Choosing a Bilge Pump for Your Boat


Choosing a Bilge Pump for Your Boat

A bilge pump is designed to remove casual water from the lowest section of the boat, known as the bilge. This part of the boat is vulnerable to collecting water as it is found below the waterline.

Generally they are centrifugal style which means they have an impeller that spins counter clockwise and thrusts water to the outside of the pump and out the discharge. To get a better idea of how this works, check out the video below:

While there are a few different brands of bilge pumps, the one we will be focusing on in this article is the Rule range of bilge pumps.

Three Types of Bilge Pumps 

  • Non-Automatic – standard pumps that require a float switch and/or a panel switch for automatic operation.
  • Electronic Sensing Automatic – advance design pumps that turn on every 2 ½ minutes to check or sense for water (spins on for about ½ second). If water is sensed, they stay on until water is gone and then reverts to checking every 2 ½ minutes.
  • Automated with Integral Switch Pumps – pumps with internal water sensors that activate when the float rises to 2 ½ inches and stays up for two consecutive seconds. The pump stays on until the water reaches ¾” and then at least another 15 seconds until it drops to 3/8”. 
Non-Automatic Electronic Sensing Automatic Automated with Integral Switch Pump

Panel Switches

A panel switch is a switch installed in the panel of the boat that can be used for manual and/or automatic operation of the bilge pump from above deck. The pros and cons of having a manual switch is that you can operate the bilge whenever it’s needed but having it constantly on can burn out the pump and/or drain your battery. Many of the Rule panel switches feature a “spring return to off” fail-safe on the manual position so you cannot leave your pump running by accident.

Standard Bilge Pump Panel Switch Bilge Pump Switch with Automatic Function

Automatic Float Switches

Automatic float switches activate a non-automatic bilge pump when water is present. Rule manufacture a range of automatic switches that are ignition-protected, ultrasonically welded and sealed for reliable trouble-free service. The wiring is blocked to keep out moisture and exits the top of the switch to keep them high and dry. Different models are available to suit various pump amperage loads. No battery drain and no exposed metal to corrode.

Selecting the Right Bilge Pump

When selecting the right bilge pump, a general rule of thumb is to have at least 100 gallons (378 litres) per hour of pump per foot of boat.

This pump performance chart is an approximate guide to the output of various Rule pumps at different pumping heights.

Remember that an electric submersible bilge pump cannot lift water, it can only push it up and so it must be submersed in water.

It is also important to consider the output, water flow and pumping height which will vary depending on your battery and type of installation.

Backup Pumps

Since bilge pumps can fail, use of a backup pump is often advised. The primary pump is normally located at the lowest point of the bilge, while the secondary pump would be located somewhat higher.

This ensures that the secondary pump activates only when the primary pump is overwhelmed or fails, and keeps the secondary pump free of the debris in the bilge that tends to clog the primary pump.

For more information on the Rule series range of pumps and switches, check out the full range online here or in the video below -

Category: Safety

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