Rust on Aluminum Pontoons?

[Olustee bus]

My friends toon is older than mine and we have them in the same lake. His has spots on the rear of each pontoon and if you scrape them off, there is an indention in the aluminum. A motor repairman said it was rust that attaches to the aluminum. I am guessing the rust is from the iron in the water.

Note that his is a freshwater lake we are on.

I am guessing that these are not barnacles.

Someone suggested painting the pondtoons at water level with spray truck bedliners such as Rhinospray.

What do you guys think is the best repair and prevention.

Thanks
Bus

[badmoonrising]

You want to use anti-fouling paint if corrosion is an issue. Trilux 33 is approved/recommended for aluminum.

[GXPWeasel]

I wouldn't use spray on truck bed liner stuff, just because that stuff is NEVER smooth if done correctly, and you are going to slow down your toon. It may not be by much, but it would be noticable. I would go with what BMR has on his if you want a paint type coating. If you don't want to change the look of the logs, then try some Shark Hide aluminum protectant. This will give you protection for 2-3 years without changing the look of the tube.

[Olustee bus]

Thanks for your responses. My buddy it taking it to a boat detailer who knew about the problem. He is going to put something like a zinc oxide on it. I will be googling that. I will do my own most likely. I may paint my toons with an anti-fouling paint once I do that. I think I will roll it on.

Got to get it up in the air somehow. I was thinking about 55 gallon drums and 4x4's safely shoring it up. Anyone do that.

[woolznaz]

Got to get it up in the air somehow. I was thinking about 55 gallon drums and 4x4's safely shoring it up. Anyone do that.

I've been wondering about that too -- how to lift the toon in the air and get the trailer out from under it to work on the logs. Any suggestions/experience with that that anyone can give would be appreciated.

[HandymanHerb]

Aluminum can't rust, and you only put zinc oxide on aluminum is when your going to paint it or seal inside of wings, you don't won't them to fail on you.

Sand the spot clean, start at 400 and go to 1000 grit

[wed]

Olustee, what color is the stuff that was scraped off. If it was red like rust then the aluminum may have been contaminated with small steel pieces during the manufacturing process (dont know why or how) if there was steel work in the same facility. Aluminum corrosion does not look like "rust"... most of what I have seen is usually either white or grey.

[HandymanHerb]

Now they could have done some welding near by and splashed the pontoon, that would rust, sand it out.

[jimrs]

Now they could have done some welding near by and splashed the pontoon, that would rust, sand it out.

I have to agree on this. If it was rust, which alum won't rust. Sand it out and just watch it. Like I have said before when we are not out on the boats we have too much time and try and find major problems to fix on them.

[Olustee bus]

Oh I know that aluminum will not rust, it will oxidize but this is only a white oxidization, out of water anyhow. Our water here is swamp fed so it has a lot of material in the water and a lot of tannin.

We have cleaned it off and the back of the log is very pitted. Not dangerously deep at this point. I was thinking Zinc oxide and then antifouling paint.

[badmoonrising]

Also make sure your anodes are in good shape, tannic acidic water will deteriorate them fast.

[wed]

Good point about the tannic acid and anodes. If the anodes are in bad shape that would be an indicator of galvanic action, possibly caused by exposure to acidic water, I wonder just how low the PH would have to get to cause problems and how long it might take to cause the pitting. Also is the boat moored in proximity to a steel bulkhead or maybe has had shore power hooked up to it? Just stuff to think about. It might simply be old age.

[WaltF]

Good point BMR.. if the anodes are gone, it would start eating at the toons...

[Olustee bus]

When you mention anodes, are you talking about the one on the motor or others. My motor has an anode, but are there others for the toons. If so, where and how would you install them.

I have decided to apply a product called Steelflex which is an epoxy coating to be used on aluminum and other marine applications.

I am going to pay a boat detailer to do it as my wife insists that I don't try to do it myself with it jacked up, supported by 4x4's and steel drums.

All of your comments are greatly appreciated.

Bus

[badmoonrising]

The anodes on the motor (in most cases) will protect the logs too. If not, flat anodes can be bolted on the step plate (usually where transducers are mounted on back of the logs). Anodes MUST have contact with both the metal hull and the water to work.