Electrolysis

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C1gator
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Electrolysis

Post by C1gator »

For you guys that run in the salt, how is your boat holding up?...I have seen the affects of one airboat with this issue, So I was wondering if some of the builders do something to the hull to prevent this, or is there anything that can be done...Thanks

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Frog
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Re: Electrolysis

Post by Frog »

install zincs, also coat your bottom. If you have poly hopefully you coated the bottom prior. Pull it out of the water!
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glades cat
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Re: Electrolysis

Post by glades cat »

Different aluminum alloys have varying resistance to saltwater corrosion. Usually the harder 7xxx alloy does poorly because of its high zinc content. The 5xxx alloys with magnesium and silicon are usually standard for marine use. Beware of what metals are next to each other. One will be more sacrificial than the other...and that one will erode (galvanic corrosion). Electrolysis involves stray current. Galvanic corrosion involves dissimilar metals in the presence of an electrolyte.
The Glades rock boats with a sheet of stainless were known for pitting the aluminum.
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Duece
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Re: Electrolysis

Post by Duece »

glades cat wrote:Different aluminum alloys have varying resistance to saltwater corrosion. Usually the harder 7xxx alloy does poorly because of its high zinc content. The 5xxx alloys with magnesium and silicon are usually standard for marine use. Beware of what metals are next to each other. One will be more sacrificial than the other...and that one will erode (galvanic corrosion). Electrolysis involves stray current. Galvanic corrosion involves dissimilar metals in the presence of an electrolyte.
The Glades rock boats with a sheet of stainless were known for pitting the aluminum.
I have a question on this as well. Was doing some research and came across this post. I have a jon boat that is getting some pitting in the bottom that I believe to be electrolysis, but seeing as how I have little clue what I'm talking about I thought I'd ask on here. The boat does have electric start and a battery. The boat DOES NOT stay in the water, gets used little and sits on the trailer, but IS IN the salt air (it's parked on the trailer less than 50 yards from the river which is salt/brackish). We store the boat with the ground wire unhooked on the battery. About 3 years ago the bottom began to leak. They were small pinholes and it appears they are where the bottom of the boat is in contact with the runners on the trailer. The runners have carpet on them. Is this electrolysis? If so, I'm assuming unhooking the battery does nothing to prevent it then. My father is currently in the process of putting polymer on the trailer runners so that the boat doesn't sit against wet carpet for extended periods of time. What are the solutions to this situation? Should we just ditch the hull and get a new one, as we are probably going to deal with this for the life of the boat or is there a way to slow/stop it? Thanks.

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bkmail
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Re: Electrolysis

Post by bkmail »

Deuce,
Get the boat off the wet carpet. Adding plastic slides will eliminate this issue.
Your suspicion was correct. The batteries have nothing to do with it.

Also note that treated wood will react with Aluminum too. Use plastic slides or rollers on the trailer.
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One Eyed Gator
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Re: Electrolysis

Post by One Eyed Gator »

If you put nice new poly on the bunks be very careful backing down a ramp with the wench strap unhooked. Boat could slide right off.

I watched this happen at an airboat fishing tournament one sank at the ramp the came off before the water and slide to the waters edge.

Not funny but at the same time funny as hell only because both boat owners were being jackazz's

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glades cat
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Re: Electrolysis

Post by glades cat »

If you want to repair the boat consider Fasco Fas-steel. It is a metalized epoxy that has great adhesion and hardness.
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barhopper
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Re: Electrolysis

Post by barhopper »

Have a friend with a big sea ark that is rotten. That's as close as I can describe it. There are places on the transom you can put your finger through. I don't what caused it but it's mainly used in the saltwater. It fairly old also but it's been building up for years.

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Duece
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Re: Electrolysis

Post by Duece »

barhopper wrote:Have a friend with a big sea ark that is rotten. That's as close as I can describe it. There are places on the transom you can put your finger through. I don't what caused it but it's mainly used in the saltwater. It fairly old also but it's been building up for years.
This boat is an 05' so I don't consider that "old" in the boat world (considering my dad's airboat is a 94' and his flats boat is a 91' lol), but it started happening about 3 years ago and appears to be getting worse.

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SWAMPHUNTER45
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Re: Electrolysis

Post by SWAMPHUNTER45 »

The issue is pressure treated wood bunks then covered in carpet or fabric. The salt water reacts with the chemicals in the treated wood and it's almost like a battery! If you use the rubber or poly bunk covers it's not an issue and there is no negative effects. Worst I had ever seen was a 16ft SeaArk it literally ate away the aluminum under the trailer bunks and when the boat was launched of water would shoot in from pinholes in the bottom.

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trailerdon
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Re: Electrolysis

Post by trailerdon »

Best not to use a riveted hull in salt water, it will generate electrolysis at every rivet and become a spaghetti strainer. Also previous post was correct "The new p/t wood WILL react with the aluminum" , the aluminum will loose that battle. A plastic bunk cover will solve that problem. And most definitely use as zinc on your hull, "below the water line" That will become the sacrificial metal and save your boat.

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Re: Electrolysis

Post by Waterbugger »

Use steel flex, this is based on 35 + years of experience in using steel flex on aluminum boats in salt water. Steel flex was old school 2-part epoxy that many use to use on their airboats as a protective coating, but those of us who also used kicker boats experienced riveted boats rotting out when used in saltwater. We used the wider john boats to commercially bullynet from 40 years ago because they were light and easy to transport to access some of the better locations that are a long distance from a boat ramp but you could drop off out of a pick up and be close to. After going through a couple of hulls one of the guy's I use to frog with suggested the steel flex as a solution for the saltwater. It made sense. Got almost 20 years from the boat we steel flexed what a night and day difference. This was for commercial use and took a beating and was frequently in the saltwater from August to March. Be sure to sand your hull for the initial coat to ensure a good bond. Put multiple coats on the first application, let each coat harden sand it to rough it good for a good bond then add another coat. We use to do four coats, probably overkill but it worked, and depending on how much you use it reapply every couple of years longer if you don't use it much. There were three of us that netted together and all three boats lasted when we started using steel flex. As stated previously by someone else if your running polymer I'd definitely apply prior to installation of polymer. I have never used it with polymer so not sure how that will work since you have fasteners that run through the hull and polymer, but I know steel flex will stick to polymer but it will wear down especially if you run dry or go across sand bars dragging bottom so reapplication would be necessary to keep it sealed based on wear.

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Re: Electrolysis

Post by happy harold »

deuce; I have just finished cutting out and installing patches on my dads 15 ft jon boat that had pin holes just like you describe. its been sitting on the trailer since he passed away in 07. like waterbugger says, i'm going to try steel flex on the bottom. also, i'm going to put a wire to ground with alligator clips from transom(just replaced). we used to do this when we painted cars before the modern paints, to stop static build up. the trailer sits under a power line. maybe i'm nuts, but its worth a try.

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Re: Electrolysis

Post by SWAMPHUNTER45 »

I have used JB Weld (original) and several years later the boat is still good.

1)Wire brush to bare metal
2) wipe with alcohol or acetone then let dry
3) mix and apply it liberally but as fast as it's mixed
4) allow to dry 72 hours or more

Just know it's a epoxy patch and not a true weld so it has limits.

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Duece
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Re: Electrolysis

Post by Duece »

happy harold wrote:deuce; I have just finished cutting out and installing patches on my dads 15 ft jon boat that had pin holes just like you describe. its been sitting on the trailer since he passed away in 07. like waterbugger says, i'm going to try steel flex on the bottom. also, i'm going to put a wire to ground with alligator clips from transom(just replaced). we used to do this when we painted cars before the modern paints, to stop static build up. the trailer sits under a power line. maybe i'm nuts, but its worth a try.
Let me know how that works. I'd like to give that a try. Thanks for the tips guys.

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Duece
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Re: Electrolysis

Post by Duece »

I have 0 experience with steel flex. Do you have to sand and prime the bottom? Any idea how much steel flex it'll take to do the entire bottom of a 16' Jon boat?

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happy harold
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Re: Electrolysis

Post by happy harold »

deuce; i'm going to lightly sand blast dad's boat. it has lots of tiny craters with white looking corrosion. need to sand or maybe wire brush it. i'm going to get 1/2 gallon of coating and mix half at a time. it been maybe 30 years since I last did one. rolled it in last time. C1gator; didn't mean to steal you site, thanks. harold

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Re: Electrolysis

Post by Waterbugger »

Deuce,
Sorry for the delayed response. No priming on the steel flex. for first application sand to bare metal. You can mix pigment into the steel flex if you want color. There are typically only a few colors to choose from; however they can special mix a color if you are trying to do something custom. After the first coat sand to lightly rough the surface of the first coat of steel flex wipe down with acetone (use gloves with the acetone) then apply additional coats lightly sanding in between each coat. Each coat needs to dry 24 hours before you lightly sand it. It is easy to mix 1/2 resin to 1/2 hardener equally measured. A 16 ft John boat takes a gallon and a half for a 16' X 56" beam john boat to do initial coating and additional coats. Mix smaller amounts (1qt) at a time unless you have help or are rolling it on with a roller. The larger amount you mix the faster it sets. If you choose to use a roller get 2 gallons, for the first application my personal experience is that using the roller is easier, but it uses more product for the same result, I guess what stays in the roller pad (cover, and using multiple pads (covers) it soaks up more of the liquid. If you get roller pads (covers) get ones that are chemical resistant so the steel flex does not melt them and make a mess when you try to apply it. A good clean roughed surface, properly mix it, and no rain until it tacks up and you will get a good result every time. Not sure what part of the State you are in, so I don't know where to advise you to go other than ordering from Glue Products Plus in West Palm beach, (561) 537-3236 they have it in stock and they have given me the best price so far that I have been able to get it for and that spans over the past 30 years. They will probably ship to you, they ship to me in Okeechobee, and they have also shipped to my place in the Key's. Their staff is very knowledgeable and can answer your questions with accurate information. I think I covered most of it, if you need any additional info let me know.

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Duece
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Re: Electrolysis

Post by Duece »

Thanks guys, I appreciate it!

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