Its all new to me grounding vrs. Bonding???

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Tookalook
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Its all new to me grounding vrs. Bonding???

Post by Tookalook » Sun Jun 04, 2017 2:26 pm

I am a kinda newbie. I now have a aluminum 27 ft Kingston SeaPro 7000. So I am just doing some research on aluminum crafts. Corrosion #1 I just can't find my negative bonding point nor an Anode attached to the hull. am I to understand The hull should have a cable larger than the neg ENG. cable mechanically ( Aluminum) adhered to the hull. Drill a hole threw the hull and bolt it with an aluminum bolt??? Aroids well that is a subject in itself, What kind? I don't see any Anode attached to the hull just the ones on the outdrive. Can someone help to shed a little light on the matter please. I would love to understand the theory on multimeter testing but the wires are 12 inches long not 5 ft. I want to be able to leave the boat plugged in to shore power to keep the batteries charged. but is this going to cause corrosion? Im not a builder just an owner.
26 ft. Kingston Sea Sport
18 Custom Skiff

Chaps
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Re: Its all new to me grounding vrs. Bonding???

Post by Chaps » Sun Jun 04, 2017 7:23 pm

You need an aluminum anode(s) securely mounted to the hull, usually at the transom if you are mooring in saltwater or brackish/polluted fresh water. In really clean fresh water you might want your hull anodes to be magnesium. You'll want your hull connected to battery ground but no need for a big cable as the hull shouldn't be used for grounding electrical accessories, be sure to run dedicated ground wires for everything that needs a ground to a negative bus bar that is connected by marine wire like #6 to your battery neg post. No need for aluminum fasteners, stainless hardware is fine. If plugging into shore power be sure your boat is equipped with a galvanic isolator so your hull is isolated from marina ground re: trace DC power that might be circulating in the marina on the green AC wire that can cause problems though if you have an AC short to ground on your boat the isolator will allow the on-dock breaker to flip off. Multi-meter testing for adequate anode protection isn't typically something you need to worry about unless you see signs that your hull is showing signs of galvanic corrosion in spite of having what you think is adequate protection. Good luck with your new boat!
1987 24' LaConner pilothouse workboat, 225 Suzuki
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kmorin
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Re: Its all new to me grounding vrs. Bonding???

Post by kmorin » Tue Jun 06, 2017 5:52 pm

Took, I'd 2X all that Chaps said and add a few notes to those remarks.

Hot dipped galvanized bolts with large hot dipped fender washers is a good way to make the hull bond to DC NEG. The reason being that while passivated SS has a good surface stability with aluminum- unless wet all the time- zinc has much lower galvanic potential than steel/iron/nickel (SS) when it compares to aluminum. So the zinc will not react as much with aluminum even if they touch and are wetted.

The terms "bond" or chassis bond refers to a 'charge drain wire' that connect the engine block, electronic or electrical cases to a single point and that point is taken to the DC Neg (and to the hull). This is not the DC Neg part of the two wire power circuit for the engine's starter, instruments, on board electronics or electrical devices- those all should have a positive and a negative.

Since boats are not part of the earth, using the term 'gr ou nd' creates confusion. Many flying and rolling vehicles use the metal chassis as the DC NEg and term that the 'gr ou nd' wire! But its not? unless the battery has two terminals- DC Pos and DC "GR ou nd" Further confusing the discussion is to say "ground it back to the battery!"

Just like right left, front and back there are other terms often used for boats that may not be as commonly used on other vehicles?

Good luck figuring all this out, and our archives here have some pretty extensive discussions about this topic: they're there for the 'searching'. Might help to get a better picture of others' past explorations?

Cheers,
Kevin Morin
Kenai, AK
kmorin

Chaps
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Re: Its all new to me grounding vrs. Bonding???

Post by Chaps » Wed Jun 07, 2017 12:28 am

Guilty! Yeah, the term "ground" is just too easy to use in these quick discussions but Kevin is right about using proper terminology. The green wire that comes aboard in an 120v AC shore power connection is a "ground" wire and your hull is grounded to earth through it when shore power is plugged in but the DC wiring in the boat is either DC Pos+ or DC Neg- The concept of bonding, that is all the metal bits of the boat exposed to seawater being attached to the hull anodes through a system of wires running through the bilge doesn't exist in a typical aluminum boat because the hull is the metal bit and the anodes are directly attached to it. In other words, aluminum boats are self-bonding in a sense.
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Tookalook
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Re: Its all new to me grounding vrs. Bonding???

Post by Tookalook » Sat Jun 10, 2017 3:33 pm

WWWW000000WWEEE Thanks so much i understand now!!! lol Thanks Chaps and Kmoran I will check it out. and Chps I love that boat.
26 ft. Kingston Sea Sport
18 Custom Skiff

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