But it also depends on your dock connections.

How many boats are common to the dock GFI circuit?

The GFI only senses the sum of the currents at the GFI, not the currents in
the individual boats, which can be large and opposite in polarity, hence
"tricking" the GFI.

What's the resistance between the AC ground at the dock and your boat
ground?

An isolator is a voltage clamp (two or less diodes in series) and still has
leakage current. There is no such thing as 100% isolation. If your
isolation is 20 dB and you are pulling 20 amps on the AC, there could be 200
mA of stray current. That, as a plating current, can throw a lot of metal.
Seriously, get your actual installation checked out. When you visit another
dock, the problem could start over again.

You must check out your particular dock set up. Have a professional do it
and get a second opinion. Don't skimp! Also get the water around the dock
surveyed for leakage currents.

Gilligan

"Capt. Rob" wrote in message
oups.com...
Running that AC will greatly increase electrolytic corrosion below the
waterline.

The system is isolated 100%. The previous owner was quite worried about
it.


RB