Our rudder is rather on the shallow side, presumably because the designer wanted to keep it above the lowest spot on our 47 ft centerboarder, which is the fin protecting the prop

The rudder is an airfoil shape, with a dead flat bottom, about 6" beam at the widest point.

I read that a wing on the bottom of a keel improves grab on the water, rather like a much longer keel, but without the depth.

I am thinking of bolting a flat plats, say 3/8" thick, on the bottom of the rudder, projecting out about 6" each side.

Any comments from you amateur and professional naval architects out there?

Anyone done somthing like this?

(the rudder is red in the photo. The white thing is the daggerboard, which drops about 5 feet from postion shown)