b393capt wrote in
ups.com:

70mA with some DC power on

There's a leak into the water from "something", probably through a
through-hull fitting and its water path....water pump is a place. Watch
the current and switch them on one at a time to see what's leaking.
Whatever's leaking will cause the meter to increase when 12VDC is applied
to the leaker.

As to shore power, that's another ballgame. One of your neighbor's is
leaking. Galvanic isolators breakdown at some preset voltage so you
still have a ground potential in the boat for AC power faults. If any of
your neighbors is applying over that breakdown voltage to the galvanic
isolator, even on the other end of the marina, your current will
increase, your fish will be consumed faster. The only way to stop it is
total isolation, an isolation transformer WITHOUT connecting boat ground
to marina ground, which is where the problem is. You may also be reading
DC current caused by AC leakage of some appliance in the boat, such as a
battery charger that has the battery ground hooked to the marina ground,
which is stupid. The DC circuits in the boat should NOT be connected to
the AC ground as there is no reason to do it...isolators or not.



Larry
--
Grade School Physics Factoid:
A building cannot freefall into its own footprint without
skilled demolition.