1995 Sylvan Transom rebuild

[Moep43]

Hello all,
Im new to the site and just picked up a 1995 sylvan on a nice trailer with a pretty solid little 85hp Suzuki. I found there was a lot of patching to the transom so with the help of a good friend, I ripped the motor off and started disassembling....

 

[Moep43]

Here is more disassembly

 

[lckstckn2smknbrls]

I would replace the foam for this reason... The copper used to treat the old transom wood has leached out of the wood and infiltrated the old foam.

 

[Moep43]

This is my plan...so far.

I will rebuild/ replace the transom with 3/4 outdoor or marine plywood glued together and then coated with resin. I was thinking also about hitting the inner transom seem with some gluvit just in case.

Next I need to patch the holes...I was thinking of cutting sections of new aluminum and riveting them over the holes. I would use 5200 between the two and around the new aluminum rivets. Also for extra precaution I was thinking of backing that with gluvit.

The inner transom skin was to far gone..It cant be reused. does this have to be aluminum? it is not structural and only keeps the wood from the elements right? could I use a 1/8 inch sheet of plastic material instead? just a though....

Also what should I use to clean the erosion on the transom skin?

Here are some pictures of the holes

any advice would be great!

 

[lckstckn2smknbrls]

Have the transom media blasted that should remove the white powder and any compromised aluminum. Then as long as the holes are below the wood of the transom riveting patches in will work.

 

[surfman]

Here is my Sylvan rebuild;

https://www.tinboats.net/forum/viewtopic.php?f=3&t=23064

to remove the crud, use a stainless steel wire wheel, you can get them from Grainger, then clean with detergent and then clean with phosphoric acid, you can find that in the pain section of the hardware store, and yes they use PT but, it is the older stuff so it does not have as much copper as the new stuff, still the wood needs to be isolated from the aluminum.

I used the west marine g-flex epoxy it is thick and where the transom was rotted through the epoxy was just sanded smooth and painted over, you can’t even tell there was a hole there. I didn’t have anything as bad as yours though but, I would bet it would work just as good.

If those holes, especially that big one is below the wood, I would consider taking it to a metal fabricator and having a new piece of aluminum welded in where the old one was. It looks pretty bad and once you grind off all the crud there won’t be much left.

 

[Moep43]

Thanks surf man.. That large hole is not below the wood line, I lucked out there! Lol

 

[Moep43]

So I called the hardware store and all I can find for plywood is AC exterior grade.. Can / should I use this for my transom and floor and just coat it with resin?

 

[Moep43]

Also what sides should I glue together the touch C side or the A side?

 

[surfman]

That wood is fine, glue the worst two sides together, do not use polyester resin without fiberglass. Polyester resin will just flake off. Epoxy is the best, it is more expensive but it will do a better sealing job. I used the G-flex and actually glued the plywood into place. My transom is rock solid and since it is made from the original PT ply it will never rot, I sealed mine up though before I glued it in so that the copper will not leach out into the aluminum.

 

[Moep43]

Ok so im set on the wood.the lumber yard down from my house has the 3/4 ACX I need. I have recently read people using Spar Urethane to coat the transom over the resin? is this also a viable option?

 

[rscottp]

Yes. Plenty of guys use it with good results.

 

[Moep43]

ok here's my progress..

I bought some acx, gorilla glue, spar Urethane, and cut and glued my new transom!

I also purchased some wire wheels and a stainless steel brush. tonight I plan on getting rid of all the crud and seeing exactly how bad the outer transom skin is...

I couldn't find wire wheels that said stainless...should I not use just normal wire wheels?

 

[Moep43]

Got most of the crud all off the transom skin. It looks pretty bad but I don't see any erosion structuraly.. corners and support brackets..

Im thinking of cleaning it all up lap patching the larger areas then filling in the pitting with JB or Marine Tex.. any smaller holes will just get JB'ed

Im I on the right path?

 

[surfman]

I would only use stainless steel, plain steel will leave iron ions behind in the aluminum and will start the corrosion over again. I have not had good success with gorilla glue either. It is brittle and cracks.

 

[Moep43]

Surfman, I already brushed it with a regular wire brush I'm going to grab a stainless today..and do it over then I may hit it with some 60 grit. Have any input on what to clean it with? Citric acid?

The gorilla glue worked great it. I did clamped it with like 12 clamps seemed to set up fine. I got my first coat of spar on it as well..

How thick should of a aluminum patch should I use? And can I just use the small sheets from the depot?

 

[surfman]

I would use phosphoric acid cleaner, get it in the paint section at the hardware store, as I mentioned before and I would not put a patch on the metal, I would have used the epoxy and just sanded it smooth, But since you already glued it in with the gorilla glue I guess you can put a patch over it or try some bondo. I don’t think the thickness matters since it will not add any strength to the transom anyway.

I would probably screw and glue the patch on with 5200.

 

[Moep43]

Surf man a bit confused about what you are saying
I used gorilla glue to glue the 2 pieces of plywood together for the transom wood..

The wood is not in place it is just a tworn up aluminum sheet as a transom right now.

I was thinking I would cut a sheet of aluminum the same shape as the transom and rivet it on the inside with gluvit between..

 

[Moep43]

 

[Moep43]

Well no turning back now