Hello Brian,

Interesting question you've posed.

Theoretically, AC will not cause a problem. Practically,
however, it can be troublesome. Being AC, of course, RF may
similarly contribute to galvanic corrosion.

The good news is that the RF ground currents will be spread
over what may be hundreds of square feet of hull submerged
in water. The current density anywhere is likely to be quite
small. I suppose it could be roughly calculated if you are
curious.

But there's even more good news. Unless your friend plans to
run a broadcasting operation (kidding, of course), his
actual time on the air will typically be small in any 24
hour period.

So, small current density and a duty cycle of only a few
percent suggests that this will not be a problem. I have not
heard of any instances of galvanic corrosion resulting from
RF currents passing thru a metal hull, but there will
doubtless be others posting here with the ability to offer
counsel of greater substance and broader experience than this.

Good luck!

Chuck





Brian Reay wrote:
I've got a query re galvanic corrosion and radio transmitters.

A friend of mine lives on a steel Dutch barge moored in a sal****er marina.
He has a transformer isolated mains supply and a number of 'sacrificial
anodes' around the boat. On the boat side, the hull is isolated from his
mains wiring 'boat side'.

He plans to erect an antenna for HF use (amateur radio rather than marine
use) which, depending on the antenna type, may require an earth connection.
From the RF point of view, using the hull (and thus the salt water) would
give him a good RF earth but he is concerned re galvanic corrosion
problems.

I'm not an expert on galvanic corrosion but my logic tells me there
shouldn't be a problem- any currents would be AC and (I believe) only a DC
differential can accelerate galvanic corrosion.

Ideas, views, comments anyone?