What BTUs for Carver 1991 280 Sedan (12' Beam)

[Flott]

I want to add A/C to my 1991 280 Sedan (the 11' 10" beam model) this spring and I'm hoping for input from this board. I'll first say that this is a very big 28 foot boat with lots of windows, but my main concern is cooling in the forward State room for comfortable sleeping. Were outside most of the time during the day anyway, but trying to sleep in the forward state room after a hot sunny day is difficult. There is an accordion style door to separate that stateroom from the main cabin and I'm hoping to use a smaller 7000 BTU unit to focus on the sleeping area. The reason I'm looking at the 7000 BTU unit is that it can also be powered by an inverter system. That's the largest size I've found that can do that. I don't have a full 15 amp plug in at my dock for normal plug-in, so I have little choice.
Any informed comments would be greatly appreciated!
Thanks,
Flott

[tomschauer]

Unless you have one heck of a battery bank, expect to run the a/c for 4-6 hours max on an inverter until your batteries are depleted.
For the 280 sedan I would want at least a 12k btu unit, run a duct to the forward stateroom to keep it cool. But if you dont have adequete power available you are in a pickle.

[Midnightsun]

My previous express was a 32 with lots of windows as can be seen here. https://midnightsun.smugmug.com/Midnight-Sun-Photos/ A single 14,000 BTU unit was more than enough under any condition. I would be leaning towards the same or a jump up to 16,000 in your case. I also agree even a small unit on an inverter is not going to work.

[tonyiiiafl]

I had a Bayliner 2850 Contessa, I used a 12K unit and it was MARGINAL in the Hew England heat. As for the inverter use? Toss that idea overboard. It just won't handle the load of even a small unit. It will chew those batteries up in less time than it takes to say "HUH?"

[RGrew176]

I have a 3007 Aft Cabin. My A/C unit is 16000 BTU's. It does a pretty good job most of the time. Can struggle a bit on really hot days say 90*+. No issues at night though. I think for your sized boat 12000 BTU's at a minimum, 14 or 16 would be better.

[bud37]

Do you have an overhead hatch in this space, they used to have marine air conditioners that fit in them if I remember right.....that might take care of that space ( v berth only ) for you.

On a later model 320 sedan like yours they are fitting 16000 btu from the factory ( for the entire boat ) and I can tell you that those model boats with the big windows have a hard time keeping up on a hot humid summer day up north, let alone Florida.
It seems you only have 30 amp shore, so that will be a limiting factor here on what you do, even if you have a very large battery bank, lets say over 800 Ah....given that the charge has to be put back...so some things to consider.

[Flott]

Thank you all for the good information! It's very informative. I have to admit I'm also not familiar with inverters and battery packs and it's seeming like that's not going to be a workable idea.
I know they have hatch air-conditioners, and I do have a front deck hatch directly over the forward stateroom but I think you have to remove them every time you take the boat out and that's not something I really want to set up as a practice. I know they're also used to have "portable" interior boat AC equipment but I've never heard that that worked very well. I guess I'll keep searching, the solution I'm looking for may not be there.
Thanks again for taking the time for feedback, I really do appreciate it!
Flott