Well I took everyones advice and decided to put my little brushless motor in a smaller hull.

But the only small hull I had left was my old 22" Kyosho Sunstorm ebay clone.
Unlike the Kyosho Sunstorm Wheelnut converted to brushless this hull has a good flatspot at on the bottom of the boat as you can see from the pic
So I spent the day converting it from a sub surface drive to a surface drive.
I put a 35mm prop on it and ran it off 12 cells. After a few teething problems with water getting in I have finally got it all worked out and it seems to run quite well.
I will put a video up tomorrow.

The only issue im having is that the 35mm Prop has a very small pitch, i tried a 30mm prop with a bigger pitch but it was too small to get the boat up to speed also i think it might be a subsurface prop, anyone have any ideas on the best prop for this boat and config?