Cracked, rotten transom repair

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zachw

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First post here. Thanks for the help!

I have an old riveted aluminum hull with a rotted, cracking transom. I've seen lots of threads on this, but my transom is a little different and the corner braces are at a diagonal to the horizon.

How would y'all fix it? I think I have a couple options.

1. Fix the rotting wood underneath the aluminum transom that's folded over and re-do the welds. (worst option, this is just going to crack again)

2. Remove the braces entirely, remove all the rivets on the stern, and fit a new 1/8" aluminum transom over the existing exterior. Then install new corner braces (riveted to allow some flex) and a new U-channel. In this case, I would make it more traditional with horizontal corner braces instead of the diagonals shown.
 

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Welcome Aboard, Zach !!

there is not a "one way" for transom repairs as there are so many different
models and versions on the market.
when do you plan to do this ?
photos with the motor off and all the wood removed will help a lot in the
reconstruction process. Kinda hard to tell with your posted photos.
plus, you may encounter other issues after the wood is removed.




.
 
Thanks, Johnny. I'm looking to start on it right away once I figure out my plans, and I'll take some better pictures tonight.

In general, I think the shape now is difficult to work with, and I could change it to something like this:
 

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A few more pictures here zoomed out so you can see a better look.
 

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yep - that is going to be a project !!
there may be some cutting involved. If so, think about three steps ahead
as to when you do get it out - how will you put it back?
try to find some aluminum sheet to fill the void when you put the new wood back on.
clean, scrape, sand, prime and paint all metal surfaces prior to installing the new wood.
filler 005.JPG
filler 007.JPG

When I am ready to make the filler permanent, I will apply a thin bead of 3M-5200
on the seams, inside and out and after that cures completely, I will put a layer of
aluminum foil HVAC tape over the joints, inside and out. a coat of primer over that.
then - I will permantly mount the new transom panels, inside and out and the new
joints will be 100% waterproof. (metal foil tape - NOT the regular cloth back duck tape).
Foil Tape.jpg


.
 
Ah very nice. That's a clean fix you have there. Think it's worth it to make that attachment from gunwale to transom horizontal like I'm proposing? Currently it seems like it's always going to be a failure point.

How are your corner brackets attached there? Weld? Rivets? Bolts?
 
Zach - I am going to put a vintage 35hp Johnson on this 14' V hull.
the extra heavy duty transom panel is a full 1.5" thick with a fiberglass mat in the center.
it will never flex - the outside "Outboard Motor Plate" is a full 3/4" thick
mainly cosmetics to cover up the alteration of the filler piece.
strategically placed 5/16" S/S carriage bolts will tighten it all up .... as well as bolting the motor on.
as well as new corner braces on the inside from the hull to the transom panel.

new transom 6.JPG
new transom 9.JPG

This boat is not for fishing - purely a family fun runabout.



.
 
if you mean glued to the metal hull - no
there are about 8 or 10 5/16" stainless carriage bolts through the transom panel.
there is a carry handle on each side of the stern that will have two 1/4" stainless through bolts each as well.
there is a stainless top plate that goes across the transom panel.
the outside outboard motor plate is the same - 5/16" stainless carriage bolts.
there is no need for adhesive between the wood and the metal hull. (IMO: glue could trap moisture - not good).
I will apply a very thin bead of clear waterproof (non-silicone) caulk around the edge of the outboard motor plate.
 
Got all the old hardware off. Much of it was rusted and broke easily. I'm still thinking the plan will be to replace the corner brackets with horizontal ones. This should allow me to build a large wood transom.
 

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Zach, refer back to your Apr 26th post about current vs proposed shapes. In my humble opinion, I'm not sure what you gain from a structural standpoint in making the proposed change to the shape of the transom. Not saying don't do it. You may like the look or the few inches of height gained either side of the outboard against backwash. Additionally, if you are going to put a plate back on the outside of the transom I would not use the shape like the one shown in your original post's photo -- the plywood one with the "wings" stretching to either side. You can kind of see an impression of a previous shape on your most recent photo. That shape would work and look better. Again, only my opinions here. I'm learning by watching how these issues are resolved so please keep posting.

Thanks.
 
LDUBS said:
In my humble opinion, I'm not sure what you gain from a structural standpoint in making the proposed change to the shape of the transom.

LDUBS- thanks for the comments. I think I agree with you here. I'm concerned that the current shape is going to lead to inevitable cracked welds and is going to take some custom shaping to work right as opposed to riveting in place and using a more traditional bracket. I also want to raise the transom up a couple inches at the motor connection, as it's too low now.

I'm open to anything- what do you think?
 
I have a 15' Klamath that has a similar shaped transom, though the angles are not near as pronounced as yours and the transom height is good. Truth be told, I would prefer to have flat (like your "proposed") as opposed to angled corner braces because I like the way they look. But, I wouldn't change them because it would simply be more work than I would want to do for just aesthetic reasons. I don't think there is anything wrong with what you are thinking other than it is a lot of work, and you do say you need to raise the transom (I assume to accommodate your outboard). Keep in mind I'm not a boat designer. Johnny and others have much more experience at this than me and have done some impressive projects.
 
Reviving this old post back from the dead to share the transom repair, which has been rock solid so far!

- cut out the corner braces and most of the inside of the transom
- wood was replaced with two pieces of plywood, epoxied with fiberglass between
- welded new corner braces
- because I was putting on a jack plate, I added a much larger backing plate inside to spread that load.

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IMG_0432.JPEG
 
CedarRiverScooter said:
Nice job on the transom.

That's an interesting fin on your motor.

Thanks. And that's a compression plate. I mainly duck hunt out of this in shallow water, and the plate lets me jack the motor up a bit more than an inch higher.
 

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