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Rogue wave hits surfaced Aussie sub

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Rogue wave hits surfaced Aussie sub

Postby U-5075 » Fri Sep 18, 2009 8:02 pm

Rogue wave hits surfaced Aussie sub
http://www.theaustralian.news.com.au/st ... 77,00.html



How freak wave hit secret submarine mission of HMAS Farncomb
INSIDE STORY: Cameron Stewart | September 19, 2009

Article from: The Australian
A FREAK wave in the dead of night triggered one of the most serious and sensitive accidents in the recent history of the Royal Australian Navy.

The rogue wave crashed into the side of the Collins Class submarine HMAS Farncomb, sweeping five crew members off the top of the boat and into stormy seas.

Those involved knew immediately this was no ordinary naval accident and that it would be no ordinary rescue. HMAS Farncomb was far from home on a covert intelligence-gathering mission in Asia.

What happened next has been held closely by the navy's top brass for more than two years.

Now the extraordinary tale of what unfolded on the night of March 19, 2007, can be told after the navy confirmed publicly it will award bravery medals to three of Farncomb's crew - the first such medals given to submariners in a generation.

The accident occurred during Farncomb's deployment in 2007 through Southeast Asia and the western Pacific.

Like many submarine missions, this five-month deployment was partly a chance to conduct joint training with the US navy in Guam, and partly an intelligence-gathering exercise where the submarine hugs foreign coastlines listening to communications, paying special attention to suspected regional terrorist networks.

Defence will not comment on Farncomb's precise location and activities at the time of the accident, although it says it took place in international waters.

The deployment was going well until Farncomb's sonar operators noticed that fishing lines had become entangled in the submarine's propeller.

"We could hear it through the sonar - it was a bit like a submarine dragging wedding bells," said Petty Officer Greg Langshaw, who was Farncomb's sonar supervisor. "Submarines try to remain stealthy, so dragging wedding bells behind you isn't part of that."

Farncomb could not continue to make such noise without risking detection, so the captain, Commander Mark Hammond, tried to shake the fishing lines off by changing the speeds and angles of the submarine. But still the line would not budge.

"So a decision was made to try to cut it off,' said Petty Officer Langshaw.

The operation to remove the fishing lines would require the submarine to surface at night to reduce the chance of detection.

In calm weather on a moonless night, the sub surfaced and opened its hatch, allowing a clearing party of five sailors to climb out, including two divers who would swim to the propeller and cut the fishing lines.

They started work, but the weather suddenly worsened, whipping up the ocean and tossing the submarine about.

Inside the boat, Petty Officer Langshaw could feel the change.

"We went from millpond conditions and in the space of no time the boat started rocking. Then I felt a big wave, and I said to the bloke next to me 'There goes the party'."

Petty Officer Langshaw was joking, but it was true.

Shortly before the wave hit, the line-clearing party had been ordered to abandon the operation because of the worsening weather. But as the five men walked back along the top of the sub towards the hatch, they were hit by the wall of water, throwing them into the ocean.

Cries of "Man overboard" echoed through Farncomb's PA system as the captain called for volunteers to rescue the men.

Petty Officer Langshaw, a 15-year veteran of submarines and the father of a baby girl, put his hand up.

As the rescue party was preparing to go outside, Commander Hammond was glued to the periscope, using night vision equipment to try to keep track of the five men being tossed around in the black ocean.

"As soon as we stepped out onto the casing (the top of the submarine) the first thing was self-preservation,' recalled Petty Officer Langshaw. "The waves were crashing over the sub, it was very choppy and there was a fair bit of wind."

Through the gloom, Petty Officer Langshaw could see the five men overboard had managed to swim to each other and tether themselves together, several hundred metres from the sub.

He ordered one of his crewmates, dressed in wetsuit and flippers and attached to the sub by a line, to swim out and bring back the men one by one.

"But he wasn't as strong a swimmer as we hoped,' said Petty Officer Langshaw. "He went out there but with rough seas he was out of breath too quickly. So we dragged him back on board using the lines."

Another volunteer, Leading Seaman Steven Rowell, then jumped into a wetsuit and dived into the ocean. He swam hard into the black night, towards the five men, and when he was within earshot he began teasing them about having fallen overboard.

Leading Seaman Rowell reached the group, put one of them in a harness and then swam his way back to the sub.

But when he got his mate back alongside the sub, the man was too spent to lift himself up on to the boat.

"He had full diving equipment on and he was very, very heavy and he had exhausted himself," said Petty Officer Langshaw.

"I looked down and thought I could make the job a bit easier if I removed his dive gear. So I jumped into the water and took his dive gear off."

As Petty Officer Langshaw was trying to undress his stricken crewmate, the sub was heaving up and down in the choppy seas. He was slammed against the side of the boat several times, breaking one of his ribs.

He and Leading Seaman Rowell eventually lifted their exhausted crewmate on to the sub, but the effort meant all three men were spent.

With four men still bobbing in the ocean, a new volunteer swimmer was needed.

Chief Petty Officer Rohan Pugh put up his hand. The 40-year-old Pugh was a veteran lifesaver and father of two from the coastal town of Secret Harbour, south of Perth.

Knowing time was running out for a safe rescue as the conditions worsened, Petty Officer Pugh did not bother with a wetsuit.

Instead, he put on his Speedos with Secret Harbour written on them, slipped on some fins, hopped out of the hatch and into the swirling ocean.

He said he didn't think twice about the risks.

"We're all mates plus we just go and do it," he said.

By this stage, the swell had risen to about two metres and the men had been in the water for more than an hour.

"The adrenaline was pumping," Petty Officer Pugh said.

"It was about a two-metre swell, very choppy and the wind was coming up. As I was swimming, I got mouthfuls of water - it was rough out there. It would have been a big day at Secret Harbour."

He battled through the swirling waves before eventually reaching the group.

"The first reaction I got from those guys was 'What are you doing here?' I told them I just felt like a swim."

Petty Officer Pugh grabbed the most exhausted member of the group and slowly swam him back towards the sub. But the waves were causing the boat to heave up and down by several metres with each wave, making it a dangerous job to lift the man back on board.

"That was an interesting task," he said. "We met the metal hull a couple of times, and we learned steel doesn't flex no matter how much you put your shoulder into it."

Petty Officer Pugh eventually got the man back on board and then swam back out to the last three. He placed a fixed line on one of the men and asked the crew members on the submarine to slowly reel in the line.

Those on the sub then threw a big cargo net over the side to help those still in the water to climb back on board safely.

Petty Officer Pugh grabbed the last two men and the three of them slowly kicked their way back to the sub. "It was hard work, it seemed to go on forever. The guys in the water were exhausted, but they were doing their bit."

Finally, the three men clambered back on board. The ordeal was over.

"I went back down into the sub and thought 'That was pretty interesting'," said Petty Officer Pugh. "I was shaking a bit, the adrenaline was still pumping, but everyone was happy."

The medics on board treated the men for bruises, but there were no serious injuries.

However, the captain ordered the submarine to go to the nearest friendly port to give his crew a break. Farncomb completed its mission, returning to Perth to tell its Boy's Own tale of courage and survival.
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Postby U-5075 » Sun Sep 20, 2009 4:49 pm

Recently, there have been a number of science programs on cable TV discussing rogue waves. Here is a better article on the internet about them and how they are now being spotted.

http://www.esa.int/esaCP/SEMOKQL26WD_index_0.html
Includes a number of interesting photos and graphics.

Ship-sinking monster waves revealed by ESA satellites


21 July 2004
Once dismissed as a nautical myth, freakish ocean waves that rise as tall as ten-storey apartment blocks have been accepted as a leading cause of large ship sinkings. Results from ESA's ERS satellites helped establish the widespread existence of these 'rogue' waves and are now being used to study their origins.

Severe weather has sunk more than 200 supertankers and container ships exceeding 200 metres in length during the last two decades. Rogue waves are believed to be the major cause in many such cases.
Mariners who survived similar encounters have had remarkable stories to tell. In February 1995 the cruiser liner Queen Elizabeth II met a 29-metre high rogue wave during a hurricane in the North Atlantic that Captain Ronald Warwick described as "a great wall of water… it looked as if we were going into the White Cliffs of Dover."

And within the week between February and March 2001 two hardened tourist cruisers – the Bremen and the Caledonian Star – had their bridge windows smashed by 30-metre rogue waves in the South Atlantic, the former ship left drifting without navigation or propulsion for a period of two hours.



"The incidents occurred less than a thousand kilometres apart from each other," said Wolfgang Rosenthal - Senior Scientist with the GKSS Forschungszentrum GmbH research centre, located in Geesthacht in Germany - who has studied rogue waves for years. "All the electronics were switched off on the Bremen as they drifted parallel to the waves, and until they were turned on again the crew were thinking it could have been their last day alive.

"The same phenomenon could have sunk many less lucky vessels: two large ships sink every week on average, but the cause is never studied to the same detail as an air crash. It simply gets put down to 'bad weather'."

Offshore platforms have also been struck: on 1 January 1995 the Draupner oil rig in the North Sea was hit by a wave whose height was measured by an onboard laser device at 26 metres, with the highest waves around it reaching 12 metres.




Objective radar evidence from this and other platforms – radar data from the North Sea's Goma oilfield recorded 466 rogue wave encounters in 12 years - helped convert previously sceptical scientists, whose statistics showed such large deviations from the surrounding sea state should occur only once every 10000 years.

The fact that rogue waves actually take place relatively frequently had major safety and economic implications, since current ships and offshore platforms are built to withstand maximum wave heights of only 15 metres.

In December 2000 the European Union initiated a scientific project called MaxWave to confirm the widespread occurrence of rogue waves, model how they occur and consider their implications for ship and offshore structure design criteria. And as part of MaxWave, data from ESA's ERS radar satellites were first used to carry out a global rogue wave census.




"Without aerial coverage from radar sensors we had no chance of finding anything," added Rosenthal, who headed the three-year MaxWave project. "All we had to go on was radar data collected from oil platforms. So we were interested in using ERS from the start."

ESA's twin spacecraft ERS-1 and 2 – launched in July 1991 and April 1995 respectively – both have a Synthetic Aperture Radar (SAR) as their main instrument.

The SAR works in several different modes; while over the ocean it works in wave mode, acquiring 10 by 5 km 'imagettes' of the sea surface every 200 km.




These small imagettes are then mathematically transformed into averaged-out breakdowns of wave energy and direction, called ocean-wave spectra. ESA makes these spectra publicly available; they are useful for weather centres to improve the accuracy of their sea forecast models.

"The raw imagettes are not made available, but with their resolution of ten metres we believed they contained a wealth of useful information by themselves," said Rosenthal. "Ocean wave spectra provide mean sea state data but imagettes depict the individual wave heights including the extremes we were interested in.

"ESA provided us with three weeks' worth of data – around 30,000 separate imagettes – selected around the time that the Bremen and Caledonian Star were struck. The images were processed and automatically searched for extreme waves at the German Aerospace Centre (DLR)."




Despite the relatively brief length of time the data covered, the MaxWave team identified more than ten individual giant waves around the globe above 25 metres in height.

"Having proved they existed, in higher numbers than anyone expected, the next step is to analyse if they can be forecasted," Rosenthal added. "MaxWave formally concluded at the end of last year although two lines of work are carrying on from it – one is to improve ship design by learning how ships are sunk, and the other is to examine more satellite data with a view to analysing if forecasting is possible."

A new research project called WaveAtlas will use two years worth of ERS imagettes to create a worldwide atlas of rogue wave events and carry out statistical analyses. The Principal Investigator is Susanne Lehner, Associate Professor in the Division of Applied Marine Physics at the University of Miami, who also worked on MaxWave while at DLR, with Rosental a co-investigator on the project.


"Looking through the imagettes ends up feeling like flying, because you can follow the sea state along the track of the satellite," Lehner said. "Other features like ice floes, oil slicks and ships are also visible on them, and so there's interest in using them for additional fields of study.

"Only radar satellites can provide the truly global data sampling needed for statistical analysis of the oceans, because they can see through clouds and darkness, unlike their optical counterparts. In stormy weather, radar images are thus the only relevant information available."

So far some patterns have already been found. Rogue waves are often associated with sites where ordinary waves encounter ocean currents and eddies. The strength of the current concentrates the wave energy, forming larger waves – Lehner compares it to an optical lens, concentrating energy in a small area.




This is especially true in the case of the notoriously dangerous Agulhas current off the east coast of South Africa, but rogue wave associations are also found with other currents such as the Gulf Stream in the North Atlantic, interacting with waves coming down from the Labrador Sea.

However the data show rogue waves also occur well away from currents, often occurring in the vicinity of weather fronts and lows. Sustained winds from long-lived storms exceeding 12 hours may enlarge waves moving at an optimum speed in sync with the wind – too quickly and they'd move ahead of the storm and dissipate, too slowly and they would fall behind.

"We know some of the reasons for the rogue waves, but we do not know them all," Rosenthal concluded. The WaveAtlas project is scheduled to continue until the first quarter of 2005.
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