Hi Erik,
thank you for your very interesting insights and the amount of know-how you are sharing. I hope it is ok, to hijack this thread for questions on tribal powerride and optimizing max speed on a R²ocket+ 133 (otherwise it would be great, if an admin could separate my posting).
With 82 kilos I am using a Rocket+ 133 and a F-Race 120 on a gusty and choppy lake with Hurricane fins in 37 and 40 and select V-Max in 45 for 6.2 to 8.3 freerace Sails (NP Speedster and V8).
I guess, my skills are somewhere in the lower to medium range of the wide field of intermediate. I rarely reach a top speed of about 50 km/h and that happens mainly on flat water. In most sessions my max speed on my choppy home spot is in the range of 45 and 48 km/h and I do not succeed in holding the speed over longer runs. I simply lack the skills and guts to get the board flying over the chop.
According to your post the Tribal Fins might help having more control in gusty and choppy conditions, so being faster and more relaxed on longer runs and I would like to try it out.
Which fin size(s) would you recommand for a Rocket+ 133 / 80 cm with 7.2 to 8.3 sails. According to tribal fin charts I'd choose 42 and maybe latwe add 38 for the F-Race with 7.2. Would you recommmad this size to or better buy a smaller fin?