: We builtt a simple one with s sheet of foil sided insulation board.
: Just sliced part way through to the foil, folded into a
: rectangle and sealed with foil tape. sealed one end with another
: piece of insulation and use a towel at the other end. Has lasted
: several years and half a dozen boats.

Great idea, I didn't know about foil sided insulation board. Was that the polyisocyanurate type which is good to 150C? Polystyrene is good to only 75C and I imagine it would melt . . .