Everything You Need to Know About Your Boat’s Bilge Pump
Bilge pumps are important parts of how your boat functions. They require routine maintenance to stay in good working order. Unfortunately, many boat owners will neglect their bilge pumps for far too long. It’s all well and good to say you need to clean a bilge pump, It’s another to actually get it done. Everyone probably knows at least one boater who has left this job for too long. Maybe you’re even guilty of it yourself. Understanding what bilge pumps are can help explain why you need to keep them in good working order.
What are Bilge Pumps?
Your boat’s bilge is the lowest, inner point of the boat. It’s designed to remove nuisance water that may splash, spray, or spill on your boat. Usually this area is covered by a flat floor. The bilge is hidden underneath. Without the bilge area your boat would flood. It’s all but impossible to keep water off of a boat after all. Because the bilge collects water, a bilge pump there to draw the water out. It will use pressure or suction to do this. Without a functioning bilge pump, your boat will be subject to flooding. Additionally, if you don’t maintain your bilge pumps the bilge water can get dirty and polluted.
Where are Bilge Pumps Located?
Bilge pumps for boats should be mounted in the lowest part of your bilge. This is where it will be able to collect and pump the most water. If you have a secondary bilge pump it may be located a little higher up. For small boats, one bilge pump is usually sufficient. But as a boat gets larger a second bilge pump is a very good idea. Some boats may have as many as three or four bilge pumps. Automatic bilge pumps are often more reliable than manual bilge pumps.
Bilge pumps are often easily overlooked by inexperienced boaters. You will find them installed under the boat’s engine on an inboard. Some boats do not even have them as they’re not legally required on recreational craft. That said, if you don’t have one you will regret it. A reliable bilge system with automatic bilge pumps are key.
How Do Bilge Pumps Work on a Boat?
Automatic bilge pumps remove excess water from your boat. Spray from waves, rain water, packing gland drips and so on. It’s not specifically meant to prevent your boat from sinking if it’s taking on water. But it can also help buy you some time in an emergency. Your bilge pump should have a pumping capacity of at least 24 gallons per minute if your boat is under 65 feet. Good quality automatic bilge pumps can more than handle this.
Bilge pumps are typically either diaphragm electrical or centrifugal. Centrifugal bilge pumps have a rotating impeller like you’d find a turbine. When water enters the pump the impeller spins enforces the water out of the pump. These kinds of pumps are able to pump out a lot of water. They’re usually low maintenance as well. They are not self-priming however, which means they have to be sitting in water in order to pump it. The further they have to pump water the less powerful they will be.
Diaphragm pumps pull water in through an intake valve. It is then pumped out through an output valve. It works a lot like a wet dry vac. These automatic bilge pumps are self-priming. That means they can work even when dry. They’re more powerful at twitching water greater distances as well. Unfortunately, they do not move as much water as a centrifugal pump. They will also get clogged much more easily by dirt and debris. The valves can easily clog which can cause leaks as well.
A centrifugal pump is usually the best option unless you have to pump water a great distance.
You should also know the difference between automatic bilge pumps and manual bilge pumps. Automatic bilge pumps have a built-in float switch. This detects water levels and will turn the automatic bilge pump on when necessary. If you have a boat that’s over 20 ft long that you can sleep in, you have to have an automatic bilge pump. That float switch is an integral piece of boat safety.
Unlike automatic bilge pumps, manual bilge pumps don’t typically come with a float switch. That said, you can add a float switch to a manual pump. This makes them operate much like an automatic bilge pump.
Keeping Bilge Pumps Clean
Regular automatic bilge pump cleaning is important for all boats. Unfortunately, a lot of boaters let this slide. If you let it go for too long, the bilge water inside can get out of hand. You need to know that even in a brand new boat the bilge area may not be clean. It could have construction materials from the production of the boat still inside. Bits of wood and fiberglass, for instance. All of this should be cleaned out before you head out for the first time. There’s no sense starting your bilge pump off with a built-in mess.
The Bottom Line
A reliable bilge system is an important but often overlooked part of your boat. With proper cleaning and maintenance, your bilge pump will ensure your boat stays afloat for a long time. If your bilge pump fails, you could be in a lot of danger out on the water. Make sure you know how to maintain your pump, and you may want to consider keeping a manual pump alongside your automatic bilge pump in case of emergencies.
Robert Hogward on July 8, 2021
Great article. Most folks have to learn this the hard way. Sure, I may have said that I favor certain products over others. I’ve already had a handful of setups that worked for a long time by sticking to your guide.
Robert Hogward on July 8, 2021
Great article. Most folks have to learn this the hard way. I’ve already had a handful of setups that worked for a long time by sticking to your guide. Again thanks!
Robert Hogward on July 8, 2021
Sure, I may have said that I favor certain products over others. I’ve already had a handful of setups that worked for a long time by sticking to your guide.
Phyllis gardon on September 10, 2021
Does the boat engine need to be on and in the water before flicking the bridge pump on?
Michael on September 14, 2021
No it does not
It should be wired in 2 ways
One is fully automatic and will come on without any interaction on your part – if you’re not there at boat or during use
In this case it must have a float switch so as water level rises float switch activates pump until water level drops
Usually turns on at 2” of water and off at 3/4” water
Two is it can be activated with a switch on helm
In either case it should be wired directly to your battery with a fuse protecting the circuit
There is lots of vids and more info on how to correctly install, wire and run drain line correctly online
wayne l robinson on May 24, 2022
should u be able to move the impeller in a small pump when off