Bilge Pumps Compared

What is a Bilge Pump and How Does It Work?

On a boat, the bilge is the lowest part. It's designed to collect water, and the bilge pump is designed to remove that water. The pump relies on the pressure generated by hand or electricity to draw in water and drive it off the boat through an exit called a discharge point.

No matter how big the vessel, some sort of bilge pump, or a system of several pumps is essential to keep the boat afloat on the open sea or small freshwater lakes.

How to Choose a Quality Bilge Pump for Fishing

Pump Type

Sometimes more control over the pump is needed. Cycling, the term for how an automatic pump senses water, turns on, drains the water, shuts off, and then senses water again, can sometimes run for too long due to sensor problems or water backflow.

In that case, a pump that can be manually shut off is useful. Some portable bilge pumps are great for a smaller craft like kayaks and also helpful as bailing tools that can be handed off to another boat in distress if the need should ever arise.

Boat Type & Size

Pumping Capacity & Flow Rate

The amount of water a pump can move in a specific time is called its pumping capacity, and it is most frequently expressed in gallons per hour or GPH. You don't always need the strongest pumping capacity.

Smaller boats will never have any need for it, and larger boats only will in the event of an emergency. It's always best to have a strong enough pump to prevent the boat from sinking, but don't go overboard with it.

Ease of Installation/Mounting

Bilges can be narrow, small, and dirty. It’s always best to clean the bilge several times in a season to make sure electronics, like those on a bilge pump, will work effectively. Trying to find a way to fit the bilge pump in with other engine parts and sensors can be difficult, but there’s always a way to get it done.

Material & Versatility

What the pump is made out of will determine how strong it is. In really bad weather or fighting a sizable leak, a pump with a strong exterior will be desirable to last through a beating from fast-moving water.

Materials like BAS plastic are durable and inexpensive. Plastic won’t corrode even if it might break after long, hard use. Other parts of the bilge pump, like the pump shaft or gears, should be made of a really tough material like stainless steel.

Noise Level

You won’t always find a noise rating for these machines, but some of them have one in decibels. As technology progresses, manufacturers are building more and more silent bilge pumps. While it’s clear that a quieter pump is better, bear in mind that you will want to be aware of what the pump is doing, so you should get a sensor of some kind if the pump is completely silent.

Price & Warranty

Bilge pumps come at every price point. It's important to plan for what sort of water your vessel might take on during a voyage. A portable bilge pump for a kayak has its place on a Jon boat or slightly larger craft, but it definitely shouldn’t be the only pump on board.

It doesn't necessarily require a ton of money to get the right pump for your boat. Luckily, even some of the less costly options come with warranties, and you can replace faulty parts for two or even three years after purchase.

1. Rule Marine

Rule bilge pumps are the standard when it comes to removal systems. Their float switch has become ubiquitous in both commercial and sport angling boats since it was developed, and the pump itself is just as dependable. Rule pumps install really easily, and once you have them set up, the pop-off cover makes the filter and impeller cavity easy to clean.

Rule bilge pumps work almost silently and, to a varying degree depending on the particular model, move a sizeable volume of water out of the boat. The 12v bilge pump works great for fishing boats, while larger boats or more cautious captains will want to go with the 24V or 32V models.

While it's slightly annoying that the float or panel switch is sold separately, once you have the complete package, your boat will have the most reliable and all-around best automatic bilge pump setup on the market. This pump can handle some very small debris but not very much, so it's always best to keep an eye and an ear out to make sure you catch any problems before they get worse.

It will continue to work underwater, and it fits into narrow spaces to suit smaller bilges. This pump can run without water inside it for a short time, which is ideal for preventing damage and for emptying the bilge all the way while avoiding cycling issues that can drain the boat battery.

2. Shoreline Marine

3. Attwood Tsunami 

4. Seattle Sports Paddler’s 

5. Rule 25S-Marine

6. SeaSense 

Although it works just fine for kayaks as well, this hand bilge pump can also handle larger craft like a Jon boat or a small bilge. It’s great to keep around as a primary bilge pump on a kayak or canoe and a good emergency pump on a Jon boat. This hand pump is more robust than other portable bilge pumps, and it's a bit hardier. The body is constructed to be leak-proof and corrosion-resistant, so it should last a good while. 

Operating the device is as simple as a bicycle pump, and the narrow tip is great for getting into hard-to-reach places. An optional hose attaches so you can direct water off of your watercraft. The only thing you might need to consider about the attachable hose is that it's quite long, and you'll need to keep it more or less straight and not entirely vertical for the best results with this pump.

A filter on the end of the pump keeps large objects from impeding the flow of water and allows for easier pumping. When not in use, this pump fits easily in storage compartments or tethered to the inside of the boat with a bungee like you might do with a paddle on a kayak.

7. Attwood 4511-7 Sahara S1100

8. Amarine Made

This incredibly inexpensive bilge pump fulfills all the requirements of a bilge pump, moves lots of water, and lasts as long as more upmarket models do. It handles dirty water pretty well if you can make sure that larger objects don't obstruct the sucking power.

Like some of the best models, if you want this one to run fully automatic, then you'll have to buy a separate float switch. There are some slight drawbacks in the comparative frailty of the plastic parts on the Amarine Made bilge pump, and it does draw out more power (3 amps), but if it's installed and operated correctly, it will still get the job done.

One reason this pump works so well on larger vessels is because it’s designed to pump water continuously if need be. This is done partly by building the motors so that they use the surrounding water to cool down and keep working for longer intervals. That’s just what you need for larger bilges. It’s also really quiet when it works, so make sure to invest in some kind of sensor to give you some indication of how often it flips on.

This pump is small enough to fit on smaller vessels and be tucked out of the way in larger bilges. It may not last as long as some of the larger models, but with a price as low as the Amarine Made pump, you might find it easier to just get a new model every few years. 

9. Seaflo 

As you can likely gather from its name, this pump is the most powerful one in our guide. It may not be as inexpensive as a budget bilge pump, but if you have just a little bit more money to invest, you can't go wrong with this one. It's ideal for a smaller boat where moving water out of the bilge can be more pressing. It can draw tons of power out of a battery but can be set up not to. The base contains a strainer and snaps right off for easy cleaning.

This pump is great for avoiding airlocks, although the tubing up to the discharge point has to be installed correctly if you really want to make sure. There are enough seals, buckles, covers, and screws inside this pump to protect it from damage, but there aren't so many parts that it's impossible to maintain. It can run dry without being ruined, but it's not meant to do so for long, and it's not really designed for continuous use.

There's no check valve on this pump, but that enables the output to be even stronger, and that will almost always prevent any excess water from draining back into the bilge. This pump is not only great at removing water from a bilge, but it's also a nice graduation toward more complicated devices for those who want to be more involved with boating.

3 Types of Bilge Pump Switches

How to Properly Use a Bilge Pump

All bilge pumps should be placed as close to the bottom of the bilge as possible. Float switches can be placed on the same level if you don’t want any water in the bilge.

Placing secondary pumps at a higher level is a good way to make a backup system in case the first pump should fail. Installing a bilge pump and float switch is pretty simple once you understand the process.

Common Bilge Pump Issues & Troubleshooting

Frequently Asked Bilge Pump Questions 

Which is better, an automatic bilge pump or manual bilge pump?

Kayaks and canoes can stick with hand-operated manual bilge pumps, but larger boats should all have both. A manual pump in case the electric ones fail can be essential to rescuing a boat from a bad leak.

What steps should I take to maintain my bilge pump?

What’s the difference between a centrifugal and diaphragm pump?

Centrifugal pumps are not self-priming, meaning the water has to be in contact with the impeller to be able to pump the water out. Diaphragms create negative pressure to draw in water using a kind of lung that inflates and deflates as it is pumped. Diaphragm pumps are often stronger but puncture and fail more easily, which explains why centrifugal pumps are more common these days.

How is a kayak bilge pump different from one that is used on a motorboat?

Kayak bilge pumps are usually entirely operated by hand and look more similar to a bicycle pump than to other motorboat bilge pumps. They are really easy to use, and most come apart to clean and clear from debris. Just like you don't need a big heavy pump on your kayak, you should opt for a more robust manual bilge pump for your secondary bilge pump on a bigger boat.

Where is the best place to buy these bilge pumps and components like a bilge pump float switch and bilge pump hose?

Even though some important add-ons are not sold in package deals with bilge pumps, all of the major brands have both pumps and components on sale on Amazon. There are also great deals there all the time, and most vendors have a nice return policy as well.

Conclusion

The best bilge pump is no-fuss and can be depended on to get water out of the boat with little fanfare. The Rule Marine pump is just that, making it both an industry star and our top pick for the best bilge pump. Set sail with the proper precautions in place with the Rule Marine on board.