I can give you double for probably less. Have her cutting glass in no time. AC unit - Dometic 12000 btu $1200

at least it`s a ton of cooling ... 6,000btu is pretty wimpy, if its too small for the space it`ll freeze up.

6k but will cool your cabin, but you'll need to cool it the night before to get the humidity out. If you keep the cabin door open much during the day it really won't keep up.
10k would be my vote.
BUT if you don't run a generator, you are stick with the 5k or 6k size. You'll need to upgrade your engine alternators to 100Amp minimum.
A 6k AC will require about 1300 watts when running but will surge over 2200 watts on startup.
1300 watts from 12v is 108 amps. Factor in 20% inverter loss, and you're up to 135 amps of running current.
Your engines and trim motors will pull about average 15 amps per side while underway (30A, taking you up to 165A.
Your interior lighting and stereo load can run as much as 50 amps which puts you at 215 amps of "running draw" on your batteries.
If you run a fridge, then that's another 7 to 10 amps of DC.
SO cruising down the lake at 50mph occasionally adjusting tabs and drive angles, listening to"yacht rock" at medium high thumping volumes with the kids at 68 degrees playing Scrabble inside and a fridge full of cold YooHoo you will be pulling 200+ amps from your battery bank and refilling them with whatever your combined alternator output is.

Each full size battery is 90amp-hrs.eans it will provide 90 amps for an hour, or 45 amps for two hours, etc.

If you run 3 batteries, you should isolate one to be used ONLY for engines and trim. That leaves 3 (180 amp hours) for your other goodies.

So if you have 180 amp hours, two 100 amp alternators, and a 225 amp LOAD... then you have a NET loss of 25amps. Running nonstop at cruise speed, you have SEVEN hours before you have 3 dead batteries.
At anchor, assuming you start off with two hot batteries, then you have ONE hour of tunes and AC before they are dead.

Adding batteries is 1/2 hour per battery at full AC, interior lights, and stereo.

This is why people buy generators.

I had a water-cooling-converted window AC unit, 6k btu that I was going to use in my 311. Ended up getting rid of it because the carry-on Cruise Aire that I have is just easier to use - just put it up on the deck over a hatch, plug it in and run it. I might use it once or twice a year, if that - much less a pain in the butt.

I had a sport cruiser with A/C. It would drain two 4d batteries via inverter in about 45 minutes. I want to say it was about 12,000 btu's, but don't actually remember.

FYI!

Steve

What make, model and size boat do you want the a/c in?

I just installed a 12,000 BTU system for a client.

We used 3- 12v 280AH Lipo batteries in parallel, with a 2000-watt inverter/charger to charge from shore power, DC/DC charger to isolate lead house batts from LiPO and charge off alternators.

It was in a small pilothouse type boat, in the end with all the components it took up a lot of space and was heavier than you'd think.