Filling in pitting before priming and painting

[Douglasdzaster]

Hello everyone, this is about my third thread since all this started. I found a Jon boat a while back to fix up and go fishing. I did the motor work first instead of checking other things like I should have being my first aluminum boat. I got it going and had been using it a lot.
The more I learned about aluminum I decided to pull the floor and clean under it. Looks like it was coated with either roofing material or bed liner I could be wrong. I noticed pitting in the cross members and decided to just redo the bottom if not paint the whole boat. The boat never leaked but I have found several patches and bumps it must have received on the near by river. Anyway water was staying under the floor after it got wet and was moist when I removed it so I think that’s the source of the corrosion. Unless the po used it in saltwater.
The more coating I removed the more I found. Some spots even looked like rust but aluminum doesn’t rust I’m told. So I kept on going taking it to bare aluminum. My questions now are what should I fill in the pitting and old screw holes with all corrosion is removed? I’d like to use something that will help the cross members stay strong if possible. Pitting on the actual floor is shallow thank goodness. And as I get to the bilge area there are places I can’t get to. What do I do there? It’s taking me over a month due to having to work outside with the weather here in Texas. I now have a cover that I use when not working on it and for when I’m finished. I pal on putting a floor back in that’s easy to remove and keep the bottom clean and dry. When I started this I was advised to leave it alone since I stay in freshwater but other things I found and had to redo that the po had done made me worry about the corrosion continuing to eat it like a cancer.. Thanks for any advice or opinions. Oh the actual holes in the cross members are from rusted broken screws that attached the floor which were rusted and I removed what was left of them with a Dremel tool.

 

[DaleH]

Concern - At just test a few spots, poke with ice pick, awl or drill tiny hole in any pit. Do you see any evidence of WHITE corrosion? Aluminum can develop a self-perpetuating corrosion phenomena called "preciptate chloride corrosion" ... usually on boats in saltwater use. On a SW boat I had, the total refurb of new transom skins in my signature, as the test hold got bigger and bigger, I was still seeing a white layer inside the tin. You might need good light and a magnifying glass.

If 'no' to the above, and whereas freshwater use only, my best advice would be to keep her clean and dry, as water or moisture helps cause where tin can corrode. You might want to scrub all areas with white vinegar on a copper scrubbie, then rinse, as the etches the tin back to a self-protecting oxidized layer.

If pits OK, I think 'clean & dry with fresh air' (make sure cover has ways to vent or air out, etc., is your best option! You could fill the pits with a good epoxy, but then the area would need to be primed beforehand and painted over afterwards (epoxy can't survive sun exposure ... ) and it really wouldn't add any strength anyway IMHO, so I'd likely not even bother.

 

[Douglasdzaster]

Concern - At just test a few spots, poke with ice pick, awl or drill tiny hole in any pit. Do you see any evidence of WHITE corrosion? Aluminum can develop a self-perpetuating corrosion phenomena called "preciptate chloride corrosion" ... usually on boats in saltwater use. On a SW boat I had, the total refurb of new transom skins in my signature, as the test hold got bigger and bigger, I was still seeing a white layer inside the tin. You might need good light and a magnifying glass.

If 'no' to the above, and whereas freshwater use only, my best advice would be to keep her clean and dry, as water or moisture helps cause where tin can corrode. You might want to scrub all areas with white vinegar on a copper scrubbie, then rinse, as the etches the tin back to a self-protecting oxidized layer.

If pits OK, I think 'clean & dry with fresh air' (make sure cover has ways to vent or air out, etc., is your best option! You could fill the pits with a good epoxy, but then the area would need to be primed beforehand and painted over afterwards (epoxy can't survive sun exposure ... ) and it really wouldn't add any strength anyway IMHO, so I'd likely not even bother.

I could see white corrosion in the pits and a Nyalox brush on a drill cleaned it out to the metal. At least as far as I could see. I’ll test several areas and use a magnifying glass. While removing the coating there where spots that had moisture under the coating. Several of the channels where clogged with all kinds of things. I also ran a flexible magnet in each cross member and found screws,nuts,hooks, and something’s so rusted they where unidentifiable. I have some Krudd
Kutter metal clean and etch I was going to use. It’s supposed to remove any oil etc. and etch at the same time. I’ll go with vinegar if that’s better.
I was also going to prime and paint for protection. Do you think the oxidized layer is just as good? (That would make things a lot easier and affordable.)Lol If it makes a difference I’m putting a floor back in over it.It will be easy to remove whenever the inside does get wet and to clean.
The main reason for the floor is , the boat is a 1983 Monark and the floor will help keep pressure off of the old rivets. Like I said it hasn’t leaked but I did find a few patched spots and the boat has a thick coat of what I think is black epoxy underneath.
Thanks for replying. I appreciate any wisdom shared. I’ll report back about the test spots. It may be a day or two looking at the forecast.

 

[Douglasdzaster]

Concern - At just test a few spots, poke with ice pick, awl or drill tiny hole in any pit. Do you see any evidence of WHITE corrosion? Aluminum can develop a self-perpetuating corrosion phenomena called "preciptate chloride corrosion" ... usually on boats in saltwater use. On a SW boat I had, the total refurb of new transom skins in my signature, as the test hold got bigger and bigger, I was still seeing a white layer inside the tin. You might need good light and a magnifying glass.

If 'no' to the above, and whereas freshwater use only, my best advice would be to keep her clean and dry, as water or moisture helps cause where tin can corrode. You might want to scrub all areas with white vinegar on a copper scrubbie, then rinse, as the etches the tin back to a self-protecting oxidized layer.

If pits OK, I think 'clean & dry with fresh air' (make sure cover has ways to vent or air out, etc., is your best option! You could fill the pits with a good epoxy, but then the area would need to be primed beforehand and painted over afterwards (epoxy can't survive sun exposure ... ) and it really wouldn't add any strength anyway IMHO, so I'd likely not even bother.

Thank you Dale. I wanted to let you know I appreciate your advice. I put a tiny engraving bit for soft metal on my Dremel and strarted checked pits. I just thought I had all the corrosion out! It’s been tedious but with a magnifying glass I’ve been chasing the corrosion until I hit good metal. It’s made some of the pits a little bigger but not any worse than the rest. I’m crossing my fingers I don’t find one that there’s no end to or goes through the bottom.
If I make it ok. Im going to use a degreaser cleaner I found then give it an acetone wipe down (probably going overboard) Then I’m thinking of going ahead and putting a coat of polish and then some Star Brite protectant. No epoxy. I’ll keep it clean and dry and every so often give it a deep clean and reapply polish and protectant. I’ll have a floor over it that will be easy to remove often so no moisture or grime gets started.

 

[DaleH]

... If I make it ok. Im going to use a degreaser cleaner I found then give it an acetone wipe down (probably going overboard) ...

I'd just use cheap white vinegar and a copper scrubbie brush/pad. Rinse well. The vinegar will 'etch' the tin. Clean and dry will go a looooong way to keep her ship-shape for you!

Good luck! You owe us pictures when done ...

 

[Douglasdzaster]

Dale, do I keep cleaning the pits as I’ve been doing or use the vinegar and copper scrub now? I’ve tried vinegar to remove the white corrosion from in the pits and it didn’t. Does vinegar neutralize it though? I’ve also tried baking soda with and without vinegar.
Heading out now to apply more vinegar and scrub with the copper and check that out.
I have some Krudd Kutter metal clean and etch that says it’s safe for aluminum but haven’t got desperate enough to try it. Don’t know if I should trust it. Lol
I don’t know if you want pictures. Lol It’s going to be scratchy because I had to get aggressive removing the coating and I’m just doing it to fix the corrosion not going to 500 grit wet sand , lol. I’m ready to get back on the water. Besides the old boat could use a complete make over but that’s coming later down the road.

 

[Douglasdzaster]

Well I ended up polishing the inside of the boat so I could keep an eye out for corrosion. It’s been 7 months and It’s in good shape.
I just posted a new post with a question about the way I’m thinking of re coating it. So look for my question about painting post.
Thanks

 

[WNCMapper]

Hello everyone, this is about my third thread since all this started. I found a Jon boat a while back to fix up and go fishing. I did the motor work first instead of checking other things like I should have being my first aluminum boat. I got it going and had been using it a lot.
The more I learned about aluminum I decided to pull the floor and clean under it. Looks like it was coated with either roofing material or bed liner I could be wrong. I noticed pitting in the cross members and decided to just redo the bottom if not paint the whole boat. The boat never leaked but I have found several patches and bumps it must have received on the near by river. Anyway water was staying under the floor after it got wet and was moist when I removed it so I think that’s the source of the corrosion. Unless the po used it in saltwater.
The more coating I removed the more I found. Some spots even looked like rust but aluminum doesn’t rust I’m told. So I kept on going taking it to bare aluminum. My questions now are what should I fill in the pitting and old screw holes with all corrosion is removed? I’d like to use something that will help the cross members stay strong if possible. Pitting on the actual floor is shallow thank goodness. And as I get to the bilge area there are places I can’t get to. What do I do there? It’s taking me over a month due to having to work outside with the weather here in Texas. I now have a cover that I use when not working on it and for when I’m finished. I pal on putting a floor back in that’s easy to remove and keep the bottom clean and dry. When I started this I was advised to leave it alone since I stay in freshwater but other things I found and had to redo that the po had done made me worry about the corrosion continuing to eat it like a cancer.View attachment 110843View attachment 110842View attachment 110841. Thanks for any advice or opinions. Oh the actual holes in the cross members are from rusted broken screws that attached the floor which were rusted and I removed what was left of them with a Dremel tool.

thanks for the post, I wasn't planning on complete redo either, but I'm really enjoying it and have a lot to learn.

 

[Douglasdzaster]

thanks for the post, I wasn't planning on complete redo either, but I'm really enjoying it and have a lot to learn.

Man I’m still not finished. After leaving it covered with the polish for a few months I inspected every little spot and it still looked like it did the day I polished it.
So I built a new flooring system that I can remove when I want to clean and inspect the bottom. That lead me to finding fasteners on the boat that were done wrong and corroding. Then what the heck may as well completely re wire it and add a few things as I go.
Everything but paint the entire boat. I painted the bottom where I didn’t put flooring. Transom area , storage etc. just for protection for now. I got three different shades of gray around in the boat. Think after I use it a while and my wife calms down I’m going with battleship gray. For now it’s a 1985 looking tin boat with almost everything redone. Lol

 

[Douglasdzaster]

thanks for the post, I wasn't planning on complete redo either, but I'm really enjoying it and have a lot to learn.

WNCMapper, I should have told you this in my first reply. If you have anything come up that you think I could help you with don’t hesitate to ask. I may have pictures or a do not do what I did. Keep having fun with it but be careful you might get carried away like I did. I just told my wife yesterday I had everything I needed to finish this part and wouldn’t be spending anymore on it. I went in my shop this morning and I check my deep cycle trolling motor battery once a week and put it on float charge when it looks like it’s starting to dip. I put the multimeter on it and down 50%. It’s only five years old. I’ve always kept a full charge and charged it as soon as I got home from every trip. But I’m not going to take a chance on it laying down on me halfway through fishing. I use my trolling motor a lot and it’s a security thing too knowing if the Yamaha quits I can ride in on the tm. Wouldn’t be the first time. Happened a few times way back when I was a single bass fisherman. Lol
Good luck on yours. Do you have a post going about it? I’ll look it up.

 

[St.Clair Flatsrat]

Hello everyone, this is about my third thread since all this started. I found a Jon boat a while back to fix up and go fishing. I did the motor work first instead of checking other things like I should have being my first aluminum boat. I got it going and had been using it a lot.
The more I learned about aluminum I decided to pull the floor and clean under it. Looks like it was coated with either roofing material or bed liner I could be wrong. I noticed pitting in the cross members and decided to just redo the bottom if not paint the whole boat. The boat never leaked but I have found several patches and bumps it must have received on the near by river. Anyway water was staying under the floor after it got wet and was moist when I removed it so I think that’s the source of the corrosion. Unless the po used it in saltwater.
The more coating I removed the more I found. Some spots even looked like rust but aluminum doesn’t rust I’m told. So I kept on going taking it to bare aluminum. My questions now are what should I fill in the pitting and old screw holes with all corrosion is removed? I’d like to use something that will help the cross members stay strong if possible. Pitting on the actual floor is shallow thank goodness. And as I get to the bilge area there are places I can’t get to. What do I do there? It’s taking me over a month due to having to work outside with the weather here in Texas. I now have a cover that I use when not working on it and for when I’m finished. I pal on putting a floor back in that’s easy to remove and keep the bottom clean and dry. When I started this I was advised to leave it alone since I stay in freshwater but other things I found and had to redo that the po had done made me worry about the corrosion continuing to eat it like a cancer.View attachment 110843View attachment 110842View attachment 110841. Thanks for any advice or opinions. Oh the actual holes in the cross members are from rusted broken screws that attached the floor which were rusted and I removed what was left of them with a Dremel tool.

I believe that the pitting was caused by electrolysis. Aluminum should never come in contact with other metals. I made the mistake of placing my first jon boat on top of my dog kennel with out sitting on 2X4’s. The galvanized kennel posts on the kennel caused the Jon boat gunnel rails to pit. Fortunately I caught it before holes would have developed. You might want to research this online. Metallurgy.

 

[St.Clair Flatsrat]

If you are going to prime and paint I recommend that you use a metal etching primer. I recently utilized a spray paint called Montana. It sprays on thick and does not run or splatter. This is the spray paint that taggers use on trains and buildings for their art work

 

[Douglasdzaster]

I believe that the pitting was caused by electrolysis. Aluminum should never come in contact with other metals. I made the mistake of placing my first jon boat on top of my dog kennel with out sitting on 2X4’s. The galvanized kennel posts on the kennel caused the Jon boat gunnel rails to pit. Fortunately I caught it before holes would have developed. You might want to research this online. Metallurgy.

I thought of that as well with the old signs that where used as part of the floor. But I still have those and I’m pretty positive they’re aluminum. No magnet will stick to them and the bare sides have that hazy look that aluminum gets to protect itself. I polished an area and didn’t put anything on it and in no time oxidation was back. The pitting in the ribs was definitely galvanic corrosion where they used the wrong screws.
It hadn’t been wet for a long time and when I pulled that floor apart there was a ton of moisture trapped between the plywood and the signs so it had been staying wet. But the signs didn’t corrode like the boat which made me wonder if the previous owner had it in saltwater any and never bothered to pull the floor and clean it. Another thing is that plywood was treated and that will cause havoc with aluminum. It’s remained a mystery as far as the exact culprit. I take that back. It was the owner. Or maybe it was his first aluminum boat like me and he didn’t know better. Since I finished the floor I found almost all the screws/fasteners were wrong. There were corroded areas in quite a few places. I replaced everything mostly with small aluminum Rivnuts where the holes were already big. Like the stern light base. I saw rust on top of the screws and when I removed it they were eating away at the aluminum under it.
The boat was neglected bad. The motor was the first thing I tackled when I got it. I didn’t know what all was wrong with the rest of the boat until I had gone through the motor and got it running. There wasn’t even a fuel filter on the thing. The head had some corrosion which sent me back to thinking saltwater environment. After installing a good fuel system I went to check the thermostat and as soon as I put pressure on the first bolt the head just twisted off like it was soft led. I felt so sick. Now I had a bolt broken off in the head. Instead of drilling I didn’t touch it other than trying penetrating fluid to try and get it out. I stopped before I messed it up more and found a guy here in town that owns a shop and custom builds hot rods and does restoration. He’s also a retired machinist. HELLO! I drug the boat to his shop with my hat in my hand. I just new he was going to tell me to leave the premises. He helped me out by staying after he closed and I couldn’t stand it so I went back and watched him patently try one thing then another and after an hour or so he had it ready to put my new bolt from Yamaha into.
Yeah this has been an adventure. Got the new floor in and now finishing up completely re wiring the boat with the proper stuff.
I new I was getting an older boat that I’d have to do some work to. It has its dents but didn’t leak so I drug it home. Found the patched holes afterwards which I redone.
Right after I got it home I found a nice cast net in it so I text the guy and let him know I would meet him somewhere so he could have it back. He thanked me but I never heard back. Now I know why. I didn’t pay a whole lot for it. Also didn’t have knowledge of owning a tin boat. But I do now. Ask me anything. Especially wiring right now that I can’t seem to get back to so I can finish and start fishing again.

 

[Douglasdzaster]

If you are going to prime and paint I recommend that you use a metal etching primer. I recently utilized a spray paint called Montana. It sprays on thick and does not run or splatter. This is the spray paint that taggers use on trains and buildings for their art work

Since this post I’ve done everything but repaint the top side. The floor got bed liner then I added foam and a removable floor.
I’ll have to check out Montana paint. Never heard of it. Thanks.

 

[Zlakin]

When removing pitting from aluminum boats with sanding alone, for deep pits that cannot be smoothed out, use an aluminum filler or putty to fill in the depressions.

 

[Douglasdzaster]

When removing pitting from aluminum boats with sanding alone, for deep pits that cannot be smoothed out, use an aluminum filler or putty to fill in the depressions.

Most of the pits where small. I used an aluminum filler in the bigger pits. I finished with a Dremel and magnifying glass to make sure I got all the corrosion with the bit then gave it an aluminum boat wash. Dried it and applied aluminum boat polish for bare aluminum. Waited 3 months keeping the boat covered and inspecting it time to time.
At the end of three months I removed the cover and it looked new and shiny like the day I applied the polish. Left it uncovered a few days and then inspected it again even with magnifying glass and no signs of any corrosion coming back. So I stripped all the polish off etched it. Used Krudd Kutter metal clean and etch for aluminum. Primed it then truck bed liner. If the liner starts to flake or chip I’ll remove it and and probably use an epoxy paint.
Then since the ribs are 2” I used 2” closed cell foam board between the ribs and built a floor system I can easily remove to clean and inspect the bottom. Built three sections. I took 15/32 untreated plywood and put several coats of Total Boat penetrating epoxy on it. Diluting the first 50/50 with acetone so it really soaked in. Then topped it with marine carpet that I installed snaps for so I can remove it then the plywood and I’m looking at the aluminum.
The flooring has held up solid and took a lot of weight out of the boat. When I’m solo I have to keep an eye on the rpms at wot because it wants to go past the limit. I have another prop I’m going to try.
Last inspection the aluminum still looked good it’s about time to do it again.

What I started with , one of the treated 3/4” plywood I found. Rest of the floor was old signs and the day I removed the flooring it was full of moisture. Boat was sitting in the sun for days without rain (typical Texas summer) so it must have stayed wet all the time. It now lives under a good cover I invested in.

 

[Martin Tidwell]

Most of the pits where small. I used an aluminum filler in the bigger pits. I finished with a Dremel and magnifying glass to make sure I got all the corrosion with the bit then gave it an aluminum boat wash. Dried it and applied aluminum boat polish for bare aluminum. Waited 3 months keeping the boat covered and inspecting it time to time.
At the end of three months I removed the cover and it looked new and shiny like the day I applied the polish. Left it uncovered a few days and then inspected it again even with magnifying glass and no signs of any corrosion coming back. So I stripped all the polish off etched it. Used Krudd Kutter metal clean and etch for aluminum. Primed it then truck bed liner. If the liner starts to flake or chip I’ll remove it and and probably use an epoxy paint.
Then since the ribs are 2” I used 2” closed cell foam board between the ribs and built a floor system I can easily remove to clean and inspect the bottom. Built three sections. I took 15/32 untreated plywood and put several coats of Total Boat penetrating epoxy on it. Diluting the first 50/50 with acetone so it really soaked in. Then topped it with marine carpet that I installed snaps for so I can remove it then the plywood and I’m looking at the aluminum.
The flooring has held up solid and took a lot of weight out of the boat. When I’m solo I have to keep an eye on the rpms at wot because it wants to go past the limit. I have another prop I’m going to try.
Last inspection the aluminum still looked good it’s about time to do it again.
View attachment 116814View attachment 116815View attachment 116816View attachment 116817View attachment 116818
What I started with , one of the treated 3/4” plywood I found. Rest of the floor was old signs and the day I removed the flooring it was full of moisture. Boat was sitting in the sun for days without rain (typical Texas summer) so it must have stayed wet all the time. It now lives under a good cover I invested in.

 

[Zlakin]

Spray polish and wax evenly. Use an electric polisher for quicker results. Combine polishes and wax to manage corrosion and prevent pitting. You're done removing pitting from aluminum boat.

 

[sonny1]

Big fan of the stainless steel wire brush. 4 inch grinder and a drill fitted with wire brushes can work wonders. Then etch and repeat. All of the white powder and blackish garbage has to be removed prior to paint. If your leaving it bare a good quality wax is a must do.

 

[Douglasdzaster]

Big fan of the stainless steel wire brush. 4 inch grinder and a drill fitted with wire brushes can work wonders. Then etch and repeat. All of the white powder and blackish garbage has to be removed prior to paint. If your leaving it bare a good quality wax is a must do.

I used new stainless steel wire brushes. Found the grinder wheel I purchased to be to aggressive . Then I found Nyalox wheels for my drills and those where awesome. I finished with my Dremel and new stainless steel scribing bits and magnifying glass. Then etched after washing and applied a good coat of polish. Then let it sit for around 3 months checking for corrosion. When I was satisfied I stripped it back down primed and covered with truck bed liner. Then the new floor in the above pics.
I used none treated plywood and soaked it with several coats of penetrating epoxy then carpet installed with snaps.
I can pop the floor out anytime to clean and inspect the boat.
Been several months now as I redid the rest of the boat. Just made it’s third trip and the floor is way lighter and solid.