They do work.But read post. (And try them)
Thats nonesense kimax.
You always need a place to start .
x5 adding 3 ; might not be perfect but it certainly gives a (good) starting point especially for people who need to ask.(ie beginners or folk not at extreme of sport)
Poster is not aking what fin to use on his speedboard chasing Antoine;or for his waveboard looping with Mat.He`s asking for general advice !
Using this is never going to put you out with absolutely wrong fin; certainly could listeing to certain folk on here.
Have you even tried it with a few sail sizes ???
Fair enough give your advice but dont deride other people`s.
Calculators DO work .(within reaon and for a GUIDE !!!)