I am considering building a proa flat an the lee side with more normal contours on the winward side.  Would the winward side have a venturi effect and cause it to run a straighter line?  The plywood lee side could be extended down to form a keel.  Would the flat side cause eddies that just slow it down or cause too much wetted surface and added weight from the added weight of a flat therefore thicker side?  Would it make sense doing the same thing on the ama?

There are some asymmetrical proa’s out there…. But none do the same with the ama. Gary Dierking has the T2 and his personal boat Te Wa. Of course there are also traditional boats done this way. I also wondered about extending the flat past the hull bottom as a lee board or keel…..

Paul Bowker of the Proa_file mailing list built a flat lee side proa, Te Wheke. There are videos on Youtube. Initially was built as a 16ft hull, then lengthened. Because of the severe asymmetry it had strong lee helm. I suspect that this type of shape works best with a very narrow hull such as the traditional walaps etc.
-Thomas

My experience with a flat(ish) leeside is that it help the hull to track straight through waves and other disturbances. If you make the leeside dominant by using a hard chine or a low aspect keel-like protrusion, it will dominate the sailing-properties, creating less leehelm.

If you watch my youtube-videos where i test my mono-proa and my barge-proa, you will see what i mean.
Cheers
Johannes.

Thanks for the replys and not flaming the new guy.  I found lots more answers on this website and the links that take me other places.  Of course every answer asks multiple new questions.

Dick Newick has for years designed trimarans with fairly “flat” lee sides to the outter hulls. And it seems to work well. But, I’d first try building a small model (20” - 30” LOA) and try it out.

Halsted