Capsize-proof MTU Engine for UK RNLI 'Severn-class' Lifeboat

By George Backwell at April 02, 2011 21:42
Filed Under: Company News, Research & Development

If a British RNLI (Royal National Lifeboat Institution) ‘Severn-class’ lifeboat bent on a lifesaving mission in foul weather were to capsize, it is designed to upright within seconds (the righting lever must be a long one) but how can the engine keep running after the boat has ‘looped the loop’?

Inverting a running diesel engine would likely cause engine oil to enter the cylinders through the crankcase ventilation system, causing uncontrolled combustion as surely as pressing the self-destruct button. A few years ago, the RNLI was looking to re-engine its ‘all weather’ boats and asked MTU if they could tackle the problem.

The Revolving Cradle Test-bed

MTU design engineers took their Series 2000 M94 engine and fitted it to a special-purpose cradle that would rotate it through 360 degrees about its own longitudinal axis in order to study closely and practically the effectiveness of modifications they made to the design of the crankcase ventilation and oil lubrication galleries.

Most importantly they fitted a valve to the crankcase breather that would close, depending upon the angle of rotation, and would then re-open automatically when the engine was restored to the upright. Subsequently, for so much depends upon it, every M94 engine destined for RNLI installation must pass through final testing on the revolving cradle before it is sent out from the factory.

Sea Trials of the Modified MTU M94 Engine

'Severn-class lifeboats', with a 39 ton displacement, are the largest in the RNLI fleet, built to operate in conditions that send boats of comparable size scurrying for shelter, so the reliability and efficiency of propulsion is key to safe operation in extreme conditions.

The same engines must cold-start to work under full load almost immediately for the duration of the rescue operation; a severe regime for any diesel engine. Despite this, the M94 engine is unlikely to be out of service much for engine maintenance, as MTU advise that the first oil and filter change is not needed until after 500 hours of operation.

To test performance in operational conditions, modified twin 10-cylinder MTU Series 2000 M94 engines, each rated at 1,120 kw at 2,450 rpm  were fitted in October 2008 to the RNLI lifeboat Margaret, Joan & Fred Nye stationed in the storm-exposed Arran Islands off the West Coast of Ireland. Such has been the success of these extended sea trials, that according to a MTU report in April 2010 RNLI had decided to re-engine more of its 'Severn-class' lifeboats with these engines.

MTU Series 2000 M94 Diesel Engine: Photo courtesy of MTU

Comments (2) -

you are up to the task. please i like to work with the company .thank you.

asu peter |     4/11/2011 8:39:54 AM #

It's about bloody time.  All ship's engines should continue to run at any angle of inclination, particularly generators.  When the ESTONIA was wallowing in heavy seas and about to sink, and people were struggling to get lifejackets and liferafts - fighting for their lives - the generators were SWITCHED OFF!  This was done automatically to ensure that the ship went to the bottom with its engine bearings in pristine condition.

Colin Henthorne |     4/14/2011 12:55:15 PM #

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