T&T: Ammeter wiring

[Mark/Susan Lindsey]

I have an 1973 Defever (single Lehman).  The instrument panel at the lower
helm may be original.  It includes mechanical tach, and gauges for oil
pressure (with small oil-filled tube providing the input), engine temp and
ammeter.  It all works.

In considering battery charging issues, I have noted that the main circuit
from the Delco alternator to the batteries runs all the way up to the helm
ammeter, and then back to the batteries.  From what little I know about DC
losses and the length of this run, my guess is that I am far from getting
the full benefit from my alternator output (which is already marginal but
I'm not up for an higher amp upgrade right now).

Calder recommends a shunt in the circuit, the use of which permits the main
current flow to take a short, direct run to the battery, with smaller gauge
wires making the run up to the helm.  My question, which likely demonstrates
my ignorance (but isn't that why we ask these questions?) is:  is it
reasonable to expect that such a shunt will work with my existing panel
ammeter, or is it more complicated than this?

Incidentally, I want to retain the ammeter functionality since it is an easy
glance to the panel in front of me to confirm that I'm not having belt
problems.

Thanks,
Mark Lindsey
Forget Me Knot 40' Defever Passagemaker
Seward, Alaska