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Burkes buckling under stress


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From Jane's

 

Arleigh Burke-class destroyers 'buckling' under stress, admits USN

By Tara Copp

11 October 2007

 

Serious structural defects have been identified throughout the United States Navy's fleet of Arleigh Burke-class destroyers, Jane's can reveal.

 

The navy (USN) has admitted that many of the 51 ships currently in service are buckling under the stress of higher-than-anticipated loads at sea.

 

The impact of rough-sea slamming on the bow has led to warping of main transverse bulkhead beams and some of the cribbing, a source said.

 

Repairs and strengthening work is already being carried out on the latest Flight IIA ships as well as vessels from the earlier production batches.

 

In September, for example, one of the newest destroyers - USS Gridley (DDG 101) - was undergoing repairs for beam warping during post-shakedown availability (PSA) at BAE Systems' shipyard in San Diego, California. Weakened support beams were cut out, reinforced and replaced.

 

Specialised labour was required because the task involved strengthening beams in very tight spots above the Gridley's sonar equipment room.

 

But the problem is widespread; according to a presentation on 21 September by Rear Admiral Kevin McCoy, the chief engineer at Naval Sea Systems Command's Naval Systems Engineering Directorate, the navy approved a USD62 million "bow-strengthening backfit" to address "local buckling of deck transverse beams" and other structural damage in a number of destroyers.

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I'm curious as to the nature of the "higher than anticipated" loads. I understand that the Burkes do not regularly operate with a full warload of missiles, for example, and afaik, most of their service is not being performed in the heavy seas of the North Atlantic. (I'm not suggesting that the Indian Ocean and the Persian Gulf are any less demanding overall, but imagine how bad it might have been in the North Atlantic).

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I'm curious as to the nature of the "higher than anticipated" loads. I understand that the Burkes do not regularly operate with a full warload of missiles, for example, and afaik, most of their service is not being performed in the heavy seas of the North Atlantic. (I'm not suggesting that the Indian Ocean and the Persian Gulf are any less demanding overall, but imagine how bad it might have been in the North Atlantic).

 

 

I think they actually mean one of two things.

 

A) the Sonar Dome creates more drag under some conditions than anticipated in the design

 

B) The ships average speed (and thus average forces on the hull as exerted by the water) are HIGHER than anticipated.

 

Sorry for me if the ship isn't designed to run at 30+ knots it should not be a 30+ knot warship!

 

Craig P

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From Navy Times

 

Report: DDG 51s heavily damaged by ‘bow slams’

Staff report

Posted : Sunday Oct 14, 2007 9:29:05 EDT

 

Thirteen Arleigh Burke-class destroyers have suffered “significant” structural damage in rough seas because designers didn’t account for the effect of “bow slams” on the ships’ hulls, Navy documents say — and fixing the problem could cost almost $63 million.

 

A Navy PowerPoint presentation, obtained by Navy Times, confirmed a report Thursday in the British defense publication Jane’s revealing the design problems in the Burke class.

 

Support beams and other structures inside the destroyers warp so much from the stress of withstanding high seas that they must be cut out and replaced, even in new ships — the destroyer Gridley, commissioned in February, already underwent repairs in September. The document listed the following ships as damaged: Arleigh Burke, Curtis Wilbur, Stout, Paul Hamilton, Stethem, Carney, Gonzalez, The Sullivans, Ross, McFaul, Higgins, Winston S. Churchill and Lassen.

 

“Damage ranges from local buckling of deck transverse beams and shell web frames and shell longitudinals resulting in several inches of permanent deformation,” said one slide in the presentation.

 

Internal structure warping is not uncommon among surface warships; the Navy’s cruisers and frigates have gone into shipyards for hull-stiffening repairs.

 

With each ship designed to serve for around 35 years, the Burkes are the Navy’s only destroyers in service. The first ship was commissioned in 1991, and shipyard Bath Iron Works of Bath, Maine, announced it has started work on the last, DDG 112, expected to join the fleet in 2011.

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From Navy Times

 

Navy: DDGs keep ‘capability’ despite damage

Staff report

Posted : Monday Oct 15, 2007 18:56:01 EDT

 

The Navy’s 51 Arleigh Burke-class destroyers have lost no operational capability despite structural damage caused to more than a dozen ships by design flaws worsened by the pounding of rough seas, the Navy said Monday.

 

Crews noticed damage on the bows of 13 Burke-class ships between 1993 and 2003, including “denting of shell and deck structures of the bow,” but this was “only discovered under close inspection,” said an announcement from Naval Sea Systems Command. “The cause of the damage was determined to be due to stress which was higher than initially estimated when the ship was designed.”

 

The NavSea announcement characterized the damage as not severe, and the Navy’s almost $63 million multi-ship repair plan as being necessary only to make sure all the destroyers in the class could serve the 35 years for which they were designed. But NavSea’s statement stood in contrast to a report Thursday in the British defense publication Jane’s, which said the damage from “bow slams” was serious, and affected even new ships.

 

A Navy PowerPoint presentation, obtained by Navy Times, identified the destroyers that have suffered structural damage in rough seas: Arleigh Burke, Curtis Wilbur, Stout, Paul Hamilton, Stethem, Carney, Gonzalez, The Sullivans, Ross, McFaul, Higgins, Winston S. Churchill and Lassen. Jane’s also reported that the destroyer Gridley, commissioned in February, already underwent repairs in September.

 

“Damage ranges from local buckling of deck transverse beams and shell web frames and shell longitudinals resulting in several inches of permanent deformation,” said one slide in the Navy presentation.

 

Internal structure warping is not uncommon among surface warships; previously, the Navy’s cruisers and frigates have gone into shipyards for hull-stiffening repairs.

 

The Burke-class ships are the only destroyers today in the fleet. The first ship was commissioned in 1991, and shipyard Bath Iron Works of Bath, Maine, announced it has started work on the last, DDG 112, expected to join the fleet in 2011.

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  • 2 weeks later...
I'm curious as to the nature of the "higher than anticipated" loads. I understand that the Burkes do not regularly operate with a full warload of missiles, for example, and afaik, most of their service is not being performed in the heavy seas of the North Atlantic. (I'm not suggesting that the Indian Ocean and the Persian Gulf are any less demanding overall, but imagine how bad it might have been in the North Atlantic).

 

I'd say that the high deployment rates are probably exacerbating the situation as well. Remember that Type 21 frigates suffered from hull cracking that required external stiffeners to be added to the design. Less ships and more deployments mean more wear and tear on a given frame set. Box girder construction and decreased scantlings only goes so far.

 

I don't know the average deployment rate of a Burke but I was once involved in a yard availability for a ship that was 20 years old, operating constantly at least 6 months of the year. She suffered from ice infested waters in the first third and heavy weather during the last third of the six months. During this yard availability she required 87 tonnes of new plating to be installed from the bow down to the leading edge of the bilge keel.

 

Later

D

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