This isn't a "car vs marine" thing.
It depends on the type of bulb. Some use a center pin with the base as the return others use two pins on the bulb. Double filament (brake/side light) have two pins one for each filament and a return via the base as well.
Can't help but think we're making a mountain out of a mole hill here.
If you were local we could sort this in two minutes.