RE: Formula or isonic 155 for max speed ?
do you really think you are usig the right tool (FW) in winds gusting to 26kts on flat OR rough water?
Even a K86 5.3 does >30kts in that kind of wind in flat conditions.
iS133 in 15 kts and you'll be hitting 25+ all the time.
ST115 in >15 kts too rough or flat.