"Reliance" by George Owens.

[Glenn]

I was examining some lines plans of the most magnificent yacht of all time "Reliance" by the master Owens recently when I was drawn to the shape of the keel. The bottom of the keel is dead flat and is reported to offer a better end plate and greater lift. This being the case, is it advantageous to literally cut my bulb in half (longitudanally that is), given that the draft (in my sailing class) is restricted? The obvious benefits are a lower C of G, slightly higher aspect ratio in the planform of the fin, and an improved end plate. But does this bulb with a dead flat bottom produce greater lift because of its altered shape or because it is a better end plate? Also, are the drag penalties for such a shape, more detrimental that the gains please.
Thanks for your time, Glenn.

[SeaDrive]

Everything depends on everything else. If the draft limitation in your class is generous, then getting an end plate effect may not be as necessary as it would be if the draft was really shoal. A well known example might be the America's Cup class where the ballast bulbs have round (or nearly) sections. Some are squashed, but the increase in wetted surface is considered of more importance than the lowering of the CG.