aluminum boat transom repair

I'm new here and was wondering if anyone could suggest some good ideas for repairing my transom. I just bought a 16' Grumman aluminum boat (my first boat) which has some transom issues. The boat is equipped with a 1988 Johnson 28hp which sits on a jack plate mounted to the transom. My transom is cracked along the top on either side of the jack plate and on the side of the left corner. Also the transom has a slight bow inwards - I suppose this is because the wood is rotten and the motor has pushed it inward??? I dont know much about boats but I'm guessing that the aluminum piece on the inside of the boat can be unbolted so I can replace the wood??? My question is what should I do about the small cracks along the top of the transom and should I do some type of reinforcing after the wood is replaced and the aluminum sheet is reattached to cover the wood on the inside, since it has a slight bow in it?

Re: aluminum boat transom repair

Welcome Saemao, the first thing that comes to mind is remove everything and take it to a GOOD welding shop. They can weld those cracks up ( make sure they know what they are doing ). Then you can intsall a new interior aluminum skin, 1/8" or 3/16", prime it all with ZC primer, paint it, install a new transom board and go fishing. I would imagine the jack plate is not needed on your boat since its light and probably put too much strain on the transom.
Anyway, thats what I would do but there are guys a lot smarter than I that will tell you better ways and they will reply soon. Good Luck.

Re: aluminum boat transom repair

Welcome to iboats.

We are addicted to repairing and restoring aluminum boats here.

I suggest you visit this link and look through the restorations.... many have detailed photos of repairs. http://forums.iboats.com/showthread.php?t=385090

Re: aluminum boat transom repair

About the jack plate. Are you running a long shaft motor on a short transom boat? I have a 25hp short shaft Mariner on my jon boat and am using a TH Mini Jacker because while the motor is a SS it's longer than most SS motors. The river I'm on is very shallow and I wanted to raise the motor as much as I could. When I rebuilt the transom I added a 1"x6"x48" oak board to the 1" thick plywood that was the original transom.

Re: aluminum boat transom repair

Welcome to iBoats. I've fixed a few aluminum boats and what would really help is if you could read the sticky about posting pictures and then take some of your transom and post them on here so we can see what you're dealing with.

A picture is worth a thousand words and right now I have a number of questions that could be answered with just a couple of pictures.

Steve

Re: aluminum boat transom repair

A 28hp shouldn't be cracking the transom or bowing it in on a 16' aluminum boat. Was this hull rigged with a larger outboard previously?

Photos would help a lot as mentioned, also make sure to NOT use any pressure-treated lumber on aluminum boats. Normal exterior plywood or marine grade ply sealed with epoxy resin is the best way to go.

Re: aluminum boat transom repair

Here are some pics of the boat. The 28hp Johnson was the only motor that has ever been on this boat according to the guy a bought this from. The previous owner put the jack plate on because he was fishing in shallow water and the motor is a long shaft. Let me know how bad off I am.

Re: aluminum boat transom repair

more pics

Re: aluminum boat transom repair

O.K. Now I see what you're dealing with. There are probably a few folks here that would recommend using DuraFix to fix this but I would like to see you take a different approach and use a 3/16" 6061 Alumininum plate overlay. You could use 5082 or 5086 but 6061 has better overall strength.

The way I would do it would be to cut the new piece to size then weld threaded studs on it and bolt it through the original transom. That will give you a good clean looking transom.

I wouldn't bother with sealants between the two pieces, instead I'd weld a water tight edge bead all the way around. You'ld tack it with a TIG every 3 inches or so and then weld around with a MIG welder.

You can TIG it all the way around if you don't want to grind off ugly welds but you need make a bunch of short welds, switching from side to side and letting it cool often. You can use solid copper bars to pull the heat off and prevent cracking.

MIG is less hassle and a good welder can give you a decent stacked dime look if you want it.

Hope that gives you an idea of at least one possibility.