On my Hunter 30' I use a 6000 btu hatch unit with a Honda 2000 watt generator and it keeps up even in 100 deg weather if I keep passageway closed and use towels to keep hot Sun out cabin. So I'm looking to go with a 10,000 btu or maybe even 7000 so my generator can run it
In my old hunter 30T I installed a unit in the back berth. The berth was so long and did not need the length so made a partition at the end of the berth and put the unit in there. Ran ducts through the head into the saloon. I think it was a 12K BTU.
Mermaid is a good company and generally in the past kept information on units sold to which boats. I was a test guinea pig in a sense for the smaller boats when I was a dealer and found them to be very knowledgable and helpful. There are other manufacturers too. Wherever you put the unit it needs space for the air to circulate or freezing will occur. In addition mermaid came out with something called the Condensator which is a tube attached to the condensation drain pan that sucks the water up and discharges out thru the discharge (water) for the unit overboard vs. into the bilge. It is expensive but worth it. I note others have made up something like that much less expensive and you should be able to reference in the archives. Hope this will help. Good luck with installation. I was a former dealer.
I have a 1983 Hunter 34 and installed mermaid m16 unit 16,000btu
It was the smallest size unit I found that produces the btu's I was looking for. Only thing i would suggest is get the largest unit you can.due Boats are not insulated and Ac units have a hard time keeping cabins cool in direct sun in the really hot summer months.
Mine does well however on extremely hot days in New Jersey in mid August the unit struggles. Anything that you can do to reduced heat gain within the cabin helps. Examples hatch covers, curtains, and insulation can really make a difference.
If you order a mermaid unit call them directly there sales rep will work with you on price and they can make up a customized package for you. I saved approximately $150 vs buying from a distribution center. Big plus was they packaged exactly what I wanted as far as discharge vent qtys.
If I were to do install over I may have gone with larger unit however I had space and power supply limitations.