Generally it's a case of suck it and see,

I regularly use sails well outside of recommended range.

I think the largest sail I've used on a FSW is 7.2m

I think there are to many variables in play to be hard and fast with recommendations

If it works then great, if it doesn't the don't

It has enough literage to carry a 6,7 .

34 -36 FREERIDE fin will help ...

Sail sizes by board manufacturers are guide lines.

You might have to flatten the sail off slightly, if its too full it could bury a rail when loading up.

Try it why not if it works you'll get more use out of the board. Might be best to put the foot straps on their outboard most position too.

The board is classified as a freewave and a 6.7 rig will not be a wave sail.

So it's not the volume of the board that's the issue here, but the rocker line.
Try a bigger rig by all means, but this sounds like an overload. Once you get planing it might feel OK or else it might feel like you have a lot of power but can't go very fast. But what will be worse is having a massive rig on a board that's meant to turn.

If you are not getting planing often enough in your local conditions then rather than overloading your wave board, try getting something bigger, like a freestyle board or something with 'slalom' or 'race' in the title.
And if you want to use it with a 6.7 or bigger then it probably needs to be at least 100 litres, and it certainly should have a single fin.

forceten said..
"At some numeric point a larger sail is no longer a valid option, it doesn't do any more in regard to performance, in relation to the board size, which is what Basher said".

This is a very interesting subject, for inexperienced sailors. I read hints about it, but never a full explanation. Would you please care to elaborate?
And what do you think would be the sail size of peak performance for a Fanatic Freewave STB 115 (231x65)?

mssp said..
Hi. I'm thinking about buying a 6.7m2 X:Move NP sail to use with a 96 liters Goya One Freewave.
But the recommended sail range for this board is 4.2 - 6.0 m2.

Seems like Goya is on the conservative side with the suggested sail sizes, since this is a relatively small range. The smallest FSW board I use is a 96, and that works just fine with a 3.7 or a 6.5. Different board (older 3S 96), but pretty similar characteristics to the Goya one.
So chances are a 6.7 will work ok with your 96, especially with a bigger fin.

On the Severne website they say the Fox 140 can take 7.5 to 9.5 then in the brochure it doesn't really recommend a 8.6 OD? At least that's what I make of the picture as the red line to the left doesn't go down to the OD

I'd suggest you borrow a bigger rig to try on the board first. If that works, then you'll know it's a good idea.
If it doesn't then you've spent the money already - and will then need a bigger or different style of board to go with that 6.7.

Not sure why the Severne Fox was mentioned, because that's not a freewave board.

You can get away with a bigger sail in flatter water, but being a freewave board you'll probably be using it in bumpier conditions. It also depends on how much power the sail generates. A grunty sail is more likely to over power the tail / fin.

As as mentioned in post above, the bigger sail may work OK but give you minimal advantage in terms of planning and trim.

As suggested definitely try before you buy.

Brienno said..

forceten said..
"At some numeric point a larger sail is no longer a valid option, it doesn't do any more in regard to performance, in relation to the board size, which is what Basher said".

This is a very interesting subject, for inexperienced sailors. I read hints about it, but never a full explanation. Would you please care to elaborate?
And what do you think would be the sail size of peak performance for a Fanatic Freewave STB 115 (231x65)?

A proper answer would require more info, ie your weight. Your Fanatic is near my MOO at 117l, a 7.5m is ok so long as I'm moving along, by that not planing but not a awkward slogging speed where holding the rig up is a bother.
A 6.4m is much nicer in those conditions. 70 kg, and proficient . So weight and level will enter, water state and wind force.
Example for me, a Formula board, 155l 7.5m for light wind was fine, even slogging , the board itself would take much larger sails. I bought an entire rig 8.5m , 490mast, the weight difference of sail and mast made it redundant ,offsetting the size increase. I don't recall if I used a GPS to compare speed, I sold the 8.5m rig. The weight was very noticeable when carrying the rig.
this all is subjective, if your a strong person. Which is not me.

so the answer is dynamic , it changes.

Okay. Thank you all for replying.
I think I was not clear enough, I don't have the Goya 96. So I can't try it. I was just trying to find a fsw board size that I could keep as my only board. It's a lot of pain to carry two boards during small trips. But I guess 96 is just not enough for light winds and too much high winds.
I have a JP fsw 102 and it should handle the x:move 6.7m2 okay.
So if I can't keep a single board quiver, I should get a 83-88 L board instead of the 96 to replace my really old small board from naish.
But again, another question of the same topic: the recommended sail range for Goya's Custom Thruster 86L is 3.7 - 5.5m2, and I wonder if a 5.7m2 sail would match with this board.