# Jon Boat Rebuild



## surfman (Dec 29, 2011)

Hi every one, I am new to the forum and will jump right in with my project. Hopefully you guys can help me steer clear of some of the disasters I am already encountering. I have lurked here a couple of times, so now I am a member and look forward to some good tips and pointers, here goes...

Okay, I have used pressure treated lumber on my jon boat not thinking anything of it and later was warned that it would corrode the aluminum. What? I don’t believe it. Then I thought about it a little and I know that copper is the main ingredient in the treatment to prevent fungus (rot) and I though maybe it would. I love PT wood and have used it with great successes in rebuilding my fiberglass boat. So it only seemed natural to use it in my tin boat. Well I had already used it before I was warned by those that had bad experiences. I questioned the danger and I was WRONG!

I walked out and started looking over the transom of my boat. I had attached a red neck jack plate, a piece of 2x10 pt to mount the motor on to raise it up mainly. I didn’t see any corrosion around it but I did notice some spots. See picture below.






What the heck? This is a hole corroded through the metal. Granted the metal is only 1/8” thick but still… This is in the area where the transom is reinforced with wood from the factory. So I pulled off my red neck jack plate and it looks like this…





Okay, this isn’t good I am going to go ahead and tear into this thing and see what I have to do to correct this problem. The transom is bolted, riveted and welded together for crying out loud. 





After looking it over I decide the only way to do this is from the top so I need to cut the weld…





Piece of cake, was easier than I thought using the skill saw and carefully working it backwards…










Oh yea, some pop rivets too…





The cap is off, yep, PT plywood…





So here is the inside aluminum cover piece…





The wood is in great shape, yea! But, I am going to throw it out now!


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## surfman (Dec 29, 2011)

Okay, so now I have some questions. What is the best thing to clean up this aluminum with?

I know there are holes in it but I don’t really care since they are all well above the water line. What I am thinking of doing is replacing the wood with a structural foam core material and then using some bed liner type stuff (not sure what yet) to basically glue the core material back to the transom where the wood was and then reassembling the thing back the way it was. I am thinking that some of the bed liner material will act as a glue and sealant and will help to restore the integrity of the transom. The liner stuff will not be seen since it will be under the core material and then the aluminum cover.


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## PSG-1 (Dec 29, 2011)

Use a stainless steel wire brush, or a SS wire wheel for an angle grinder (you'll probably have to order it from somewhere like Grainger or McMaster-Carr, as places like Lowes or Home Depot do not carry items like this) Use the brush or the wire wheel to remove as much oxidation as possible.

Once you have the oxidation removed, use phosphoric acid (Ospho) to etch off any remaining crud, then a rinse with some baking soda and then a final rinse with water. This will neutralize the oxidation process a good bit.

If you decide to repair the corrosion holes, there are a couple of ways to do it. You could use 5200. You can also use a product called "Ce-Ram-Grout" It's a 2 part ceramic grout that is used to repair corrosion on metal storage tanks, and on boat hulls. Also, there's a type of zinc-based solder that some people here have used to seal rivets (I forget what it's called)


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## surfman (Dec 30, 2011)

Thanks, instead of phosphoric acid what about muriatic acid, I have some of that.


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## PSG-1 (Dec 30, 2011)

Definitely NOT. Muriatic acid will probably dissolve the aluminum into alka-selzer.

Phosphoric acid is the active ingredient used in aluminum mag wheel cleaner, as it is designed to etch and clean aluminum without damaging it as other acids will do.


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## surfman (Jan 3, 2012)

Thanks, I asked that question of the supplier and he said it could potentially catch fire as well, he said definitely use the phosphoric acid. Looks like I will be using a product called Nida (sp) core which is a reinforced structural foam board. It costs the same or less than maring ply and I won’t have to epoxy coat it to protect it from rotting. I will be epoxy-ing it together though. I am also thinking of epoxy-ing the nida core to the transom skin as well, this will fix the holes and add more stiffness.


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## surfman (Jan 3, 2012)

Okay, been doing a little more research on the Nida-core panels since I wasn’t too familiar with it and found out it is a honey comb material, I think it will work great for the transom but not too sure about the decking. I just want to be able to screw it down and I am afraid the screws might just pull through. Don’t really want to put big fender washers down either. Now I am back to looking at Marine Ply and epoxy, more than I wanted to do. Will keep researching.

Anyone on this sight familiar with Nida-core?


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## surfman (Jan 4, 2012)

Well after further discussion with the folks that sell the nida-core board I talked to a different gentleman this time and he said the nida-core won’t work for what I want to do. In the transom he said it could and probably will crush from the motor clamps and torque of the motor. There is an aluminum skin and it may work but, it may not.

He recommended a denser foam core board that is designed for transoms. It is very expensive and not worth it for this project. The nida-core board is basically a coring material for decking and hulls and such where the load is spread out more. I could use it for the decking but you can’t screw it down since the screw will just pass through it, I would need to make a plug which I could do and it still needs to be glassed over, might as well use good old plywood.

Looks like I am right back where I started, oh well.


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## surfman (Jan 4, 2012)

Next question...

If I coat the original PT Plywood from the transom with epoxy will it seal the copper and protect the aluminum from reacting with it? Has anyone tried this before??

Thanks.


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## lckstckn2smknbrls (Jan 4, 2012)

Just use exterior grade plywood.


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## surfman (Jan 5, 2012)

Yea I know but I already have these pieces cut and fit and there is nothing wrong with them other than they were soaked at one time in a copper ion solution, eerrrr. I was hoping someone out there had tried this and it worked. Maybe I should be the first? It seems that if the copper is sealed up in the wood then it won't be able to get at the aluminum. But at this point it is a guess. I suppose I could try an experiment but corrosion is such a slow process.


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## Ictalurus (Jan 5, 2012)

lckstckn2smknbrls said:


> Just use exterior grade plywood.



X2


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## surfman (Jan 9, 2012)

Here is what I have decided to do. I have found out that there is a kiln dried pressure treated plywood that uses the old style treatment (prior to 2003). It is also a marine grade wood and is used by some plastic boat manufacturers in boat building. Let’s face it wood is pretty good stuff it if wasn’t for the fact that it will rot, eliminate that and you have a product that is almost unbeatable when you compare all aspects including value.

The problem with the treatment is that it is not friendly to metal like aluminum (we already know that) but, if you use a barrier you can reduce or eliminate the problem. It is also used by pontoon boat builders. They use it for decking without any kind of sealer and they claim it won’t hurt aluminum but, they do isolate it from the aluminum with some sort of barrier material, and that is what I am going to do. 

Basically, I am going to do what I originally proposed doing. I will use the original wood since it is the old style treatment, I will seal it and then bed it in gflex epoxy for the transom. For the decking, again I will use the wood I used before since it is still good and seal it with the epoxy, although I will not glue it to the stringers I will use something else as a barrier, I haven’t figured that one out yet. I will keep posting my progress for those that are interested or for those that want to call me an idiot. 

By bedding the transom wood in the gflex epoxy I will accomplish to things, one it will isolate the wood from the aluminum and two it will prevent water from being trapped between the wood and the aluminum, another potential for corrosion no matter what the material is.


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## randolph49 (Jan 9, 2012)

One thing that could help with your corrosion after you get all that stuff cleaned off your aluminum is to get a good self-etching primer and get a nice good coat of that on there. That will help out with protecting from corrosion im sure. Make sure you clean the aluminum really good with some rubbing alcohol and let it dry before you put the primer on if you go in that direction anyway.


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## surfman (Jan 9, 2012)

Right on r49, surface prep is the most important thing to applying any kind of coating. I am not sure however that I will need or want to apply a primer for the epoxy, I will see what the manufacturer recommends. Aluminum can be tricky stuff.


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## PSG-1 (Jan 9, 2012)

surfman said:


> Thanks, I asked that question of the supplier and he said it could potentially catch fire as well,



Hadn't thought of that hazard, but that is absolutely correct. Aluminum reacting with hydrochloric acid will release hydrogen gas. If there are any sparks, you could have a fire or an explosion, particularly if working under a shed or other structure where the gas can collect at the highest point.


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## surfman (Jan 23, 2012)

Okay here is a picture of the original wood transom. It is in fine condition even though it is around 18 years old. I am getting ready to start sealing it with a thinned epoxy so that it will soak into the wood the maximum amount.





Here is a picture after several coats of epoxy to seal up the wood. I am getting ready to final sand the epoxy for installation back into the boat.





Here is a picture of the inboard skin that was covering the wood transom after I have wire wheeled the crust off of it. Getting ready to clean it with detergent and then phosphoric acid cleaner/etcher.





Here is a shot of the transom after cleaning, and etching. Getting ready to epoxy in the wood.





Here is a shot of the outside, you can see the light shining through the bolt holes and unfortunately the corrosion holes as well. I will be gluing in the wood using West Systems G-flex thickened epoxy. This will seal the entire thing up and also prevent water from getting between the wood and the metal.





All glued up.









Started removing some of the decking I put in a couple years ago and the copper/aluminum corrosion is obvious here to. I believe this wood is the ACQ treated plywood as opposed to the CCA treated plywood used in the transom. It has a much higher copper content and is really not friendly to aluminum at all.





I think I am just going to go with marine ply for the deck since I don’t have a local source for the CCA marine plywood. I don’t want to spend the $$$ for shipping ply wood. I will just seal it with epoxy. It will last a long time.


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## surfman (Feb 1, 2012)

Okay a little more progress. I installed the inboard transom skin back into the boat this past week end.
G-flex epoxy 50-50 getting ready to mix it up.





Skin all glued up. Wow, is this thing solid, not flimsy like it used to be, can’t wait to get the top cap reinstalled, maybe next week.


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## JamesM56alum (Feb 1, 2012)

Great work, cant wait to see the finished product!


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## surfman (Feb 2, 2012)

The top cap is typical of a tin boat and lays on top with plenty of air space under it so that it is basically just a flimsy piece of sheet metal covering the wood below. I am going to lay a thick mat of fiberglass basically to fill in the space and then gluing it on as well. It will be as solid as a fiberglass transom when done.


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## surfman (Jun 4, 2012)

Okay a little more progress. I ended up getting some exterior plywood and epoxy coating it for the floor.






I then added some sand for non-slip surface.





I didn’t use the good stuff but it turned out okay.





The power plant arrived.





I didn’t take a pic of the final transom but it turned out great and solid as a rock.


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## surfman (Jul 20, 2012)

I finally got the motor mounted and got to run it for a few hours to break it in last weekend. She runs good. There are a few more things I want to do like build a front casting deck that will cover the battery and provide more room although, the standard deck is decent sized.

Port view, the duck silhouettes should bring the flocks in. 





Starboard View;


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