This is what I usedhttp://www.zizypools.co.uk/hot_tub_a...32oz_P4844.html

Posting this as I was asked at the meet about it.

You need to know! This is the reccommended stuff, BUT when wet ie when being applied it ATTACKS fibreglass (so that will be your upper and lower roof then!

You either need to spend time masking up OR take the canvas out, I did this on our Troll in about 30 minutes, to put it back in took about 40 minutes.

It takes about 8 hours for this stuff to dry even in heat and a blowing wind.

I hope that helps those who asked