If you can believe the specs for the new mini CruiseAir A/C, it puts out 3500BTU of cooling for a sustained DC amperage draw of 13 amps @ 12V.
Thus, figuring an hour or two of cooldown prior to sleeping in a very small cabin
(like the V-berths on many boats), and getting a full 8 hours sleep, the total usage would be:
13 amps x 10 hours = 130AH @ 12V.
Now, the relevant question: could you have sufficient battery storage
to draw down 130AH overnight without any recharging?
Clearly, the answer is "yes"....most cruising boats have at least that much capacity (say, around 300AH total capacity in the house banks).
However, after a good night's sleep you are now faced with the challenge of putting back those 130AH into the battery bank. Including losses, this would involve a little more than 150AH charging current
A good generator
could do this in about 90-100 minutes run time. So could a typical engine-mounted alternator
of, say, 110A capacity.
None of this calculates other loads on the house system...lights, frig, instruments, anchor light, windlass
, etc. If your daily energy consumption
-- without the A/C -- is on the order of 150-200AH (which is typical of many mid-size cruising boats these days), then you'd be looking at replacing that amount PLUS the 130AH drawn down by the A/C.
Bottom line: it's probably JUST doable with a capable onboard fuel-driven charging
system. It's probably NOT practical with solar-power only unless you have a huge solar panel system and lots of sunlight.
It's probably a great solution for smaller boats -- and maybe bigger ones -- for overnight stays on the boat plugged into a shoreside electrical system
What's a good night's sleep worth, anyway?
BTW, having spent many years in the Eastern Caribbean
, I second the thought that at anchor most times you don't really need A/C, but in sheltered marinas where the tradewinds don't blow it would sometimes be a godsend.