Having a hands-free means of pumping out a flooded cockpit has great advantages and I have always outfitted my kayaks with a foot-operated bilge pump. However, in the back of my mind has always lingered the desire to build my own battery-operated kayak bilge pump.
Recently I took on the challenge. My first limitation was a personal rule that all my kayaking electronics are powered by AA NiMH rechargeable batteries. Second on my list was a simple design and third was a modest budget. This pump setup uses parts that should all be readily available at an electronics or marine supply store for about $100.
The system has exceeded my expectations on all accounts. Most notably the battery power has proven to be more than adequate. Eight times I sat in the cockpit flooded so that the water level was over my thighs and eight times the pump cleared the water in about four minutes.
I learned that I did not need any fancy switching on deck. Held under the deck by two snug bungies, the switch on the battery box can be toggled left or right (on or off) by means of my shin.
The basic system is easily adapted to various locations for the pump and the battery box.
Instructions for your battery‑operated kayak bilge pump
DIY Bilge Pump Assembly
The fully submersible pump, 600 gal/hr (38 L/min), is connected to the battery box with the wire provided with the pump. This pump came with an alternate 90-degree elbow. The rubber tricuspid one-way valve provided with the pump was of poor quality and was replaced with a new 3/4-inch one-way valve shown near the end of the clear plastic tubing. The toggle switch is covered with a rubber protective sleeve.
DIY Bilge Pump Wiring
Twelve 2500 mA, 1.2-volt NiMH batteries are held in a combination of one eight-cell and one four-cell battery holder wired in series to produce a maximum of 14.4 volts—well within the tolerance of the 12-volt pump.
An optional 2.5-amp fuse and a simple toggle switch are wired into place. The wires and toggle switch have been fitted snugly through holes drilled through the case. Inside the case the wires have been tied in a knot to prevent any tension on the internal wiring. The toggle switch is fitted with a supplemental rubber cover from the marine supply store.
Waterproof the holes drilled into the case with some seam seal or marine caulking. Wires can be connected with solderless connectors, or soldered and then insulated with shrink wrap. A small piece of foam sits on top of the batteries to keep them in place when the box is closed. The battery holders come out of the box easily by unsnapping the connector.
Parts List For Your Battery-Operated Kayak Bilge Pump
- Pump, $25
- Plastic box, $13
- Toggle switch, connectors, fuse holder (optional), battery holders, waterproof case, $25
- One-way valve, $12
- 3/4-inch tubing, hose clamps, wire connectors, through-hull fitting $10
Note: Through-hull fittings vary greatly in cost. I use inexpensive nylon fittings that cost about $2.