# Galvanic corrosion or stray current eating poling platform



## rickc (Nov 7, 2018)

Doesn't have anything to do with your electrical system.

Galvanic corrosion. Aluminum, steel and stainless steel with salt water.

Aluminum is the less noble metal. That is why you see the corrosion on the polling platform feet. Not much you can do about it unless you have some way of isolating the two metals.

If it were me I would remove the existing fastners, drill out the existing holes and through bolt it with a substantial stainless backing plate.

Where it is corroded the protective anodizing is gone. Aluminum will build up a layer of aluminum oxide that looks terrible but acts as a protective barrier. Once it starts it is difficult to stop.


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## Smackdaddy53 (Dec 31, 2012)

They must have used a steel backing plate. I would remove the fasteners and backing plate, clean the platform feet and replace backing plate with 1/4” thick aluminum drilled and tapped with 1/4x20 stainless machine screws with TefGel on threads and back of the screw head.


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## rickc (Nov 7, 2018)

Oh
And when you put it back together seal everything up with a quality marine sealant. Wouldn't use 5200 unless you never want to take it apart again. Seal the backing plate, bolt holes and the platform feet. Might even use salt away before putting it back together. Kill any salt that might still be in there.

Using salt away regularly after fishing trips might slow the corrosion


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## CKEAT (Aug 26, 2015)

I also spray the screws with yamalube often, it soaks in and is a really good inhibitor. The Tef Gel as mentioned above is a must, it’s great stuff.

Never seen platform feet that bad


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## C.Ward (Jan 19, 2016)

Thanks guys.
I’m unable to access the backing plates for the mounting without cutting into the deck. That may be my only option though. I will email East Cape skiffs to see if they can help me figure a way to get the mounting plates out and replace them.


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## Smackdaddy53 (Dec 31, 2012)

The backing plates are glassed in and you are sure they are rusted or is that speculation? The rust could be from the stainless hardware. I doubt EC would glass in anything but aluminum plate.


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## C.Ward (Jan 19, 2016)

Smackdaddy53 said:


> The backing plates are glassed in and you are sure they are rusted or is that speculation? The rust could be from the stainless hardware. I doubt EC would glass in anything but aluminum plate.


I’m positive one side is completely gone. I can push the machine screw all the way into the deck


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## rickc (Nov 7, 2018)

Smackdaddy53 said:


> The backing plates are glassed in and you are sure they are rusted or is that speculation? The rust could be from the stainless hardware. I doubt EC would glass in anything but aluminum plate.


If it were a glassed in steel backing plate rusted up it would have expanded and delaminated the fiberglass deck by now. Surely they wouldn't have done that.

Might be able to retap the backing plate to a larger bolt. The head probably wouldn't fit correctly in the recess in the feet.


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## topnative2 (Feb 22, 2009)

money($1) is on a damaged or bad anodize job and the salt is doing what it does best


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## CKEAT (Aug 26, 2015)

I would start with EC, looks like there may be some
Repair work to be done and new poling platform


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## captjsanchez (Sep 8, 2015)

Might have chaffing wiring to stern light


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## Silent Drifter (Apr 29, 2021)

When i see something like this it makes me wonder if its even marine grade aluminum, but even marine grade will state corrosion "Resistant" Not proff! when i installed my pony motor on my Keywest 2220 i utilized the holes from the lifting ring ,when i took it off the aluminum backing plate was corroded out so bad i could almost pull it over the nuts 😅 and it was only a few years old 🤨 so im pretty sure they grabbed a piece of non marine for that job 🤔 

EC would definitely be my first approach if i had that skiff 👍😎 they will know the best way to fix it 👍


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## sjrobin (Jul 13, 2015)

Poling platforms can be fabricated from any number of aluminum alloys, even mixed alloy parts...base, tubing, tabs, welding wire, etc... also if the platform is grounded to any other metal due to poor rigging the aluminum could pit.


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## Smackdaddy53 (Dec 31, 2012)

Silent Drifter said:


> When i see something like this it makes me wonder if its even marine grade aluminum, but even marine grade will state corrosion "Resistant" Not proff! when i installed my pony motor on my Keywest 2220 i utilized the holes from the lifting ring ,when i took it off the aluminum backing plate was corroded out so bad i could almost pull it over the nuts 😅 and it was only a few years old 🤨 so im pretty sure they grabbed a piece of non marine for that job 🤔
> 
> EC would definitely be my first approach if i had that skiff 👍😎 they will know the best way to fix it 👍


Even the highest grade “marine aluminum” will corrode if not installed correctly or exposed to stray current.


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## rickc (Nov 7, 2018)

That second picture seems strange to me. Only that 1 fastner location? The head of the bolt looks like it had backed out. Aluminum oxide is white, iron oxide is red. That looks like rust but the fastner looks like stainless. Too bad you can't get to the other side of this location.

Don't need stray current from the boats electrical system although that certainly would do it. Since the OP says he cuts the battery switch off when not in use I discount that source. Aluminum and stainless steel or steel in salt water creates its own current (a salt water battery). Aluminum being the less noble metal is where corrosion occurs.


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## captgeorge (Jan 2, 2022)

Do you spray down with soapy fresh water after each fishing trip? It can happen quickly if you don't


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