Marine Air Conditioning for 1 Cabin
One self-contained unit, ducted to a single grille.
Air Conditioning Zones and BTU for 1 Cabins
This is the thing most people have backwards. The sizer works from the volume of air that has to be cooled, and the volume does not change because you drew a bulkhead through it. A boat with one cabin needs the same total cooling as the same hull with one big saloon.
Nothing to zone and nothing to balance. The unit sits under the settee or the V-berth, one duct run, one return. This is the cheapest job in the category and the one most owners of small boats should be pricing.
| On a typical 32 ft boat | Cooling |
|---|---|
| Total, subtropics | 10,000 BTU |
| Per zone, if you split it 1 ways | 10,000 BTU |
| Total in the tropics | 12,000 BTU |
| Total in temperate water | 8,500 BTU |
10,000 BTU per zone is 2.9 kW each — small enough that the per-zone hardware is cheap, which is exactly why the argument is about ducting and compressors rather than about capacity.
1-Cabin Marine Air Conditioning Installation Costs
Self-contained. A single 10–12k unit under a settee, ducted to one or two grilles.
Supplied and fitted on a boat of about 32 ft, ex GST, including the seawater side and the 240 V work.
The units on this site that suit this architecture at roughly 10,000 BTU a zone.
Ducting and Zone Control Limitations
Running long ducts from one box to reach every cabin is the cheap answer and it is usually the wrong one. Airflow falls off with duct length and with every bend, so the far cabin gets a trickle while the near one gets the noise. If a quote proposes to feed one cabin from a single self-contained unit, ask what the duct run to the furthest grille actually is, and ask what happens if that cabin does not cool. Agreeing that in advance is far cheaper than arguing about it in February.