24v is much better for transmitting large amounts of power. If you will have a bow thruster, electric windlass
, etc. -- go with 24v. Providing 12v to a few things which are hard to find in 24v is a trivial problem.
Completely separate engine
(and generator) charging
and starting, with separate alternator
, and this can be 12v without any problem.
For AC power, 110/60 vs 230/50 depends on where you will spend the most time. Choose whichever system matches your most frequent cruising area.
Then, install an inverter
large enough to run all your AC equipment
(or a gang of them -- you can combine two or three Victron inverters). Separate shore power
inlet to run a separate battery charger
on the "other" voltage -- whichever one you did not choose for your native on board AC system.
So now when you are in a region which has power different from your "native" power, just use the second shore power inlet and run everything off the inverter
It will add complexity but also efficiency if besides the battery charger
, you can switch over your immersion heater to the "other" voltage (to save inverter capacity), and have perhaps a few sockets with the "other" voltage for devices which don't care.
TIP: If you decide on 230/50 as your "native" AC power, size the wiring
so that the boat can be converted to 110/60 later in case you end up living permanently somewhere with that power. That means the wiring
should have double the cross section of wiring which would be suitable for 230/50.