Hard to say without hands-on experimentation, and it might depend on how many battery banks you have on board...
But a thought that comes to mind, FWIW, is that maybe the boat's battery system was set up for fishing
? Maybe separate banks for motor
, live-well, etc.? Switching available so a bank can be held in reserve?
The parallel switch is often a get-out-of-jail-free card, giving the ability to start a main engine
by momentarily coupling two battery banks together... That's fairly straightforward, but our parallel switch is a three-way rocker, completely different from our main rotary battery switches.