b393capt wrote in
oups.com:

Will this actually plate my prop, shaft, etc ? Is that desirable ?

Nothing seams out of sorts with the measurements above ? Doesn't it
seem strange to get these reading when I already have a zinc
protecting my prop ?


I just read about an iron keel. Is that yours, too? The more metal
underwater, the higher the current's going to be.

It won't plate your prop so you'll notice because the currents and
distance between the zinc and the prop will carry off the ions. Any ions
passing your prop/shaft that get sucked into them by the galvanic current
will plate (and I suppose protect) them, which isn't bad at all.

The more zincs you put in the water, the more total galvanic current will
result from the exposed surface area of more and more zinc anodes. The
current you're measuring is just from the fish. There's even more
current from all the other zincs, especially the shaft zinc wrapped right
around the shaft with much less series resistance.

Want to see lots more current? Connect a big battery plate, lead,
through an ammeter to the ground post in the boat and drop it over the
side. Current will go up when it hits the water.

What you're effectively doing with all these extra zincs is making a
bigger shorted battery with larger plate surface areas. This ISN'T going
to "save" the shaft zinc, by the way. Its natural galvanic current isn't
determined by the additional fish zinc's galvanic current, at all.
You're just making the battery bigger.

Now, if we could only get the damned zinc current from the fish to LIGHT
THE CABIN LEDs!....(c;

Larry
--
Grade School Physics Factoid:
A building cannot freefall into its own footprint without
skilled demolition.