This is a really nicely put together video explaining sail shape. I liked the way you explained that a deep sail is like low gear and a flat sail is high gear, I never heard it put that way and I found that comment really helpful.
You are a great teacher. I am greatful for the tutoring me. This was exactly what I learned in my first Sailing Lesson. Thank you, once more you have help me understand the physics of sailing.
How do you know when the air flows on each side of the sail a vacuum doesn't exist? Its like the air flow on each side of the sail are talking to each other saying: now guys make sure we meet at the same time or else a vacuum will be created!
I feel that not only the explanation of the wing physics is wrong, also the keel part is confusing and probably wrong. I think there is lot of bad advise with regard to sail trim out there
I came back to this video because I don't quite understand the principle of how heeling causes the keel to act like a sail underwater, allowing the boat to move to windward. How does that effect differ from weather helm, where automatic turning into the wind is from the center of effort being aft of the center of resistance?
QUESTION ( raising my hand ) 4:28 into the video, does that mean 1) if i am designing for a single sail i should increase my SA\D ? or 2 ) i just need to design the one sail like it's one sail ? #1 i can do, and #2 i would need a sail specialist...but i have to know if it's #1 because that would affect the mast and rigging.
Your explanation of how a "wing" works is wrong. The theory about the airflows travelling different distances and "having to meet" at the trailing edge has been discredited. Think about it, how then could an aerobatic plane with a symmetrical wing section fly? see: www.grc.nasa.gov/WWW/k-12/airplane/wrong1.html
John Luftenberg Though in fairness, airplane wings and boat sails is an apples to oranges comparison since a wing is a solid airfoil and gets at least some of its lift from deflecting the incoming airstream downwards.
John Luftenberg Yes, and according to the BS theory an airplane cannot fly upside down. Please tell those brave Airforce Pilots not to fly upside down in a dog fight, the theory says it is impossible!
+Peter Worsley No, no no little pixies lift an airplanes wing by flying across the surfaces passing very quickly over and under the wing! If your way was true they would never meet on the far side of the wing! Pixie's get very lonely if separated and they rush across the wing on either side to meet at the trailing edge. It's Orville and Wilbur's greatest discovery!
If one will disregard the explanation of how a wing works with the air flow, which is still used today in sailing classes , then the rest is good info still to today.
The explanation at 0:48 is total nonsense. "The parted particles have to meet at the other end..." No they don't. They don't meet. And furthermore, the air on both sides travels exactly the same distance. Actually, the air touching the sail doesn't really move at all.
The explanation about how the sails work is wrong. Particles of air do not have "to meet at the end". The air on the top of the wing/sail travels much faster and never meet the same air at the bottom. The faster air has less density than the slower air thus it pushes the wing/sail into the low pressure area.
Too bad this is far from the basics. From a total beginners point of view 90% of the sailing jargon and terms went over this boys head. A basic sailing video should explain sailing terms and then how to apply them. This video missed that for me anyway. Guess I need a basic sailing video.
As a beginner to sailing, almost 10 minutes of my life wasted. This is not for beginners at all. Why do i need to know about a racing main sail!!! Sorry, but very disappointing.
