Identifying stray electric current in marinas

[skylark]

Another odd request...

Does anyone know a way to detect stray electric current in marinas?  I am wondering if there is an instrument that could be moved around marinas to find electric current from bad electric systems.

The goal would be to identify dangerous current that could harm a swimmer, and possibly also to find currents that cause electrolysis and damage to boats and equipment.  The priority would be to locate dangerous current.

Preferably this instrument would be operated from a boat and could be used to move through and assess large areas in marinas and dockfronts.

[Delezynski]

Skylark,

I did something like that many years ago before we went cruising. What I did was to stop by Home Depot and bought about 21 foot of copper tubing, you know the 3/8 or so stuff. I cut it into 3 foot sections. I used 2 to drop into the water on the sides and ends of the slip and measured the the SMALL voltage between them. There was some. SO, I then put them equally spaced, 3 to a side (with at least 2 foot into the water) on the each side of our slip, and one in the front of the slip. I then used very low cost wire (again from Home Depot) to connect all of them together. It stopped all action in our slip.

Just an idea that worked for us, your results may vary.

Greg

[skylark]

I think copper poles and a sensitive voltmeter must be the way to do it.  However the question is, should I be looking for AC or DC voltage.  Also, can this be measured without a connection to the AC ground?

I don't think I will be doing this, but somebody roped me into being harbormaster and now I have to be able to respond to these ideas that people have that they think the harbormaster should do. 

[Delezynski]

Paul,

When I checked my slip a long time ago, I used the poles and just flipped the meter from AC to DC. It was no problem and I did NOT have one side on ground. But I was trying to see if any stray voltage was moving across MY slip. For a marina, I think I would try to get professional help!

I once met a guy who was working on marina power systems. He had a lot more info and tools than I did. I seem to remember he had to change out a number of the power fixtures on the docks due to leakage.

Greg

[s/v Faith]

I was diving boats in the slips at my old marina.  It was always exciting, especially with the ever present alligators.

  I would generally secure power to whatever boat I was diving on, turning off the pedestal.  There was an old Catalina 27 that was one of our resident dock queens.  I noticed the power cable was hanging down in the water so I pulled on it... the end that was coming from the cockpit did not move.

  I pulled it up, and there were the mangled ends of the wires...   The breaker on the pedestal was not tripped, and was in the on position  :o

  Gotta love it when folks try to cleat off their shore power cables.   ::)

 

[Lynx]

You will need to attach to ground and an amp meter. It is the amps that do the damage.

Check with the local electric co as they may be able to help.

Check for Volatage Drop when everybody turns on power, like heaters and dinner.

I suggest that the locals put in extra zinks outside their boats and ground them to their boats. You can check these for wear and easily see where your problem is.

Good luck. These things can come up pertty fast. Expecially with non-marine electronics.