: Don't use this. It is not as flexible as you need, and it will crack in a
: short time. Obviously, the cracks will allow water to slowly seep in,
: shortening the amount of time you can paddle between bailing. You want a
: rubber-based elastomeric roofing compound (snow roof) or an exterior latex
: paint (latex is natural rubber), or an oil-based exterior house paint
: which has been mixed with additional boiled linseed oil to increase its
: flexibility.

"Latex" paint hasn't had real latex in it since the 40's, and all that nastiness with the Japanese who controlled the supply of natural rubber beginning in the 30's. It's all acrylic now, and has been for decades. Not as flexible as real latex, but flexible enough for this purpose. Still, Sno-Roof or something like it builds thicker with fewer coats and stays flexible indefinitely. Mike Hanks did an interesting experiment though, and concluded that the coated fabric is less likely to tear if coated on only one side.