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Grounding through an aluminum hull.

Old 04-26-2007, 01:13 AM
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Default Grounding through an aluminum hull.

Here is a question for everyone. Should an aluminum hulled boat be grounded to the electrical system?

When I connect the accesory ground power wire ( lights, gps etc ) to the negative terminal on the battery, I can get a multimeter to read 12 volts by touching the positive probe to a positive lead on iether battery and the negative probe on any part of the hull.

Is this correct ?


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Old 04-26-2007, 04:26 AM
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Default Re: Grounding through an aluminum hull.

Never ground anything to an aluminium hull, NEVER NEVER NEVER, your hull will be eaten away in no time especially in salt water. Is that clear enough!!!!!!
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Old 04-26-2007, 10:34 AM
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Default Re: Grounding through an aluminum hull.

Mhyshen,
Mine is a weldcraft. I'm a big fan of aluminum. My last boat was aluminum and even though it was 40 years old it was still in great shape. I have had fiberglass and prefer the aluminum for the upkeep and durability. I will check out the site you suggested.

I have seen suggestions to actually run a ground to the hull from the battery. So I may be worried about nothing. It's interesting though that it would be set up that way. Perhaps that helps prevent corrosion. I run scotty downriggers which have ground tabs that actually bond the ground to the hull. That was one source of the ground return. I am trying to figure out where the others come from. It must be somewhere in the accesory bus bar.
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Old 04-27-2007, 01:43 AM
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Default Re: Grounding through an aluminum hull.

The battery should be "grounded" to the hull. The hull should not be used as a "return path" to the battery.
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Old 04-27-2007, 03:45 AM
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Default Re: Grounding through an aluminum hull.

ISeeFish - 4/27/2007 4:43 PM

The battery should be "grounded" to the hull. The hull should not be used as a "return path" to the battery.
Battery "grounded" to the hull is already in place via the engine ground. Multiple and separate "grounds" from battery to hull is not the intention?
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Old 04-27-2007, 03:49 AM
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Default Re: Grounding through an aluminum hull.

When I connect the accesory ground power wire ( lights, gps etc ) to the negative terminal on the battery, I can get a multimeter to read 12 volts by touching the positive probe to a positive lead on iether battery and the negative probe on any part of the hull.

Is this correct ?
Correct? Now that will depend but what you are finding is possible with or without being correct. The -ve battery is connected to the engine which in turn is bolted/bonded to the hull. So yes positive probe to positive battery and negative probe to hull will show battery volatge.
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Old 04-27-2007, 09:46 AM
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Default Re: Grounding through an aluminum hull.

pri6748 - 4/26/2007 3:26 AM

Never ground anything to an aluminium hull, NEVER NEVER NEVER, your hull will be eaten away in no time especially in salt water. Is that clear enough!!!!!!

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Old 04-27-2007, 04:50 PM
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Default Re: Grounding through an aluminum hull.

Thanks for the replies. It looks like the ground bus is the culprit and it should be doing exactly what it is doing. It just seemed a little out of place for some reason.
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Old 04-27-2007, 10:21 PM
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Default Re: Grounding through an aluminum hull.

The battery should be "grounded" to the hull. The hull should not be used as a "return path" to the battery.The battery is grounded to the hull with any engine install on a plate boat, you can't get away from that, But you should never use the hull as a return path. Thats what I meant by my previous post. How do I know that well we won't go into that, suffice to say its not fun recovering a boat in the middle of winter.
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Old 04-28-2007, 02:10 PM
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Default Re: Grounding through an aluminum hull.

pri6748 - 4/27/2007 6:21 PM

The battery should be "grounded" to the hull. The hull should not be used as a "return path" to the battery.
Sorry, I may not have made the question clear enough. I would not try and use the hull as a return. It was more curiosity as to why the hull might be grounded at all.
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