Having first demonstrated that you don't have to be all that concerned about getting your reboxed fin at 90 degrees -

www.seabreeze.com.au/forums/Windsurfing/Gps/Asymmetric-fin-ready-for-test-run/#640906

I moved on to see how critical the finish is to fin performance. This fin is a select medium weedie (30cm) that has been sheathed in carbon. The trailing edge has been extended. It's a decent sized weedie. It's an unfinished project, the carbon soaked up all the resin leaving the woven texture fully exposed, plus some discontinuities where the layers overlapped.

I'm planning to fair the profile, fill the weave, polish it up, but thought I'd take it out as is just to see if it would work. Gave it a quick sand of the worst high spots, mainly at the leading edge. I'd half expected to have to walk back. (Not a big problem in Lake Illawarra)

Ended up sailing all day with it. Top speed of 32.5 knots on a 64 wide freeride board with a nocam 5.7. Did an unofficial pb for the 1 hr. It cranks upwind.

It works better than it did as standard. It's a little prone to spin out at low speed but more secure as speed rises. The unmodified fin was the other way around.

Conclusions.

Finish isn't all that important up to the low 30s.
A weed fin must be stiff.
A little bit of weed caught on a fin is way worse than the worst finish.

(I will get around to finishing it, it should go even better)