galvanic corrosion

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vic33004

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this is a great article that helps explain this often complex and troubling issue.

http://www.passagemaker.com/Magazin...Article/tabid/277/articleID/1237/Default.aspx

as the author notes, if you have an electrical issue on your boat it is wise to hire a marine electrician. a galvanic survey will find the source(s) of the problem(s). While the solutions may be very simple and straight forward, finding the source is the challenge.
 
I was fighting a gavlanic isolator fault light on my boat for several weeks. A very long story made short is; a boat only two slips away has/had something wrong with his battery charging system. After much trial and error at the docks when a service tech finally went on his boat and turned off the battery charger breaker (his first suspect), my red fault light went out and the green light came on. Several more trials proved that every time he switched on the other boat's battery charger breaker, my red fault light started blinking. To this day I don't know if his problem has been corrected or just that his battery charger breaker is still off.
 
quote:
To this day I don't know if his problem has been corrected or just that his battery charger breaker is still off.

Click to expand...


Next time he tries to start his engines you'll know. I hope he doesn't have a hose failure that requires his bilge pumps to stay afloat.

Bob
 
unfortunately IMO the comment below is incomplete. When a generator is onboard the neutral and ground are indeed connected to gether at the generator. When on shore power those connections are excluded from involvment in the circuit buy the shore/ship switches.
quote:
In addition to the failure-to-bond problem, many vessels are plagued with other AC electrical land mines. The most notorious of these is connecting—aboard the boat—the AC neutral conductor (the white wire) and the safety grounding conductor (the green wire). Unlike in a house, aboard a boat, these two conductors should have nothing to do with each other. Rather, they must be connected only ashore.
Click to expand...
 
Remember that cable TV can bypass a galvanic isolator eliminating the protection. The outer sheild on the cable connects to the ground on the shore and the ground on the boat effectively putting a wire acroos the isolator.

Solutions, buy a DC isolating transformer for the cable tv cable, or disconnect the cable when not using the TV.
 
quote:
Originally posted by lark

Remember that cable TV can bypass a galvanic isolator eliminating the protection. The outer sheild on the cable connects to the ground on the shore and the ground on the boat effectively putting a wire acroos the isolator.

Solutions, buy a DC isolating transformer for the cable tv cable, or disconnect the cable when not using the TV.

Click to expand...


I don't have any serious problems other than changing all my zincs once a year but the above quote has me re-thinking.
I leave my boat in the water and leave the cable TV and shorepower permanently connected.
I think I will disconnect the TV cable when I leave the boat in future.
Good call, Lark....thanks
 
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