Chuck,

Here are two quick tests you can make:

1) Measure the voltage between the fish
and the engine stud, noting the
polarity. This may confirm that
something is adding to the galvanic
couple set up by the zinc and the prop.

-- With the engine connected to the black wire, and the fish on the
red wire, I got -127mV

2. Disconnect the battery positive
terminal wire and see if your symptoms
change. If you have a breaker at the
battery, or a switch, or a fuse, then
there is no need to remove the wire, as
long as absolutely nothing is connected
to the battery terminal. That includes
bilge pumps, etc. Be careful working
around the battery.

-- No change, between the case of batteries disconnected and running
minimal DC. Both had - 42 mA; However, when I increased the number of
devices I had in use I saw a change to -21 mA. I realize these
readings are different then yesterday, I used better equipment and
measurement process (see other thread)

-- You made an earlier point, summarized here, that you don't expect
to see any potential if there are two zincs in close proximity both
connected to boat ground (the prop and the fish). That makes a lot of
sense to me, does that statement still make sense to you ?

-- Please look at the new thread and comment


Chuck