What Is A Bilge Pump – How Does It Work – Do I Need One

Bilge pumps are a very important part when it comes to owning a sailboat. Whether you have a 42-foot boat or even a 22-foot boat, they may be something to consider.

What Is A Bilge Pump?

A bilge pump is a pump designed to remove water from a boat’s bilge area. The bilge area is the lowest point of the boat if the boat was sitting on level ground. Water is accumulated in the bilge area due to water splashing onboard or any small leaks in the hull.

A bilge pump is a great peace of mind to have when sailing on the high seas. Most bilge pumps today are automatic as well. This means that when the water level gets to a certain height inside your boat’s hull, the pump will automatically turn on and start pumping water out.

There are two main types of bilge setup, submersible bilges, and non-submersible.

The submersible bilge pump is designed to be mounted at the lowest point in the boat’s hull. Most of the submersible pumps have a built-in float switch. When the water fills up around the pump, the float switch will rise to activate the pump. Once the pump is activated, it will begin pumping out water. These types of pumps are made to be underwater and will not be damaged by the water.

The second type of bilge setup is a non-submersible style pump. These types of pumps can be mounted in a more convenient area that is easier to reach. There will need to be a float switch mounted where the water will collect though. This will allow the pump to turn on when the water reaches a certain level. Once it does, the float switch will rise to activate the pump.

This is a great option if you don’t have much room at the boat’s lowest point. Bilge pumps can be a bit large and don’t always fit where you want them to. Take a look at the two different types of setups in the images below.

How Does A Bilge Pump Work?

A bilge pump is activated or turned on automatically by a float switch. When the water level in the boat rises, it will raise the float switch. Once the float switch reaches a certain level it will activate the pump. The pump will pump out water until the float switch goes down to a certain level.

The float switch is a necessary item when it comes to automatic bilge pumps. There are some bilge pumps you can turn on and off by a switch as well. I recommend using an automatic setup for your sailboat. This will keep you from having to check and see if there is any water in the bilge area.

Another important thing to check regularly is the bilge pump itself. I check mine every time I board my vessel. I check to make sure the float switch is not blocked by any debris that may be in my hull. I also test the power and make sure the pump will come on if the boat takes on water. You should always be prepared for anything.

Does My Boat Need A Bilge Pump?

As a general rule, all boats do not need a bilge pump. A bilge pump is good to have for emergencies. Boats can take on water for many different reasons. Hull leaks, waves splashing overboard, and rainstorms are all reasons boats may have water in them.

My first sailboat was a Catalina 22. When I bought it, it did not have a bilge pump. Naturally, I thought that would be a necessity. I installed a small bilge pump right in the middle of the hull near the drain valves. It was a very simple process and anyone could do it.

Over the time that I had the vessel I never actually needed the bilge pump. I just never took on enough water to activate the float switch. The small amount of water that did get into my bilge would evaporate over time. Basically, I never needed a bilge pump but it was a nice peace of mind. Also, I sailed on lakes only so the water wasn’t as rough.

I have been on boats where the bilge pump was necessary. A 30ft hunter I use to sail in the gulf, definitely used its bilge pump. You would hear it turn on from time to time and the water would spit out the side. It was not that often but necessary to have.

Another good reason for having a bilge pump is to help when the boat is sinking. Now, this will not save your boat if it is out in the middle of the ocean with a huge hole in the hull. What I mean is, when the boat is at the dock and you are away for a few days, the bilge pump can help slow down the sinking process.

Let’s say there is a small leak you didn’t know existed. Over 2 weeks after this leak occurred, the boat would sink. If you had a bilge pump, depending on the size, this could help extend that time to 3 or 4 weeks. Gives you a lot more time to discover the issue and get it resolved. If you show up at the dock and your boat’s bilge pump is running, you better check things out and make sure you don’t have a leak.

How Do I Install A Bilge Pump?

Check out the video below for a tutorial on how to install a bilge pump. I could type out the steps but this video makes it much easier to understand.

This video is a good basic install of a bilge pump on a Macgregor sailboat and it should help you with installing one on your boat.

What Could Cause A Bilge Pump To Stop Working? 8 Reasons

1. The breaker has been flipped.

Check the breaker to the bilge pump and make sure it has not been flipped.

2. The bilge fuse has been blown.

Remember the bilge pump usually has its own fuse. Check and make sure a new fuse is not needed.

3. Float switch is stuck or broken.

If you have an automatic bilge pump, check the float switch if the pump is not coming on even though the water line is high enough.

4. Bilge screen is clogged.

Bilge pumps usually have a screen or filter of some type to prevent chunks of trash from getting into the pump. If your pump is not pumping out water it may be blocked.

5. Drain line is clogged.

Sometimes the line where the water is pumped out of the boat gets clogged as well. Be sure to make sure your lines are empty to allow the water to flow out.

6. Battery is dead.

If the bilge will not turn on at all, make sure your battery is charged.

7. Wiring has come disconnected.

A lot of sailors will install their bilge pump themselves, which includes the wiring. Just double-check your wiring if the bilge pump is not turning on.

8. Impeller is not turning.

The impeller is what pulls the water into the pump. When the pump is on but no water is being pulled in the impeller could be jammed. Try turning your impeller to break loose the blockage.

9. The pump will not turn on or do anything.

As a LAST resort! The pump itself may just be bad. If it is old it may need to be replaced. If you just installed it, see if you can return it for a working one.

There are some common questions below that don’t need a long answer. Check out the list below for the 5 common bilge pump questions.

5 More Bilge Pump Questions

1. How Often Should You Turn On Your Bilge Pump?

As a general rule, you should run your bilge pump 2 times every hour. This will allow you to check and see if any water has entered your sailboat. If possible, consider installing an automatic bilge pump that will turn on by itself when the water level rises.

2. Do Bilge Pumps Come On Automatically?

When the bilge pump has a float switch, it will come on automatically. Bilge pumps without a float switch will have to be turned on manually.

3. Can Bilge Pump Get Clogged?

A bilge pump can be clogged by trash and debris that gets into your boat’s bilge area. It is a good rule to check your bilge pump regularly to make sure debris is not clogging it. A clogged bilge pump will not operate correctly causing water to fill your boat.

4. Can You Run A Bilge Pump Dry?

The bilge pump is designed to run until the water has been cleared out of the boat. This means that it may run dry for a few moments when clearing out the line. You may also test the bilge motor without actually putting it into water. This should be fine as long as you don’t run it for a long time.

5. Do All Boats Have A Bilge Pump?

All boats do not require a bilge pump. The bilge pump need depends on the boat and the conditions the boat will be in. If you are not sure, having one is always a safe way to go.

Now that you know everything about bilge pumps. It’s time to make a purchase. There are a lot of different options out there so let’s take a look at 8 good ones for purchase.

Top 8 Bilge Pumps For Your Boat

1. Submersible Boat Bilge Water Pump 12v 1100gph Non-Automatic

This is a non-automatic option, just keep that in mind. Click here to view it on amazon. to view it on amazon. $14.99

2. MAXZONE Automatic Submersible Boat Bilge Water Pump 12v 1100gph Auto with Float Switch

This is a great automatic option for your boat. Click here to view it on amazon. $29.99

3. AIRTAK Bilge Pump for Boat DC12V 1500GPH Small Bilge Pump 12 Volt Electric Water Pump Low Noise

This is a 1500 gallons per hour pump. Might be a little large for some boats, but it’s better to have too much than too little. Click Here To Check It Out! $38.88

4. Oasis Marine – Automatic Boat Bilge Water Pump 12v 1100 GPH 1 1/8 inch Outlet

The Oasis Marine is a good option for bilge pumps. This model has a built-in float switch. Click Here To See It On Amazon. $39.99

5. Rule LoPro Series Bilge Pumps, Compact, Horizontal or Vertical Mounting

If you have a very tight space this might be your best option, but it does come with a high price. Check It Out On Amazon! $70.88

6. SEAFLO Non-Automatic Bilge Pumps for Boats 2000 GPH 12V

Another non-automatic option. This does have a very high GPH rating. Consider this if you are looking for high output. Click Here To See It On Amazon! $54.99

7. Attwood 11596-2 Emergency Hand-Operated Livewell Bilge Pump

This is a non-powered or manual pump. This would be a good option for something very small with no drain. Click Here To See It On Amazon! $27.04

8. Rule 14A 3700 GPH Heavy-Duty Bilge Pump, Non-Automatic, 12 Volt

The most expensive model on the list. I don’t think this is necessary but if you are looking for heavy-duty pumps, this is the one. Check It Out Here! $207.00

All of the pumps in this list are a great option. It all depends on your boat and the water it takes in. Just remember that every boat is different and has different needs.


Boatlifehq owner and author/editor of this article.

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