Features January 2018 Issue

The Worry-free Bilge Pump

Out of sight, out of mind, this critical pump needs more respect.

 

Due the lack of maintenance they receive from the average sailor, I often refer to bilge pumps as the Rodney Dangerfield of boat equipment, meaning “they just don’t get no respect.” It’s a funny, but also troubling statement, particularly as bilge pumps are often the first and only line of defense against sinking.

bilge pump
Photos by Frank Lanier

The secondary bilge pump (visible in background) should be mounted higher than the primary, not at the same level as it is here.

Bilge Pump vs. Emergency Pump

First off, don’t confuse your bilge pump with an emergency pump, which provides much greater dewatering capacity. That being said, although their primary job is clearing incidental water from the bilges (packing gland drips, rain water, etc.) bilge pumps can provide crucial extra time when taking on water, allowing you to find the source of a leak, don lifejackets, or hopefully keep your boat afloat long enough for help to arrive. It’s a mighty tall order for a fairly simple piece of equipment.

General Considerations

No amount of pumping capacity can overcome a bilge choked with trash and debris. The first step on the path to bilge pump nirvana is making sure your boat’s bilge is clean and free of trash and debris. Routine bilge cleaning is a fact of life for older boats, but even that new boat you’re purchasing can have a bilge littered with pump-clogging bits of construction material (wood shavings, screws, bits of fiberglass, gobs of epoxy,  etc).

Oily bilge residue should also be cleaned up and disposed of properly. In addition to the ecological concerns of accidentally pumping it overboard, oil combines with dirt to form a gooey sludge that can clog pumps and prevent float switches from operating properly.

Use marine grade hose for pump discharge runs and secure them at each end with marine grade stainless steel hose clamps. Hoses should be routed as directly as possible to their discharge thru-hull and should also be properly supported (approximately every 18”) to prevent chafe and excessive movement.

Speaking of discharge thru-hulls, they should be situated well above the waterline to prevent water from siphoning back into the bilge. Siphon breaks and riser loops are also recommended and should reach at least 18 inches above static waterline. This prevents back-siphoning.

Automatic float switches (if installed) must be securely mounted and installed clear of wires, hoses and other obstructions that can impede operation of the floating-arm or flapper type switch. Enclosed switches eliminate this worry, but they’re sometimes difficult to inspect and test. Regardless of the type you choose, make sure each pump has a manual switch as well; none of the automatic systems is failsafe.

Maintenance tips

Problems with centrifugal pumps typically involve clogging, defective automatic float switches (if installed) or corroded electrical connections, a common problem with any electrical gear installed in corrosive environment of a vessel’s bilge.

Maintenance is generally limited to clearing the strainer (centrifugal pumps have one built into the base) and water proofing of all connectors. When it comes to repair, with the exception of the larger, rebuildable units, most centrifugal pumps are cheaper to replace than repair. The September and October 2010 issues identify our favorites.

Maintenance and repair of diaphragm pumps typically involves opening up the pump body, clearing the pump chamber of debris, and checking the diaphragm and valves for damage or deterioration. Other than clogging, most problems will be caused by torn or damaged check vales. The diaphragms can also fail, however they will typically outlast several valve changes. For long cruises, you’ll want to take spares.

Finally, check all hose runs for kinks, cracks, or splits. If you have a check valve installed (something that is not recommended due to the possibility of clogging and failure) make sure it is clear and operating properly.

Comments (4)

My own experience is that the switch fails more often than the pump.

I have heard, but cannot verify, that bilge pumps are supplied with a specific length of wire that should not be shortened. Underwater connections are always undesirable.

Some boats have a fitting at the propulsion engine raw water intake that allows using the engine as a bilge pump. One of the these days, installation will get somewhere near the top of my punch list.

As they say, the best bilge pump is a scared sailor with a bucket.

Posted by: Boston Barry | October 21, 2019 6:50 AM    Report this comment

Photo shows a dirty bilge. First rule of thumb is keeping a really clean bilge. Second rule is understanding "boat bilge pumps" are low quality disposable items. So they need be replaced every few years. Anything that sits in water deteriorates. Third rule is always have 3 bilge pumps installed. That makes sure one will work. Fourth rule is understanding bilge pumps do not prevent sinking. Pumps have low quality 12 v. motors that always fail when used for long periods. Fifth, every boat ought have one high quality Rule Commercial 3500 GPH pump with a good 20/25 feet of flexible hose and alligator clamps to allow attachment to the battery. Every fish boat uses these pumps. Will run continuously virtually forever. Sixth, remember that production boats (power or sail) never ever have serious bilge pump installations. Commercial boats do because they are inspected by USCG or others. Seventh, if you cherish your boat, yourself and your sailing companions you'll always go Blue Water with an undated SOLAS liferaft and a well known gasoline emergency bilge pump. Hundreds of thousands of such pumps, e.g. Hondas, are found on commercial fish boats throughout the world. Why ? Because they get used.

For those who had a high school physics course. Electric motors give off lots of heat. Typical 12v bilge pumps give off lots of heat. So their windings fail. That's why serious bilge or dewatering pumps need be heavy to dissipate heat. And if you have generator on board buy a standard 110 v. Sump Pump with suitable hose for emergency use. Such pumps can run for months.

Why spend all this time and attention on bilge pumps ? Because serious Blue Water Sailors know that after bouncing off rocks and having anchor gear fail its the bilge pump system that fails sending the boat to Davy Jones lockers.

Last word. First thing a well qualified marine surveyor looks at is whether the engine is rusty with shabby hoses. And whether there's a first rate bilge pump system on board with suitable emergency backups. And that ought be the first thing a prospective new buyer ought to look at too. If the bilge pump systems is shabby you know all you need to know.

Peter I Berman
Norwalk, CT

Author; "Outfitting the Offshore Cruising Sailboat" Paracay Publishers.

Posted by: Piberman | October 19, 2019 11:52 AM    Report this comment

Photo shows a dirty bilge. First rule of thumb is keeping a really clean bilge. Second rule is understanding "boat bilge pumps" are low quality disposable items. So they need be replaced every few years. Anything that sits in water deteriorates. Third rule is always have 3 bilge pumps installed. That makes sure one will work. Fourth rule is understanding bilge pumps do not prevent sinking. Pumps have low quality 12 v. motors that always fail when used for long periods. Fifth, every boat ought have one high quality Rule Commercial 3500 GPH pump with a good 20/25 feet of flexible hose and alligator clamps to allow attachment to the battery. Every fish boat uses these pumps. Will run continuously virtually forever. Sixth, remember that production boats (power or sail) never ever have serious bilge pump installations. Commercial boats do because they are inspected by USCG or others. Seventh, if you cherish your boat, yourself and your sailing companions you'll always go Blue Water with an undated SOLAS liferaft and a well known gasoline emergency bilge pump. Hundreds of thousands of such pumps, e.g. Hondas, are found on commercial fish boats throughout the world. Why ? Because they get used.

For those who had a high school physics course. Electric motors give off lots of heat. Typical 12v bilge pumps give off lots of heat. So their windings fail. That's why serious bilge or dewatering pumps need be heavy to dissipate heat. And if you have generator on board buy a standard 110 v. Sump Pump with suitable hose for emergency use. Such pumps can run for months.

Why spend all this time and attention on bilge pumps ? Because serious Blue Water Sailors know that after bouncing off rocks and having anchor gear fail its the bilge pump system that fails sending the boat to Davy Jones lockers.

Last word. First thing a well qualified marine surveyor looks at is whether the engine is rusty with shabby hoses. And whether there's a first rate bilge pump system on board with suitable emergency backups. And that ought be the first thing a prospective new buyer ought to look at too. If the bilge pump systems is shabby you know all you need to know.

Peter I Berman
Norwalk, CT

Author; "Outfitting the Offshore Cruising Sailboat" Paracay Publishers.

Posted by: Piberman | October 19, 2019 11:52 AM    Report this comment

Outstanding article and advice, Frank. Thanks also for the sidebar photo examples of a pump horrors. It's the little things like this that domino into major issues down the road.

Posted by: Lakota44 | October 12, 2019 10:22 AM    Report this comment

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