Power bus on luxury yacht

Hello,
What is the power bus on a typical luxury yacht, -presumably it is pseudo sinusoidal (stair-step) mains 230VAC?
(ie, this coming off the battery which is 24VDC?)

The battery being replenished by the motor/alternator?

Depends a lot on the vessel.

Usually there is a LV DC bus (24V or so) used for nav lights, radios, radars and navigation instruments, plus sometimes things like cabin and emergency lighting. This may or may not be shared with the engine starting arrangements and may or may not be also used for highly inductive loads like bow thrusters and powered winches, if you treat this bus like it was a heavy truck DC supply you will not go far wrong.

Charging arrangements for the DC battery bank vary and can be (depending on the nature of the vessel) anything from engine driven alternators to chargers fed off the AC network to solar to towed generators driven by pulling a prop thru the water.

The AC network (where fitted) is either an inverter (of highly variable quality) or (on bigger things mostly) a diesel set, these vary from a few KVA (with rather variable voltage and frequency and more then a little flat topping) to large three phase machines. Note that you sometimes find the three phase networks set up as 230V DELTA, with the loads wired phase to phase and no neutral, somewhat common in vessels originating in scandinavian yards.

These guys https://www.victronenergy.com/inverters are popular, but you see all sorts of stuff fitted.

Oh, and a warning about shore power, marinas get unfortunately creative here, trust nothing.....

Regards, Dan.