14' aluminum boat transom replacement?

I need to replace the wood in the transom of an old aluminum boat. It doesn't look the hard but I want to make sure I replace it with the correct wood.

Should I use pressure treated or marine grade plywood?

Thanks!

Tim

If you have access to it, marine grade would probably be best. It is stronger, as there are no voids in the plywood.

Use marine grade, and coat it with epoxy. If you dont feel like doing the epoxy coat, use whatever ply you want, it will rot anyhow. I wouldnt use pressure treated for anything though, the chemicals in it do dry out and it rots uncoated, and when its still moist I have my doubts on how well an epoxy will bond and penetrate it if its still moist...

If you want the ultimate and you have motor mount holes or something, drill your holes oversize before setting it in, and fill them with a mix of epoxy resin and wood flour. That way when you drill the holes in it, all you are drilling into is the epoxy not the wood. This keeps moisture from ever getting to the wood again.. here is a pic of what I am talking about...

http://img.photobucket.com/albums/v4...0005Medium.jpg

What do you mean when you say epoxy? I have used fiberglass resin for cars before. I want to make sure I use the correct stuff.

Thanks,
Tim

The resin you probably used is polyester resin. If it stinks real bad, and your hardener is measured out in quanties more like a table spoon, you have been working with polyester.

Epoxy is more expensive, but for something like you are doing you dont need much. If you have a boaters world or something around nearby you can get a small amount of epoxy for probably 30-40$. You can tell epoxy because the mixing ratio is like 1:2, one part hardener to two parts resin.

Polyester does not bond well to wood, nor does it bond to itself once its hardened, and its hygroscopic(water will soak through it into the wood). Epoxy bonds very well to wood, it bonds very well to itself, and it bonds very well to polyester, and it is not hygroscopic.

The filler I refer to in the holes is simply a matter of mixing up some epoxy resin, then you add filler to it to make it thick. I have been using wood flour, but there are other materials available at boaters world such as cabosil and milled glass fibers. Milled fibers are STRONG.

Rather than go to all that work see if a local shop around you has a piece of aluminum that may fit. That is how I repaired mine. To me it is stronger and I sure do not have to worry about rot.

I will be the disagreeing person here.

You don't need marine grade plywood. At 85 bucks a sheet, it isn't worth it.

Also, you should not use the fiberglass and epoxy resin. If your are replacing a transom in a fiberglass boat, it would be needed. With aluminum boats, you don't. That is one of the joys of aluminum boats - keeps fiberglass out of the picture completely.

Now, all of this is assuming your 14er has exposed wood on the transom, right?

For your wood, don't use pressure treated either. Certain PT woods will corrode certain aluminums. Get a sheet of regular ply. Either sheathing, or the furniture grade, which has no voids on the outer layer, of both sides. If you get sheathing, look for minimal knots, and warpage. Coat it with a water sealer, or oil based paint if you must, but it is not needed. Have had boats from 1955 with the original transom wood, that was regular ply, with knots. Sure, it was getting real worn, but had lasted alright for 56 years. New jons these days often have bare ply as the transom.

Now, if your transom is the type where the wood is sammiched in between 2 layers of aluminum, and covered completely, you should definitely consider using a product called Sea Cast. Haven't used it yet, but will look highly into it on my next transom repair.

Good luck, and have fun (you do this too much, you will get bitten by the boat resto. bug. It requires you to constantly scrounge Craigslist for good deals on broken boats and outboards, have up to 6 boats in the yard, even though only one runs, and have up to 7 outboards on various stands throughout the shop, only to fix them, and then buy more.)

I highly doubt that Seacast is an option for an old boat. The price of that stuff is outrageous. The plywood method is probably the most economical repair, though a little more labor intensive. If you have the money and want to stick it in an old boat, then Seacast may be an option. I have heard good things about it.

Just my opinion, but I would never use wood on a boat without coating it with at least 2 coats of epoxy resin. You want to find a way to seal the wood from the elements. I think epoxy resin is the best way and it is strong. Maybe it is just me, but I want to be sure it is the last time that I have to do that repair.


Modified by ProcraftMike at 7:53 AM 11/21/2007

Your right on the Seacast being outrageously high. It has no purpose on a 14 footer, especially as most don't have the right design for it. It can only be used on the kind that have the wood inside the transom, whereas most 14ers have it on the outside. But, I still threw the idea out there.

On the resin versus non resin, there can be a couple different sides to that arguement. If you are doing ANYTHING on a glass boat, go ahead and resin it up.

On a larger aluminum boat, the choice is yours, but most would keep resin out of aluminum boats altogether. There are different ways to seal wood, and on aluminum rigs, they are often superior.

On a jon, there really is no need to resin. Replacing the transom can 15 to 20 minutes on many of them, as all the wood is exposed, and just bolted on. Coat it with some oil based paint, and you basically ad the dry time to that estimate. Seems to me that if you have to do it every 5 years, 20 minutes isn't going to kill you. But, I have had jons, from the 50s, that still had the original plywood. Because the wood is on the outside, it drys better. That is why it lasts longer. I also have a boat from '87 sitting out back, that has a rotted transom, as the wood is sammiched in between aluminum, and flotation foam, so the water would stay there, and be absorbed.

If you want, go ahead, but I wouldn't bother with it. Also, I don't know about all brands, but most brands of jons have exposed wood still, and it will be plywood that has some sort of water sealer. If you want, I can post pictures of a boat from 1997, that just has wood with a water sealer, and a boat from 1971 that has exposed wood, with nothing. The one from 71 doesn't look pretty, but is still structurally sound, and aside from the lake mud on the one from 97, it is in showroom condition.