Properly Bonding Your Boat

[Cielo e Mar]

Hi
My boat is bonded completely from the stern zinc to three seacocks plus a large so Called "guppy" hung over the side at a depth slightly lower than the keel and attached by a battery clamp to one of my engines. Plus one zinc collar on each of the shafts (inboard engines) and one each rudder.

Our 43 ft Trawler is in a salt water environment 365 days per year. We add new zincs once a year.
I test the ohms on my boat and my neighbors to make sure we are in sync with each other. This is not a true science rather than something I have done for too many years to count. We both wear out zincs almost the same amount.

The only difference is my neighbor hangs over an extra guppy clamped to his other engine.

My neighbor is a live-aboard I am a weekend warrior. His use of electricity from the dock is much higher than mine.

I am thinking of installing an isolator, from what I have written so far any thoughts.

Let the blog begin

[boatman61]

Your neighbours got a sense of humour....

[CDunc]

Cielo,

For what its worth I would clamp around your shorepower cord an ampmeter. The amount of incomming AC amps should equal your outgoing amps and therefore the Amp meter should read (0) amps. if this is not the case then you have a (leakage) of AC amps and this could be one of the causes of your plight. If this is the case, then you must find the reason for the Stray amps as this is a dangerous situation. I would aslo check your neighbors vessel's shorepower cord as well ( with their permission of course). If your vessel shows (0) but your neighbors shows a leakage I would ask the marina to move your dock space further away (toward the sea). The reason is the stray AC amps could be comming from an outside source ( a neighbors vessel) thru your zincs and then through your bonding system and out the grounding wire of your AC system. Another possiblility is there is such a thing of over protecting your system. a silver silver cloride anode for your multimeter that you suspend in the water and check amprages along the submersed part of your hull will show you where you might be having problems. I like the book The Boatowners Guide to Corrosion by Everett Collier for more information on corrosion issues.

Good luck,

Chris

[Cielo e Mar]

Thank you, Chris

[Mimsy]

Talk to your boat and lavish her with positive reinforcement.
Oh wait. Not THAT kind of bonding... never mind.

[S/V Illusion]

Most ammeters are not sensitive enough to measure a stray current as small as one might expect on a boat. The silver chloride anode is the only precise measure if you have the right equipment.
The OP didn't mention that he has a problem which begs the question - what's the question?

for what it's worth, there was also no mention of Dc grounds which can be an equally menacing problem compared to AC issues.

[CDunc]

From what I have understood from the OP's post is that he is considering installing a galvanic isolator. It seems that from the post he is concerned with Stray AC currents.

[Cielo e Mar]

"a galvanic isolator. It seems that from the post he is concerned with Stray AC currents."
That has been a thought of mine...A lot of live-boards where I am and I'm afraid there is always a problem from carelessness...Right now we battle ice flows which careen the docks plus ferry waves all the constant battering here in the Northeast Hudson River.
But ya got to love the excitement.

[St. Elsewhere]

It is possible to accurately determine if there are damaging or dangerous leakage currents in a moorage. It does take proper equipment.

The list includes the following items:
1. An amp clamp meter capable of reading in the milliamp range. A Fluke 360 will cost about $600.
2. Some 30 amp and 50 amp connectors to make "break-out" adapters to speed up checking shore power connections, as applicable.

The amp clamp must be placed over the power and neutral wires bundled together with the green ground wire excluded. The "break-out" adapters enable doing this without disturbing the shore power cables which have the power, neutral, and ground wires bundled inside the cable jacket.

Amp clamp readings should be less than 2 milliamps for each boat's shore power connection. It may not be zero because there are some electronic devices, such as polarity error indicators, that apply very small currents to ground.

What you need to find are boats with shore power connections where ground faults exist. Worn or defective insulation can result in modest leakage current leakage in the 10 to 100 milliamp range, and wiring errors (where the ground and neutrals are reversed) can result in leakage currents above 1000 milliamps. Such currents can be lethal to anyone in the water.

I have used such equipment, and have found boats with leakage up to 3500 milliamps.