How To Install A Bilge Pump


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1. Before You Start


Installing a bilge pump is straightforward but to get the best performance
out of your pump it is essential to consider the following before you start.

• Type of Bilge Pump setup - Centrifugal Bilge pump running a manual
or auto operation. This will decide what switch operation, and cable setup
you will run.

• Make the hose run short and straight – The shorter the hose run and
the less bends will allow a greater pump output.

• Fasten your bilge pump – Fastening the bilge pump to the hull stops it
flipping over and potentially sucking in air which will burn it out.

• Place the discharge outlet above the waterline – This helps prevent
water siphoning back into the boat, which could potentially flood your
boat. Ideally position the discharge outlet so you can see the pump
discharging when you’re at the helm.

• Use the correct cable size – Bilge pumps draw a large amount of amps,
make sure you get cable big enough to handle this.


Products you will need

2. Getting Underway

Decide on the fastening point for your bilge pump. The centrifugal bilge
pumps at Burnsco are designed to be submerged underwater, so mount
the pump at the lowest point possible.



All of the centrifugal bilge pumps we stock are designed to be submerged
underwater so as low in the bilge as possible is a good location.


3. Discharge Hole & Skin Fitting

Locate your discharge hole and double check it is above the waterline.
Choose an appropriate size of skin fitting to match the bilge pump outlet
and discharge hose, eg if the bilge pump outlet is 1 1/8” in diameter then
choose a 1 1/8” skin fitting.

Now that you have the location of the bilge pump and the skin fitting.
you can determine where the hose will run. Remember that you want
the run as short and straight as possible. Cut your hose to length - better
to cut it slightly longer than you need because you can


Drill a pilot hole in the side of the boat where the skin fitting will be
located. Cut the correct size hole with a hole saw and check that the skin
fitting is a snug fit. Use Sikaflex 291 to improve watertightness.

Connect one end of your hose to the bilge pump and the other to the skin
fitting. Tighten the hose at both ends using hose clamps.

4. Wiring The Bilge Pump


First measure the cable run you need. If you’re running a manual pump
it is best to measure two runs from the bilge pump. The positive wire
runs from the bilge pump to the switch panel and the negative wire runs
from the bilge pump to common earth (eg battery negative). Allow extra
length for the twists and turns to keep the cable out of the way.

If you have an auto bilge pump or are running a float switch see below.

Use this cable chart to discover what size cable you need. This is a guide
only depending on your run length you may require a bigger cable size.


Use Duraseal connectors and heatshrink to connect your bilge pump
wires to your power (positive) and common earth (negative) wires.

Slide the heatshrink over the wires and out of the way before you make
the connection, place the exposed wires into the Duraseal connector,
positive to positive, and crimp. Use a heat gun on the Duraseal connector
first, then slide the heat shrink over the Duraseal connector to give it the
best possible chance of being watertight. Finally heat the heatshrink.

Repeat this process for the negative wires.

Complete the circuit by using a ring connector to connect the negative
cable to the negative terminal on the battery and a blade connector on
the positive to connect it to the switch panel.


 5. Finishing


Check your wiring is secure and the circuit is completed.

Check all other connections and attachments and make sure they are

To test that the bilge pump works correctly, fill the bilge with water, and
turn the bilge pump on. Check the flow and make sure all your seals are