"Ian Malcolm" wrote in message ...

DANGEROUS BULL**** FROM SIMPLE SIMON. we use zinc ANODES to make the hull
cathodic to protect it.

Now consider S.S.'s idea: Hull +ve, = ANODE (and everybody knows the anode
gets eaten away). So if the end of your wire falls in the bilge water,
instead of the wire getting eaten away, you cursing the faulty circuit and
fixing it right, the steel is eten away at the nearest tiny defect in the
bilge paint and you dont know anything is wrong until you sink.

Impresssed current systems use a noble metal electrode and a carefully
controlled small voltage, electrode positive with respect to hull. Too
much causes paint failure, too little gives insufficient corrosion
protection.


Your understanding of electrical current is truly lacking.

The positive pole of a battery is where electrons congregate.
Electrons will follow a circuit to the ground side of the battery and
they will do work to get there. They will light a bulb, run a radio,
or turn a windlass.

Electrons have a NEGATIVE charge. If you make the steel hull the
positive pole the hull will have a net NEGATIVE charge. Any metal
with a negative charge will draw positive ions to it and will build
up and not waste away. It will take metal from any source and
actually plate it to the hull. This is how zinc plating of an anchor
or chain works, btw.

Therefore, sacrificial zincs aren't needed. The hull remains healthy
and expense of wiring is reduced.

I hope this helps.

S.Simon - electrically neutral