Catamaran Air Conditioning Sizing by Cooling Zone
The short answer
Assess each hull and the bridgedeck saloon as separate cooling zones using their dimensions, glazing and occupancy. A length-based monohull estimate may understate a catamaran’s accommodation and solar load. Choose equipment after checking zone loads and routes, rather than adding a universal percentage to boat length.
Catamaran Air Conditioning Sizing by Cooling Zone — Requirements and Limitations
The saloon is the problem. On most cats it is a glasshouse sitting above the water with sun on it all day, and it drives the total more than the cabins do. Reflective covers on that glass are worth more here than on any monohull.
Because the hulls are physically separate, one big unit cannot serve both. Practically this means either a unit per hull plus one for the saloon, or a split or chilled-water system with an air handler in each zone — which is why cats push owners toward the more expensive architectures earlier than their length suggests.
Related Sizing, Installation and Service Guides
Each of these answers a different part of the same problem.
- units that suit catamaransthe shortlist, and why each is on it
- three zonesthe architecture a cat usually needs
- size each hull separatelyrun the calculator once per zone
- what a multi-zone job coststhe split and chilled-water bands