RE: what fin size for a 6.8m on a S type104
I have seen you sailing and from my perspective your idea of ?just good pure sport sailing? is high speed blasting and running circles around everyone else on the ocean. Is it fair to say that you are not just good but unbelievably fast; can we say a difference of ?quantum?, in the top 1% of the windsurfing elite? If I (or the other 99 or 95 or 80 or whatever % of us windsurfing mortals) used your set up, I would be spun out and lying in the ocean as I would not have the fin area for my skill level to get me up to speed.
We know that required fin area is inversely proportional to the square of the speed. If you go twice as fast you can use a fin up to one quarter the area. Conversely if you go twice as slow you need four times the fin area. This is why so much of the forum discusses techniques to get up to speed before loading up the fin. So for you the coefficient seems to be 0.36 rather than my ?normal? 0.53. (As an aside it seems that you are sailing 21% faster than me which is the square root of the ratio of coefficients) But your specific coefficient should hold for your different combinations of sail sizes, boards etc. So if you did not have your vast experience and intuitive sense you could use your specific coefficient in the formula to pick equivalent fin sizes for all your different gear combinations. Also the few other sailors in your league or race could use the same coefficient as they are in the same speed range. So the formula works even for the advanced users of the AskTeam forum, but I concede that it would not be as valuable a tool for this level of sailor. It is the other 95% of your total market that I often see struggling with grossly incorrect fin sizing that would benefit immensely from some initiative with basic guidance from Starboard and that is where the formula is easy with a constant coefficient and a complex matrix project is overkill.
Have a great day.