[sailaway21]

The only practical way I can see to operate the a/c using a smaller gen-set is through the use of a very large inverter, relying on the reserve capacity of the battery bank for "rock over" amperage.

That being said, has anyone considered changing the motor on the a/c unit to a 3-phase, say 204 volt, unit? There is technology out there, I'd start with Franklin Motor, to "trick" single phase 220 into acting like three phase. Mind you, the unit that Franklin makes to do this for submersible well pumps runs about a grand.

Grundfos, another pump manufacturer, has their own motor (everyone else uses Franklin) and it has a "soft-start" feature. It runs on 220 volts and the frequency is varied to slow and speed the motor.

Both of these are radical departures from capacitive start motors and quite specialized for the constraints of well casing installation. I would imagine the technology is available in some form for surface use.

While on the topic, why not switch the a/c motor to 220 volts, and power it direct off the gen-set? Amps, which are what count, would be halved as would starting amps. Most motors come pre-wired for either 110 or 220 volts and it would be rather simple to make an external voltage input switch on the unit. 220 at sea. 110 alongside. Of course you could just leave the motor wired for 220 and parallel the gen-set with shore power once alongside. The port authorities might want a "blast radius" diagram on file before your attempting this.