Battery ground to hull?

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martindesign
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Re: Battery ground to hull?

Postby martindesign » Mon May 25, 2015 9:04 am

My boat hull is completely isolated. Battery grounds only to engines and buss bars that dist. Throughout the boat. It was this way when I bought it so I assumed it came from the factory but from what you guys are saying that isn't the case. Is this not a safer way to prevent possible corrosion issues?
Machanic, fabricator, carpenter, plumber, electrician, designer, hotrod builder and glutton for punishment. :ugeek: current boat; 1969 Marinette 32 express bridge 440's
Catawba Oh

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bill
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Re: Battery ground to hull?

Postby bill » Mon May 25, 2015 11:28 am

BigM
martindesign

Thank You for the signature.
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Last edited by bill on Wed Mar 22, 2017 2:17 pm, edited 1 time in total.
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Located on LakeErie
37' F/B Sedan
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barkleydave
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Re: Battery ground to hull?

Postby barkleydave » Mon May 25, 2015 2:14 pm

Your engine is bolted to stringers thus to hull
Your isolation is to protect disimular metals
Shafts props rudders etc
1987 Marinette 29 FB Sedan
Retired Boat Accident UL and USCG trained investigator
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martindesign
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Re: Battery ground to hull?

Postby martindesign » Mon May 25, 2015 3:20 pm

The mounts are isolated in rubber. The hull is totally isolated from the battery ground. Bill. Thanks I will, I just bought The boat a am not the first owner.
Machanic, fabricator, carpenter, plumber, electrician, designer, hotrod builder and glutton for punishment. :ugeek: current boat; 1969 Marinette 32 express bridge 440's
Catawba Oh

Tranquilo
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Re: Battery ground to hull?

Postby Tranquilo » Mon Nov 07, 2016 12:38 pm

I am going to rewire my grounding system because my corrosion issue is still bad and I'm noticing that my starter isn't engaging like it used to and the ground wire is warm after turning it over.

Not sure how it will effect the fact that my CAPAC doesn't read anything even after replacing my underwater anodes (that was real fun) and hanging a bunch off the side at the dock by ss wire. All I know is that my engine block is a rusty mess!

https://www.dropbox.com/sh/ge8zfppoaix04h7/AACMBlA3bxPABhwzUGP5fOJIa?dl=0

If I can determine the damage to the hull, I may just replace the engine.

Let me know if we have a procedure for redoing the grounding system. I am also tempted to move the batteries to the other side because there is no crapper tank on the starboard side and my boat leans a bit to the port side. I guess while I'm doing that, moving the batteries should be easy. Feel free to tell me I'm nuts :)
2x 1973 28 Express - Single 318
New electrical panels, water system and velvet drive
Miami FL & Catawba OH

barkleydave
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Re: Battery ground to hull?

Postby barkleydave » Mon Nov 07, 2016 3:15 pm

The proper grounding for your DC is: A ground cable which you attach to the fwd bulkhead lug. (one for EACH BATTERY BANK) Your ground buss is also connected at that point and ran up to your helm area electrical panel. (Remember the Ground Buss wire must be able to take the amperage of your entire DC panel circuits.
You mention you starter ground cable gets hot.
1. Poor ground
2. Someone replaced with a lighter gauge cable or both or bad starting winding pulling excessive amperage.

Insure that there a NO DC or AC connection that in submerged in water. A common problem is bilge pump splices which are not waterproof and end up submerged.

You also should have a Galvanic Isolator or Galvanic Transformer in you AC Safety Ground. This prevents stray DC voltage from leaking into the hull.

There 3 types of corrosion to deal with.

1. Electrolysis (DC voltage leakage will attack sharp edges (chines, Rudders etc.) Often a combination of Electrolysis and Galvanic.
2. Galvanic (dissimilar metals ex: Bronze VS Aluminum Bronze Wins
3 Chemical (Acids etc. spilt in bilge spaces, Salt/Brine water standing in bilges)

That is as straight forward as I can get. There are lots of printed resources one can study.

Odds are that you Cathode is defective. Do not add a bunch of anodes over the side until you are able to get an accurate reading. Buy or barrow a tester. Adding too much anodal protection can do as much damage and too little.

Safe Harbors

dave
1987 Marinette 29 FB Sedan
Retired Boat Accident UL and USCG trained investigator
Retired USCG Captain

Tranquilo
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Re: Battery ground to hull?

Postby Tranquilo » Tue Nov 08, 2016 7:53 am

Thanks for the simple instructions. The internet has not been so straight forward :)
2x 1973 28 Express - Single 318
New electrical panels, water system and velvet drive
Miami FL & Catawba OH

jralbert
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Re: Battery ground to hull?

Postby jralbert » Tue Nov 08, 2016 11:59 am

"...Buy or borrow a tester. Adding too much anodal protection can do as much damage and too little...."

Jeff Perry once made a simple, effective tester. Perhaps he can post the how-to here...
-joel-
former owner 1988 '32 FB Sedan
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twin 318 / 240 hp
Potomac MD

Fastjeff
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Re: Battery ground to hull?

Postby Fastjeff » Wed Nov 09, 2016 5:25 am

You buy a probe from (I forget--try the internet. about $50.) Next, buy a cheapo ohm meter ($5 from Harbor Freight). I then used a small plastic box to connect the wires together: the + to the probe, with the - to the ground. The ground wire has a clip on the end that goes to a railing post. You then lower the probe into the water, set the meter on the 0 t0 2 volts (or so) scale, and take a reading, with 0.9 volts the optimum.

Jeff
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barkleydave
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Re: Battery ground to hull?

Postby barkleydave » Thu Nov 17, 2016 10:58 am

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1987 Marinette 29 FB Sedan
Retired Boat Accident UL and USCG trained investigator
Retired USCG Captain