Mar 162015
 

One might be forgiven for believing that controllable pitch propeller systems are the illegitimate children of HAL, from the science fiction movie 2001: A Space Odyssey, with a dangerously psychotic mindset all their own. Take the grounding of  the Cyprus-flagged MV Merita at Steubenhöft in Cuxhaven.

Germany’s Bundesstelle für Seeunfalluntersuchung, Federal Bureau of Maritime Casualty Investigation, tells the tale of a disobedient vessel caused by the failure of a worn coupling in the wrong time and place:

The Merita was  sailing from Skulte in Latvia to Rostock in Germany, was fully laden with wood. She reached the sea canal to the port of Rostock on the evening of 9 January 2014. At 2050, the pilot boarded. When the passenger pier was passed at 2120, the ship began to turn slowly to starboard. Following that, the pilot recommended that the speed beincreased slightly to improve the manoeuvrability of the ship. The chief mate executed this on the engine telegraph.
After a few seconds passed by without any response, the pilot said that th

One might be forgiven for believing that controllable pitch propeller systems are the illegitimate children of HAL, from the science fiction movie 2001: A Space Odyssey, with a dangerously psychotic mindset all their own. Take the grounding of  the Cyprus-flagged MV Merita at Steubenhöft in Cuxhaven.

One might be forgiven for believing that controllable pitch propeller systems are the illegitimate children of HAL, from the science fiction movie 2001: A Space Odyssey, with a dangerously psychotic mindset all their own. Take the grounding of  the Cyprus-flagged MV Merita at Steubenhöft in Cuxhaven.

Germany’s Bundesstelle für Seeunfalluntersuchung, Federal Bureau of Maritime Casualty Investigation, tells the tale of a disobedient vessel caused by the failure of a worn coupling in the wrong time and place:

The Merita was  sailing from Skulte in Latvia to Rostock in Germany, was fully laden with wood. She reached the sea canal to the port of Rostock on the evening of 9 January 2014. At 2050, the pilot boarded. When the passenger pier was passed at 2120, the ship began to turn slowly to starboard. Following that, the pilot recommended that the speed beincreased slightly to improve the manoeuvrability of the ship. The chief mate executed this on the engine telegraph.
After a few seconds passed by without any response, the pilot said that the bow thruster should be operated hard to port. Merita’s speed was about 6.5 kts and she continued to turn to starboard.
To prevent a collision with the pier there, the pilot ordered full astern. At the same time, he informed VTS Warnemünde about the incident on VHF. Several seconds later, the bow thruster was set to hard to starboard. The speed ahead dropped continuously but the rate of turn to starboard increased. When the bow was at an angle of roughly 90° to the actual heading line, the pitch was set to zero. There was still no response from the engine, however. The starboard anchor was then dropped and the emergency stop switch pressed.
The anchor did not grip, resulting in the stern grounding on the eastern bank of the sea canal at 2124. Two tugs had to be ordered, which then pulled the ship free and towed her to the next berth.
Just four minutes elapsed from the failure of main engine control to the grounding, during which the master had also tried using the tiller, which was supposed to override all the other control units but had no effect either.
The chief engineer explained what happened: Two hydraulic pumps drive the CCP system: One runs continuously and the other is on standby. Each pump has a coupling between its motor and the rotor blades. This coupling consists of a metal cap and plastic insert. The purpose of the plastic insert is to absorb vibrations until it is mechanically worn out, when it should be renewed.
  meritainsert
The yellow plastic insert, seen here on a new coupling, had worn out, then the metal cap also wore until the connections ran smoothly over each other. Consequently, the rotor blades stopped turning and the pressure in the system dropped. The second pump was actuated automatically but this needed a few minutes until the pressure in the system was sufficiently high again but the Merita was aground by the time it could become effective.

Says the BSU report: “According to the ship’s maintenance plan, this coupling was renewed in May of the previous year and was not due for inspection for another four months. Therefore, it must be assumed that this coupling did not meet the material standards and thus wore out long before it was scheduled to (be replaced)“.
The BSU report does not mention whether the vessel’s maintenance plan followed manufacturer’s recommendations, or whether the coupling manufacturer’s specifications.
Either way, you may want to check your couplings.

See Also:

[catlist name=CPP]

 

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