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. Its a funny, but also troubling statement, particularly as bilge pumps are often the first and only line of defense against sinking.
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. Its a mighty tall order for a fairly simple piece of equipment.
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 boats 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 youre 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 preventfloat 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 theyre 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.
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 vessels 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, youll 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.