Another Fiberglass Transome Repair Question

[Porshaah]

Hi All

I'm about to apply the 2 layers (i.e. in 3 part sections) of 3/4" plywood to inside of the outer layer fiberglass/gelcoat tansome (i.e. Glastron CV16 ski boat). which I've carfully cut out to fit. I plan on coating the plywood with resin, screwing the 2 layers together with stainless steel screws first, then fiber glassing it in along the outer edges leaving the top open. Because the transome fberglass/gelcoat outer layer is slightly concave I plan on pouring resin in from the top (i.e. as mentioned above, which I've left open at the top) to fill the voids between the inside of the outer skin and the flat pieces of 3/4" plywood. Does this sound like a good method?

All responses welcome
Bill

 

[ondarvr]

Re: Another Fiberglass Transome Repair Question

You didn't say what type of resin you're using, but its best to not fill large gaps with straight resin.

If the concave surface is supposed to be flat, then you should be able clamp or screw it, forcing back into shape, it will typically much more flexible than the plywood.

If you are using polyester resin you should have at least one layer of mat between the ply and existing fiberglass transom, you don't need it with epoxy.

With either, the entire sheet(s) of ply should be covered with glass, not just resin.

 

[Porshaah]

Re: Another Fiberglass Transome Repair Question

Thanks for your response Ondarvr

I'm using polyester resin. The outer gelcoat/fiberglass transom is meant to be concave and the only holes that currently exist are for the ski rope U-bolts on either side (i.e. where most of the gaps exist - about 1/2") as well as the 4 holes to mount the motor (i.e. no gap here in the middle of the transome). I really don't want to put anymore holes in the metalflake gelcoat. I don't believe the gelcoat/fiberglass outer skin is strong enough to pull in the plywood without pulling through. On second thought if I use a piece of wood in order to create more surface area so the bolts don't pull through then fiber glass it in along the sides and let it set it should be OK. But the plywood will be under tension (i.e. at least for a while) - not sure if that's a good thing? Also, if I fiberglass the plywood before I put it in I'm not sure they will bend without cracking the fiberglass after it has hardened.

TIA
Bill

 

[ondarvr]

Re: Another Fiberglass Transome Repair Question

If the transom is supposed to be curved, then you need to follow that curve a close as possible with the plywood.

You don't need to glass the wood completely before installing (although it can be done that way), but yousaid were only going to glass it around the edges and leave the top open to pour resin in.

How was this curve handled in the original building of the boat?

 

[Porshaah]

Re: Another Fiberglass Transome Repair Question

Again Thanks for your response Ondarvr

It's difficult to tell (i.e. due to the amount of rot and having to chip it out) but I believe the original is just as I described in my method. I figured if I encapsulate the wood in resin before I install, it will give added prevention from moisture getting into the wood and causing it to rot again. I've left whatever filler was originally used and just removed the loose pieces.The filler they used is grey in color and doesn't appear to have any long fibers embedded in it but it may have short ones. The best way I can describe it, is it's like a polyester resin bondo material - very hard/brittle and can be chipped away from the fiberglass/gelcoat transome if I try hard enough. This leads me to believe that it was poured in after the fiberglass/gelcoat transome was made and allowed to harden. The surface wasn't prepped in any way (i.e. like ruffing up the surface) to make it adhere to it. I was thinking maybe I should add some short fibers to the resin (i.e. to give it some strength) but I'm afraid it would hinder the resin from flowing into every "nook and cranny". Your thoughts?

"yousaid were only going to glass it around the edges and leave the top open to pour resin in." After I pour in the resin I will cap the top with fiberglass too, so that the wood is completely sealed from moisture along with sealing any bolt/drain holes. Also, this will give it mechanical strength transferring forces from the motor into the botom and sides of the hull.


TIA
Bill