sausage said...
[br]Excel spreadsheet that calculates approximate sail size / board size / and fin size for your weight. Sorry if posted before. For 4knots of wind and my weight I need a 31sq.m sail

jimbodouglass.blogspot.com/2010/11/updated-windsurf-calculator-online.html

That's to get planing in 4 knots

That confirms why I get blown away in winter gales - 35kts +..I need a 2m for 40kts..The crappy 3m I have is only ok in 28kts....I suppose I knew that anyway..

Sorry don't agree with this chart. I have a bad habit of sailing too small and by this chart I should go smaller???????
Think I'll give this one a miss.

does it only work for heavyweights like me?

used it when i was 220 pounds (now about 235 )
10.0 - 13 knots about right
8.4 - 16 knots right
7.0 - 19 knots right
6.3 - 21 knots right
will need a 5.3 for 25 knots - when i am ready

also used it for sail spacing ...

as lonewolf says - "basic guide" = starting point
then play with the numbers

there are others too
http://www.riggeek.com/gear-calculator/for-windsurfers
believe this one was less accurate than james' - for me and my carcass that is

as i said

[ "basic guide" = starting point
then play with the numbers

then skill, technique come into play

however, i need to see these 50 kg girls in action
if that RS:X sail is wide luff and they drop it - i would like to see them uphaul in a lighter wind
----------
just looked up the RS:X 8.5 sail
7 battens with 2 cambers = free-race and prob NOT wide luff
still - 5.5 kilos - not nothing
those be some strong girls !!