Balance of sailboats is a huge myth. The whole CP, CLR, Lead business
was just a way for yacht designers to look scientific. The fact that
you can make huge area changes, such as the mizzen, without much helm
angle change shows how silly the whole idea is. There are schooners
with 10% negative lead and they sail fine.

Mainsail shape is more of an issue as a tight leach is a huge trim
tab. The primary source of weather helm is the fact that, while
heeled, the drag of the hull is over here and the drive of the sails
is way out there. To go to windward, the hull must make leeway which
means there is sideways flow on the rudder. Unless it has way too much
balance, it is going to have pressure on it.

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Roger Long