Positive buss bars are seldom used after the electrical system
is installed. It is not for individual pieces of equipment
to be attached to. Your circuit breaker or fuse panel(s) are for that. If power is need at remote
sections of the boat additional sub-panels with both ground and hot (with breakers/fuses) installed in that area.
My boat does have a positive buss bar for the house batteries
that allows the windlass
and the generator
starter to be taken off before the main hot cable goes to the master panel.
Then there are several sub-panels : one for lower station electronics
and stereo, another under the aft deck
reels, wash down pump
polisher. Another set of sub-panels for each engine
handle all the electric
losds needed to run the engines ( each engine
it’s own) for things like exhaust
shutoff solenoid, hour meter, synchronizer, instrument gauges. All too much to try snd run directly off the key switch. Key switch turns on a solenoid and powers up the little run panels and takes the load off the key switch and makes fusing each much easier than a bunch of inline fuses
that are a hassle to deal with.