It advised against using the hull as your negative return like they do for
cars where the chasis is used as the negative return.

If the hull is used, current flow through it will create potential
differences across joints and create points for electrolysis action which
will ultimately eat away the hull. Fresh or sal****er only changes the
severity and speed of the electrolytic action.

This is different from bonding where you want to create zero resistance
between metal parts, like the engine and the hull as you described where
there is already electrical contact, a bonding wire is used to
provide/improve the electrical bond. With zero resistance (I mean real
zero, not achieveable in real life) you can eliminate galvanic corrosion
which occurs when 2 dissimilar metals come into contact with each other.
The severity of this corrosion is a function of the 2 material and is
reduced by the effectiveness of the bond.

This corrosion can be diverted through the use of anodes (zinc/magnesium
anodes) where something else is sacrificed. Note that this does not stop
the corrosion, something else takes the brunt of it.

Tan PS


"CCred68046" wrote in message
...
I was reading a website from a manufacturer of all welded aluminum boats.
There is a warning on the site that says:

"DO NOT GROUND YOUR ELECTRICAL WIRING DIRECTLY TO YOUR BOAT. Direct
electrical
contact on the boat will break down the weakest point of the aluminum and
cause
holes in the boat. This is especially important if you are a SAL****ER
Boater.
This is called ELECTROLYSIS and is not a defect in workmanship or
material."

How could you avoid this? The motor is bolted directly to the metal
transom
and is grounded, there is contact there. I checked my aluminum boat with
a VOM
and there is definately continuity between the boat and the motor. Whats
the
difference in letting the motor ground to the boat and not the wiring?
What am
I missing here?