Ray,
You are correct that the boom outhaul controls, the fullness of the main. Tensioniong the foot reduces the draft, at least in the lower half of the sail.
However, downhauling the Cunningham does not flatten the sail. It's purpose is to move the location of the maximum draft forward, which is what you want to do to get a more effective airfoil shape as the wind velocity increases. This works because of the orientation of the weave of the sailcloth with respect to the luff, something built into the sail by the sailmaker.
With regard to pinching, whether to pinch or foot is a common and constant dilemma to a sailor trying to make good distance to windward.The proper choice depends on a number of factors, such as the helmsman's steering ability, sea conditions, wind conditions, and hull characteristics.
It is my belief, as discussed in the excerpt from Ross that I cited, that in light airs, probably the 2-5 knots he mentioned, you will get there faster by centerlining the boom and sailing higher. Of course as the wind comes up you have to ease the sail to keep the boat on its feet. I don't know the conditions under which Aldair suggests it is better practice to sheet to windward..." to get a better sail shape"
As for the roles of the vang and mainsheet in controlling sail shape we may have only a semantic difference. My point is that when the boom is within the range of the traveller so that the pull of the maunsheet is straight down, the vang does nothing. You are correct in stating that when you sheet out because of increased wind velocity, it is the vang which holds the boom down. If you believe the vang has some effect when the boom is over the traveller, check it out next time you are out sailing.
Further, I don't think the Vega has a bendy boom,as asserted by AldairMort
You are correct that the boom outhaul controls, the fullness of the main. Tensioniong the foot reduces the draft, at least in the lower half of the sail.
However, downhauling the Cunningham does not flatten the sail. It's purpose is to move the location of the maximum draft forward, which is what you want to do to get a more effective airfoil shape as the wind velocity increases. This works because of the orientation of the weave of the sailcloth with respect to the luff, something built into the sail by the sailmaker.
With regard to pinching, whether to pinch or foot is a common and constant dilemma to a sailor trying to make good distance to windward.The proper choice depends on a number of factors, such as the helmsman's steering ability, sea conditions, wind conditions, and hull characteristics.
It is my belief, as discussed in the excerpt from Ross that I cited, that in light airs, probably the 2-5 knots he mentioned, you will get there faster by centerlining the boom and sailing higher. Of course as the wind comes up you have to ease the sail to keep the boat on its feet. I don't know the conditions under which Aldair suggests it is better practice to sheet to windward..." to get a better sail shape"
As for the roles of the vang and mainsheet in controlling sail shape we may have only a semantic difference. My point is that when the boom is within the range of the traveller so that the pull of the maunsheet is straight down, the vang does nothing. You are correct in stating that when you sheet out because of increased wind velocity, it is the vang which holds the boom down. If you believe the vang has some effect when the boom is over the traveller, check it out next time you are out sailing.
Further, I don't think the Vega has a bendy boom,as asserted by AldairMort