Pete,

Sailrocket is a rocketship, literally. They have custom foils because they are reaching custom speeds!!! You're not doing anything crazy with your Blade and standard airfoils designed to operate in turbulent flow are fine (NACA series). Others have generated perhaps better for our cats but these aren't freely available.

Rolf,

Good to know, that makes sense, thank you. You pay a little drag penalty going thicker on the NACA foils, but the advantage is a higher stall angle of attack, which is why you want a NACA0012 on the rudder. You should never approach stall with your dagger boards unless you are doing something wrong with boat handling, so the key there is minimizing drag. On a long board, you may select a thicker foil for structural reasons mentioned elsewhere in this thread.

I've come full circle and decided I would rather go sailing than build foils. I don't have time to repair boards because my layup was insufficient, nor do I want to deal with broken foils 30+ miles from my destination. Finally, I have a hard time justifying my materials cost relative to a set of production blades. Mold cost is staggering for the required materials; this is with free CNC time on a $50K+ machine! Carbon alone is $800 for the pair of long dagger boards!