The Rot Doctor


Subject: Soggy balsa cored FG deck
Date: Fri, 13 Nov 1998

Dear Doctor Rot:
I am just recovering consciousness after getting the estimate for recoring the side deck of my '76 Tartan 30. I am going to have to bite the bullet and have full recore surgery done on one side, since it is far gone and involves the chainplates. However, on the other side, the yard says the core under the genoa track is quite wet, most likely from failed bedding on the track.

Tomorrow, I will be personally drilling some test holes to see if the balsa is just wet, or rotted to mush. If the balsa seems intact, would CPES injected into the deck through the genoa track screw holes be a reasonable solution? I am looking at a $3000 surprise on the port side if I let the yard at it, but by the same token, I want a real fix, not a stopgap. Are there any rules of thumb on the required volume of resin per unit volume of core? Thanks!

Brad W.


Yeah, you are facing one of the glass boat owners worst problems -- there is just no easy or inexpensive repair. Regarding what the yard is going to do on one side of your Tartan, you should 1) ask them how much additional it would be to use a non-wood coring material (there are some honey-comb-type cores available), or 2) that the balsa that is put in place is epoxy-soaked to prevent future rot. Our CPES would be a candidate for epoxy-soaking, as long as the yard realizes that the carrier solvent will dissolve the film backing on the balsa. The CPES should be applied only after the balsa is cut and in place. It will saturate the balsa and help resist future rot. So will a standard epoxy resin -- if you can get it to soak through the balsa before it cures. Insist also that all fittings be replaced with a high-grade bedding compound, such as 3-M 4200. The fittings should be mounted in the compound, secured about 3/4 of the way, and secured finally AFTER the compound has had a chance to set. This will get you the watertight seal you need.

As for the other side, the test drilling is appropriate and will give you an idea of what you are facing. Your biggest problem in using CPES to repair damage is that the balsa must be dry. This can take time, and/or a system for pumping air through the cored area. We have done both. After that it's just a matter of injecting the CPES. One ends up putting in more than is necessary, but that's not a major problem. Actually dry balsa soaks it up readily. Some owners will elect to follow the CPES (after it has cured) with a slow-setting standard resin, such as our Layup & Laminating Resin. It fills and adds structure. What you do depends largely on what you think is happening in the core.

Good luck and come back if you have more questions.