The Rot Doctor


Subject: Glass hull/core repair (Part 5)
Date: Sun, 25 Apr 1999

Hi there,

Well things have been going rather quickly with my boat. The inner deck has been removed exposing the wood core. The core is 3/4" thk x 2"wd x 8" lg segments of what I think is balsa. I removed the wood in handfuls and now it is enjoying a beautiful Wisconsin spring day. Ok I've ventured this far, what do I replace the core with? This project isn't nearly as much as I thought it was going to be..whew!!

"Yellow Jacket" Paul


Well, good! Glad you're seeing it as a not insurmountable project. You're correct in assuming that the old wood was balsa, since it is the most common core material used by the boat builders. It's (relatively) cheap and comes in end-grain sheets with a backing glue. You just tack it down and there you are!

Unfortunately it rots easily, as you now know so well. A better, non-rotting material is a synthetic honeycomb material called something like "Polycore" (I can't remember the exact trade name). But it's more expensive. I think you need to figure how many square feet of core you need and then find and contact a source for core materials. I wish I could give you a source in the midwest, but I can't. Time for the yellow pages or YAHOO! maybe. Anyway, compare costs and see which way you want to go.

If you choose balsa it can be protected to some extent with CPES. Our suggestion here would be spray the balsa after it is in place with CPES. The auto stores sell these little aerosol spray units pretty cheap and you can spray CPES with those. We've tested them and know that it works.

Let me know what you find out and which way you decide to go. We're interested!