Bilge Pumps

Boating Know How

Identifying Your Ideal Bilge Pump System

When choosing a primary or secondary bilge pump for your boat, there are many factors to address, such as gallon-per-hour rating, mounting location, cartridge versus non-cartridge, quantity, and brand. ... read more
Bilge Pump

With an ocean of articles covering these subjects, I'm skipping ahead to an aspect of bilge pump selection less commonly addressed:  choosing a bilge pump system and component type that's most ideal for your boating routines and needs, primarily dealing with automatic versus manual bilge pumps, and the switch options and variations to control the pumps.

Since slight variations in terminology can indicate different products/traits,  it's important to understand the different primary components most commonly used for standard bilge pump systems:

bilge pump float switch

: mounts to the bottom of the bilge, which works much like any other float-switch; when water levels increase, the float is raised, which activates the the pump.  Manual Bilge pumps that utilize float-switches become automated, and are commonly referred to as "automatic bilge pumps"

Bilge Pump Switch

Bilge pump switch
(non-float): mounts to the dash.  Depending on the switch, you'll have the option of “on/off” or “Auto/Manual/Off”.  "Manual" or "On" will be for when you want the pump on, regardless of water level readings by the pump (or float-switch).    Auto will activate the functionality of the float-switch or built in sensor, allowing the bilge-water removal process to be automated.

Automatic Bilge Pump: have built-in water sensors that periodically turn on to check for water.  If water is present, the pump will activate.  The sensor will usually turn on once every few minutes.  The advantage of automatic bilge pumps is that you get an automated water evacuation system without requiring any components other than the pump and wiring hardware to connect to the electrical system, which is simple and takes up minimal space.  The biggest disadvantages of an automatic bilge pump, assuming it's not connected to a bilge pump switch, is that if the pump is not disconnected from the battery, it's sensor will continue to periodically activate.  If you store your boat outside of the water, this feature becomes pointless and will slowly drain your battery.  The second disadvantage is the lack of manual on/off control, though there are some exceptions

Manual Bilge Pump: activated by either a float-switch or a (dash mounted) bilge pump switch.  If a float-switch is used, the pump becomes an “automatic” bilge pump, but rather uses a float-switch to activate the pump rather than the water sensor.  It's common for manual bilge pumps to be sold with float switches and be labeled as as “Automatic”.  If you have a system consisting of manual bilge pump, float-switch, and bilge pump switch, you'll have full control of how and when the pump activates.  The auto feature will use the float-switch to activate the pump, with on/off turning the pump on/off regardless of float-switch readings.

With the above components options, you have several ways you can choose to manage your primary or back-up bilge pumps system:
  • Manual bilge pump with 3 way pump switch and float-switch:  complete control of your pump including choice of automated water evacuation.
  • Manual bilge pump with float-switch: Bilge pump becomes automatic, but doesn't allow for direct on/off control.
  • Automatic Bilge pump with 2 or 3 way pump switch:Automated bilge pump with the ability to turn it completely off.  Some Automatic pumps give the ability to manually turn the pump on, which would have the same results as a manual bilge pump system that uses both a float-switch and a bilge pump switch.
  • Automatic Bilge Pump with no switches: Automated bilge pump without the ability to manually turn on or off (some exceptions) and will drain battery if not disconnected.
Relatively speaking to the rest of boating, bilge pumps and components are exceptionally inexpensive, making not "cheaping-out" almost painless.

If you're in the market, we carry bilge pumps from Rule, Johnson, Attwood and SeaSense who all offer a wide variety of top quality pumps, cartridges and switches.  Addionally, with the Low Price Guarantee, you can be sure to get the very best price available.

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Airlocks in Bilge Pump Hoses (Video)

A video demonstration on explaining how an airlock happens in a bilge pump hose. ... read more

Thanks for watching

I’m Jeff Lander. And I’m Mike Irvine.

And today we are going to talk about Rule bilge pumps and avoiding dips and sags in your discharge hose line.

Now the big thing is, when you install your Rule bilge pump, has to go continuously upward. That discharge line if it has any sags in it, it is going to cause a water trap.

We made you a cool fixture to show you what is going on. So this is pretty cool. We have some clear pvc, hooked up to a 500 gallon per hour bilge pump. We made it so we can raise and lower the pump to simulate the water level dropping in the bilge. So as the water level goes down, the lower switch shuts the pump off, and residual water in the line drains back down into the system.

So what happens is, some of the water remains in this little valley here. And there’s a whole bunch of air that goes from here, all the over to the other side of the pump. Actually to the underside of the impeller cavity. Now as the water level raises again, you still have this air bubble that goes from here and up and over to just about there where that water level is.

Pump switch turns on, it can’t pump the water, and that’s because these pumps are centrifugal style pumps. They are not self-priming. Which means the water has to be in contact with the impeller to be able to pump the water out.

That’s a great example of an air lock right there. See that big air bubble on the underside of that running pump? That air cannot move through the system because of that air trap right there. That water is stuck and can’t move through the system of that valley. Gravity is pulling the water down to the bottom of that valley there. And this air can’t go any place. So the pump is running, but it just can’t displace that air.

So there you have it. We just showed you what happens when you Rule bilge pump has dips and sags in the discharge hose line.

Now the big takeaway is to run that discharge line continuously upward. If you have any valleys, that is where the water is going to collect, and that could cause an air lock.

Well, I’m Mike Irvine and I’m Jeff Lander. Thanks for tuning into this episode of Jabsco Tech.

Hopefully it was helpful to see what can happen when there are dips and sags in your discharge hose line. Come back soon, we’ll have more videos for you.

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About Bilge Pumps
Submersible bilge pumps are a necessity for almost every boat. At offers a massive range of bilge pump models from brands such as Rule, Johnson, Attwood, SeaSense, Seachoice, and Jabsco. Choose from a wide selection of GPH ratings (gallon per hour), outlet sizes, voltages, and choice between Automatic pump vs. manual bilge pump, or cartridge vs. non-cartridge. Are you looking to make that manual bilge pump automatic? No problem, we have a wide selection of floats and switches that give you the ability to choose how and when you want your bilge pump to activate, as well as replacement cartridges to keep your pump working smoothly.