Can stainless cause pitting in fresh water on toons

[robster]

Howdy- we're getting some mild pitting on the stern end of one pontoon, the pitting is below the water line, (I'll take pictures when we pull it out in Sept. to change the oil and replace impeller) the depth sounder sender is mounted on this same tube, I have the depth sounder wire covered with a stainless mesh sleeve to keep the musk rats from chewing on it, I also covered the stainless sleeve with a plastic cable cover to keep the stainless from touching the pontoon. Our boat sits in a fresh water slip year-round on Lake Wylie,SC.
Could the pitting be caused from the stainless sleeve? the other pontoon end does not show any signs of pitting, when we had the boat pulled out last spring for a acid wash on the toons there were no signs of pitting on the toons as far as we could see. The engine cables and gas line is also covered with a ant-musk rat stainless wrap and they rest partly in the water at the transom. We don't have shore power on our boat, I just keep a 120volt box fan running to keep air flow going under the boat cover and the perko battery switch is turned off when in the slip.
I don't have any nearby boat neighbors using shore power. But.. I did have a neighbor beside me on shore power for 1 year until he sold his boat a few months ago.
I also keep our motor tilted up, but now I'm thinking I should keep it in the water so the anodes can work 100%.

Thanks,
Robert
Lake Wylie,SC fresh water ,but it's dirty

[Bryden24shp]

Last summer I expirienced the same thing when our boat was in my slip for 4 weeks. The starboard pontoon had pitting just below the water line. About 2 weeks later their were reports of 2 deaths down at LotO for swimmers being eletrocuted, swimming around docks. (Not where our place is) As a results, alot of places had their docks electrical checked. I asked about ours this spring when we were down, they said they found a short in our boathouse, in the slip that was 2 down from us, on the right. Hmm, the guy next to me, on the right had his lift bolts corrode to the point where his lift dropped on his starboard side, 2 years ago.
Anyway, with the short fixed, I had no pitting this summer when the boat was in the water.
To shorten this up.... May want to check the wiring on your slip, or a neighbors.
Hope this helps!

[badmoonrising]

Yep, if it happens fairly fast it's usually due to leaking electrical systems at marinas...not caused by the stainless.

[robster]

Thanks guys.. I'll check with the marina manager for shorts.

[Rudebob]

Sounds like everyone is on the right track. it is called "stray current corrosion" if you want to research it.

'Bob

[FAT BOTTOM GIRL]

What would you use to check for stray current around the dock area ?

[lakerunner]

Throw a cat in the water and see what happens.

[curtiscapk]

Throw a cat in the water and see what happens.

[Ron Burgundy]

I'm suspicious of the underwater wires on your transducer. I had a pin hole next to my live well pump a couple years ago. I think it was from leaking voltage.

And I agree with the cat test.

[FAT BOTTOM GIRL]

I guess I'm the cat , I've been in swimming to hook the cables to the boat in case it gets windy.
Would b nice to know cus I have gfci circuit to the waterline at the bottom of the steps for shore power.

[tms0425]

I guess I'm the cat , I've been in swimming to hook the cables to the boat in case it gets windy.
Would b nice to know cus I have gfci circuit to the waterline at the bottom of the steps for shore power.

A GFCI isn't going to protect you from stray current in the water. Sometimes it's DC, not AC.
http://www.boatered.com/forum/topic.asp?TOPIC_ID=94685

There is a very good explanation a few posts down here http://www.boatingabc.com/forums/ubbthr ... hread.html

This is an interesting product Google turned up called "Dock Lifeguard" http://dragonrealty.com/

Tom

[robster]

The Dock Lifeguard retails for $850 any cheaper ways to locate stray current?http://dockrealty.org/search/Process_DL ... _Num=80252

[Bryden24shp]

They tested ours with multimeters, found we indeed had a problem then found the source as they traced towards the slip 2 down from us. I believe it was faulty wiring to his water pump he had mounted on his slip to wash the boat with lake water.