"Joe" wrote in message
om...
My next slip neighbor was set to take off sailing about the world
today for the rest of his & her lifes. They have a P40 that they
tricked out. 6 mo. ago they were struck by lightning. He re-wired the
whole boat, all the wires were melted on the boat. Well last thursday
he pulled his boat to rise the water line due to all the extra gear
they installed. To everyones horror his 3 month old shaft and prop
were eaten by electrolysis, and I mean eaten up, the prop looked like
a noodle strainer and the shaft was over half eaten away. My zincs
took a beating, I jumped in the Ice tea temp water yeaterday to check
out my underside hull. My zincs were approx 30-50% gone.

My guess is that he missed wired a DC ground on his boat.

Or possibly someone else missed their ground and he was an unfortunate
victim.


Question is: Will his screw up eat his boat totally up before it
drifts to others here in the marina because electricity seeks the
shortest path of least resistance, or is it just as likely he ate up
other shafts here in the marina.

Electricity follows the path of maximum electric potential gradient. The
electric field is what moves the electrons. Resistance is a material
property. The forces between charges in a current force the electricity to
flow outside of the path of least resistance.


I metered the water on all the boat slips and it seems with him gone
most of the slips measure .21 VDC. Is this voltage due to the metal
leads of the meter in the salt water, or is it perhaps due to
something else charging the water like a nicked telephone line ect.

You must use electrolytic leads to accurately measure the potential. Did you
reverse your leads and measure the same potential? What did you measure for
current? Current is a more accurate indicator of galvanic action. Make sure
you reverse the leads and see if the current direction reverses.


One of the guys here went to west marine and bought a Galvanic
preventer, and when he wired it up he had 4.8 DC volts in the water at
his slip. He said the stupid F**Ks at the factory most likely put the
diodes in backwards and took it back. Perhaps my slip neighbors put
the same defective preventer on their boat.

Or maybe it is hooked up wrong by the installer.

Is there any type of permanent meter I can install on my boat that
will show electrolysis activity in the water?

Yes, a milli or micro ammeter between the hull of your iron hulk and the
power cord ground.


And with half my zincs still in place would you recommend pulling the
boat and shaft just incase? This will cost me 300+ dollars, and if I
haul I will go ahead and do a bottom job a year or 2 ahead of
schedule, this will cost me another 1,500 dollars.

Why not just put an underwater fence of galvanized chicken wire around your
boat and hook it to shore power ground. Your iron hulk will then be
protected. Cheap, effective protection that even a simpleton like you can
understand.



Lesson learned: If anyone in your marina is doing electrical work on
their boat, grab your volt meter and meter from his plug-in ground and
drop a lead in the water next to his boat and check for DC current
every night until he is finished !!!!!!!!!!!

Better yet, don't buy a boat made of iron from oil refinery scrap. You can
make a simple isolated electrolysis alarm that is powered from the water and
two dissimilar metals.


How can the lovely Ms Terry put up with you?

Also check the Ground Fault Interrupter at your dock as well as the Arc
Fault Interruptor (if they have one). If you throw empty beer cans and old
galvanized/zinc metal in the water under your boat it will be protected.
Also dunk Ms. Terry and see if her navel ring turns green or cameltoe foams
up, a sure sign of galvanic action.

Van



Joe
MSV RedCloud