Thanks for the info above. I have a new is111, weight 80kg and am a pretty good sailor. Better at formula than slalom.
My questions -
The standard fins that come with the is111 (44cm and 38cm) are a bit larger than your above recommendations. I understand that down wind slalom doesn't need large fins and my use of the is111 will likely be 95% free sailing and 5% slalom racing. I like the challenge of the race board.
My experience so far on 8 outings - I am very aware of how to avoid spin out, but the smaller 38cm fin seems quite prone to spinning out & is very sensative to rear foot pressure . Especially in the beginning half of a jibe in small chop. Spinning out in the middle of a jibe is not fun. I usually sail in a protected area where 20 knots of wind creates 12" chop, close together. Fin? Technique? Suggestions?
I have other similar sized boards with smaller fins than 38cm, but they are not nearly as sensative to spin out as the is111
I much prefer the 44cm fin up to 20 knots (6.5 or 7.5 sail).
Obviously, I am doing some upwind work as well as a little down wind so the only advantage of the smaller fin is increased speed and control if it is really windy.
Would the SL2's improve the spin out? I am not compelled to purchase custom fins for free sailing, but I might if the control and spin out can be improved.
Thanks for your advice.