Typhoon Core Replacement

[Bensimon132]

Hey all,
I recently replaced the balsa core on a segment of the port side of my Typhoon Weekender. I scraped out all the old core and replaced it with new core. Then, because the new core was sticking out a little bit, and was not flush with the deck, I sanded it down a bit. I then epoxied over the core to bring it perfectly up to the deck, after sanding of course. I used west system epoxy (105 resin 205 hardener) first with a colloidal silica additive, then with a fairing additive to make the sanding easier and get a nice clean flush surface. Does anyone think I could run into any problems because I did not put fiberglass over the new core? or any problems while putting the new topside paint on? Please respond if you have experience with this.

[sloopjohnl]

Ben,

a little different than your effort, but i removed the deck from the front mooring cleat area down to what i thought would be the plywood core. it was about a 1.5 square foot area where the gelcoat was badly crazed and i wanted to get to the repair before what i thought would be plywood deteriorated. turns out there was no plywood, but rather balsa core. i dug out the balsa which had become wet and replaced it with plywood as core, then used the same West system materials as you to replace the deck. i ground the surrounding foredeck to a gentle taper and made three separate applications of the West materials to replace the gelcoat decking. no fiberglass cloth was used due to the thickness of the plywood core. i topped it off with Petit paint and non-skid grit additive and it has held beautifully for ten years now. no cracks or crazing and a much stronger mooring cleat.

[Steve Laume]

It must be the fiberglass layer under the deck that is saving these repairs. I suppose if the epoxy is thick enough it would have some strength but it is the glass fibers that really do the work, not the epoxy. You can lay up glass with very little epoxy and it is strong as hell but the opposite is not true.

I would have at least used a few layers of glass tape to cover the seam, Steve.

[Markst95]

I have to agree with Steve. The epoxy doesn't have much strength by itself and could easily crack and let in water. John was probably saved because he used plywood. The two layers of glass give the deck strength, think of cardboard in a shipping box.

[Ron M.]

Use thinner plywood and more layers of cloth with filler to build up to the appropriate level.
End grain balsa is soft........I hope it was totally saturated with epoxy.

[Steve Laume]

I have to agree with Steve. The epoxy doesn't have much strength by itself and could easily crack and let in water. John was probably saved because he used plywood. The two layers of glass give the deck strength, think of cardboard in a shipping box.

Better yet, think of concrete. We think of the stuff as being very strong but whenever you drive by a job in progress, take a look. It is bristling with rebar and wire mesh. That is the equivalent of the glass fibers in our boats. Our bridges, roads and buildings would all be crumbling and tumbling down if not for steel reinforcement of the concrete.

Epoxy is more flexable than polyester resin but it still needs glass fiber reinforcement, Steve.

[hilbert]

D'oh! I have had many Homer Simpson moments when I have found out that I didn't do it "right".

It is really difficult to do professional quality work, when every skill is new. I guess the trick is to read as much as possible and ask questions before hand. Even then, I have an older book on fiberglass repair that recommended applying smaller to larger discs of fiberglass cloth, when filling a hole. After doing the work, I found a very good "newer" explanation on why I should have applied "Big First".

It is possible that it will turn out as well for you, as it did for sloopjohnl. The question is whether you can sleep at night, knowing that it wasn't done as well as it could have been? If not, then grind it down and apply fiberglass, before you paint.