Another advantage of the wider fabric is being able to cut the fabric on the bias. It conforms to the shape more easily and the edges don't unravel.

Lay the pattern diagonally on the fabric from one edge to the other. This will leave a triangle at each end from which you can cut strips on the bias for around the coaming, hatch lips, etc. For mine I figured a little more than 2 1/2 boatlengths to get a second layer on the football.