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Marine Air Conditioning for Catamarans

Australia sails more catamarans than almost anywhere, and almost every guide to marine air conditioning is written for a monohull. The differences are not cosmetic — they change which system is correct at a given length.

Catamaran Cooling Zones, Weight and Saloon Heat

Zoning Ducting cannot cross

On a monohull one box can serve the whole boat. On a cat, the hulls are separate volumes joined by a bridgedeck — so one self-contained unit means a compressor in each hull, or long, inefficient runs.

Weight And where it sits

Cats are more sensitive to weight and to how it is distributed. Two compressors in the ends of two hulls is a worse place for that weight than one chiller near the centre.

Load More glass, more deck

A bridgedeck saloon is mostly window with a large flat roof over it. That is a real solar load and it pushes the sizing calculation up.

Result Chilled water, earlier

Together these mean a 45 ft cat often lands where a 55 ft monohull would. A single loop with a fan coil in each cabin solves all three at once.

Marine Air Conditioner Options for Catamarans

These examples illustrate installation choices. They are not a complete market survey or a verified ranking. Compare current exact-model data and obtain an installation assessment.

01Chilled-water layout

Webasto BlueCool C27 · chilled water

27,000 BTU cooling No comparable test data Confirm exact model draw Chilled water Size to cabin heat load Request a current quote equipment

Webasto BlueCool C27 is part of the C-Series chilled-water range. A complete installation also needs compatible air handlers, circulation, controls and a designed seawater circuit.

Good

  • A water circuit supplies local air handlers for multiple zones.
  • Manufacturer documentation is linked for exact-model checks.

Against

  • Performance depends on the installation and actual operating conditions.
  • Australian availability, warranty support and final pricing require supplier confirmation.

Watch: Confirm supply voltage, frequency, capacity at design conditions, dimensions, minimum flow, service support and the complete installed price.

Full write-up Ask if it suits your boat
02Staged-system concept

Dometic Chilled water · staged system example

36,000 BTU cooling No comparable test data Confirm exact model draw Chilled water Size to cabin heat load Request a current quote equipment

This is a Dometic staged chilled-water system planning example, not a single 36,000 BTU product SKU. Have the installer select compatible chillers and fan coils for the actual zone loads.

Good

  • A water circuit supplies local air handlers for multiple zones.
  • Manufacturer documentation is linked for exact-model checks.

Against

  • Performance depends on the installation and actual operating conditions.
  • Australian availability, warranty support and final pricing require supplier confirmation.

Watch: Confirm supply voltage, frequency, capacity at design conditions, dimensions, minimum flow, service support and the complete installed price.

Full write-up Ask if it suits your boat
03Split-system layout

Dometic Emerald split system · 16k example

16,000 BTU cooling No comparable test data Confirm exact model draw Split Size to cabin heat load Request a current quote equipment

Dometic Emerald is a split-system condensing-unit family used with compatible evaporators. Equipment matching, refrigerant routing and controls require a complete system design.

Good

  • Separate condenser and evaporator locations can suit constrained cabin layouts.
  • Manufacturer documentation is linked for exact-model checks.

Against

  • Performance depends on the installation and actual operating conditions.
  • Australian availability, warranty support and final pricing require supplier confirmation.

Watch: Confirm supply voltage, frequency, capacity at design conditions, dimensions, minimum flow, service support and the complete installed price.

Full write-up Ask if it suits your boat

Sizing Air Conditioning for Both Hulls and the Saloon

Our calculator works from length overall, which under-reads a catamaran — a 45 ft cat has considerably more interior volume than a 45 ft monohull. As a rough correction, size a cat as you would a monohull five to eight feet longer, then have an installer confirm it against the actual accommodation.

If you charter, size for the boat full and closed up at 3 pm, not for the two of you at anchor in a breeze. Charter cats in the Whitsundays run their systems hard, and undersizing shows up as complaints rather than as discomfort.

Size your boat What a chilled-water system costs