A short update, now I have had a dozen outings from drifter to breezy: I stuck this down with waterproof contact adhesive and used cans (paint, beans) to hold it down while the glue went off. It was a nice hot day when I did it and I spent a lot of time washing the deck and drying it thoroughly to make sure it was dust and dirt free before getting the glue out. I waited until it was hot as I thought that would give the best chance for the glue to be runny and pliable, thinking I would need to spend a while patting it down to spread it all out. In the end, as I had kept the pro-grip as flat as I could before tying to apply, it was quite a quick job, I did get a helping pair of hands at one point, as this made it easier to apply the glue and then 'peel down' small sections at a time, rather than trying to get the whole lot down in one.
The result? Well, probably obvious but it does provide great grip
. It is not as spongy under the knees as I was hoping for, but certainly better than without it. Far less slipping about in waves (I sail at Felpham) and during or coming out of tacks/gybes.
A 1m section was fine, even on breezy days, I don't get far enough back that my feet are behind the pro-grip.