Join Date: Feb 2000
Location: Annapolis, Md
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heeling, weather helm and rudder control
One minor point, I would like to comment on your note, "at all angles the rudder is nothing more than a brake". Strictly speaking, that is not true except on a dead run. All boats make a small amount of leeway (1 to 5 degrees being quite typical on a beat). That side slip is necessary to allow the keel to have enough of a incident angle to permit it to function as a wing and create lift resisting sideward motion. If the rudder is aligned with the centerline of the boat, then it is actually at an angle to the flow of the water. As counter intuitive as this may seem the helm would actually need to be to leeward to not act as a brake.
But that is only a small piece of the story because a little bit of weather help is actually a good thing from a performance basis. In the case of a boat with an attached rudder, a little bit of weather helm angle helps to make the keel act as an assymetrical foil and provide lift to windward slightly more efficiently. In the case of a spade rudder, a small amount of weather helm angle helps to provide lift that is in addition to the lift provided by the keel and therefore reduces leeway was well. Of course in either case that additional lift comes at the price of additional drag so there is a point where the losses due to drag offset the gains due to reduced leeway.