San Juan 21 Class Association

Just a couple of comments re deck recoring---approximately 35-40% of both the foredeck and the cabin roof of my MK 1 needed attention. Because the topsides gelcoat was in such good shape I elected to tackle the repair from the undersides. Be assured that this is a difficult and time consuming project, this coming from one who has a lot of experience in both wooden and FRP boat repair! Typically I worked with Baltek balsa core and the subsequent fiberglass cloth sheets, in nominal 18X24 sized pieces I held the epoxied Baltek up in place using a thin piece of luan plywood, again 18X24, which I covered with Saran wrap. The luan/Baltek was held up with multiple stick props. After the balsa cured I put a couple of coats of epoxy with cabosil on before starting with the cloth . I found the best way to make the cloth defy gravity was to roll on a heavy coat of epoxy thickened with micro balloons, place a DRY piece of cloth on the epoxy, then squeegee the cloth into the thickened epoxy mixture using an auto body spreader. I tried wetting out the cloth first and then hanging it but more often than not it would sag and/or fall down, so the secret seems to be start with dry cloth. Once the cloth had cured I would roll on 2 coats of epoxy/cabosil, let it cure and then do the heavy microballon/epoxy coating for the second layer of cloth. A total of 3 layers of cloth were applied with multiple coats of epoxy in between. I rebedded all the deck hardware by using a 5/8" spade bit and drilling again from the underside up to the underside of the top deck skin and filling the cavity with very thickened epoxy. Then I placed masking tape over the filled hole to prevent the mixture from falling down. I realize this topic has been discussed before but wanted to let other owners who are confronted with rotten deck cores know that you can do it----just allow plenty of time and patience.

I'm doing a similar job on a boat about the same size as a 21. When you expoxied the balsa up against the bottom of the top skin, did you use straight epoxy or did you thicken it with something first? And the micro balloons you mentioned, were they the red-brown phenolic type, or some other kind?

I used a product from US Composites called Q-cells. It doesn't matter much what you use, just a thickener that keeps the epoxy from dripping down from the roof of the deck.

Well moving along slowly. Just flipped the boat and had a look. After 2 years under a tarp, still saturated.
Bill

Great that you are able to work on the deck upside down---a much more effective method of repair!!