Successful boating means keeping copious amounts of water out of certain areas and judiciously bringing it into others. Watertight seals and cleverly scuppered decks keep water out. Pumps complete the tango by bringing it in, say to fill a livewell or to wash a sandy or fish-bloody deck.
Choosing pumps for these jobs means balancing the limits of onboard power, livewell capacity and the space available for installation.
Washdown pumps have pressure switches that shut them down when there’s no demand for water. We tested two top brands, both offering kits that include a sea strainer to protect the pump.
Kits like our Johnson 5.2 that include hardware, hoses and quick-disconnect fittings speed installation. Even the sea strainer snapped in place, and the kit featured a fused switch panel that can be mounted near the pump’s outlet for convenience. The only thing we didn’t find in the kit is a bulkhead-mounted spigot, which will be needed to bring water to the cockpit.
How We Tested
Livewell pumps were mounted on a floating panel in a 25-gallon aquarium to maintain constant ideal contact with water.
Washdown pumps were set on the bench near the receiving tanks, and intake hoses were dropped into the reservoir tank.
Amperage draw was measured using a multimeter while the pump was under load with 20 inches of head.
Voltage applied was 12.5 volts. Some pumps are capable of running on 24 volts, but that voltage was not tested.
Average head of 30 inches was determined by measuring and averaging the increasing vertical distance from the reservoir water level to the receiving tanks — five-gallon buckets.
Pricing is the lowest acquired value located during our research and testing prior to publication, and could be subject to change.
Pumps for Under-40-Gallon Livewell
Bait Sentry 800/No. 1700-010-0
Special Features: Bait Sentry’s magnetic drive allows the impeller to stop turning when debris is ingested, while the powerful magnetic “clutch” allows the motor to spin harmlessly.
Special Hardware Included: The 3/4-inch threaded intake is ready to mate with a seacock.
Materials Not Included: Sea strainer, Teflon plumbing tape, sealant and through-hull with seacock.
Performance Report: On my boat it lasted five years — far longer than for many pumps. It pushed 28 percent more water at a 30-inch head than its rated flow.
Cartridge Aerator 750/No. 2870
Special Features: Removable motor cartridge design makes emergency repairs or replacement easy.
Special Hardware Included: The 3/4-inch threaded intake pipe and included nut may be used to form its own through-hull fitting, according to Johnson. Straight and elbow tailpieces add options.
Materials Not Included: Sealant, gaskets and sea strainer are required to complete the installation. Consider using a seacock.
Performance Report: Our pump exceeded its no-head flow rating of 750 gph by 29 percent. The cartridge was among the easiest to replace thanks to “wing nut” ears on the cartridge and a simple locking device on the pump body.
Tsunami T800/Nos. 4608/4650/4670
Special Features: A replaceable motor cartridge eases change-outs should the pump fail. The integrated through-hull intake eases installation in cramped bilges.
Special Hardware Included: The threaded outflow port receives either a straight or elbow tailpiece, included.
Materials Not Included: Sealant, required for through-hull mounting, or Teflon thread tape. Sea strainer is not included, nor is a through-hull or seacock, should the installation allow for it.
Performance Report: Turning the threaded cartridge counterclockwise releases the locking mechanism, allowing the cartridge to unscrew easily. The Tsunami 800 gave good flow, drawing a scant 2.9 amps — ideal for single batteries.
Special Features: This compact pump will fit easily in any small bilge area.
Special Hardware Included: The 800 ships with a straight through-hull installed and an extra 90-degree base for transom installations.
Materials Not Included: The pump includes a simple strainer to stop damaging debris from destroying it, but we’d still recommend a sea strainer. Consider using a seacock.
Performance Report: This compact R2D2-shape pump surprised us by exceeding its no-head flow rating by 22 percent. Its 5⁄8-inch spur has ample room for double clamping.