Self-contained marine HVAC units are typically the best choice for smaller boats up to about 12 meters (40 feet) due to the lower cost of the units and installation.
Illustration of Self-Contained A/C Installation
A self-contained air conditioner has all of the major components mounted on a single chassis, which is installed in the living area; usually under a bunk or settee, or in a locker. Cooling-only models are available, as well as reverse-cycle, which can cool or heat. Also available are air conditioning kits, which include the self-contained unit, water pump, ducting, and grilles -- all the components needed for a complete system.
A single unit can cool each cabin, or can be ducted to two or more cabins to save space and cost. Self-contained units often require less power than other systems due to the highly efficient rotary compressors.