I note that this is a shaft anode.

Many consider that this is good enough but note that some gearboxes do not
have a good electrical connection through them, some are intermittent, it
depends on the design and I suspect the fluid (oil or ATF).

I consider that a hull anode is essential as well as a shaft anode, if there
is no positive connection from the shaft to the engine etc.

An alternative is a set of slip rings from the hull anode wiring system to
the shaft, then no shaft anode is needed and the hull anode can be large
enough to last a long time.

Alec


"larry" wrote in message
...
Bil wrote in news:4593e5ee-8dc2-463a-bd1d-
:

After checking my zinc anode, I'm fairly certain I'm getting
accelerated erosion of my shaft zinc anode when transmitting Sailmail
e-mail via my HF radio and PacTOR modem.

Sailmail and the PacTOR modem drive the HF radio (an ICOM IC-M710)
fairly hard.

Does everyone transmitting with a PacTOR modem suffer accelerated
erosion of their zinc anodes? Or is this something specific to my
installation (and can be corrected)? If the latter, what should I look
for and correct?

Cheers

Bil


You must send an awful lot of email.....

You may want to disconnect the tuner ground from the underwater propulsion
and zincs and go to a ground screen system inside the hull. Start right
under the tuner and just lay out a roll of chicken wire screen along the
hull as big as you can. This forms a series capacitor with the seawater
outside the plastic the other plate. If your screen has a large enough
area against the hull, (The bigger the better), the RF to ground flows
through this series capacitor's "hull dielectric" into the sea....without
direct contact with the zinc protected underwater metals. With no
RF current flowing through the zincs....the RF problem bypasses it right
through the hull.