Google analytics

Sunday 15 January 2012

So called experts

Save us from them.

I refer in this case to the Costa Concordia incident. I’m no expert on diesel electric propulsion but I have had extensive service on ships with that system.

Last night Malcolm Latarche, editor of the global shipping magazine IHS Fairplay Solutions, said the problem may have been caused by a phenomenon known as 'harmonic interference'.

If the vessel was travelling at cruising speed it is unlikely to have suffered this effect. This is normally applicable at low powers and is usually designed out at build. Additional safeguards are that harmonic filters are employed to negate any transient lower power risks. On my last ship we had two. One in use and another as back up.

This next paragraph makes no sense either.

The expert said the harmonic interference – a type of power surge – could have caused a malfunction in the generators feeding the ship's six diesel electric engines with which the back-up systems could not cope.

What are these generators that feed the diesel electric engines? What are the generators that supply the diesel generators? Where do they get their power from? Doesn’t make sense.

A diesel electric propulsion system consists of multiple diesel engines synchronised together. Each engine drives a generator supplying  AC at say 6.6kV (Alternating current) to a synchroconverter which converts the AC to DC (Direct current) to drive the propulsion motors.

This would have caused the ship to lose navigational power and steering control and veer off course, he said.

Again this is mere guesswork. Bearing in mind that  fifty per cent of the steering motors are fed from the emergency switchboard, I feel this is mere supposition. If power to the emergency switchboard is lost, an emergency generator, well away from the main machinery spaces, will automatically start and within sixty seconds be supplying the steering motors.


Mr Latarche added: 'Although the damage caused to the ship was severe, there are many safeguards in the design of a state-of-the-art cruise ship to prevent it turning over.

'There is a second hull within the outer hull. Inside the inner hull there is a steel structure like an ice tray to contain the water and prevent it spreading through the ship.

This intrigues me. As far as I know the only vessels required to be double skinned are oil tankers.

Before I retired we had just built four landing ships which were classified A1 at Lloyds register of shipping, which is the maximum possible certification standard. They did not have a double skin.

Much has been said of the evacuation of the vessel. In my opinion it is an almost impossible task to evacuate people who have no idea about the procedure involved. I’ve done various courses involving lifeboats and evacuation systems and realise that even those trained would find it difficult to escape given these particular circumstances.

I’m heartened to here that the number of missing is now down to 15, and that voices have been heard within the hull.

My condolence's go out to the bereaved. 

Sunday silliness

A woman was having a daytime affair while her husband was at work. One rainy day she was in bed with her boyfriend when, to her horror, she heard her husband's car pull into the driveway.

'Oh my God - Hurry! Grab your clothes and jump out the window. My husband's home early!'

'I can't jump out the window. It's raining out there!'

  'If my husband catches us in here, he'll kill us both!' she replied. 'He's got a hot temper and a gun, so the rain is the least of your problems!'

  So the boyfriend scoots out of bed, grabs his clothes and jumps out the window! As he ran down the street in the pouring rain, he quickly discovered he had run right into the middle of the town's annual marathon, so he started running along beside the others, about 300 of them.

  Being naked, with his clothes tucked under his arm, he tried to blend in as best he could. After a little while a small group of runners who had been watching him with some curiosity, jogged closer.

  Do you always run in the nude?' one asked.

  'Oh yes!' he replied, gasping in air. 'It feels so wonderfully free!'

  Another runner moved a long side. 'Do you always run carrying your clothes with you under your arm?'

  'Oh, yes' our friend answered breathlessly. 'That way I can get dressed right at the end of the run and get in my car to go home!'

  Then a third runner cast his eyes a little lower and asked, 'Do you always wear a condom when you run?'
  'Nope...just when it's raining.'