Safest way to recore a soggy deck

[ajardine]

Hello all, my first post here.

I've got a '74ish Tylercraft 24. Deck was cored with end grain balsa. Water got into the deck alongside the cabin roof through poorly sealed holes left behind when the stanchions were removed. Water got into the foredeck through lots of poorly sealed fittings. Where I took those fitting off, I can reach into the middle of the sandwich and pull the gooey black balsa out with a hooked finger.

I'd have been tempted to ignore it all, but freezing and thawing of the squishy balsa has split the bottom layer of fiberglass, so the icky balsa is falling into the cabin itself. Both top and bottom layers of glass seem pretty thin.

Here's my plan - cut the top off, clean her out, bevel the edges of what's left behind, build up the interior again, put the old skin back in place. Never done this before, but I don't see much choice.

So - what kind of glass and what thickness do I use for this adventure? Am I really stuck using balsa again? Any decent books or videos cover doing this? Of course I'd like it to look perfect, but I need it to be solid.

Regards,

Andrew

[rescuesailor]

First of all I like to say "I feel for ya". I had the same problem and have already completed my deck recore. Tim has a great section on the recore of his own Triton that you should carefully study. On my boat the core was 3 inch squares of 1/2" plywood. This was common on boats built in china during the 70's. I cut off the top layer of fiberglass and removed all of the plywood chunks and beveled all of the edges where I made the cuts. I then sanded the remaining inner layer of glass smooth. I researched all coring materials and decided on end grain balsa mainly for economy. However not ever wanting to do this again I saturated all of my balsa with CPES epoxy before putting it between the decks. Before putting the balsa back in I put one layer of fiberglass cloth on the bottom or inner layer of the deck. I have to say that supporting the deck before removing the core would have been a good idea. I spent many hours trying to regain the gentle curve of the deck towards the bulworks because they flattened out with no supports when the core was removed. I left all areas where deck hardware would be fastened solid fiberglass. These areas were built up with alternating layers of mat and cloth. Once the core was replaced I troweled on a thickened layer of epoxy and cabosil using a toothed trowel. I used the same technique one would use putting down tile on a cement slab. The old deck which was sanded and beveled was replaced and held down by screws and weights. I used several layers of 4" and 2" fiberglass tape to reattach the two edges. Along both sides, (close to the bulworks and the cabin trunk), I drilled several holes in the remaining fiberglass deck and injected thickened epoxy via caulking tubes available from West Systems. This ensured no dry spots between the new core material and the old glass. I built sheets of fiberglass approx. 1/2 " thick and cut out raised areas for all deck hardware. I then epoxied all of these raised areas to the deck in the appropriate places. After it all cured I spent several days fairing and filling the deck areas. The result I hope will be a solid and dry deck. It took several hours, (100's I'm sure), but so far I am happy with the results. Hope this helps.

[mitiempo]

I agree with Andrew's method. As far as what to use for a core, any core is a problem if it gets wet, even foam in a freeze/thaw climate. Balsa is the strongest for its weight, and because of the way it's made it easily follows the curve of the deck. If properly installed it will outlast you. And Andrew's reference to Tim's Triton is worth a look except that Tim used plywood and later said he wouldn't again. All his more recent recores are balsa, I believe without exception. Plywood is not a good choice because it is heavy, doesn't follow the deck curve, and if it gets wet in one location it will travel through the plies to other places. Balsa is end grain and this can't happen. The only reasons we are recoring our boats now is that the manufacturers didn't properly epoxy pot deck fittings and previous owners over the years ignored it.

[ajardine]

David,

Thanks for your comments; What weight cloth did you use to re-enforce the bottom layer of glass? Did you use woven, mat or biaxial?

I'll almost certainly go with balsa for the core, both for economy and because it seems to have the reputation of being easiest to work with. The foredeck is slightly domed while the deck along the cabin is obviously flat, so I might break down and use plywood if I under buy the balsa (don't think I can pick up the balsa locally).

I've got bulkheads right under the foredeck that should hold the shape, but putting some support underneath anyway sounds like a good idea.

How did working with the CPES go? Does the balsa sheets remain flexible after you treat it, or do you have to treat it in place?

I've studied Tim's web pages on his recore project, and it makes me very, very glad I don't own a bigger boat.

Andrew

[rescuesailor]

Sorry it has taken so long to get back to you. I was able to purchase a roll of biaxial cloth on ebay. i do not know what weight the cloth is. It is very heavy and when saturated with epoxy it becomes very strong when dry. I swear by CPES. It is amazing stuff. i would take balsa and soak it until until it will take no more. I have also used it on plywood squares. The epoxy makes the wood hard but not impossible to work with or sand. The biggest draw back is the cost. I justified the expense by not ever wanting to have water soaked core again. I also put solid glass where any hardware is attached to through the deck. The whole process was lengthy but hopefully will pay off. I definitely would recommend to add additional bracing under the deck. Hopes this helps.