I have yet to come across a fiberglass boat with wood in it that is actually waterproof. We have replaced a lot of transoms and stringers and even entire bottoms constructed with balsa core. We recently went with some friends to look at the new boat they were about to purchase, and quickly pointed out several areas of wood in the bilge that had come straight from the factory simply brushed over with gel coat. In the bilge a piece of plywood coated with gel coat will simply draw in moisture like a sponge but wont be able to dry out and will soon begin to rot. When you store your boat always try to keep the boat bow high and the bilge dry. A little bit of water that gets left in your boat all year round can be drawn into places that will not simply dry out and the rest of that story can get very mushy.
With over 50 years combined experience in the industry we know why boats rot. We also know how to eliminate these problems when we make the repairs. A properly installed transom, stringers and even balsa core will last as long as the boat. Done right, wood and balsa can be used with confidence, and we guarantee all our transoms and stringers for as long as you own the boat. It does take a little more time to do this type of repair correctly, but no one wants to pay for these costly repairs more than once?