2ND TIME REPLACING TRANSOM

[nite fisherman]

I have a 1986 Starcraft FM 160. I replaced the Transom back in August, 2012. It is rotten again. Back in 2012, I used regular plywood with waterproof glue. I think was BX grade but not positive of that number. I do know not to use Pressure Treated on this aluminum boat. I had to use a double layer of 3/4 since the wood in my Transom was 1.5 inches. I used a quality glue between layers and pressed them together with clamps and used screws also.
I then sealed it with 3 layers of #635 Epoxy from U.S. Composites I used the 3 to 1 ratio product. I honestly cannot remember if I drilled all holes before or after I sealed it.
But anyway it is needing to be replaced again.
My question is, should I use the same material as before? Supposedly I can get a "Marine Grade" Plywood from a cabinet shop. (Regular plywood with waterproof glue}
Does that sound sufficient as far as the plywood goes or should I order some ACX Plywood from somewhere? It is not ready available in my area.
And also is the #635 Epoxy at a 3to 1 ratio what I should use again or is there a Better Product?

Thanks in advance for all responses and help.

 

[Scott Danforth]

where did the rot start? I would personally not use epoxy to "seal" the wood. epoxy will crack vs flex

I would use either linseed oil, Old Timers Formula or oil based paint.

could always buy marine plywood. difference between ACX and marine ply is the wood itself as the glue is the same

 

[cyclops222]

What is the motor H P ? Long or short shaft motor ?

 

[Mc Tool]

I just not long ago last year stuck a new bit of wood in my dinghy transom . I used a bit of 2 x 8 treated pine . Being as the old one had rotted I used treated even tho its sposed to react with the ally , but I sprayed the back of the wood with plasticoat paint to isolate it ...... time will tell if I made it .
Benefit of hind sight the dinghy should have been scrapped .

 

[redneck joe]

At the top end i learned is MDO grade. In my small twon lumberyard it was 100 buck a sheet. It is the grade used for outdoor signs. I used old timers plus since floor i did mar8ne epoxy paint.

 

[redneck joe]

Interested to know where rot started, 12 years is not long.

 

[cyclops222]

It could be for mine. tied to dock. May 15 to Sept 15. No cover on it

 

[lgaytan]

I used seacast transom repair kit, it was easy to apply and seems that will last for ever.

 

[racerone]

Don't use any wood.----Go with composite / coosa board / or any number of " no rot " materials.

 

[StewartL]

I have a 1986 Starcraft FM 160. I replaced the Transom back in August, 2012. It is rotten again. Back in 2012, I used regular plywood with waterproof glue. I think was BX grade but not positive of that number. I do know not to use Pressure Treated on this aluminum boat. I had to use a double layer of 3/4 since the wood in my Transom was 1.5 inches. I used a quality glue between layers and pressed them together with clamps and used screws also.
I then sealed it with 3 layers of #635 Epoxy from U.S. Composites I used the 3 to 1 ratio product. I honestly cannot remember if I drilled all holes before or after I sealed it.
But anyway it is needing to be replaced again.
My question is, should I use the same material as before? Supposedly I can get a "Marine Grade" Plywood from a cabinet shop. (Regular plywood with waterproof glue}
Does that sound sufficient as far as the plywood goes or should I order some ACX Plywood from somewhere? It is not ready available in my area.
And also is the #635 Epoxy at a 3to 1 ratio what I should use again or is there a Better Product?

Thanks in advance for all responses and help.

Your plywood was the problem. Regular ply has internal voids that rot. Marine grade is best. ACX is a good alternative.
Your epoxy was fine. The 3:1 slow is a good choice.
The critical mistake was likely the holes. You must drill all holes after the final epoxy coat. Then you must coat the inside of every single hole with epoxy to seal the exposed wood.