How a Boat Sails in Apparent Wind

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Most popular comments
for How a Boat Sails in Apparent Wind

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Leonardo Po - 7 years ago

what about angle of attack?

Captain John's Skipper Tips - 7 years ago

Leonardo, go here: Genoa Luff Telltales: https://youtu.be/sW9lbZSAMrM

dontrell iommi - 7 years ago

? I do not get it at all

Captain John's Skipper Tips - 7 years ago

Dontrell, did you have a question on the apparent wind video?

jp400motox - 7 years ago

I have been researching designs for building a sailing rig for my kayak. also i need to learn some about sailing before i head out and your simple and to the point explanation here has helped allot. I will probably be sailing mostly rivers so a good understanding of how much into the wind and sail position for sailing into the wind will help allot. Thank you.

Captain John's Skipper Tips - 7 years ago

Thanks for your comments. Good luck with your kayak!

Jeffrey 1957 - 7 years ago

Thank you.

Captain John's Skipper Tips - 7 years ago

You're welcome!

EpicFishFingers - 7 years ago

1:41 in both of those examples the sail is parallel to the wind, so how the hell does the sail move the boat forward when it's directly against the wind? Why wouldn't you turn the sail anticlockwise a bit to tack, or whatever?
Never sailed in my life and I still don't see how you can physically sail into wind, at all.

Captain John's Skipper Tips - 7 years ago

Most of the flow over the sail creates side force when sailing to windward or on reaches. Lift to windward comes from the keel, which provides lateral (sideways) resistance. This results is forward motion. See this article: http://physicsbuzz.physicscentral.com/2015/05/the-physics-of-sailing-how-does.html

Somendra Kharola - 7 years ago

Hello Sir,

I would be grateful if you could address the following questions:

1. If I wished to set sail in an African dhow (non-motorized) with a fixed lateen sail, in which direction should I point my sail for maximum speed, and in which direction should I point my sail for maximum stability?

2. Is it possible to sail faster than the true wind in such a crude sail-boat (7m in length) if I was to trim my single lateen sail close-haul?

Thanks

Somendra Kharola - 7 years ago

Thank you!

Captain John's Skipper Tips - 7 years ago

Somendra, on most sailboats, beam reaching will be fastest. I am not familiar with the dhow, but you might keep provisions in the center and low in the boat, the crew to windward, and reef the sail to increase stability. That applies to most boats. Ease the mainsheet if you need to spill more wind in in gusty conditions. On your second question, close hauled sailing is exciting, but not that fast. You are sailing more to the side than ahead (leeway). Reaches are always faster. You can sometimes sail faster than the wind when running (called "surfing").

Max Stevens - 8 years ago

you are talking about boat wind when motoring and you keep doing so , are you saying this demo is done with the motor running contantly because if the motor is off naturally the boat wind should not be there right. Thanks.

Captain John's Skipper Tips - 8 years ago

No worries. Glad to help.

Max Stevens - 8 years ago

Got cha that makes since, forgive me just learning this stuff.

Captain John's Skipper Tips - 8 years ago

You produce boat wind if you are moving through the water by any means of propulsion. Boat wind is the result of boat speed. So, if your sails are up and you are generating just 1/10th of a knot of speed, you have boat wind. Same with an engine, oars, paddle, etc. Boat wind is simply produced by the forward motion of a boat moving through the water. Whether in a dead calm or raging storm.

Boobe Bee - 8 years ago

Why is that when the apparent wind is parallel to the sail it reaches max lift? Is there still pressure difference on both sides of the sail (driving force)?

Ro Ro - 8 years ago

Captain John's Skipper Tips

Captain John's Skipper Tips - 8 years ago

You build high pressure on the windward side and low pressure on the leeward side. The lift component on a sail is quite small. Keep your sails trimmed to maximize lift. This generates speed and your keel will provide a lot of lift to windward. Sailing is about getting all of your foils working in harmony. The result is a fast boat with less heel and weather helm.

Coast Life - 8 years ago

So... Is apparent wind what happens when true wind and boat wind interact?

Captain John's Skipper Tips - 8 years ago

Exactly. Apparent wind is a result of boat wind and true wind. Your boat sails in apparent wind. You trim your sails to the apparent wind. There are only two times in sailing when the apparent/true wind line up with one another.: when you are headed directly into the wind (i.e. to hoist or lower a sail or getting stuck 'in irons') and when running dead downwind.

10. comment for How a Boat Sails in Apparent Wind

Mary Cate O'Malley - 9 years ago

Great information.

GaryChap - 9 years ago

Why do you say to angle the boom parallel to the apparent wind. That's going to flap, collapse and generate no drive forces - only drag. Also, I thought your explanation of 'three winds' rather than 'components' could be a bit confusing to some.

Most of your other videos are truly wonderful. This one just felt a little poor.

john jamieson - 9 years ago

+GaryChap Gary, thanks for your comments. More accurate might be to state to trim the sail to the apparent wind.

Don Monnot - 10 years ago

Nice explanation, but I see a minor problem with the diagram. If your boom lines up with the apparent wind, you'll be luffing your sail. The boom needs to be pulled in to prevent luffing. It needs to be pulled in to get the leading edge of the sail to be lined up with the apparent wind. How far that is depends on the draft of the sail.

Armando Palha - 10 years ago

Dear Captain

Besides your simple and highly effective explanations I love the drawings showing the events.
I wish I had it on a single dvd
Thanks, Cap
Armando Palha

Captain John's Skipper Tips - 10 years ago

Armando, thanks much for your comment. I have been thinking about doing that. Perhaps this would make a good project for the new year.
Best - Captain John

Captain John's Skipper Tips - 11 years ago

Thanks for your comment!

Bugod i - 11 years ago

Great vid

Adnan Medic - 11 years ago

Good videos my friend ...

rs8684 - 11 years ago

Captain John, I know the masthead fly shows the APPARENT wind. But where is the TRUE wind, when sailing, in relation to the masthead fly while moving? I assume that if the wind is forward the beam, it is in front (toward the nose) of the indication of the fly, but if the wind is behind you, then the true wind is aft of the direction of the fly. But I've never been sure, and I can't comprehend it in my head...

rs8684 - 11 years ago

When I am out sailing, I am always confused with where my masthead fly points - is the true wind before the fly or after the fly? I have a hard time figuring that one out.

spelunkerd - 11 years ago

I didn't expect to learn anything in this video. But, to my surprise, it clarified the important detail about how the sail actually works. Good job!

20. comment for How a Boat Sails in Apparent Wind

Hayden - 11 years ago

thx for the video this helped me a lot. I am learning how to sail right now I got my first boat a few weeks ago after helping my dad sail his boat for 10 years I figured it was time to get my own so I got a 19 foot y flyer and fixed it up. its a fast boat!

Angus McIntyre - 11 years ago

'Similar' is an understatement. Wings and sails use exactly the same principals to generate lift. One just happens to be made from cloth...generally. Consider the solid 'wing sails' on the AC72s!

Frank Newcomb - 11 years ago

Oh ya ok ,so my boom should line up with the flag then ,thank you for that : )

Frank Newcomb - 11 years ago

I put a small flag on top on the mast so all i have to do is look up for TW .

Nautical PappyStu - 11 years ago

It sounds like you are saying the sails work like a wing of an aircraft rather than being pushed along, (note: I'm a power guy not a sail one so on a learning curve even with 40 plus years on the water LOL)

DrTTube - 13 years ago

Awesome, thanks!

frank0067 - 13 years ago

lol .. man in all my years i never yet seen anyone who could teach how a one sails against the wind.. they ALways suppose the wind is in back pushing where ya wanna go.. well how about if where ya wanna go is straight against the wind?

Pedroskini - 13 years ago

Love the videos. Thanks for making them and sharing them.

rusty keller - 14 years ago

There's a fourth kind of wind. That's the wind that blows when your Captain is speaking! Actually, I enjoyed your presentation. I've been sailing for a long time, and I found your description of wind effect very knowledgable and helpful. Thanks.

gkel365 - 15 years ago

Great explination...Thanks for your help. Keep up the good work

30. comment for How a Boat Sails in Apparent Wind

ZipTumbleFast - 15 years ago

This video will totally changed my sailing habits. For whatever reason, I have always thought the main had to be perpendicular to the apparent wind (or as close as possible). What an eye opener. Oh, and I joined your SkipperTip site too. Thanks!

About How a Boat Sails in Apparent Wind

The "How a Boat Sails in Apparent Wind" video is part of the Sealing, tipps, boating category, which contains similar videos like this one.