According to the online calculator, it has you input the one-way length but says that the round-trip (double) length is used in the calculation. The 14AWG or even 12 AWG I intended to use was essentially Monster-type stranded speaker wire (oxygen-free). I found a 200' spool of the 14AWG selling locally for $29.
There are a few peeps I know that have built ROVs with virtually an identical setup sending down 12v on a simple 75ft outdoor 14gauge extension cord. Obviously they aren't getting nearly 12V to the motors. I wanted full capability out of the motors and a greater range of travel that I was hoping a longer cable and more input voltage would afford
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Thanks for the reply!
Pcola