12,000 BTUs
I installed a 12,000 BTU reverse cycle air conditioner in early spring. I mounted the unit in the port side cockpit locker. With three air outlets (v berth, head, galley) it heats and cools adequately - even this summer in North Carolina's high temperatures. The system I used is Mermaid. They're in Florida and have mail order dealers that sell it for less than you can buy it directly. I paid just under $1400 and did the job myself in 2 days. Good luck.