Transom Question on a 23

[Boonie23]

Hey guys just picked up a 1975 23 Sceptre hull that I am going to completely redo and make into a center console fishing machine. Hull is already stripped deck is out and the previous owner closed the transom last year and the boat just sat for a year under a tent. My question is the previous owner used two sheets of 3/4” marine ply but did not glass inbetween the sheets. He used thickened polyester resin with cabosil. It seems very well bonded but I’ve been told usually there should be glass inbetween the sheets. Do we think it is good with just the thickened resin? He also did a nice Coosa strongback that is tabbed into everything with 2 layers of 1708. The inside of the transom has 4 layers of 1708 on it so 6 layers where the tabbing is. I’ll attach some pictures please share some insight if you can. Really excited for this project!

[Boonie23]

Outside just has one layer of 1708 on it that the guy cut because he said it didn’t bond properly on the edges

[uncleboo]

My 18 sf did not have any glass between the 2 sheets and was stapled together. I would hope they bonded it as well, but, could not tell.

[uncleboo]

This was from the factory.

[captsuperfly]

can't speak much to the bond between the sheets, others will chime in - but the other glasswork and tabbing seems pretty clean. I think I saw this boat posted - did you pick it up on LI? Are you on LI?

I'm thinking of doing a strong back like that. curious how wide yours is?

Good luck with the project, I'm deep into a 23 restore too.

[Boonie23]

Yes superfly I’m on Long Island and picked this boat up in west islip last week. The strongback is probably 4-5” wide I’ll measure when I go out today but yes his other glasswork seems pretty neat so I think I should be good

[flyingfrizzle]

Originally Posted by Boonie23

My question is the previous owner used two sheets of 3/4” marine ply but did not glass inbetween the sheets. He used thickened polyester resin with cabosil. It seems very well bonded but I’ve been told usually there should be glass inbetween the sheets. Do we think it is good with just the thickened resin?

Glass between the plywood sheets dose little to aid in strength and is not necessary at all. I sometimes use CSM mainly to hold extra resin as the wood will wick it up. Thicken epoxy will not absorb into the wood as well and I actually thin my resin instead of thicken it when bonding ply. But I use VE or poly not Epoxy between them. Thicken epoxy is fine and honestly the original way they boat was built the ply were just stapled together with no bonding resin. The transom strength is in the outer and inner layers of glass on either side of the core. The middle of the core dose little for strength and the outside layers build an "I" beam type structure. If you add glass in the middle it is really just a waist and adds unnecessary weight with little strength benefits. I use thinned resin between mine mainly just to make the wood soak up as much resin as possible to aid in water proofing the wood. I used to add several layers of glass in the middle many years ago but learned that it is better to keep it on the outer sides of the core. (some old wise men up here taught me better) You can rest at ease long as the outer core lay ups and tabbing have good thickness.

[Xcomunic8d]

What others have said about strength. Like uncle boo. Mine was stapled from the factory and absolute mush except for the final bit. The grain was bonded to fiberglass.

I used PL Premium waterproof polyurethane adhesive between my 2 plies Of thermolite (coosa from Australia).

My transom disintegrated b/c the PO put 1 layer of 6oz cloth and then drilled holes in it.
I would add another layer or 2 over that 1 external layer. I put 3 layers on mine. And tried to put wet on wet and did my seems from bottom up trying to avoid a place water could sit. Not sure I’d do that again after the fairing and gelcoat I put down though.