Mathematical modeling of gear selection is for sure a very complex issue...I'm a bit skeptical to predict gear selection with a magic mathematical formula. Both calculators shown above were way off the mark for the real world conditions. Fins size for a slalom board is not the same as for a wave board with same sail and wind for the first model (the 110 L volume cutoff has a very distinct outcome between a 65 kg or a 100 kg rider IMHO). Sail range were way too small and fins way too large for the second model in 20-40 knots winds.
a) Example of real world gear selection in 20-25 knots wind with a 5.4 sail, 183 cm x 65 kg rider:
1) HS105, Carve111 or S-Type 93: identical 26 cm slalom fin is fine (30-32 slalom fins cm is way too large).
2) Kombat 86 : 24 cm wave fin is fine (30 cm freeride fin is way too large).
3) Acid 62 : 21.5 cm wave fin underpowered; 21 cm wave fin well powered; 20 cm wave fin overpowered (23-24 cm wave fins is too large).
b) Another example with Kombat 86 and identical 6.9 sail in 12-18 knots wind:
4) outboard and back straps : 30 cm fin is fine for freeriding.
5) inboard and front straps : 23 cm wave onshore fin is fine for wavesailing.
c) 3.6 sail on Acid 62 : I have no power and am sinking in 24 knots wind as predicted by the second model. I need at least 10 knots more to get going on a planing mode (real world wind range 35-40 knots with this combo)...
Last edited by Jean-Marc; 1st February 2008 at 05:18 AM.