Been thinking about this one and comparing it to what my own boat's electrical system does. My accessories are all wired to a separate power switch than the ignotion, but its i,possible to remember to flip it off when you start the big motor. So there's a safety relay thats cuts off the accessories when you turn the ignition key. my electronics cut off when I start the engine but I can just turn them back on manually once its started. sounds like yours doesn't cut the power back on so you can do that.

if yours has that relay, I'll bet that's it. it'll be a relay on like a crowbar circuit that protects the accessory power circuit.

BKB