The most you could achive with surface treament would be no more than removing your drive fin........ http://www.geocities.com/wunderboyi/ninetysixpercent.html
I once left the bottom of my board cloth texture, just masked off the rails, edges and fin, sanded them for the smooth water grip, the edge for clean release, and went surfing. It definitely didn't slow it down and felt as slippery as any other board I'd ridden.
I have always thought there was room for improvement in fin designs. Ever see a fish with hard stiff fins? All I have seen have soft flexible trailing edges. some firmness in the base then more flexible on out toward the tip. I have thought about what you are describing but haven't figured out how to do it yet.I recently made a fin from a polypropalyne sp? cutting board. A swept back design thined out at the tip. It rides well but I need to figure out how to make one thicker in the base as to not flop there. the cutting board material is just slightly thicker than the fin box slot.
Hey guys heres a Penguin tip........One way Flex.......... http://www.geocities.com/wunderboyi/ninetysixpercent.html
i've also thought of the fact that most fish fins including porpoise fins are anything but ridgid, rather flexible with soft edges...then I realized that their bodies(fuselages) are also flexible and wriggly. There went that comparison.
One way flex I agree with. But in camber, not in cant. http://www.blakestah.com/fins/
Plus animals have muscles that can continually self-adjust, the dolphins body is a perfect example.
I already know the answer to this question... How do you get a fibreglass fin to flex one way? http://www.geocities.com/wunderboyi/ninetysixpercent.html