Installing A New Washdown Pump
Washdown systems draw water from outside your boat and sends the water through a common garden-type hose.
by Chris Caswell
May 1, 2003
Whether you're cleaning up after a fishing trip or hosing the crushed potato chips out after a
family cruise, a washdown pump makes the task fast and easy even when you're offshore. Washdown
systems draw raw water from outside your boat, strain it for impurities, and deliver it to a pump
that sends the water under pressure through a common garden-type hose. They can be added easily by
any boatowner who grows weary of using buckets of water to clean a boat.
Step 1: The pre-packaged Washdown Kit from Shurflo (about $190) is chosen in this
example. It includes a Pro Blaster pump, raw-water strainer, connection fittings, coiled hose and
spray nozzle. The pump generates water pressure of 45 pounds per square inch (psi), a turn-on
pressure of 25 psi, and is designed to be waterproof in a 'splashed water' area. With an epoxy
powder-coated finish, it can be mounted in an exposed cockpit to eliminate the need for installing
a separate faucet: Simply attach the supplied hose directly to the pump, energize the pump circuit,
and trigger the hose nozzle. In addition to the basic kit, you'll need enough tubing to connect
from seacock to strainer to pump, hose clamps, an inline fuse holder, an ignition-protected switch,
and wiring to connect the pump motor.
Step 2: Mount the pump in a dry location that allows easy access for maintenance
and hose attachment, such as underneath the cockpit coaming. The pump generates heat, so it should
not be in a closed space of less than one cubic foot unless ventilation is provided, since the heat
may trigger the integral thermal breaker. The pump must be mounted higher than the outside water
level, and in the case of the Shurflo Pro Blaster, is self-priming up to six feet above the
waterline. The pump should be mounted on a solid surface that will not amplify the sound of the
pump. Use No. 8 stainless-steel fasteners and be careful not to overtighten the pump, because the
rubbery mounting feet will lose their ability to isolate vibration and noise if flattened.
Step 3: The strainer is necessary to trap debris that might clog the pump and must
be above the waterline so that it can be opened for cleaning without siphoning water from outside
if the seacock is open. The strainer should be in line where it can be inspected and cleaned
regularly, and the quality of the water in your boating area will determine how often you need to
check the strainer. Use only hose that is rated both for high pressure and for vacuum so it doesn't
collapse. The Shurflo kit is designed for 3/4 inch, and in this example West Marine Series 148 hose
with vinyl reinforcing ($2.19/foot) is chosen. Use the supplied barbed fittings to attach the hose
from strainer to seacock with Teflon tape on the inlet side of the strainer to prevent leaks. Do
not use Teflon or sealant between strainer and pump, since particles may clog the pump. Secure with
hose clamps.
Step 4: The DC electrical connections are straightforward, and the Pro Blaster
pump draws just 4 amps. It should be on a dedicated (individual) circuit that is protected on the
positive (red) lead with a 15-amp 'slow burn' fuse. An inline fuse holder is used to create a
separate washdown pump switch on a Blue Sea Systems DC panel. The wire size you'll use depends on
the distance from power source (DC panel) to the pump, with a minimum of 14-gauge and 12-gauge for
wire runs of 20 to 50 feet. In this example, 14-gauge Ancor marine-grade insulated wiring is
selected. It's a bit more expensive but tinned to prevent corrosion in the damp marine atmosphere.
Story and photos by Chris Caswell. May 2003.