RE: iS145 vs. FT148
My husband has got a FF-158 (not the F-Type 148) which is 1 m wide.
The board is feeling big with the Retro 11 and a 70 cm fin (SB Jim Drake 2004).
He uses an adjustable outhaul but it has not been "fine tuned" yet (he has to improve it).
His next sail down is my "biggest sail" - a Retro 9.0m which he uses with the standard 64cm fin.
The mast foot position for the 11.0m?? is a little bit at the front of the track.
I think you brought up something interesting to know:
if he looses only 1 knot in the low end range it's worth trying the 10 and 9.5 in order to find out which of the 2 sails gives him the best feeling and than buy one.
Thanks for your help!
NB: At my weight (62kg) I still have lots of fun with my FF-138 (F-Type 148) and the Retro 9.0m because I am planing on days that a lot of people are just waiting for the wind to come!