posted 03-20-2000 11:16 AM ET (US)
Ed. I am working on an old 13 ft. Whaler. My boat had lots of those small cracks too. I took the boat to my local fibreglas shop to get their opinion. They told me that these small stress cracks were normal with older fibreglas and that they were cosmetic in nature. They said that only the gelcoat was crazing and the fibreglas was still structurally sound. They see it all the time on old fibreglas, boats or otherwise. The foam should be OK as the cracking would not be through to it. BW foam is supposed to non-absorbing. This is how they told me to repair the cracks.
1. The boat must be cleaned with a solution of water and TSP to remove any old grease or oil. Then let it dry and clean it with acetone.
2. Let the boat dry for a while. It must be VERY dry before you can do any fibreglas work.
3. Sand the area with 80 grit paper, remove the dust, and wipe it again with acetone.
4. Apply a coat of resin, a layer of 6 oz. cloth, and then another layer of resin. Then sand and fair the surface.
5. Apply 2 coats of gelcoat to finish and sand/buff out.
Keep in mind that this is the procedure for those small stress cracks. Big cracks require a bit more prep work and some extra filling.
I have followed the advice and it has turned out well. Anyone with average mechanical aptitude can do the work. It is quite tedious and time consuming, which is probably why it is so expensive to have a shop do it. Shop rates in my area here in Canada run about $60.00/hr. It does not take too many hours and you have a BIG bill. The materials don't cost that much.
Hope this helps.