Mike I presently use a 6.0 on my SUP when I am flatwater sailing and in the one or two times I have tried it in waves I have used a 5.2 or 4.7. I find the board glides so easily that it does not need a large sail. That combined with the fact that it does not really plane makes me question the use of larger sail. That being said I presently jump from my 6.0 wave sail to a 9.0 freerace sail in my quiver and the 9.0 on the SUP seems all wrong. Although I could ride my SUP all the way to 15 knots and probably more there is way too much rocker to give this board the speed I am looking for. Instead this board covers the < 8 - 10 knot range and I enjoy it very much. Kudos to Starboard on another excellent product.
To Roger thanks for your patience. Your last post makes me think that maybe I should be considering between an IS122 and a FU144 or FU155 your thoughts please