By now, most boats in the region are snugly shrink-wrapped against the elements. With summer months away, owners might not be overly concerned about their spare parts inventory for the next engine emergency. On these cold nights, one might think more about winter boat shows or a good nautical read by the fireside enjoying a glass of something with rum in it. But faithful to Murphy’s Law, any critical engine component that can fail will fail at the worst possible time. And when it does, it can sometimes take astute investigation to get to the bottom of things.
It was just such investigation that took place in a lawsuit involving the failure of an impeller for a raw water pump on a 44’ powerboat with twin diesels. The impeller failure led to a fire, and the ensuing lawsuit resulted in a detailed analysis of the operation of the vessel’s cooling system.
The story started when the vessel’s starboard engine overheated enroute to summer storage. Sea conditions were rough. At first, the problem wasn’t apparent. A temperature alarm sounded, but a burned out light bulb caused the temperature gauge to lose illumination. With a flashlight, the owner saw the gauge pegged at 220 degrees.
The starboard engine was shut down and the vessel continued with only the port engine. About ten minutes after shutting down the starboard engine, the owner discovered a fire in the engine compartment. At that point, he deployed fire extinguishers and made the decision to return home with one engine.
When the owner attempted running the port engine almost two weeks later, heavy black smoke came out. At that point, the boat was trucked to a yard for inspection. There, it was determined that the impeller for the starboard raw water pump failed prior to overheating. As a result of the loss, the vessel’s insurer sued the company that distributed and sold the pump, seeking $278,207.40 in damages.
The impeller failed; that much was known. But how did it fail? That part was at the heart of this lawsuit. The insurance company argued that the pump malfunctioned because the pump company manufactured, constructed, assembled, and inspected it in a state where it was defective, dangerous, and unsafe for its intended uses. In response, the pump company argued that the pump failed because it ran dry, meaning there was no water flow to dissipate the heat generated by the friction of the rotating impeller.
So which version of the failure analysis would prevail? It would take experts to get to the bottom of that question. An expert for the insurance company was a research metallurgist and professional engineer. He claimed the impeller failed because of residual stresses from the manufacturing process. He also claimed that porosity or voids were contributing causes.
An expert for the pump company was a professor of engineering and material science. He argued that voids could be formed by normal wear and tear. Another expert for the pump company was called in. He was a mechanic and certified fire inspector. His theory was that the pump ran dry. He explained that when an obstruction to the raw water inlet is held in place by suction, the pump could run dry until the impeller and blades fail.
Another expert, this one a marine engineer, testified for the insurance company that evidence didn’t suggest the pump ran dry. He found water in the pump housing and sea strainer after the incident. He further supported this position by pointing out that about 90% of the broken impeller fragments were found in the suction hose and about 10% in the pump itself.
With this mountain of technical evidence before it, the court ruled in favor of the pump manufacturer. It determined that it did not act negligently and that the pump was not defective. This shows that lawsuits involving complex machinery could be costly. They often involve testimony from highly specialized experts whose time on the witness stand doesn’t come cheap.
Best wishes to all of you for health, happiness, and good things for the year ahead!