Hello Andrew
I like the style of Your fins. Designed like effective aircraft wings.
I have been designing fins for my slalom and speed bords for some years  now, but I have never tested designs with "wing fillets" yet.
As an aerospace engineer, I think it's the right design objective, together with high AR. Is it possible for You to send some additional info about: where to buy, test results, etc
  Glad to hear from You!

Regards/ Anders Robertson
Linköping
Sweden

Anders Robertson TOLC-AR
Requirements Management
Saab Aerosystems

Hello Andrew
Have tested Your fins with forward swept base and high AR.
The result: some of the best working fins that I ever have used. No spin, no tailwalking, low drag etc.
The smallest one nearly broke the 40 knot limit on a 90L Fanatic Slalom. In non ideal conditions with 6.5m sail.

Many Thanks.
/Anders Robertson


Dear Andrew
I have tried to figure out why the concept with the fillets work so well. The secret lies perhaps in the pressure around the fin and board. But there is no way of calculate these pressures, they tends to be very complex figures and there are no formulas yet.
A better way, as you know, is to use your intuition. In this case I got a hint to look at the pressure around the fin base compared to the board pressure. There is a possibilty that pressure around the root of the fin is more equal to the pressure produced by the planning surface board. (Different areas on the boards normally need different type of fins.) This also can explain why there is no wake aft of the board. I will try to make some mesurements in a water-tunnel, we have here at my company, and see if I can figure it out.
Many Thanks.
/Anders Robertson