive speed on the outside of the sail. watch the die in the vid.
doodo478
doodo478 - 8 years ago
Sorry but the video is wrong in regards to what is generating lift. It is the angle of attack of the wing that generates lift. The shape of the wing, sail is the most effective means of reducing drag or turbulence when traveling through air or liquid.
Cassiopea
Cassiopea - 8 years ago
No
Brawndo
Brawndo - 9 years ago
Yes
mrmrlee
mrmrlee - 9 years ago
Dynamical? Is that a word?
woodwind314
woodwind314 - 9 years ago
google "nasa theory of lift"
woodwind314
woodwind314 - 9 years ago
Argh...always the same, wrong explanation given. Around 3:30 -"...since the streamlines are curving, it has to accelerate a little bit..." And according to what physical law? This is the rape of Bernoulli's law. For anything to accelerate, there must be a force acting upon it. So, air (or water) accelerates *because* there is a pressure differential. The pressure differential is *not* created by the differing speeds of the fluid flows - just the other way round!
Michael Angelo
Michael Angelo - 9 years ago
the best video giving you the buzz of this amazing feeling when sailing.. Very well done. :)
Andrew Poole
Andrew Poole - 9 years ago
I can't believe there's trash talk here, of the nerd variety. UFC meets NASA!
TheMrEM4N
TheMrEM4N - 9 years ago
We get it. You took a class and learned some shit. Noone cares about the equal transit time explanation. We just want to understand aerodynamics and how pressure generates lift.
Ronplucksstrings
Ronplucksstrings - 9 years ago
4:20 ...ah, the old blowing-over-the-piece-of-paper-to-show-lift.demonstration ..but if it was that simple, you'd expect the paper to sag further if you blew UNDER it, wouldn't you?...and it doesn't... Now all we need is an "Equal transit time" explanation and the illusion will be complete...STOP ABUSING BERNOULLI!
Hermann Otto
Hermann Otto - 9 years ago
Manfred Curry a famous American Regatta Sailor stated in the 30s already how important Laminar flow is on both sidesof the sails,and how easy one can have Eddies, unseen, so one has to let the sails go from time to time and gently retrim, Very effective when sailing hard on the wind/
2KHelium
2KHelium - 9 years ago
There should be a follow up video made around the enhanced performance of AC45 and AC72 wingsails...
Véronique og Rasmus Møller
Véronique og Rasmus Møller - 9 years ago
In fact, for normal lift conditions for sails and foils, the leeward "particles" reach the trailing edge long before the windward "particles", even for thick foils, where the leeward "particles" travel further than the "windward" ones.
Véronique og Rasmus Møller
Véronique og Rasmus Møller - 9 years ago
Now Bernouilli _does_ apply, just differently: The foil will push the liquid sideways by a higher pressure on the windward side than on the leeward side. Higher pressure => slower liquid and vice versa. Most of the time the air/water/liquid "particles" will NOT meet their "neighbours" at the trailing edge, and there is no law stating that they should meet again, only intuitions.
Véronique og Rasmus Møller
Véronique og Rasmus Møller - 9 years ago
Basically, the Kutta-Joukowsky condition says that foils can change the direction of flowing water and air. No big deal, but _that_ is why you have lift: the foil pushes the air or water, which pushes back. The back push of the liquid being pushed _is_ the lift. That goes for all foils: wings, propellers, sails, keels etc.
Véronique og Rasmus Møller
Véronique og Rasmus Møller - 9 years ago
Thanks for a great video, that I enjoyed a lot. About lift: it is due to the air(and water) viscosity. Whatever foils/sails you put in the flow of a superfluid with zero-viscosity will NOT generate lift. But air and water are not superfluids, so they obey The Kutta-Joukowsky condition: when the flowing air/water leaves the sharp trailing edge of a foil, it will continue flowing in the direction of that sharp edge instead of making a sharp turn around it (like a true superfluid would).
Diver6106
Diver6106 - 9 years ago
Great, now back to Zack's for a brew and turtle races?
WarBeer
WarBeer - 9 years ago
Being new to sailing....I assume that the way the sail function changes with the way it needs to preform? When you're hauling...the sail acts more like a "wing"....where as when you're running it's acting more like a drag chute? And then on a reach...somewhere in between? Is this correct?
Danny Hamilton
Danny Hamilton - 9 years ago
Note that a wing will also loose it's force vector perpendicular to the chord if the angle of attack is decreased too far, and when sailing a boat in any direction with a component into the wind, the sail is best used with the chord nearly parallel with the apparent wind. Increasing this angle will result in loss of laminar flow and reduced performance of the sail. So, yes, I think that makes them essentially the same (see hang-glider and PlaneSail).
Danny Hamilton
Danny Hamilton - 9 years ago
Yep, another mistake on my part, and some confusion because the word stall seems to carry different meaning between the two objects. On a wing, "lift" generally refers to the force opposite gravity, and stall refers to the reduction in this force vector. On a sail, the force that is often associated with "lift" refers to the force perpendicular to the chord, and stall refers to the reduction thereof. Even when vertical, a wing still provides a force vector perpendicular to the chord.
Danny Hamilton
Danny Hamilton - 9 years ago
"The lift produced by a keel adds to, not balances, the turning moment of the wind" : Yep, I'll agree, I made a mistake on this one. The lift created by the keel does not balance the turning moment created by the "lift" produced by the sail. The resistance to heel is due to it's mass. I'm pretty sure there is a force vector on the keel that resists sideways movement of the boat, but I'm at a loss at the moment as to the common name for this force.
Danny Hamilton
Danny Hamilton - 9 years ago
If you are comparing vectors relative to fuselage/hull, then you will absolutely find different results, the plane is using the force on the wing to oppose gravity, while the boat uses the force on the sail for propulsion, so the position of the wing/sail relative to the vehicle is significantly different. I agree that a boat doesn't work like a plane, but a sail does work a lot like a wing. Figure your forces about the chord of the wing/sail. Also see here: watch?v=ELL5lTE9Tek
UnitedEarthEmpire
UnitedEarthEmpire - 9 years ago
even modern sailboat need large human power... now sailing ship-of-the-line? whoah!
Danny Hamilton
Danny Hamilton - 9 years ago
While some keels have a significant mass at a significant distance from the center of gravity, this is not a necessary attribute of a keel to function properly. See daggerboard and centerboard as examples of low mass keels.
Danny Hamilton
Danny Hamilton - 9 years ago
Your "pull this, and pull that, and release this" analogy has nothing to do with the physics of how a sail works. You are describing how a sailor controls the shape of the sail. Using a plane analogy, you are essentially saying: If I do this with the flaps, and this with the pedals, and release the stick... SEE EVERYBODY, the plane is crashing!
Danny Hamilton
Danny Hamilton - 9 years ago
A wing can be tilted and not stall until it reaches its critical angle of attack. Beyond this angle it still has lift, but the lift falls off quickly. The same is true of a sail. The useful component of the thrust vector increases as the sail angle of attack increases. Eventually the sail moves beyond it's critical angle, and the useful thrust vector falls off quickly (the sail stalls). Sailors refer to this as "luffing" rather than "stalling".
Danny Hamilton
Danny Hamilton - 9 years ago
I'm not sure how you are defining 'positive' and 'negative' with respect to airflow direction and wing/sail orientation, but I suspect that you are changing your frame of reference between your description of the sail and the wing. The thrust vectors on a sail generated by the airflow over it's surface is always slightly downwind of perpendicular to the wind (just like a wing).
Danny Hamilton
Danny Hamilton - 9 years ago
I'm not saying that a sail and wing actually are "exactly the same", but I think that vertical wings on sailboats have been demonstrated to work. I know that a rotating vertical cylinder has definitely been demonstrated to work. As for flying with a horizontal sail, I'm pretty sure that it's called "hang-gliding" and is a rather common practice.
Pixelated Fable
Pixelated Fable - 9 years ago
I`ve made up an eqaution on my theroy of sailing relaxing!
Rohun Joseph
Rohun Joseph - 9 years ago
Bro, you wrote a physics paper... in youtube comments. respect...
cgpilk
cgpilk - 9 years ago
And bam, we're sailing.
obaidCarkey
obaidCarkey - 9 years ago
i hate aeronautical engineers!
FourDollaRacing
FourDollaRacing - 10 years ago
@jenkins0009 ...because the bitch didn't watch past the intro!
Will Jenkins
Will Jenkins - 10 years ago
@beeaich how is this not physics?
88horrorfan
88horrorfan - 11 years ago
I learnd a lot from this,Thank you so much!
wildblue2
wildblue2 - 12 years ago
Nice production. Not all pre-modern sailing ships were slow and could only be dragged along with the wind. Airfoil shaped sails and boats that can sail into the wind have existed since the middle ages. Even a square sail can move a ship in a vector 90 degrees to the wind. Most tall ships had special sails to move into the wind. Most long journeys follwed the trade winds, but if your ship can't be rowed, it has to sail into the wind at some point.
SailTimeCa
SailTimeCa - 13 years ago
Thanks for a really great video primer on sailing !
TeleTubeee
TeleTubeee - 13 years ago
I missed the original broadcast. Thanks for posting this show. Doug Oakland, CA

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