BTU/h: Marine Air Conditioning Definition
British thermal units per hour — the unit marine cooling capacity is sold in. 12,000 BTU/h is about 3.5 kW of cooling, sometimes called “one ton”.
BTU/h in a Boat Air Conditioning System
Every marine air conditioner is described by this number first, and it is the number our sizing calculator produces. The thing to know is that it is a rating at a stated seawater temperature — almost always 25 °C. In 30 °C water in the Top End the same unit delivers ten to fifteen per cent less, which is why the tropics get a higher climate factor.
Using BTU/h Specifications in Quotes and Manuals
Use this definition to understand a quote, manual or fault report—not as an instruction to modify the boat. Before buying, compare the wording against the current manufacturer documentation. For refrigerant, fixed 240 V wiring or below-waterline work, use the official licensing and standards sources and an appropriately qualified tradesperson.
Start with the complete system guide for context, or check the owner questions for plain-language answers. Technical information can change or be wrong; the disclaimer explains the limits.