Sealing pits in pontoon - on the cheap

[pnut]

I posted about the pits in my pontoon toons:

viewtopic.php?f=2&t=4885

I very much appreciate the opinions and advice received. I have little time, and little money to put into the boat and am only interested in sealing the pits. It will be on a lift and only in the water on the weekends. Everyone else I know on the lake has no problems with pitting on growth or corrosion, this is a very mild lake which is unlikely to advance the problem. At this point I only need to seal what is there knowing it will not continue worse.

So here is the question:
What can I apply to seal up the pitting, easily and inexpensively? This assumes I do not remove what coating is there (yes I know). My thoughts so far:

- Sharkhide: seems to be a protectant and not really a sealer
- 3m 5200 sealer: would be kind of ugly and icky but should worl
- hardward store silicone sealant: like above but can be had in clear
- Paint: cheap but maybe not last
- other: ??

[badmoonrising]

First, since someone put copper based paint on the logs, ALL OF IT MUST COME OFF...I can't stress that any more than I did in your original post. Corrosion is happening because you have copper in contact with the aluminum. It will get worse, doesn't matter if it's in the water a few days per week or sitting on the trailer. Trailer bunks are almost always damp and that's all you need to keep the process going..even high humidity will keep it going. Covering it up will accelerate the corrosion. You have dissimilar metals and the aluminum is suffering being the softer metal. Only way to prevent the holes from getting worse is to sandblast all the copper based paint off down to the bare metal and fill the holes with epoxy, use an etching primer and repaint with a paint safe for aluminum hulls like Biolux (you should only need 2 quarts). Paint will not adhere to 3M 5200 or silicone. Sharkide is a metal protectant, used only ABOVE the waterline and will do nothing over paint.


Sorry but that's what must be done unless the person responsible for using the wrong paint steps up and reimburses you for his incompetence.

[pnut]

First, since someone put copper based paint on the logs, ALL OF IT MUST COME OFF...I can't stress that any more than I did in your original post. Corrosion is happening because you have copper in contact with the aluminum. It will get worse, doesn't matter if it's in the water a few days per week or sitting on the trailer. Trailer bunks are almost always damp and that's all you need to keep the process going..even high humidity will keep it going. Covering it up will accelerate the corrosion. You have dissimilar metals and the aluminum is suffering being the softer metal. Only way to prevent the holes from getting worse is to sandblast all the copper based paint off down to the bare metal and fill the holes with epoxy, use an etching primer and repaint with a paint safe for aluminum hulls like Biolux (you should only need 2 quarts). Paint will not adhere to 3M 5200 or silicone. Sharkide is a metal protectant, used only ABOVE the waterline and will do nothing over paint.


Sorry but that's what must be done unless the person responsible for using the wrong paint steps up and reimburses you for his incompetence.

I've seen some various types of anti fouling paint including trilux33, specifically made for aluminium. How are you aware this is copper specific?

Thank you, I value your opinion.

[Bamby]

BMR is probably and quite possibly right in his advise. The issues you are having with your pontoon are all characteristics of the "wrong bottom paint" being applied to your pontoons. Maybe it would be best to send a sample of the paint out for testing "and see" before maybe making it bigger issue that would still haft to be dealt with.

[pnut]

Another follow up..... question

Is there an easy way to tell if primer was used? Or that it really is a copper based paint? I can't tell from my photos really. Here is a VERY close up shot. I do see whitish yellow stuff under the black, including in the old pits. Maybe this is primer? Dunno.



Let me explain the pitting further..... When I bought the boat there was growth of barnacles or something similar (not zebra mussels) - looking almost like calcium deposits, on the tubes. When I picked it up, the dealer had cleaned the tubes of the stuff, revealing the above paint pitting (he should have painted higher clearly). Whatever was growing had eaten into the tubes, probably from corrosive deposits. It appears from the pitting which was painted over, that this was the case before as well, that something was growing, was removed, then the paint applied.

My real concern at this point as mentioned is that no primer was used, AND/OR copper anti fouling paint was used. At this point I would much like to determine these things. HOW CAN I DETERMINE THESE 2 THINGS? I don't want to sink time and money into it more than I have to, but I also don't want the tubes to fall apart in a year. If there is primer or the correct paint was used, then I am good, I expect no growth or corrosion from my lake.

I plan to put some basic marine paint on the open pits just so I can get the boat into the water for the family, while I read and research this problem of my toons, to determine if I need to do anything.

Comments or direction appreciated.

[big daddy]

pnut, seriously bro listen to your elders. The damage is done and irreversible YOU HAVE TO SAND BLAST OFF WHAT IS THERE. It is apparent that some idiot has tried to "buy some time" by painting over the older pits repeatedly and ITS NOT WORKING! The "easy" way never works if it did I would have my children do all of my work. You really only have scrap aluminum. If the rest of the boat is in good shape then consider replacing the toons only with used or new.

Maybe Duct Tape will buy you some time. Good Luck

[WaltF]

Your metal seems to be disappearing.
You can either take off what is eating it or let it go until it is all gone.
Youre choice.

Course you could ask the question again and see if you get a different answer...

[Ghost Rider]

Looks like it is what BMR said. The two diffrent types of metal are causing the problem. The paint has to come off and the logs need to be cleaned and sealed.

[pnut]

Don't get me wrong, I appreciate the advice, and if the opinion is right that this is copper based paint with no primer, that I must remove the paint and seal the tubes. I agree with this, regardless of the required pain.

What I am trying to determine is how it is known that it is a copper based paint, and that there is no primer. You guys are not here to see it, so I have to rely on the pictures to provide the opinions on these two items.

I am interested to hear BRM's opinion on these two items.

Thank you.

[HandymanHerb]

All that pitting tells you have battery action going on, you have a chemical reaction going by two differant metals, and eating the aluminum.

If it wasn't the wrong stuff your toons would look like BMR's in great shape with no pits in them.

[big daddy]

No B. M. R. here but if they had used a anti fouling paint that is used on aluminum, from what I had to do, there would be three coats of primer. Each being a different color. For me it was a coat of gray then white then gray again with the anti paint being applied to the third coat just before it tacked off. Sorry I cant remember all the names and numbers of the products. As a guess, cause I'm not there, judging by the pics I do not see the different colors of primer in your pits.

The deterioration of your toons is exactly what happens when you have two dissimilar metals, copper in the bottom paint and the aluminum haul, mixed/touching each other. It is called electrolysis.

You have a bad case of the pits

[badmoonrising]

Best way to tell if it's a paint non-compatibility issue is to scrape a little off. White, chalky substance is aluminum deteriorating caused by contact with a dissimilar metal. Anti-fouling bottom paint meant for fiberglass applications ONLY contains copper these days, gone are the days of toxic poisons to prevent marine growth. It can't be anything else. Putting that boat in water after band-aiding it is asking for trouble. Some of your pits appear to be painted over. They are most likely deep enough that they are all the way through. Whoever owned the boat previously no doubt either had water in the tubes or realized he screwed up and sold the boat. Around here in the Chesapeake that boat would sink in a single season. Freshwater, maybe 2-3 tops depending on PH levels.

I know this because:

1) I restored several aluminum boats over the years (23 years experience working with aluminum boats), all have bottom paint because I use them in brackish or saltwater. All have 2 coats of Interlux Primocon followed by 1 coat of Interlux Biolux. No hardware other than stainless steel, period. Everything else accelerates corrosion on aluminum.

2) I spoke with Interlux Prior to allowing my marina to paint my pontoon when it was new and was advised to use non copper paint. I touch up every year. The hull is spotless/corrosion free due to it having the correct paint. You can call them and send them the same photo you posted here and they will tell you the exact same thing I am telling you.

3) From looking at you pics, there is no gray color anywhere. Gray etching primer is tough stuff and remains intact unless: The metal fails underneath or it is blasted off. Period.

Trust me, that's the problem and there's no cheap fix.

[pnut]

Thank you.

I am going to a local Marina today to see if they can do the work, or can point me the right way.

Bear with me, I am an engineer by trade and like to know the details behind this

1) If the paint is causing the pitting, why would the pitting be above the paint line, and worse on the back half of the boat? I did some research in the last day on the internet and I can say with fair certainty that there were barnacles all over the engine area, and at the water line (which was above the paint).

2) Do barnacles cause pitting?

3) Is there anything wrong with painting over pitting with a standard marine paint (intended for below the water)?

Best way to tell if it's a paint non-compatibility issue is to scrape a little off. White, chalky substance is aluminum deteriorating caused by contact with a dissimilar metal. Anti-fouling bottom paint meant for fiberglass applications ONLY contains copper these days, gone are the days of toxic poisons to prevent marine growth. It can't be anything else. Putting that boat in water after band-aiding it is asking for trouble. Some of your pits appear to be painted over. They are most likely deep enough that they are all the way through. Whoever owned the boat previously no doubt either had water in the tubes or realized he screwed up and sold the boat. Around here in the Chesapeake that boat would sink in a single season. Freshwater, maybe 2-3 tops depending on PH levels.

I know this because:

1) I restored several aluminum boats over the years (23 years experience working with aluminum boats), all have bottom paint because I use them in brackish or saltwater. All have 2 coats of Interlux Primocon followed by 1 coat of Interlux Biolux. No hardware other than stainless steel, period. Everything else accelerates corrosion on aluminum.

2) I spoke with Interlux Prior to allowing my marina to paint my pontoon when it was new and was advised to use non copper paint. I touch up every year. The hull is spotless/corrosion free due to it having the correct paint. You can call them and send them the same photo you posted here and they will tell you the exact same thing I am telling you.

3) From looking at you pics, there is no gray color anywhere. Gray etching primer is tough stuff and remains intact unless: The metal fails underneath or it is blasted off. Period.

Trust me, that's the problem and there's no cheap fix.

[badmoonrising]

1) From your pics, it appears worse below the waterline and gradually better above. If you coat aluminum with copper and expose it to water (especially saltwater) you will get damage above the waterline, this is called electrolysis. The damage is so severe the boat also may have sat in a marina (in water) where there was also an electrical issue (leakage into the water, very common). This will damage metal hulls, painted or not. Aluminum hulls painted with copper, you will see rapid deterioration.

It's worse on the back half of the boat because:

Pontoons sit lower in the water at the stern or your boat was sitting close to an electric leak and the stern happened to be closer to it. Most people back into slips. Most slips have their electric pods here as well. A faulty GFI or small electrical leak into the water can cause severe problems with nearby metals (boats, dock hardware, anodes, outdrives, etc.)

2) No...I get a few barnacles every season. Barnacles only occur in tidal waters (saltwater, brackish water up to a certain ppm of salt). We only get them bad in the Upper Chesapeake in drought years...didn't think you were in waters like this ? Anyway, they do not cause pitting on metal or fiberglass hulls. They can damage wood hulls though. Besides, they can only attach themselves below the waterline.



3) I suspect after you remove the copper paint you will have a ton of holes. These are going to have to be fixed, preferably by a competent welder. No "sealer" other than marine epoxy is going to be a permanent fix. Standard marine paint contains copper...you MUST use paint containing zero copper. Stripping the old paint off and painting over pits that have not caused holes is going to prevent further damage, but if it were mine I'd fix/fill them all. End result of painting over the pits is that it's going to look horrible, and every pit is a potential leak down the road.

Once again - strip every last bit of the copper paint off. Fix the holes/pits. Paint with 2 coats (minimum) of etching primer. Follow that with 2 coats of Biolux or equivalent.

This is for yours and anyone else's safety that you take on your boat. Back in the day I saw a guy limping in to dock on a sunken port log, not a fun day for him and his family.

[FloterBoter]

i wonder if a couple used toons for a 22 footer might be cheaper than all that labor.
just sayin...