18 ft transom replacing

[sponge]

Hey guys, im replacing my transom on my 18.
measuring the wood it looks like 1 3/8 does that seem right.
so i guess i need a sheet of 3/4 and 5/8.
its going to really tight to install.Maybe I should go thiner.
Is it ok to put transom in in pieces to get it behind the 3" flange.
Doing transom from outside.

[CHANCE1234]

That thickness sounds about right. I just redid my 20 and it was about that. If I was gonna do it again I would do it from the inside. It may seem like more work but after doing it from the outside I doubt it. Also doing it from the inside means it does not have to look perfect like the outside. Doing it from the inside is probably stronger too. I'd strongly consider doing it from the inside. Lots of info on here just search transom and you'll get all the info you could ever want

[erebus]

I just finished replacing a portion of the transom on my 1975 18SF.
Found slightly mushy plywood around the original engine bolts during my winter repower.
Cut all the core out from the outside to about 6 inches past the splashwell sides vertically and about 6 inches above the transom horizontally. Found good dry plywood out there.
Laminated in two sheets of 3/4 coosa board as well as a few layers of 1708, and a new outside skin of 3/16 thick pre-fab fiberglass sheet from mcmaster-carr.
I could easily tell that the original core was two sheets of 3/4 ply from the cross section.

You could go 1 3/8 for your core and add a lot more layers of glass to make up the difference.
Would sure be nice and solid!

I also, just for fun added a nice big knee in where my baitwell was from the inside of the transom to the top of the fore and aft stringer. Also made from 3/4 coosa and a lot of glass.
I used epoxy for the whole project.