Marine Air Con is contrary to all my principles of sensible cruising (Sensible Cruising: The Thoreau Approach). Then again so is heat stroke and divorce. So I see an AC unit in my immediate future. OD and I have have some conversation on the subject so I may as well post my thoughts here.
1. If I have to have a built in AC, I only want to deal with one.
2. It must produce sufficient BTU to cool the boat on a HOT day, in a hot place.
3. Its primary task is to cool the saloon and galley but if I can duct some air to the aft cabin I will.
4. I am prepared to carry a small window unit which can be used in the after hatch to cool the aft cabin if I cannot use the main a/c. (e.g. On the hard, when the main system in down).
This Site has a formula that seems to agree with the the opinion of my fellow boaters in Miami. (This does not mean that they are all not wrong).
Area of saloon and galley (12ft x 12ft x 6.5ft x Factor 12.31) gives 11.5K btu. If you add the V-Berth and have any hope of getting some cool air to the aft cabin you are looking at a 16K unit.
At the moment I am looking at the;
Dometic Turbo vector series 16K unit