chuck wrote in news:hAskf.8744$N45.1460
@newsread1.news.atl.earthlink.net:

What happens, Larry, is that your fridge cabinet is connected to the
green equipment grounding conductor and to an AC ground/neutral
junction
on land. Your engine is connected through the water to the hot AC wire
on the neighboring boat. The voltage between those two pieces of metal
could approach 120 volts. Even a zinc/copper galvanic couple will
result
in a measurable potential difference in seawater. No need for massive
currents and no need to think in terms of raising the potential of the
whole ocean. :-)


Negative. The green wire is connected to EARTH GROUND. The engine is
connected to EARTH GROUND, too! The seawater IS EARTH GROUND!....and a
nice one it is. Your idea of floating the ocean 120VAC above that
grounded fridge cabinet just isn't gonna happen....

Hook a big ground symbol to the prop...That's the circuit....

Here, a much safer test. Plug the boat into the dock but leave the other
end unplugged from the boat. (leave the breaker off to be safer as we're
fooling with ground, not AC. Measure the resistance from the engine
block in the boat to the ground in the dropcord to the dock ground.
Unless you have a rubber shaft coupler somewhere...you'll find the
resistance VERY low through the water....salt water.

Still think the engine isn't grounded through the underwater metals?
Turn on the breaker and touch the black hot wire to the engine block and
tell me how big an arc it draws for you. Be careful the melting black
wire doesn't burn you....ok?