Aluminum Transom

[geeco1]

I am trying to think ahead here a little bit. I am going to have to do a transom repair this fall and when looking at the cobbled up mess that the PO did to the transom, it looks like I might have to replace the entire outer skin. What is the suggested aluminum grade and thickness for the transom? Would aluminum diamond plate work? I will be replacing the wood as well with exterior ply that has been sealed in epoxy. There are bucked rivets all around the perimeter to hold the transom to the sides, etc. Can I just use pop-rivets (with 5200 sealer) to re-attach?

 

[Bob_VT]

Re: Aluminum Transom

Pop rivets will not have the fit or strength required for a transom

You can overlay the current one with a piece of aluminum which has been done before and it will not compromise the current rivets.....

OR

Bring the boat (minus the current wood inside the transom to a welder and have him weld it up.

 

[Bondo]

Re: Aluminum Transom

and when looking at the cobbled up mess that the PO did to the transom, it looks like I might have to replace the entire outer skin.

Ayuh,.... Pictures,... It can't be That Bad...

 

[geeco1]

Re: Aluminum Transom

I will try to get some more pictures this w/e. But here is one that I happen to have with me. When the PO tried to fix this, he welded on this piece of aluminum. I don't know what, if anything, is behind this plate. I have some cracking on the trim piece that covers the top of the transom. The right side of the transom looks to be full thickness, the left side looks to be about 1/2 the original thickness. He welded this plate on the back, top, and inside the splash well. When I pull up on the motor, I notice some flexing right on the side of the weld shown in the picture. To get the wood out, I am going to have to cut the weld. My fear is that the transom behind this plate has been compromised and thats why he welded this plate on there.

Again, I will know more once I tear into this but I'm just trying to put thoughts together.

 

[geeco1]

Re: Aluminum Transom

I finally tore into this bad-boy and posted some pictures. I can't quite tell the integrity of the aluminum skin until I get the old wood out. But it looks like to do it right, I will have to grind out some of the old welding. You can see in the pictures that the transom is not the same thickness all the way across where the motor mounts. After pulling off the trim pieces I can see that the wood is water logged and rotted.

My fear is that the rear alumimum skin was torn at one time and that is why they welded on the alumimum plate, but I won't know until I tear into it some more. I will probably have to remove the splashwell and such to get everything strait again.

Any ideas on the best way to go about this???

 

[ezmobee]

Re: Aluminum Transom

All that crap was apparently added after the wood failed. I'd grind it all off as best I good and start fresh. Hopefully the original transom skin won't be too badly damaged. If it is, I have seen other members reinforce it from the inside with a large sheet of aluminum (like a street sign). Your most immediate issue is that "wrap" over piece they put right where the motor mounts which is over top of squished wood so you be able to remove the old wood or reinstall the proper thickness of new wood with that there.

 

[jasoutside]

Re: Aluminum Transom

Huh. It's hard for me to even really understand what all is going on there. Looks like aluminum added and wrapped over top of bad wood??

Yah, I would think that all needs to come out/off and start over with new wood, sealed up properly and likely new aluminum skin too. Anything short of that I'd be afraid my OB might go for a swim!

Good luck!

 

[geeco1]

Re: Aluminum Transom

I plan on removing the piece that is wrapped over the top of the transom so I can get the old wood out. They also welded the splashwell to the transom so I will have to grind out the weld to remove the splashwell. I hope to be able to leave the large alum. plate that is on the back. The PO said that he paid $1000 to get it repaired. I think that it would have been cheaper if they would have done it correctly.

If I do have to put in a sheet of alum. what grade is normally used?

 

[robert graham]

Re: Aluminum Transom

Well you can repair/patch it some more, but maybe just rip the entire transom out and replace it with a new all-aluminum unit, using the old one for a pattern? All that rotten wood, cracks and welds just don't look too good to me, and you're gonna hang a 200LB. outboard off that thing? Just a thought, and good luck!

 

[geeco1]

Re: Aluminum Transom

My first inclination was to remove the entire transom. My only problem is trying to replace all of the rivets. I suppose that I could have it welded in instead of rivets???

 

[chrisp929]

Re: Aluminum Transom

i certainly think it best taht you remove the transom entirely.

I would drill out the rivets along the sides and bottom, remove the transom, purchase a sheet of aluminum the size of the transom, use the old transom to trace out new transom, cut new transom out, hammer over an edge like on factory transom to have a place to rivet new transom onto rest of boat. then buy new rivets and rivet gun and reinstall transom correctly.

then seal with 5200 ..

I was looking at my transom the other day on my Holiday. Not that i need to, but it would be very easy to do the same on my boat.

The biggest expense would be the sheet aluminum in the right thickness, and the rivets and rivet tool. all easily found online or at local metal supply store.

That transom has had it ... it's got to go.

edited to add .. i would NOT have it welded. to reinstall new rivets in same location will be easy. Reuse the holes on the boat, and predrill transom using old holes as guide. of course, pre fitting and hamming is required.

 

[jasoutside]

Re: Aluminum Transom

Holy smokes, $1K to fix!!??

At first I was thinking that a welder might have just done whatever the owner told him to weld up, but a thousand dollars!? That sure sounds to me like boat builder prices, not just a welder. Wow, that is scary, and a bummer. If an actual boat builder did that, yikes!

I am a bit of a hand talker and you can't see me so...

I am thinking if you cut out the whole center section of the transom and then either weld on or through bolt/5200 a new piece of aluminum skin overlapping the outer sections. Then rebuild your transom boards. I am thinking that you won't have to cut away anything that is riveted anywhere.

That sorta make sense?

If you click on the "Starcraft rebuild" link in my signature check out jspano's thread. He does a nice job of fixing up his transom. Maybe something along those lines might work for ya.

Have fun!

 

[geeco1]

Re: Aluminum Transom

Thanks for the input folks. I have to purchase a cut-off grinder tonight so that I can start removing the stuff.

I don't quite believe everything the OP told me. He said $1k, but who knows. I don't know what type of shop he took it to. I am thinking that they had more to repair than just the transom. The splashwell is welded in spots and where the splashwell is riveted under the gunnels keeps popping loose. The splaswell is in a severe torque when I try to tighten it up. I think that the OP hit something pretty hard. There is a pretty good size chunk taken out of the skeg. There was a good size dent in the bottom right at the edge of the transom. And the the splashwell issues. Of course, he didn't admit to all of this, he just said that the transom was repaired. My bad, though, I didn't put all of the clues together. I just wanted a boat of this style and the $1500 purchase price was in my range. All-in-all, I have used it for a year+ with no major mechanical issues.

My concern with rivets is can I reach them all from the inside of the boat with a bucking tool?

I will post more pictures as I tear this bad-boy apart.

 

[ezmobee]

Re: Aluminum Transom

Use stainless nuts and bolts for the rivets you can't get at.

 

[geeco1]

Re: Aluminum Transom

After seeing how rotted the wood was, I am lucky that I didn't lose the motor and have just a row boat on my hands. This stuff was mush except for the very top outer corners.

Splashwell is removed after grinding out all of the welds. The inner skin is too beat-up to salvage. I called an alum supplier and they guessed about $70 for a sheet of alum. I think it will be cheaper as I guessed at the dimensions and I see that I was guessing too large. After looking at the rear skin, I think that I may keep it. Although it looks ugly from the outside, I think I may try to clean it up. It seems to be pretty sturdy. That's probably what was holding my motor on.

Is it better to go with 2 pieces of 3/4 inch or 3 pieces of 1/2 inch ply?

My other concern.... you may be able to tell in the photo's but I streched a string across the transom. The starboard side seems to stick-out a little more than the port side. Should this be straight across the stern or is there a little natural outward curve? I am think that when I put the plywood in, then it will straighten out????

 

[jasoutside]

Re: Aluminum Transom

Scary is right! Your OB might have had to learn to tread water lightning fast had that let go!

Nice job getting all that mulch out of there man. Yah, another sheet of aluminum, new boards all sealed up and you are money

About everybody around here goes 2 pieces of 3/4 but 3 pieces of 1/2 would work just as well too (maybe better, more glue/epoxy).

Once you slide the new transom boards in and bolt them up that skin will straighten right out for ya.

Keep up the good work!

 

[fshngho]

Re: Aluminum Transom

Geeco, if you take the splashwell and tip it on its back end on the floor, you will see it should be straight. If it isn't, it should be. That is a lot of your structural support when its attached to the transom.
I'm glad you will keep the outer skin, less work for you.

 

[geeco1]

Re: Aluminum Transom

After getting the measurements, it looks like 1 sheet of 3/4 ply will be enough. The transom was 6 ft by just shy of 2 ft, so I should be able to get it all out of a single sheet.

I will check the splashwell to see if it is straight across the back. Hopefully it is.

I am still amazed that the PO didn't just fix it right to begin with....or at least attempt it. He must have not had the advantage of this forum to help him along.

 

[geeco1]

Re: Aluminum Transom

Ooopsss ...... forgot to ask this question.....

When sandwiching the two sheets of plywood together, I was planning on using the West Marine epoxy as the glue and setting concrete blocks etc on it until it dries. Is that correct, or should I put in screws, or what?

 

[jasoutside]

Re: Aluminum Transom

Ooopsss ...... forgot to ask this question.....

When sandwiching the two sheets of plywood together, I was planning on using the West Marine epoxy as the glue and setting concrete blocks etc on it until it dries. Is that correct, or should I put in screws, or what?

Yah, sounds like a good plan you have there with throwing a bunch of weight on. The only trick is to make sure the two pieces don't slide apart when you put the weight on.