Mermaid M12 – Cool Only Marine A/C Unit 12,000 BTU’s 110V

The Mermaid M12 is built by FMS Manufacturing for boats around 32 to 34 feet, sized to cool roughly 1,000 cubic feet of cabin space without the bulk of a larger system. This cool-only version runs on 110V, and its compact, hand-built construction gives it the smallest footprint in Mermaid’s 12,000 BTU class — a detail that matters most when headroom or cabinet space is already tight.

Why Choose the Mermaid M12

This is a cool-only unit — it does not include reverse cycle or electric heating, which makes it a straightforward, lower-complexity option for boats in climates where heating isn’t a priority. For boats that need both cooling and heating from the same unit, Mermaid’s M12 Cool & Reverse Cycle model covers that instead, at a similar footprint.

Mermaid builds these by hand in the US, and the company reports selling 900 to 1,200 units per year across a range from small cabin cruisers to 75-foot sailing yachts — worth noting if hand-built, lower-volume manufacturing and personalized support matter to your buying decision.

What to Know Before Installing

• Pump is not included — a separate water pump must be purchased for installation
• An 1,800-watt Statpower pure sine wave inverter with 450 amp-hours of battery is Mermaid’s recommended setup for anchoring out overnight without shore power
• 4-inch ducting requires at minimum two 4-inch round supply grilles per Mermaid’s installation guidance
• The V-shaped taper on the blower housing is designed specifically to simplify odd-angle discharge installs — worth checking against your cabin’s layout