If you&#;re a new boat owner, you probably have a lot of questions. It doesn&#;t matter if you purchase a new or used boat; everyone needs to become familiar with bilge pumps. From what they are to what they do and how to choose one, let&#;s review everything you need to know about boat bilge pumps.
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What is a Bilge Pump?
A boat bilge pump is a device that removes water from the bilge area of your boat. If you&#;re unfamiliar with the term bilge, it simply means inside of the hull. Water collects in the bilge area of almost every boat for one reason or another. It doesn&#;t have to be a hole in the hull; many causes exist.
Rainwater
Water from Cleaning
Draining Coolers
Emptying Live Wells
Leaks
Although it&#;s normal for water to end up in the bilge area, it should not stay there. You need to remove the water when levels get high, and that&#;s what a bilge pump is for. There are many different types and sizes of boat bilge pumps and switches. It&#;s important to choose the right one, as the wrong choice could result in calling your insurance agent to tell them your boat is at the bottom of a lake.
Do All Boats Need a Bilge Pump?
Yes, all boats should have a bilge pump of some sort. It&#;s even a law in many states and on certain waterways. Bilge pumps are needed in emergencies and for normal day-to-day use. For larger boats, there could even be multiple bilge pumps used for different compartments in the bilge area and for backup use. It doesn&#;t matter what type of boat or how you use it, you should have a boat bilge pump on board.
Manual versus Automatic Bilge Pumps
Bilge pumps can either be manual or automatic. Manual bilge pumps are hand-operated, meaning no electricity or motor drives them. You&#;ll typically only see this type on small watercraft such as kayaks and canoes. They are offered in both a diaphragm and piston style.
Automatic bilge pumps are powered by an electrical current. This is a much more common style of bilge pump and is used on almost all watercraft with an on-board battery. These are more complex than the manual style, with different types, sizes, ratings, and controllers.
Types of Automatic Bilge Pumps
You&#;ll typically see automatic bilge pumps offered in two styles: centrifugal and diaphragm.
Centrifugal &#; Centrifugal boat bilge pumps are the most common. They use an impeller to force water up and out of the boat.
Pros: Cons:Moves Large Volumes of Water
Poor Uphill Performance
Handles Small Debris
Not Self-Priming
Cost Effective
Can&#;t Remove All Water from Bilge
Great for Large Ships
Bad for Small Ships
Diaphragm &#; Diaphragm bilge pumps use a valve to remove water. It pulls water in when the valve opens and expels it when it closes.
Pros: Cons:Great Uphill Performance
Poor Flow Capacities
Self-Priming
Cannot Handle Debris
Manual Option
Bad for Large Ships
Great for Small and Medium Ships
Self Priming &#; Self-priming simply means the pump does not need to be submerged to operate. If you operate a non-self-priming pump out of water, you can cause damage.
Automatic Bilge Pump Switches
There are more ways than one to operate an automatic bilge pump; most use a switch. A manual switch requires user activation. This means you&#;ll have to monitor your bilge frequently to ensure water does not rise to an unsafe level.
A float switch does not require user activation and turns on when water rises above a certain level. The float switch is located in the bilge with the pump and adjusted for proper height activation.
Most commonly, you&#;ll find that boats come with both a manual and float switch. This lets you turn the pump on manually when needed or rely on the float switch.
How to Choose a Bilge Pump
Factors that go into selecting the correct bilge pump once you determine what type you need are GPH and boat length.
Gallons Per Hour (GPH)
Boat bilge pumps are rated by gallons per hour, known as &#;GPH.&#; This relates to how much water the pump can remove in one hour, measured in gallons. The listed GPH rating, however, is not always the true rating. Factors such as head, the distance between the bilge and outlet, hose type, and hose length play significant roles in the pump&#;s ability to remove water.
Generally, you can factor the pump&#;s efficiency at 60% of the listed rating. For example, a pump rated at 1,000 GPH has a true efficiency rating of around 600 GPH.
Boat Length
The boat&#;s length also plays a role in selecting the correct pump. A longer boat will require a higher-rated pump as there is more area to remove water from. Here are some recommended pump sizes based on boat length.
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<20&#;700-1,000 GPH
20-25&#;1,000-1,400 GPH
26-30&#;1,200-1,600 GPH
31-35&#;1,400-1,800 GPH
36-40&#;1,600-2,200 GPH
41-45&#;2,000-4,000 GPH
How to Install a Bilge Pump
The installation of a bilge pump will vary by boat and pump type. However, there should be at least one at the lowest point of the bilge. If the boat is large enough and there are multiple compartments, you could have one in each area.
Step 1: Mount the Pump
Once you&#;ve determined the lowest point in the bilge, position the pump directly against the hull. Mount the pump using a bracket or nearby structure.
Step 2: Mount Float Switch (If Applicable)
The float switch will also need to be fastened inside the bilge. Refer to your instructions on placement and how to secure.
Step 3: Route Hoses
Smooth hoses are best as corrugated hoses can reduce pump output. Route hoses to the nearest exit, whether that be the side of the hull or the transom. Long stretches of hose can also reduce pump capacity. Don&#;t loop hoses; if necessary, adjust the pump for better routing angles. The discharge must be above the waterline, or water can get in through the outlet and damage the pump.
Step 4: Wire Power
Use only marine wire when routing power to and from the pump and switch. Since most pumps draw upwards of 10 amps, you&#;ll need to use a larger gauge, usually 10-gauge or 8-gauge wire. All connections must be sealed with heat shrink or other watertight connectors.
Step 5: Test Function
Once all your connections are made and there&#;s power at the pump, place water into the bilge and watch for activation. If there is no activation, check the fuse and battery level. If the pump engages and water flows freely, you&#;re ready to go!
A bilge pump is a vital piece of equipment for every boat. It should be incorporated into your pre-launch checklist as you do for your drain plug and life jackets. Knowing what the pump does and how it works will help you become a better boater.
Check out some of these other articles about your boat:
Let us know in the comments below if you&#;ve ever replaced the bilge pump on your boat.
Water discharging from a through-hull fitting as a result of automatic bilge-pump activation serves as a warning that the boat is taking on water.
Jason Arnold / jasonarnoldphoto.com
&#;Hope ain&#;t a tactic.&#; The gritty mantra uttered by Mark Wahlberg&#;s character in the film Deepwater Horizon sums up the principle behind bilge-pump systems. Failure to maintain a way to effectively evacuate bilge water implies that you&#;re relying on hope that a through-hull fitting won&#;t fail, a livewell hose won&#;t come loose, or a floating timber won&#;t hole the boat and sink you.
I&#;ve been to the edge more than once, most recently on a run in heavy seas from Key West, Florida, to the Dry Tortugas. About 30 miles out, the captain noticed that the boat &#; a newly built 39-footer &#; had grown sluggish.
The crew opened the bilge hatch and were met with a gusher of seawater. We discovered later that one of the hose clamps for the livewell pump had come loose. Meanwhile, water poured in. The bilge pump, its strainers clogged with fiberglass shards from the construction process, could not keep up.
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We had one last option. The captain carried a portable high-capacity bilge pump rigged with a long hose and a plug to connect with the ship&#;s 12-volt DC power. Within minutes, this &#;crash pump&#; had drained the bilge. With the water gone, the crew could find and fix the leak and clear the strainers. It&#;s this kind of experience that inspires deep appreciation for bilge pumps.
Pumping Capacity
There&#;s no federal requirement for bilge pumps on recreational boats, though a dewatering device is among items recommended when Coast Guard-certified examiners conduct a vessel safety check.
However, virtually every new powerboat comes with a bilge-pump system. How much bilge-pump capacity does a boat require? Most boatbuilders use guidelines from the American Boat and Yacht Council to determine the number of pumps and the gallons-per-hour capacity based on bilge configuration and volume.
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Yet, what about older boats? How do you determine the bilge-pump capacity when refitting? If in doubt, use the same number of pumps and same capacities (if not more) as when the boat was new. If the old system is gone and there&#;s no clear-cut answer, the late David Pascoe, boat surveyor and author of a number of boating books published in the early s, offered the following formulas based on boat length.
Bilge compartments on some boats are equipped with two bilge pumps, as seen here. This boosts capacity and provides a backup system in case one pump fails.
Jim Hendricks / Sport Fishing
Don&#;t Skimp
Keep in mind that gph ratings for pumps from brands such as Attwood, Jabsco, Johnson, Rule, and Shurflo are measured at the pump itself and do not account for lift (the distance that the water must be pumped upward to the through-hull fitting above the waterline), drag generated by elements such as corrugations in the hose, or dips in supply voltage. With this in mind, count on about 60 percent of the rated capacity.
Multiple bilge pumps are better than one, because if one pump fails, others will likely remain working. You might want a second pump in a forward bilge compartment separated by a bulkhead, or even a third one in a compartment amidships.
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Some skippers also equip the aft bilge area with two pumps, with one mounted 4 to 6 inches higher than the primary pump. In this configuration, the secondary pump does not see as much service as the lower primary pump, and thus tends to last longer, and stands ready to assist when things grow dire. Each pump should have a dedicated through-hull fitting.
Rule fully automatic submersible bilge pump
Courtesy Rule
Automatic Systems
Most new saltwater-fishing boats feature automatic bilge-pump systems with sensors to turn on pumps when bilge water rises to a certain level. Some pumps, such as the Rule-Mate (about $250), have a built-in automatic switch. Other pumps require the addition of a sensor such as the Shurflo float switch (about $32), which is electrically connected to the pump. You can also flip on the pump manually with a switch at the helm, but the pump can activate on its own, assuming it is receiving power, if bilge water gets too high.
I like mechanical automatic switches versus those that use electronic sensors. Most mechanical switches let you perform a physical test, while most electronic systems do not.
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Automatic systems are particularly helpful in preventing sinkings when a boat is left unattended at the dock. The system should be wired directly to a battery so the automatic feature will still be active even if you turn off the main battery switch. Automatic bilge-pump systems can also warn you while you&#;re out fishing; it&#;s hard to ignore the sound of water streaming out of the through-hull fitting when the automatic pump kicks on.
Maintenance Matters
Check your bilge-pump system before every trip. Make sure the pump runs when you activate the manual switch. Also, reach into the bilge and lift the automatic float switch to ensure that the pump powers up. Rule&#;s Rule-a-Matic switches feature external levers that make it easy to conduct this test.
Malfunctions can occur for a number of reasons, including corroded or broken wires and connectors, a blown fuse, a worn-out pump, a broken float or even the switch at the helm. Fix the problem before you head out on the water.
Read Next: An Emergency Hand Pump Can Keep Your Boat Afloat
While your head&#;s in the bilge, check around the switch to make sure there are no obstructions (such as a bucket stowed in the bilge). Take a close look at the strainer and clear debris that might impede water flow to the pump.
Auxiliary Systems
A bilge-pump system can fail at any time, so carry a backup such as the crash pump described earlier or a manual system such as the Beckson 36-inch Thirsty-Mate portable hand pump (about $48). Whale Pumps also offers the Titan manual (about $170), which mounts permanently and will pump 28 gallons per minute.
At the very least, carry a bucket, but check ahead of time that it will allow you to scoop water out of the bilge compartment. The ubiquitous five-gallon bucket might be too big and/or too heavy, once full, to effectively bail water. Follow these guidelines, and avoid relying solely on hope to prevent your boat from sinking.
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