Battery ground to hull?

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ericinga
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Battery ground to hull?

Postby ericinga » Sun Aug 10, 2014 7:19 pm

Hey guys,

My neighbor's Marinette has the batteries grounded to the hull and the engine.

Everything I've read states this is wrong. My batteries are grounded to the engine.

I think this would cause galvanic corrosion problems.

http://s1280.photobucket.com/user/erici ... 9.jpg.html

Eric
Eric Spies
1989 32 SDFB
Twin 318s
Lake Lanier, GA
Marinette Boat

Fastjeff
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Re: Battery ground to hull?

Postby Fastjeff » Mon Aug 11, 2014 4:00 am

Mine are grounded similarly.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

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bill
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Re: Battery ground to hull?

Postby bill » Mon Aug 11, 2014 8:21 am

Mine are that way also. :!:
bill
ALUMINATION
Grosse Ile MI
Located on LakeErie
37' F/B Sedan
1975
Twin 360 Chrysler Marine
Raw water cooled
Hydraulic steering both helms
USCG Master Lic. Retired

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jtalberts
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Re: Battery ground to hull?

Postby jtalberts » Mon Aug 11, 2014 9:09 am

I will have to verify, but I believe I only have the ground from my engine to those grounding points. I have two separate tabs. One for each engine.
1973 Marinette Seacrest Executive
41x14
Twin Chrysler 340's with Velvet Drive 71C
"Figment"

GB49
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Re: Battery ground to hull?

Postby GB49 » Mon Aug 11, 2014 8:35 pm

ericinga wrote:....

My neighbor's Marinette has the batteries grounded to the hull and the engine...


This is the correct, factory method.
All negative battery terminals and all engine blocks connect to those welded hull posts. Ultimately every negative wire (sans trim tabs, fuel gauge) on the boat should make an isolated run back to these 2 points on the hull. These 2 negative points can be broken out into bus bars around the boat but they should all make contact with the hull only at those 2 points.

-karl
1986 Sedan 32'. Twin Chrysler 360in^3, 275hp, with K&N flame arrestors

75Express
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Re: Battery ground to hull?

Postby 75Express » Fri Aug 15, 2014 11:32 am

My Batteries are also ground on the two studs. However,I noticed that my AC Green wire is also connected to one of the studs, after it goes through the Galvanic Isolator.

I am assuming this is correct???

Stan
1975 Express Flybridge 32
Twin 318
Lake Lanier, GA

barkleydave
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Re: Battery ground to hull?

Postby barkleydave » Fri Aug 29, 2014 8:20 am

That is correct.
If you have a generator or an isolation transformer, the AC neutral and AC ground are tied together on your boat.
It can become confusing. In an AC circuit current alternates between the Black and the White (common). The Green wire is a safety wire. If there is a short which means the circuit is not completed then the safety ground wire provides a path to ground. When tied to shore power (at the dock) that path will normally travel back through the green safety ground and ground to a grounding rod on shore. (Remember current will follow the path of least resistance. It is always looking for a ground path!

Your isolation transformer or galvanic isolator prevents DC current from leaking to ground through your hull. DC current is what causes electrolysis and eats your hull, rudders etc.

I am attaching a link to a ABYC diagram to help untangle the confusion.
The link provides printable diagrams for public use.

http://www.marinemechanic.com/site/120v-diagram1.htm

In addition if you do not have GFIC outlets install them! Only .65 of an AC amp can be deadly. By having Ground Fault outlets if there is a leak, they will trip before a potential lethal accident. The way they work is an internal circuit that measures current. If the return is not the same as the output in AC it will trip. They are very sensitive so just about any ground leak and they will trip. If they do trip then you MUST look for the source.

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

Rivetman
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Re: Battery ground to hull?

Postby Rivetman » Sun Aug 31, 2014 5:40 am

Redoing and testing all electrical now (on the hard). They are a bit spendy, but I suppose I will change out all outlets to GFI unless I hear otherwise. The process has been a test of SUPREME patience, newly invented curses and swears, buckets of sweat, high angst. Working now on a rewad system....find a problem, have a cold one! (I'm buying a lot of beer). :shock:
1973 28FB Express "Whisper" on the hard @ Tucker Engineered Lumberyard Yaght Club and Reggae Bar...I dream of H2O, not gravel!

barkleydave
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Re: Battery ground to hull?

Postby barkleydave » Sun Aug 31, 2014 8:40 am

Here is a tip.
You do not have to replace all your outlets. Replace the first outlet in a circuit with a GFIC outlet. All you outlets downstream on the same circuit will be GFIC protected.


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

Dougrose
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Re: Battery ground to hull?

Postby Dougrose » Mon Feb 09, 2015 1:46 pm

It is very convenient to use the ground lugs provided in the hull, but be sure to put the eye terminals on top of each other so that there is direct contact from one cable to another. Do not use the stud or the aluminum hull to carry current.

A slightly better method is to wire directly from the battery ground to a stud on the starter motor, and then use a smaller wire from the starter motor to the stud on the hull. This eliminates a connection in the starting circuit, which is a point of possible failure. Most cars and trucks are wired this way.

It is a good idea to provide a wire from the alternator down to the ground stud on the starter. Grounding the alternator through its brackets is a possible failure point.
Doug Rose
32' Cabin Cruiser
Twin Perkins 120hp Diesels
Merritt Island, Florida