ric wrote:
gregs wrote:
What sort of inverter setup would be required to take the place of the generator at night
Possibly too:
Expensive
Weighty
Little room
Two 6v 200ah agm batteries 12inx6x8. 65lb each. 100 amp hours of available power. A modern marine heat pump that draws 7-8 amps so that's my calculations. Secondary high amp charging alternator to charge battery bank (optional but not expensive if you don't have shore power). 2000w inverter. That would provide 12 hours of constantly running A/C and recharge during the day quickly. AC doesn't run constantly so longer. Make sure all other accessories are power efficient. LED TV's, ability to shut down radio amps at night, LED lighting, etc.
If you own a boat without a genset it's not even a big investment. Under a grand and you have a full nights worth of power. Shop around for battery wholesalers. I have a Deka outlet near me that will sell the sealed AGM 200ah 6v batteries for around $100.
You are forgetting that the AC current draw is 7 amps, that 70 amps of DC, even more since inverters are not 100% efficient. Even at 70% duty cycle, and figuring the batteries are designed for 50% discharge repeatedly you are going to need a lot more battery to run everything on a small cruiser for 12 hours with AC use.
Even if it could be pulled off it has to be charged the next day, even if you had an alternator that could handle it would you rather run the main engine to charge and run the AC for hours or just fire up your generator at 1gph and let that run the AC all day..