I've used Great Stuff, for weatherproofing & sealing door jams etc. I always thought it would absorb water over time. It does stick like bear shyte to a buffalo blanket if you get it on your clothes, it will never wash out.
This is a great project to make an album. Put the album under "technical help".
Here is the intel on how to do it.
http://www.thebeachcats.com/faq/view/Main/10002/
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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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