Thread: Ply for dinghy transom?

Do I need marine grade or can I just paint standard ply?also if I need to glue 2sheets together what’s best to use?
Thanks

Get marine grade - water gets in and you have problems with rot that can be more than a weekend job to fix. Penny wise, £££ foolish in this instance.

check out the utube channel [ fish bump tv ]hes the expert watch and learn .

Demolition Traders in Hamilton used to have (may still do) a dinghy hanging on the wall that looked to be very well built. They had a sign up pointing out the use of MDF in a couple of vital locations.

If you're going to the effort to do it, do it properly

Fark... I wish I had access to this guy and the materials he's using back in 1993/4... I had the unenviable task of rebuilding 3 transoms on Acecraft cats that had started to rot out. Don't listen to my advise in post #2... listen to to him! https://youtube.com/playlist?list=PL...7G8NA5sL3TxfMx

Marine ply all day long, the clue's in the name, to glue together just use some aliphatic PVA and clamp it well overnight (or if you can't clamp it, put a LOT of weight on it, I'm talking 100kg+) after it's cured use metalex on the cut edges and paint them, jobs a good 'un

Originally Posted by Bol Tackshin

Fark... I wish I had access to this guy and the materials he's using back in 1993/4... I had the unenviable task of rebuilding 3 transoms on Acecraft cats that had started to rot out. Don't listen to my advise in post #2... listen to to him! https://youtube.com/playlist?list=PL...7G8NA5sL3TxfMx

Thats the dude hes awsome . Ive done a few transoms for my self being a joiner/ builder but he will watched carefully soon when I raise the transom on my haines hunter .

Originally Posted by Bol Tackshin

Fark... I wish I had access to this guy and the materials he's using back in 1993/4... I had the unenviable task of rebuilding 3 transoms on Acecraft cats that had started to rot out. Don't listen to my advise in post #2... listen to to him! https://youtube.com/playlist?list=PL...7G8NA5sL3TxfMx

I'll second that!

Hmmm. Marine ply comes in a lot of different timbers and grades, just because it's called "marine" can mean anything from shit to pretty good, from very light and soft, to hard and durable and everything in-between. Our standard NZ pinus ply is glued to marine standards, and we have used it (treated) in many boatbuilding projects. It's a bit soft for a transom unless you take special precautions to stop it getting compressed but plates etc can solve that problem. In times past some NZ plys were LOSP treated and this played hell with a lot of glues. Current stuff glues fine with epoxies, which is the only glue type you should be using in home boatbuilding. Treated ply, glued with the right grade of epoxy will outlast most commonly avaliable marine plys.

Here’s what I’m dealing with..

A fine-ply (or to put that another way) a marine grade ply that looks like it has more ply layers than the usual stuff is the one you want to go for. Meranti is what I usually try to get, I've not had problems with it. It's a darker brown the usual pine ply we get.

You can usually get it in the thickness you want and it's better to not have to glue it if you can get what you need. Another option is container decking ply, 28mm. That stuff is nearly indestructible...

If you have to glue it, a thinned marine epoxy that soaks into the timber and a good quality well sealed plastic bag that's big enough to cover the whole shebang is really useful. Position everything and set it in the bag and then use a strong vacuum to drag the air out. Air pressure outside the bag will clamp it nicely. You can use the same thinned epoxy to seal the outside of the ply. Burnsco has most of the stuff you need in smaller quantities but at the usual price.

Fark thats a piece piss on a tinny if you have any container repair yards local , go see them a bit of container floor is all you need 32mm thick and offcut new or even used is cool , not like its got a 150 hp behind it . Just no silicone use polyurethane if using sealant and clean alloy .

Originally Posted by m101a1

Fark thats a piece piss on a tinny if you have any container repair yards local , go see them a bit of container floor is all you need 32mm thick and offcut new or even used is cool , not like its got a 150 hp behind it . Just no silicone use polyurethane if using sealant and clean alloy .

The "no silicone" advice is right on the money, the number of boat repair cock-ups due to the use of silicone based sealants would have made me rich if I'd kept at the game. Make sure you use a polyurethane type sealant! (Silicone acts at a molecular level to make just about any material un-glueable, and it sorta "travels" a heck of a long way, especially on fiberglass!).

Only running a 27kg outboard on her so don’t need to go to hard I reakon.