Yacht design the hard way. learning from Kav800 (most beautiful boat EVER...etc LOL!)

yes, that is true

"What reynolds numbers do boats of my size have? It can't be much. I imagined that they would be like an RC airplane."
RC airplanes are faster, so their Reynolds should be higher, too.

 

How do I figure out what the reynolds numbers for my sails will be? Should I just pick a NACA foil that I think should work and make my sails the same shape?

 

I would just make the sails from suitable cloth I have at hand.
For ~60cm LOA boat, even strong shopping bag could prove acceptable material for the first few sets, to get a hand at the matter.
Just the slight positive curve of mainsail luff, to accommodate mast bend +!2mm extra for "belly"; definite negative curve in headsail luff, to accommodate sag of stay.

For full size sails (not spinnakers) stitched from many cloths, deviation of single cloth edge from the straight line is about the 20-30mm maximum.
Scale it down to ~60 LOA, and dimension to follow will be few times less than accuracy of home model shop, and far less than stretch of material under working load.

 

Thanks! I was going nuts trying to decide how to scale down the sails. I finally decided on maybe making a sail like the jib in the attachment, but it was going to take forever to put together, then I realized that it wouldn't even fit right because it is 8mm to long from head to tack. So, I spent all that time on the dimensions and getting the twist right, a good camber, and none of it will probably be worth it.