Marine Air Conditioning Running Costs
The install is the expensive part. Running the thing is cheap on a marina berth, expensive on a generator, and a genuine engineering problem at anchor — and those three answers are far enough apart to change which system you should buy.
Marine Air Conditioning Running Cost Calculator
Set the cooling you have or plan to have, and the electricity price you actually pay. Marina berth power is metered at or above the residential rate, and some marinas add a margin on top — check your last berth invoice rather than assuming.
Australian residential power ran about 28–35 c/kWh through 2026; NSW averaged about 28.5 c/kWh in June.
Not hours switched on — hours the compressor actually runs. Once the cabin is cold a fixed-speed unit cycles around 60 % of the time.
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Shore Power, Generator and Battery Running Costs
Per hour of compressor running time, for the cooling you set above.
| Source | Per hour | Per 10 h day | What it really costs you |
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The generator figure is fuel only. It ignores servicing, the hours going on the meter, and the fact that nobody at anchor near you will enjoy it — which is usually the binding constraint rather than the money.
Battery Energy Required for Cooling at Anchor
Off the lead the question is not cents per hour, it is whether the bank lasts the night. A fixed-speed unit drawing 1.6 kW at a 60 % duty cycle takes roughly a kilowatt-hour an hour out of the bank. A 400 Ah lithium bank holds about 4.8 kWh usable, so the arithmetic is short and unforgiving.
This is the whole argument for variable-speed DC units. They slow down instead of cycling, run around 45 % duty once the cabin is cold, and skip the inverter entirely — which is worth more overnight than the efficiency figure alone suggests.
Reducing Boat Air Conditioning Energy Use
A bimini and a windscreen cover cut the solar load through the deck and glass before the machine ever sees it. Cheaper than any efficiency gain you can buy.
Cooling where you sleep, with the door shut, rather than the whole boat, roughly halves the running hours on most yachts.
Bring the boat down to temperature while you are still plugged in or the engine is running. Holding a cold cabin costs far less than cooling a hot one.
A partly blocked strainer makes the compressor work longer for the same cooling. It is the cheapest efficiency measure on the boat and it is on your side of the bill.