Overspeed Protection Alarm Causes Ship’s Engine to Stop

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Summary

On 4th of December 2016, the German-flagged Hanni ran aground in Hamburg. The master and chief officer were on the bridge. An overspeed protection alarm was issued for the main engine. After that, the main engine reduced the revolutions and finally stopped. 

At 0622, the bosun was instructed to operate the anchor. At 0623, the vessel Finja approached from the opposite direction and was just able to avoid a collision with her by setting the rudder to hard to starboard. At 0625, the main engine’s control system was switched over to the engine control room.

Hanni then drifted to the other side of Elbe. More engine alarms sounded, including the shaft generator. The ship lacked its main engine, something that means that the vessel was not in control for a long time and only its momentum made the steering possible.

They were operating with starboard rudder and the main engine did not start until 0626.

At 0628, the Hanni’s speed over ground stood zero and as a result she was grounded to the other side of the fairway. The propeller’s pitch was set to zero and the vessel’s traffic service indicated the accident on a VHF channel 74.

After the traffic service informed about the accident, two tug boats, PROMPT & RASANT each with a bollard pull of 71 t maximum, as well as a harbour pilot attempted to salvage Hanni. Their first attempt was not successful, but the second attempt a few hours later was successful.

The HANNI suffered damage to her underwater hull and propeller. No injuries of personnel or pollution were noted after the accident.

Probable Cause

Germany’s Federal Bureau of Maritime Investigation stated the accident happened because an overspeed protection alarm made the main engine to stop automatically, in order to avoid irreparable damage. The alarm went on due to a defective pickup.

Though she was still making headway and only operated with starboard rudder angles, Hanni drifted to the other side of the fairway, because of hydrodynamic forces.

Recommendations

Germany’s Federal Bureau of Maritime Casualty Investigation proposed to Hanni’s owner the following:

  • To include the pickups and speed sensors in a maintenance plan and take precaution in exchanging them on vessels, in compliance with values suggested by the manufacturer.
  • To revise the wheelhouse poster and the pilot card, complement all queried data and include CPP’s direction of rotation.

Furthermore, the master of the ship was instructed to change the underway watch schedule so that officer are not on watch more than ten hours each day.

Moreover, the Federal Bureau of Maritime Casualty Investigation recommended the engine manufacturer, MAN Diesel and Turbo SE, to configure the main engine’s pickups for newly built crafts, in order for plausibility check of the measurements to be made between the sensors.

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Source: BSU

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