I used 4 layers of Raka 5 oz glass on the Guillemot hatch seal rim. They get a little soft in really hot weather. On the Explorer, I used 7 layers of the same glass, seems much stiffer. On the coaming for the Explorer, I used 7 layers of 5oz glass and a layer of 6oz tape. The layup is about 3/16" thick, and quite solid.
Have fun, Steve
www.steve-frederick.com