With respect Kamau.. you are right, however, dead wrong.  I don't think these extremely well heeled (pun intended) sailors, are saying they require ANY of these instruments, but rather are saying they prefer to have them.  When you get into the size boat they are sitting on, Depth is essential, no getting around it.  Then adding speed, and wind (Apparent, and True), can help you not only not having to figure wind direction, but also lifts, and headers... as well as which are gust lifts and shadow headers.

I agree, that a decent sailor can sail on feel alone (and watching the water color)... but if you race, or if you are optimizing VMG, sailing by the seat of your pants isn't enough.  It becomes even more critical when you are talking ocean crossings, and figuring SOG, and distance to waypoint.  Its how you are going to determine your next move to the better air pressure.

Humm... not sute about that advice. A sailor lives by the wind. If you need a windex and wind speed monitor you probably shouldn't be a skipper. I learned from an old salt that taught me to feel the wind on my face and neck, and how to judge wind speed by the sea state and flags. Thank God for old school instructors. :-)