Your description of the foam flotation on mast reminds me of a C-Scow at the yacht club here. C-Scow has a very tall mast, hugely over-powered sail plan. He has some kind of triangular foam slabs sewn onto top section of sail, almost like life jacket panels. It's masthead flotation, for when he tips over. The shape is flat, so as to reduce wind drag, I guess. It works.