Rudder Foam Core Question

I'm doing a modification to my rudder which involves filing down through the outer skin of epoxy reinforced fiber glass and into the polyurethane foam core. My boat is a 1988, so I'm assuming the rudder was made the same year.

My description of "epoxy reinforced fiber glass and polyurethane foam core" comes from the APS description of their Laser rudder construction. Don't know if the one I have is made the same way.

Here's my question. Now that I've exposed that foam core, will it absorb water? The reason I ask is because think of the hole that's drilled into the side of the rudder that allows for one end of the knotted rope that you cleat on the tiller on the other end to keep the rudder down. It seems as though that drilled out hole is just covered with paint. Or is it gelcoat?

I was planning on sealing my work with either some kind of epoxy paint... or even a bit of fiberglass painted over with paint. But I was curious to know if that polyurethane foam is water proof or not. Is it kind of like closed cell foam?

Thanks,

- Andy

I believe that the rudders built at that time are closed cell foam so it shouldn't matter if you expose it.

Andy, a 1988 Laser foil has no epoxy, no fibreglass, no gelcoat. Just painted foam, with an internal steel-rod "skeleton" (if needed, you can easily locate the rods with a magnet). It doesn't absorb water.

Those foils APS is selling are of the type built from 2011 on, with a completely different construction.

Van and LaLi,

You guys are exactly right. After I posted, I took a closer look at the rudder where I had filed it down. No glass over the top of the foam. Just foam and paint.

Thanks,

- Andy