Marine AC PumpSelector Tool

The industry standard is 180 GPH (gallons per hour) per ton of air conditioning. One ton equals 12,000 BTU. So a 48,000 BTU system (4 tons) needs approximately 720 GPH of water flow. Our selector calculates this automatically — just enter your total BTU load or select your AC system model.

Centrifugal pumps (Scot, Oberdorfer) use a mechanical seal and are the industry standard for marine AC — they handle higher flow rates and longer pipe runs. Magnetic drive pumps (March, Little Giant) have no mechanical seal, which means zero seal leaks, but they're limited to shorter pipe runs and lower heads. For most boats under 50 feet with a single AC unit, either type works. For multi-zone systems, centrifugal is the standard.

Yes. The Oberdorfer 107M series is designed as a direct drop-in replacement for the Scot 67/68 series. The 107MA replaces the 1500GPH Scot (P120 systems) and the 107MB replaces the 2000GPH Scot (P700 systems). Many technicians prefer Oberdorfer for their precision-machined impellers and quieter operation. Both use the same mounting pattern and plumbing connections.

Only if your pump is installed above the waterline. Most marine AC pumps are installed below the waterline and don't need self-priming capability. If your pump location is above the waterline (common on some sailboats and catamarans), you'll need a self-priming model like the Oberdorfer 300B, Scot 77, or MP Pump FMX100. Our selector has a self-priming filter option.

Chilled water systems use a closed-loop freshwater circuit instead of raw seawater. They require different pumps — typically Calpeda, Cal Marine, or Gianneschi models designed for freshwater circulation. Our selector has a chilled water option that filters to the correct pump types. If you're unsure whether your system is direct expansion or chilled water, call us at 239-323-9600.