The problem with the expanding type foam like great stuff is that if the skin that forms on the foam breaks down or is damaged, the foam will absorb and hold water. I have thought of removing the mast head and packing the mast with some polystyrene (sp?) you know the stuff the cheap coolers are made of. You can buy it in sheets from the home improvement center and glue it together with liquid nails.



Haven't given it a try yet though.