I have read much about different boats pointing abilities. Things like hull shape and wing vs. fin keel, draft, weight etc. seem to be key factors. I must be mising something. If my foresale begins to luff when I'm headed too directly into the wind, what does the hull or keel have to do with that?
pointing ability
- Thread starter Bill C320 Papillon
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side slippage
Your boat may be pointing about 45* to the wind, but your boat will slip sideways with the wind somewhat. Depending on the type and depth of the keel, you will experience more or less slippage. Other factors also apply, such as how big is the profile of your boat, because the wind will push the boat itself sideways. A good way to see this for yourself is to use a GPS and track your route. You'll be surprised to see how much slippage affects your progress!
Your boat may be pointing about 45* to the wind, but your boat will slip sideways with the wind somewhat. Depending on the type and depth of the keel, you will experience more or less slippage. Other factors also apply, such as how big is the profile of your boat, because the wind will push the boat itself sideways. A good way to see this for yourself is to use a GPS and track your route. You'll be surprised to see how much slippage affects your progress!
Exactly
Just because your foresail is full and drawing and your bow is aiming where you want it to, the boat can be making so much leeway that it is actually losing out to a boat that is heading lower but getting more lift from its keel and rudder. Additionally, the angle of attack of the foresail, which ultimately is determined by how far inboard the tracks are located, can have a lot to do with pointing ability. Where the boat is aiming and where it is going are two different animals - some call the former 'pointing', but actually the latter is functionally correct.
Just because your foresail is full and drawing and your bow is aiming where you want it to, the boat can be making so much leeway that it is actually losing out to a boat that is heading lower but getting more lift from its keel and rudder. Additionally, the angle of attack of the foresail, which ultimately is determined by how far inboard the tracks are located, can have a lot to do with pointing ability. Where the boat is aiming and where it is going are two different animals - some call the former 'pointing', but actually the latter is functionally correct.
ok
I understand the side slippage concept but what I don't understand is how one close hauled boat can have its bow pointed more directly into the wind without the foresale luffing than another closehauled boat. This assumes that they both have trimmed their sails to maximize pointing ability. I get it that if the 2 boats are on exactly the same heading one my "slip" more and they won't sail a parallel course.
I understand the side slippage concept but what I don't understand is how one close hauled boat can have its bow pointed more directly into the wind without the foresale luffing than another closehauled boat. This assumes that they both have trimmed their sails to maximize pointing ability. I get it that if the 2 boats are on exactly the same heading one my "slip" more and they won't sail a parallel course.
Why math matters
You have accurately described the problem: one boat can point higher into the wind than another can before the sails begin to luff. It has everything to do with the vageries of hull shape (and everything that comes under that rubric, such as draft, rudder shape, beam placement and width, bilge shape, keel form, etc.), as well as sail shape, condition, placement, size trim and probably a hundred other variables. If you want the mathematical whys and wherefores explained, check out the website below. All I know is that my boat (with a keel/centerboard) doesn't point nearly as high as my friend's keel model.
You have accurately described the problem: one boat can point higher into the wind than another can before the sails begin to luff. It has everything to do with the vageries of hull shape (and everything that comes under that rubric, such as draft, rudder shape, beam placement and width, bilge shape, keel form, etc.), as well as sail shape, condition, placement, size trim and probably a hundred other variables. If you want the mathematical whys and wherefores explained, check out the website below. All I know is that my boat (with a keel/centerboard) doesn't point nearly as high as my friend's keel model.
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