Tips for Installing a Bilge Pump

You need a bilge pump if you own a boat, period. Maybe even two: a low capacity pump to deal with the nuisance water, and a high capacity emergency bilge pump to keep you afloat in the event of a hull breach.

After choosing the bilge pump(s) for your boat, the next step of course is the installation process. Here are some tips for making a boat bilge pump installation easier and more effective.

Find Easy Access Installation Spots

Make sure the bilge pump(s) are easily accessible once installed. Bilge pumps need periodic maintenance, and their intake screens or strainers require regular cleaning. 

Burying a bilge pump where you can’t reach it will cause you endless headaches over the years. Larger capacity emergency bilge pumps can be mounted higher in the boat. However, finding an accessible location for a low capacity bilge pump for nuisance water isn’t always easy because the pumps tend to need mounting lower in the bilge. Place the pump as near to an opening or access panel as possible.

Plan for Multiple Bilge Compartments

Larger boats may have more than one bilge compartment, which means you’ll have to choose between getting multiple nuisance water bilge pumps (one for each compartment) or running a network of intake hoses to each compartment from a single bilge pump.

Plan out your emergency bilge pump system too. Calculate whether a single pump has enough capacity to manage the volume of water the bilge could potentially take on. Larger boats may require a second emergency pump to raise the total emergency pumping capacity.

Replacing Bilge Pumps

If you’re replacing a pump, buy a new pump that uses the same diameter hoses and gauge wiring as the previous unit. By matching the new bilge pump to the old pump’s ancillaries, you can simply plug in the new pump and go.

Bilge Pump Installation Tips

• Always mount centrifugal bilge pumps with the outlet facing upward to ensure air doesn’t create an air lock in the pump’s body.
• Keep all hoses and pipes as short as possible to minimize the resistance the water will encounter and maximize the pump’s performance.
• Avoid corrugated pipes and hoses that generate much higher water resistance and greatly reduce the bilge pump’s performance. Always use smooth bore input and discharge hoses and pipes.

• Make sure the thru-hull discharge outlets are high above the waterline to prevent water from entering the fitting and siphoning back down to the bilge through the pump.

• Install a check valve or non-return valve in the discharge line to prevent any water running back through the line into the pump and bilge. This provides protection against water remaining in the discharge hose when the bilge pump is switched off, or any water that enters the thru-hull discharge point.

• Fit the lowest-rated fuses set by the manufacturer so if the pump gets clogged and overworks its motor, the fuse will blow before the motor does.

• Add a bilge alarm that sounds or lights up when the bilge water level reaches an unacceptable level.

• Make sure the wiring between pump and battery is the correct gauge per the manufacturer. Using the wrong gauge wiring can cause a voltage drop in the pump and a corresponding drop in performance.

• Install a quality automatic float switch if the new bilge pump doesn’t have an automatic on/off switch. This automatically turns the pump on when the bilge water reaches a certain level, and off again once sufficient water has been pumped out. 

Inspect Your Boat’s Bilge Pump System

Don’t neglect your bilge pumps after installing them. The pumps’ intake screens and strainers need regular cleaning and the pumps themselves need annual maintenance. Inspect the hoses and couplings regularly for leaks or splits, and make sure the wiring and electrical connections are free from corrosion.