Transom replacement

[lgrayson]

Hi All,

I recently was given a mid 70's fibercraft fiberglass boat, the transom and floor stringers are bad so removed them and I am ready to install replacements, the question I have is, do I have to use marine plywood if I am going to resin the whole surfaces of the plywood? What is the differences between marine plywood and standard plywood? I would appreciate any advice anyone can give me, this is a first for me. Thanks.

 

[Robj]

Re: Transom replacement

You can use exterior grade ply. I like douglas fir and used pressure treated douglas fir plywood on my stringers. You will hear many people saying not to use pressure treated ply because resin does not stick. This is not true, just make sure it is DRY DRY DRY. Marine grade is more expensive, and a better quality ply because it does not have the voids within layers. Exterior grade works just fine.

Have a great day,

Rob.

 

[tashasdaddy]

Re: Transom replacement

exterior grade ply is all you need, the treated will over time eat the fasteners you use to screw the floor down with. 45 years of experience with work with wood. glass it in good. keep it cover when not in use, your good for another 15 - 20 years.

 

[lgrayson]

Re: Transom replacement

Thanks for the info, I have to build up about 1.5" or so, what would offer the better support laminated, 2 (3/4" piecesof plywood) or 3 (1/2" pieces of plywood), and do I have to put cloth or woven in between the pieces of plywood? Thanks again, this has been a world of great information.

 

[tashasdaddy]

Re: Transom replacement

stabdard is 2 3/4 glue the together, i usually use screws to hold it together, then remove and coat filling the holes.

 

[lgrayson]

Re: Transom replacement

Thanks again, should I use construction adhesive to bond the plywood together? Then epoxy resin the whole thing before instalation?

 

[Robj]

Re: Transom replacement

If you are using epoxy then I would use it to glue the wood. If using poly, coat both pieces of wood with resin, apply a thin layer of a wet putty mixture of cabosil, resin and chopped fiber, lay a piece of matt, wet it out then clamp and screw the two pieces together. I like to use the putty because it helps to fill some of the voids between the two pieces of wood.

Have a great day,

Rob.

 

[lgrayson]

Re: Transom replacement

I have been debating on what type of resin to use for the transom and the floor, I have read that epoxy will stick to anything, but what choices do I actually have?

 

[Robj]

Re: Transom replacement

Your choices are epoxy, polyester and vinylester. Poly comes in different grades, I used an iso resin which is a better grade than a general purpose poly resin. I used poly when replaced my stringers and transom. It is cheaper than epoxy and vinylester. People say epoxy is the best, but remember your boat was originally built with poly. In my case, the failure occured due to lowsy workmanship when it was built, not because the poly failed. Plus I cannot justify the increased cost of epoxy.

Have a great day,

Rob.

 

[lgrayson]

Re: Transom replacement

Thanks Rob,
I talked to a supplier for the resin and they are going to give me a discount so I think I will go with epoxy resin, when I am wetting the 2 sheets of plywood for the first coat, should I thin the epoxy at all or will it absorb into the plywood enough as is? Thanks again everyone, this is a very good website, with a huge amount of information.

 

[Robj]

Re: Transom replacement

I think some of the epoxy guys need to answer that question. I only have experience with polyester.

Good luck and have fun.

Rob.