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16 ft Duranautic Aluminum Boat Transom Repair


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#1 Oneofour

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Posted June 05 2009 - 5:04 AM

I just recieved a 16ft duranautic aluminum boat from a co-worker/friend of mine. I noticed the plywood on the transom was rotting so I removed it. After doing so, I noticed the aluminum under the wood had begun to oxidize. Other than the "rot" on the transom, the rest of the boat is very sturdy. What are some options I have to fix the transom?



Should I look into have a piece of aluminum welded to repair the rot or are their other options? Thanks in advance!


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Quote:Originally Posted by Eric_Sfirst hit turned out to be a 13lb bass on a big plug. Very happy to see stripes again so I humped it then sent it on its way.

#2 Wayne Tj

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Posted June 05 2009 - 7:23 AM

How bad is the aluminum oxidation? Has there been a substantial lose of material. If not, I would just wire brush off the surface, clean with acetone, and then apply two coats of Rust Bullet (silver). If you feel that it is not structurally sound, it would be advisable to have a plate welded on.
Lastly, replace the plywood with marine grade or CA plywood.


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#3 Oneofour

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Posted June 05 2009 - 9:03 AM

How bad is the aluminum oxidation? Has there been a substantial lose of material. If not, I would just wire brush off the surface, clean with acetone, and then apply two coats of Rust Bullet (silver). If you feel that it is not structurally sound, it would be advisable to have a plate welded on.



Lastly, replace the plywood with marine grade or CA plywood.



Thanks Wayne, I would be more comfortable if I had a piece welded to the transom, just because there is one spot where there is a hole the size of a quarter where one of the screws went that has oxidized.


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Quote:Originally Posted by Eric_Sfirst hit turned out to be a 13lb bass on a big plug. Very happy to see stripes again so I humped it then sent it on its way.

#4 Wayne Tj

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Posted June 05 2009 - 11:24 AM

If you have a hole like that, I would definitely have a plate welded on. If you have 1/2" thick plate welded on, you could probably skip the plywood.
If you do put plywood on again, I would still paint the aluminum with Rust Bullet - it will prevent any oxidation in the future. The reason being that moisture gets trapped between the two materials.


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#5 Oneofour

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Posted June 05 2009 - 12:29 PM

If you have a hole like that, I would definitely have a plate welded on. If you have 1/2" thick plate welded on, you could probably skip the plywood.



If you do put plywood on again, I would still paint the aluminum with Rust Bullet - it will prevent any oxidation in the future. The reason being that moisture gets trapped between the two materials.



Thanks for your help wayne, that is what I suspected was the cause of the current oxidation. The boat I believe sat in the woman's yard for a while and when I got to it the plywood it was rotting so badly it looked like mulch when I tried to remove it. I know there is a thread going on right now about "rhino liner" but before I do that I would like to strip the paint, should I use rust bullet on the entire boat?


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Quote:Originally Posted by Eric_Sfirst hit turned out to be a 13lb bass on a big plug. Very happy to see stripes again so I humped it then sent it on its way.

#6 Chief2

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Posted June 08 2009 - 7:20 AM

104, you shouldn't have to "rust bullet" the boat. Generally with corrosion, the biggest problems occur when you have a situation where water can sit somewhere. Wherever you have air flow, and water can't "pool" up, you should be fine having it exposed.


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#7 Wraith

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Posted June 08 2009 - 1:42 PM

I would never weld a 'plate' over existing Aluminum.



You can never keep moisture out from between the Hull and the plate. It will corrode again over time. Cut out the 'bad' area and weld in a replacement piece, or sandwich the area with a piece of 1/8" Aluminum on both sides, coat the pieces with 5200 and Rivet it together with Closed end Aluminum Pop rivets.



ETA: What you are seeing is Galvanic corrosion. Cause is dissimilar metals. On all the 'Tin' boats I have owned, I bolt on a Zinc Anode someplace and change it every couple of years.


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SLOP. (Standard Liberal Operating Procedure)

#8 Chief2

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Posted June 08 2009 - 3:20 PM

well if the bolts are stainless, it's probably more of the dusting, which is oxidation, but it could be galvanic corrosion.

I think Wayne TJ was calling a "plate" was the entire sheet of transom aluminum. And be careful about choosing a Tig Welder, make sure the guy works with aluminum a lot, because Tig is tough, especially in structural applications.


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#9 Oneofour

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Posted June 09 2009 - 1:13 AM

Thanks for the tips guys. My dads buddy does a lot of welding with aluminum. We are going to cut out the piece that is rotting and then make the transom out of marine grade plywood which we will coat with fiberglass to try and keep out maximum moisture. fortunately the man's father whom I used to baby sit for used to deal duranautic boats in the area so he is very familiar with them!


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Quote:Originally Posted by Eric_Sfirst hit turned out to be a 13lb bass on a big plug. Very happy to see stripes again so I humped it then sent it on its way.

#10 floridajoe

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Posted October 05 2011 - 2:53 PM


My friend has the same boat and same problem.  He feels it is an electroyosis issues.  His transom was replaced under warranty but again is corroding.  His solution is to disconnect the battery when the boat is not in use.



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#11 PM Casting

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Posted October 06 2011 - 6:35 AM

I realize this is a 2 year old post that was added to recently but just as an FYI, Duranautic now uses an all aluminum transom and transom support bracket.

I bought a used 2007 that originally had a wood transom. The previous owner cracked it by hanging too large of an outboard. The Duranautic dealer replaced the wood with a new factory built aluminum one. The boat now has no wood in it at all.


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SOL #905

#12 Eric_S

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Posted October 06 2011 - 7:14 AM

Hey PM Casting,

What did it cost?


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#13 PM Casting

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Posted October 06 2011 - 11:28 AM

Eric S, I bought the boat from the Duranautic dealer after the repair was done, so I don't know the cost. The dealer told me the story behind the transom repair.
The previous owner hung a 40hp outboard on a boat rated for a 25hp max. I think just bouncing the extra weight on the transom while trailering is what probably craccked the wood. The aluminum replacement looks like an easy bolt on installation.


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SOL #905

#14 Eric_S

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Posted October 06 2011 - 2:18 PM

Oh ok, thanks. Was the dealer Bry's? I bought mine there in 2000. I'm having the same issue as Oneofour. I didn't realize they could just replace the transom. Maybe I'll inquire there as to the cost if that was the same place that did the repair.


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#15 PM Casting

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Posted October 06 2011 - 6:14 PM

yup, it was Jim Bry.


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SOL #905