[Capt. Debbie]

two concerns:

#1 Marine wire is very very multi strand for flexibility. Unlike standard NEC household wiring like stranded wire THHN or THHW it will be wiggling from boat movement. The insulation for these are fine for a marine environment, but you need a starnded (never solid) wire with lots of strands.
Example is auto jumper cables which are extremely flexible b/c the # of strands in the #6 or #8 AWG wire used is much higher. Open it up and it looks like each conductor strand is a little thicker than a hair. Household wiring may carry the same current- but it is not meant to take the bouncing and over time and individual conductor strands will break and create hot spots inside the wire.

Item #2 WIRING AMPACITY:
#18 AWG copper conductors 5 amps
#16 AWG copper 10 amps
#14 AWG copper rated for 20 but de-rated by NEC to 15 amps
#12 AWG copper is good for 20 amps
#10 AWG copper is good for 30 amps

Not many things in a set up like we are taking about are high current draws. Most things will be far less than 5 amps like GPS, VHF's, and FF's. We are not talking radar and a half dozen spreader lights.

My experience is the best wiring connections are made by- soldering, liquid electrical tape over that solder and finally cover that all with shrink tubing.

I hope this may be a lttle more helpful.

Capt. Frank