One sure way to sink your boat ...

[Rich_V174SS]

Working at the shop today my task was to go through a boat that had 'sunk' and repair bad electrical connections. First thing I noticed upon opening up the bilge compartment where the batteries were kept was how they were connected. There was a thick green wire connected to one of the positive battery terminals. I followed where it led right on down to a bronze thru-hull fitting in the bottom of the bilge.

Can you guess what happened? ;-)

[dorelse]

Why would there be a wire connected to the thru hull fitting?

[Rich_V174SS]

Metal thru-hull fittings below the water are supposed to be neutral to avoid electrolysis, especially in SALT WATER. Therefore they are 'bonded' to the negative ground of the boat, same as engine and drive components.

[CVX Fever]

Rich - Is that normal to run the fitting ground right to the battery? I'd think you'd have a bus bar tied to ground for something like that.

[Rich_V174SS]

Rich - Is that normal to run the fitting ground right to the battery? I'd think you'd have a bus bar tied to ground for something like that.

A buss bar would be the ideal way to do it to avoid having multiple connections at the battery.

[Rich_V174SS]

I guess no-one caught on that the thru-hull fitting was connected to the positive side of the battery instead of the negative side, it rotted away from electrolysis right where it went through the hull and the boat sank.

[CVX Fever]

Rich - Any idea how long it took for that to happen.

[Rich_V174SS]

Assuming the error occurred when he put his boat in this spring I'd say 2-3 months.

[Rich_V174SS]

Spoke with the owner today. He said the boat was in water about a week when it sank and that he wired up the batteries. But doesn't know if they were wired the same previous seasons.

[thedeuceman]

Crazy that it would go that fast, I assume that has something to do with salt water


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[Rich_V174SS]

Sure. Whenever you immerse 2 dissimilar metals into a salt solution you are basically creating a simple battery and one of the two metals is going to disintegrate, especially when you apply voltage with a lot of current through it.

[Rosscoe]

I guess no-one caught on that the thru-hull fitting was connected to the positive side of the battery instead of the negative side, it rotted away from electrolysis right where it went through the hull and the boat sank.

Nope. Cant tell what color that wire used to be.

[Plugcheck]

So are you saying electrons are color blind?  I would think an easy mistake to make since the connectors are the same.  If the wires or connectors aren't color coded, and it's not powering something, prob never notice till you return to the slip and find the boat on the bottom.