# Hull voltage on aluminum boats



## Smackdaddy53 (Dec 31, 2012)

I used anodes on my aluminum hull just in case. They are cgeap and easy insurance. Contact the Zinc Guy to get the right size anodes for your hull.


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## Hungrygator (Jan 9, 2021)

I wouldn’t be that worried about a volt could be a ground and or switch. Best thing to do is have a battery shut off switch. Mainly for the health of the battery but is could be another reason. I’ve never checked my aluminum hulls for voltage. But I have noticed a lot of my buddies mud boats at the ramp drained when it’s time to get to the blind. 

Trace your grounds and make sure your not bleadimg voltage from an accessory or switch Battery cut off switch


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## woodduck (Oct 7, 2019)

That's the interesting thing, the volt and negative .4 volt is present with or without the battery switch being on. 

Sounds like I've got nothing to worry about for this week at least. I'll pull wires and try and track down what exactly it is after this trip. Thank you both for the advice.


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## DuckNut (Apr 3, 2009)

Is your motor electrically isolated from the hull?

If not your hull is ground and you are fine.

Voltage can be measured without completing a circuit. Try this, take the black lead and stick it in the ground. Then take the red lead and wave it around and check your screen. Then take the black lead and hold it in your left hand and the red in your right and wave it around, check your screen. You will be measuring the earths electrical field.


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## mro (Jan 24, 2018)

woodduck said:


> out of curiosity


I've never checked to see if what you found is a problem.
Couldn't hurt to check.


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## Smackdaddy53 (Dec 31, 2012)

Pretty sure you can measure voltage that low ftom just about anything but anodes are good insurance on an aluminum hull.


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## DuckNut (Apr 3, 2009)

Smackdaddy53 said:


> Pretty sure you can measure voltage that low ftom just about anything but anodes are good insurance on an aluminum hull.


This is why all motors have 1 or 2 anodes on them. There will be stray current in the form of ohms and the anodes will dissolve before harm is done.


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## Smackdaddy53 (Dec 31, 2012)

DuckNut said:


> This is why all motors have 1 or 2 anodes on them. There will be stray current in the form of ohms and the anodes will dissolve before harm is done.


C’mon maaan!


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## woodduck (Oct 7, 2019)

Think I found the problem... It's the outboard motor. Started disconnecting wires and it still had about 13.6 volts going to the hull. Figured I haven't check the outboard so I disconnected it. 
Wouldn't you know it there isn't any voltage going to the hull anymore. Since it's tied off to the dock should I just leave the outboard disconnected unless I'm using it? Or am I just overthinking it?


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## Smackdaddy53 (Dec 31, 2012)

Leave it disconnected until you can figure out why your outboard is energized. That is crazy...


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## woodduck (Oct 7, 2019)

After googling a bit I think it might actually be alright. 
Reading full battery voltage to the boat hull [Archive] - Walleye Message Central

I'm reading about 13 volts connecting the voltmeter positive to the battery positive and negative to the hull. It sounds like the engine is grounding to itself and is connected to the transom by the jackplate/mounting bolts. Does that make sense to anyone else? It makes sense that the engine couldn't really be isolated from the hull since it's connected via metal bolts.


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## bonitoman (May 20, 2021)

Just remember to never have your aluminum hull to sit on pressure treated bunks , even with carpet. They will eat thru the hull. Get cypress .It lasts


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## woodduck (Oct 7, 2019)

Alright I'm an idiot, just ask my wife.
Reconnected everything and checked the voltage from the negative to the hull, it's about -0.02 volts. Checked the voltage in the water at the dock and other docks further down and they were both 0.017. The voltage from the boat to the water is 0.765 volts same as all the docks I checked to the water. It seems like I'm just being overly paranoid even though every wire is grounded to the battery. Let me know what y'all think since I'm not an electrical engineer and figuring out how to make sure there isn't any electrolysis.


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## Smackdaddy53 (Dec 31, 2012)

woodduck said:


> Alright I think I'm an idiot, just ask my wife.
> Reconnected everything and checked the voltage from the negative to the hull, it's about -0.02 volts. Checked the voltage in the water at the dock and other docks further down and they were both 0.017. The voltage from the boat to the water is 0.78 volts. It seems like I'm just being overly paranoid even though every wire is grounded to the battery. Let me know what y'all think since I'm not an electrical engineer and figuring out how to make sure there isn't any electrolysis.


I would still get some hull zincs from The Zinc Guy. Contact him with your hull size and he will get you the correct zincs to protect the hull from corrosion. Zincs are cheap, hull corrosion is not.


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