RE: ISonic fine tuning (For Ian and Kevin)
To add to the comments at the link shown by Phill above, in your weight/sails/conditions the iS111 will be marginal up until around 12 kts (in reality it depends on the quality of the wind and the flatness of water, plus rider skill/energy to get the very bottom of the planing threshold, and with 7.7 you are "OK" but would benefit from more sail size to really get the best chance at a real 10 kts.
Top end, yes, but again it will be marginal and mostly determined by the solidness of the 40 kts, and the water state (flat offshore or rough onshore both in 40kts are totally different situations. In general I would suggest the iS87 is really a bit much board for true 40 kts in anything except very flat speed trial conditions, and even then because actual board speeds will be so high, a smalle rboard would mostly be ideal. Think about the practical top end range being mor elike 30-35 true knots.
Either way, you'll have fun. Let us know how it goes !
You too, Phill !
Cheers ~ Ian