| Most of the difference was from the increase in surface area when moving from a half circle cross section to a semicircle/oval. But it
|had not much difference in wave making, which I guess is because an ncrease in beam (negative effect) leads to a decrease in draft (positive effect), if the displacement is kept constant.

So very interesting! It seems hull bottoms don't matter much?
Is it possible to see the effects of a flat bottom?
Can you do round corners vs square?
Different radius corners?

If cheap hull bottoms work well, then...

| What I found was that the most important parameter is that the profile of the waterline seen from top, is a smooth curve, like a semicircle or sine.

So, the ?profile at the waterline? behaves like a airfoil or 2 dimensional fluid dynamics problem?

You are looking for a low drag, double symmetric 0 camber foil of a given thickness %. That does well at your Reynolds number, Right? Drag bucket right where you want it.

If so, there should be lots of tools like xfoil to help.

Exciting!
But perhaps you all already knew this?