The humble impeller is one of the smallest pieces of equipment on board, but it tends to cause the most problems. Impeller failure is responsible for more boating vacations and summer cruises than any other reason.

"The impeller is one of the smallest components on a ship, but one of the most important, and can fail at any time, often without prior notice. It can also cause significant damage to other equipment; Fail."

While the impeller is a critical component of all pumps (found in marine engines, toilet systems, refrigeration and air conditioning units, and washdown pumps), the impeller in engine water pumps is the most important.

"If one of these fails, not only will it stop the engine, it can cause serious damage. Fragments of the damaged impeller could end up in the heat exchanger or cause clogging in other parts of the engine. This may require dismantling major parts of the engine so that these clogs can be cleared , and check the rest of the engine for small pieces of the faulty impeller.

"This is not easy to do in remote anchorages, and the vessel often has to be towed back to port before repairs can be completed."

A failed toilet pump impeller, while not so catastrophic, can also be very unpleasant and put a damper on an otherwise pleasant vacation.

Impellers can fail for a number of reasons, they are hard parts and wear out easily. They can also be damaged if they dry out or are not run for a long time.

impeller damage
The impeller should be inspected annually, by an expert or a competent DIYer. The things to check are impeller blades for cracks, damaged blade peaks, missing blades, missing blade parts, and deformed blades.
If boat owners have any doubts, they should take the suspect impeller to an experienced marine engineer and have them take a look. "

The humble impeller is actually 'boating's enemy number one, as impeller failure causes a lot of problems every summer. Of course, for the affected crew members, this is no joke.