"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.


The key word here is "directly".

What they are saying is that you should NOT use the hull of the boat for
carrying current (remember that this is about aluminum boats).

On a car, it is standard practice to use the frame of the car as the
return lead to the battery. Thus, the wiring harness carries only the
positive side.

On a fiberglass boat you have no choice but to run "ground" wires to
everything. On an aluminum boat, you might consider using the hull of the
boat as a conductor, but it could lead to problems. To start with, aluminum
is not that great of a conductor. Second, every connection is likely to
have a copper to aluminum bond, which puts to dissimilar metals in contact.
Two dissimilar metals plus electrical current can do bad things. Third,
every joint in the hull could suffer from electrolysis.

Note that this is a separate discussion from the electrolysis to the water
problem. There will be those that argue that the hull should be completely
isolated from any electrical source, but that is not an easy thing to
accomplish.

Rod McInnis