Bilge Pump Selection Guide

Bilge Pump Selection Guide

By: CraigComments: 0

We’re asked lots of questions about our selection of bilge pumps, from brands including Attwood, Rule and Johnson, both in our Rochester based store and online - and with so many brands and models available, it is understandable to feel a little lost when picking the right pump for you and your boat. 

In order to help you make the most informed decision, we've collected some of our most asked questions and answered them in this easy to read guide. But if your question remains unanswered at the end of reading this post then feel free to contact us either through email, telephone (01634 295 233) or even pop in to our store. 

What is the difference between an electric and manual bilge pump? 

An electric bilge pump is a bilge pump that requires connection to the electrical system in place on your boat to pump water out of the bilge area. A manual bilge pump is one that does not require connection to your boats electrical system - manual pumps feature handles in some configuration that control the pumping of bilge water.

Even if you have an electric pump on board your boat, it is still highly recommended having a manual pump as well, simply as a backup should you lose power while out on the water. Though it should be noted that any number of pumps will be insufficient should you suffer a severe enough leak while out on the water as pumps are only equipped to deal with water volumes that may accumulate from spray, or small leaks such as those from portlights or hatches.

Automatic vs Non Automatic Bilge Pumps:  

Electric bilge pumps are also differentiated into automatic vs non automatic.

A non automatic bilge pump requires a manual panel switch that will allow you to control the pump from where the switch is installed, typically on the dash.

A panel switch can be installed with a sensor allowing it to highlight a warning to you via a small LED light, a warning alarm or even through a connected app on your smartphone. The pump can then be operated remotely until the warning systems switch off to inform you that the water level in the bilge area has returned to an acceptable height.

An automatic bilge pump is one that can operate on its own. Typically, this is done by the pump turning itself on every few minutes to check the level of the water. It can also be done by the use of float switches, these are switches placed low in the bilge area that, after the water level becomes high enough, switch on the pump.

There are also switches that detect the water level by using what is known as the Mirus effect. This is done by the use of detector cells that send a signal to the pump when they detect a disturbance in water levels. Once these detectors and switches sense the water levels are lower they will then turn off the pumps they are connected to. 

How many gallons per hour do I need?

When choosing a bilge pump for your boat, it is important to know the size of your boat. Smaller boats will have smaller bilge compartments and so will still need good-sized pumps as their bilges will fill up faster. Other boats may have separate bilge compartments. When that is the case, it is a good idea to have a pump for each compartment.

Pumps are rated on the amount of gallons they can pump in an hour. It is highly recommended that you choose the largest model that is still practical for your boat. It is also important to consider the size and capacity of your boat's wiring and battery, as well as the output hose. If you have any queries about what will work best for you, feel free to ask us directly about what bilge pump we can recommend for you.

Boat SizeNumber of PumpsPump Output (GPH)
16’ - 20’22500
21’ - 26’23500
27’ - 35’34500
36’ - 42’36000
43’ - 49’38000
50’ - 59’410,000

What does a bilge pump float switch do?

Float switches are the most common type of bilge pump switch. They use a pivoted float to sense water level. When water level is low enough, the switch will be in its off position. When water levels rise, the switch will begin to float, rising with the water level and turning on the pump. The inverse will then happen while the pump removes the water from the bilge, as the water level lowers the switch will begin to lower until it returns to its off position switching off the pump. 

What does a bilge pump rocker switch do?

A rocker switch is a bilge pump switch, usually a panel switch, that provides control over your pump - with three controls available on the switch, automatic, off and manual.

In the automatic position the pump will operate under automatic control, if (for example) you have a float switch, the pump will be under the control of the float switch. Toggling the rocker switch to manual will allow you to bypass the float switch and operate the pump from the panel. While resetting the switch to the centre position will turn the whole pump system off.

How often should I service my bilge pump?

Inspecting your bilge pump should be something you perform regularly and frequently, carried out as part of your overall preventative maintenance. Doing this will help you know when to replace worn or damaged components, such as float switches or the hose that the pumps are connected to. It is also important to make sure the pump has power and is working properly, meaning it is able to actually pump water overboard. If you need to make a repair to a pump we stock a healthy supply of repair and service kits

Allow us to introduce ourselves..

   We hope that this blog post has helped you with any of your bilge pump questions. If you have any further questions, whether that be about the bilge pumps mentioned - or other pumps including freshwater pumps, shower pumps, or even macerator and toilet waste pumps, feel free to contact us via  email, telephone (01634 295 233) or even pop in to our Rochester store - one of the largest chandleries in the United Kingdom! 


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