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Reliance Upon Mechanical and Electro-mechanical Devices and Machines.

There have been concerns shown about the reliability of R.C.D.s in the past, and the cruise liner Viking Sky's engines and also this......

https://www.youtube.com/watch?v=aPKJRikunJw

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0 Alasdair Anderson over 6 years ago

broadgage:

Returning to the cruise ship on which all the engines were stopped by low oil level alarms, that was in my view a defective design. IMHO such engines should have a means of bypassing such alarms. If the ship is in danger, it is arguably preferable to allow the engine to run until destruction, rather than to risk loss of the vessel and the many lives therein by running onto rocks.

This was not a defective design. The engines on ships have different requirements depending on their service but the principles are as follows. There is an alarm (not a shut-down) to warn the crew that there is a low oil pressure. If the oil pressure drops even further then there is an independent sensor which operates a shut-down. If it is a propulsion engine there IS an over-ride so that the crew can hit a button to keep the engine running, on the basis that there is not much point in having a working engine if the ship is sitting on the rocks. However auxiliary engines driving generators do not have an over-ride as there are multiple engines/generators and so safety through redundancy - the chances of all engines having simultaneous faults in independent oil systems are so low they can be ignored. Please note that the Viking Sky did not have a fault in any of its oil systems, it was being operated in rough weather without extra precautions being taken. In my days at sea if we had rough weather we put extra oil in the sumps of the diesel generators to prevent such an occurrence.

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0 Alasdair Anderson over 6 years ago

broadgage:

Returning to the cruise ship on which all the engines were stopped by low oil level alarms, that was in my view a defective design. IMHO such engines should have a means of bypassing such alarms. If the ship is in danger, it is arguably preferable to allow the engine to run until destruction, rather than to risk loss of the vessel and the many lives therein by running onto rocks.

This was not a defective design. The engines on ships have different requirements depending on their service but the principles are as follows. There is an alarm (not a shut-down) to warn the crew that there is a low oil pressure. If the oil pressure drops even further then there is an independent sensor which operates a shut-down. If it is a propulsion engine there IS an over-ride so that the crew can hit a button to keep the engine running, on the basis that there is not much point in having a working engine if the ship is sitting on the rocks. However auxiliary engines driving generators do not have an over-ride as there are multiple engines/generators and so safety through redundancy - the chances of all engines having simultaneous faults in independent oil systems are so low they can be ignored. Please note that the Viking Sky did not have a fault in any of its oil systems, it was being operated in rough weather without extra precautions being taken. In my days at sea if we had rough weather we put extra oil in the sumps of the diesel generators to prevent such an occurrence.

Alasdair
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Reliance Upon Mechanical and Electro-mechanical Devices and Machines.

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