I actually have some video footage that I shot at the Triumph factory of a test they've done for a couple years on how much water is retained in closed cell foam. It is really interesting as they have different cubes of closed cell foam that have been weighed before submerging in water. They have weights on top of the cubes to completely submerge the cubes in a bucket of water over time. And then they pulled the cubes out of the bucket and reweighed them to see how much water had been retained. It is a small amount that is quickly dissipated when no longer submerged.
It is a very interesting experiment. But as Vic pointed out, any time we drill a hole into the hull there is a chance that water can seep into the inner hull. That is why sealing any intrusion with RULE Elastomeric sealant is a must. And in my opinion, providing a hull drain is just a good way to allow any seepage to get out. When my boat is on the trailer I just open that plug and leave it open till the next trip. All I have ever gotten is a slow drip.
If I can ever get caught up on all the work I've got to do, I'll post that footage and/or add it to the DVD (which is still not done yet!
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