At 02:44 PM 8/8/2013, neil n wrote:
>So adding 3' of wire(s) causes a voltage drop of 0.03 Volts?

Checking a few different tables I'm getting closer to
1.0-1.1R/thousand feet for #10 at room temperature, but yes, you're
doing the arithmetic correctly.

Assuming .03 volts and 8 amps, that three feet of wire will dissipate
I^2xR = 64 x .03 = 1.9 watts.

>My panel wires have MC4 connectors crimped on.

Weather-sealed connectors for PV panels.  Do not disconnect under load.

You might look into the Cable Clam
http://www.bluesea.com/products/category/Clam , a fitting designed to
pass connectors through the deck of a boat.

Yrs,
d