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How to Size a Bilge Pump for a 25-Foot Boat (2026 GPH Guide)

How to Size a Bilge Pump for a 25-Foot Boat (2026 GPH Guide) For a 25-foot recreational boat, size your primary compact centrifugal bilge pump at 2,000 GPH (rated) with a 1,000 GPH backup on a separate circuit — and remember that a "2,000 GPH" pump only delivers about 1,520 GPH once it lifts water 3 feet to the discharge fitting. That gap between the box rating and real output is where most owners get caught. Run your own breach scenario with our free Bilge Pump Calculator(/marine/bilge-pump-calculator) before you buy. I have spent more weekends than I care to admit elbow-deep in a 24-foot center console's bilge, and the lesson that stuck was numeric: my "1,100 GPH" cartridge pump measured roughly 700 GPH at the transom outlet 3 feet up, and once I added a 14-foot hose run it crept lower still. A friend's failed 3/4-inch raw-water hose on a...