i have 5.8 sometimes the wind just isnt strong enough for me to plain if i get a much largers sail will my speed increase?

Hiya Rob

A bigger sail may get u on the plane earlier, but u need to consider your other kit too.

It also depends a bit on your technique & what board you are using.

Assuming you have a good technique and it is just a lack of power that is the problem - you may want to consider getting a bigger sail.... but

A bigger sail will probably also mean a bigger mast and bigger boom - and so more weight.... What volume board do you use? Using bigger kit requires a board with quite a lot of volume, and a pretty big fin. So - depending on what you currently own - a bigger sail may not work very well with your board...

Suitably vague? Hehe - well - I used to use a 6.5m on a 90l board and it was OKish, although uncomfortable & damn hard to uphaul & tack, I'd have preferred a bigger board. Most boards have a manufacturers recommended sail size range - check out what that is for your board - and then decide if it will work with a big sail.

Hope thats of use.