Onboard A/C
I would go with a Mermaid System. Not only are they quiet they will fit in anywhere. I have a 331 and I specifically requested a Mermaid from the factory. You will need at least a 12,000 btu system. You can install it in the bow under the Vee berth. (You need to remove the big water tank and install a flex tank instead. Also get the condensator option, you then won't have condensate draining into your bilge. Also if you need it get the reverse cycle option, then you can use the system in the winter. Just remember you still need to winterize the A/C system, but it is a simple matter of disconnecting the hose at the seacock, AFTER CLOSING THE VALVE, and blowing air though the water system. You can do this with a shop vac unit. I am convinced that Mermaid makes the best, one reason is the condensate pan is 304SS not painted Carbon steel line Cruiseair. Hope this helps.
