Aluminum transom has had heat distortion

[Seasons Recreational]

I’m hoping to circumventdiscussion about whether pontoons or float pods are effective, and I have a problem.

I bought float pods from Beaver tails and had a local welder weld them onto the transom. The process of doing so completely distorted the transom. He’s willing to bang it back in the shape, but it’ll never be straight as it was. Are there any suggestions as to what is the best course at this point? Should I have him try to bang it back in the place? Should I replace the top section of the transom above the float pods? There’s some distortion below the float pods, but it’s minimal and I think it would be OK to leave. But I really need the upper section to be straight so that once the Coosa board transom is in, I can apply the cap over the top.

Any suggestions from the pros would be greatly appreciated! Thank you so much.

Adrian

 

[MikeSchinlaub]

Wow, I hope you didn't pay for that. The welds are good, but he should have known not to just do it in one long weld.

I don't know, that's a lot of warp to try to hammer out.

 

[Seasons Recreational]

Wow, I hope you didn't pay for that. The welds are good, but he should have known not to just do it in one long weld.

I don't know, that's a lot of warp to try to hammer out.

I will not disclose whether I paid for it or not, but I guess that answers the question for you!

I'm not a welder, but I think they do look good. He did say that he was going only about 4" at at time, but you're right, as soon as he got some deformation he should have stopped.

The good thing is that he is on-board to try to fix it, but I am just not sure what the best fix is. Aluminum does get work-hardening, so I am worried that it might be brittle. The transom has a flange all around that rivets to the gunnel. I was thinking if he cut the material out about an inch or 1 1/2" from the edge of the transom, and if he provides me a new sheet, I can maybe run a ton of rivets from the new transom to the flange, using 5200 to seal the two.

Last think I want is the transom to break loose in the middle of the lake!

 

[Scott Danforth]

Should have had a backer in the boat, like a sacrificial chunk of wood to help control warping also, in addition to a heat putty, should have stitched it 1/2" at a time, jumped 12" rinse and repeat. 4" is too long on thin sheet metal. also, the fillets are for 1/4" plate, so there is way too much heat.

 

[MikeSchinlaub]

Ok, I'm not much of a metal guy, I mostly do fiberglass, but I'll give my opinion on fixing that.

I think it's stretched too much to just bang it back into shape. The only chance, and this is with no experience, would be a lot of work with a shrinking hammer (picture attached below). It looks like a meat tenderiser, and works by making loads of little dents to shrink the metal. I don't know if it can take that much out, or if the texture would be too deep for the thin aluminum, but I think it's the only chance of saving that sheet metal. Then it would have to be filled and resprayed, and sanded before hammering if you're going to try it.

The other option would be as you said, to replace the whole panel, which means drilling out all those rivets, shaping new metal, putting in probably about 200 new rivets with an air hammer and dolley, and repainting the rear and sides. Oh, and redoing the work for those pods, which is a real kick in the nuts.

If you go with a new panel, maybe next time have some brackets made and weld those on so the pods can be removed if that would work.

 

[Seasons Recreational]

Should have had a backer in the boat, like a sacrificial chunk of wood to help control warping also, in addition to a heat putty, should have stitched it 1/2" at a time, jumped 12" rinse and repeat. 4" is too long on thin sheet metal. also, the fillets are for 1/4" plate, so there is way too much heat.

Sounds like you are versed in welding! Any suggestion for best course to fix?

 

[Seasons Recreational]

Ok, I'm not much of a metal guy, I mostly do fiberglass, but I'll give my opinion on fixing that.

I think it's stretched too much to just bang it back into shape. The only chance, and this is with no experience, would be a lot of work with a shrinking hammer (picture attached below). It looks like a meat tenderiser, and works by making loads of little dents to shrink the metal. I don't know if it can take that much out, or if the texture would be too deep for the thin aluminum, but I think it's the only chance of saving that sheet metal. Then it would have to be filled and resprayed, and sanded before hammering if you're going to try it.

The other option would be as you said, to replace the whole panel, which means drilling out all those rivets, shaping new metal, putting in probably about 200 new rivets with an air hammer and dolley, and repainting the rear and sides. Oh, and redoing the work for those pods, which is a real kick in the nuts.

If you go with a new panel, maybe next time have some brackets made and weld those on so the pods can be removed if that would work.

Thanks for your suggestion Mike.

 

[Mc Tool]

The bit I dont get ......wouldnt you stop welding when you saw the distortion starting , I mean it didnt suddenly boing outa shape after the job was finished .
I believe thats a replacement panel job .....not fixable .

 

[Chris1956]

To fix it, can't you bolt or weld a 3/8" thick aluminum panel to the transom, gunwale to gunwale? Maybe remove the knees, and put the panel on the inside of the transom, and then replace the knees?

 

[Texasmark]

Am I correct in assuming that there is an aluminum cap that goes over the parts shown in your last picture? If it were mine I'd force the cap in place and bolt everything together as tight as it would let you.

First I'm not a metallurgist! So in thinking I would consult one (of sorts) I did a Google AI search and came up with this: if sheet aluminum is over heated, does it have a memory......plug this statement into your search engine and check out the results.

The worst part of the answer is that the aluminum that has been overheated looses its hardness due to destruction of the additives that make it hard....answer contained in the statement. With that said, and being a farmer that sometimes having to (field) modify things to get a job completed, X-lifelong boater, I would try to fix it.

First thing I would do would be to bolt the transom to the piece of wood shown in your last photos. If the aluminum accepts the tension and moves, or attempts to move back to the wood where its bowed out, I'd look around for a 1/4" thickness of 5052-T6 Alum sheet and scab it to the outside of the transom with bolts and sealer, covering as much of the transom that's allowable.

Then, assuming that the aluminum cap won't cover the increased width, either "joiner" down the thickness of the wood 1/4" (best idea) to fit, or cut the rear vertical part of the cap off.
Since this is a small boat and probably won't see more than 10 HP, I think the gamble is worth a try.

On the extensions on the transom, it really helps keep the stern up and on the Texas coast, when I was growing up. these extensions were common on popular, upper class, wooden boats at the time, and they were dual usage.....helped to keep the stern up at slow speeds, and were ported, allowing ambient water to come and go making a convenient place to put live shrimp when bay fishing for Speckled Trout (Spotted Weakfish) schools.

 

[Scott Danforth]

Sounds like you are versed in welding! Any suggestion for best course to fix?

First, smack the "welder" in the head.

The metal is already half its strength from welding. Best you can do now is back-cut the inside along the weld and weld over the seam. It will take someone who knows fabrication of aluminum. You ain't going to beat that out. You need to thermally relieve it by back welding.

You need someone that understands ship hull welding