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World
Naval Forces News - USA |
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| Lessons Learned from First Littoral Combat Ships Lead to Improvements in Follow-on Ships | |||
The
U.S. Navy and its shipbuilding partners have incorporated lessons learned
from the first two Littoral Combat Ships (LCS) in the design and construction
of the follow-on ships. “I think the lead ships are pretty good,”
says Rear Adm. Jim Murdoch, the Program Executive Officer for LCS (PEO
LCS). “I think LCS 3 and 4 will be better.” LCS 1 is the USS Freedom, built at Marinette Marine in Wisconsin by a team led by Lockheed Martin, and commissioned in November of 2008. The ship deployed to U.S. Naval Forces Southern Command as well as participated in the RIMPAC fleet exercises around Hawaii in 2010. Freedom is currently in a scheduled maintenance period in San Diego. Commissioned in 2010, USS independence (LCS 2) was built at Austal USA in Mobile, Ala., and recently called at Naval Station Newport in Rhode Island for the 20th International Seapower Symposium. Independence is conducting tests at sea with both the Remote Minehunting Vehicle and MH-60S Seahawk helicopter using the AQS-20 sonar in simulated minefields. Several ships of each design are under construction at the two builders’ shipyards. Fort Worth (LCS 3) completed builder ‘s sea trials in Lake Michigan on Oct. 24., and is due to be commissioned next year. Coronado (LCS 4) will launch next month at Mobile. Milwaukee (LCS 5) is under construction at Marinette, and construction of Jackson (LCS 6) has begun in Mobile. Murdoch said that criticism regarding the cost overruns of the first two ships was well founded. But thanks to a robust competition, the follow on ships will cost much less. “We have two great contracts in place to provide ships at a very affordable price, and maintain a stable design,” Murdoch says. |
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LCS is the first ship built to address these focused missions of mine countermeasures (MCM), anti-submarine warfare (ASW), and surface warfare (SUW), and can be configured for those missions by changing modularized mission packages. The ship itself has ample internal volume to carry mission packages to address one of the three focused missions, and these mission packages can be quickly changed to give the ship an entirely different combat capability depending on the specific threat being addressed. These mission packages come in containerized modules which carry offboard vehicles and sensors. Employment of off-board manned and unmanned vehicles at a distance from the ship allows the Navy to rapidly engage threats while the ship stays at stand-off ranges. The Navy had planned to select just one of the two competing variants to be the Navy’s choice for LCS. But in a surprise announcement last December, Lockheed Martin Corp. and Austal USA each received a fixed-price incentive contract for the design and construction of a 10 ship block-buy, for a total of 20 littoral combat ships from fiscal 2010 through fiscal 2015. The average ship target-price across the entire dual-block buy for the Lockheed Martin LCS variant is $362 million; and the average ship target-price for the Austal USA LCS variant is $352 million, according to Navy officials. |
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 USS Independence LCS-2 (picture: General Dynamics) Link to Independence class LCS datasheet and pictures |
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To provide additional buoyancy on LCS 1, buoyancy tanks were attached on the stern on each side of the stern door. In LCS 3, the hull was lengthened below the water line providing more buoyancy without the tanks, and space for an additional 10 percent fuel capacity. With the extra length, the ship is actually faster. LCS 1 has a “clean focsle,” Murdoch says. The anchor windlass, used to raise and lower the anchor, usually found on the main deck of most combatants, is actually inside the ship on LCS 1. But water came into the ship in heavy seas. By having the opening on the deck, any water coming through the hawse flows overboard. “The new design will allow the ship to go faster in high seas.” "With that longer underwater hull, the ship is a little more efficient,” says Murdoch. “Just operating on the diesel engine alone, she's about a knot faster. We're probably one to two knots faster on the gas turbine (engines) alone than Freedom was." The LCS 1 design will have a more robust shaft seal system and improvements to the stern door leading from the waterborne mission zone top the sea so as to reduce the impact of salt water corrosion, as well as larger bridge windows. LCS 1 has a 5-meter ridged hull inflatable boat (RHIB) as a lifeboat, mounted on the port side. “We want a larger boat. A design change is in the works.” Design improvements will permit heavier loads to be carried on the LCS 1 stern ramp. This way the 11-meter RHIB can remain on the ramp between evolutions instead of being stowed and unstowed each time, a time-consuming task. “These are small ships with a lot of propulsion plant in them,” Murdoch says. However, Murdoch says care is being taken not to make structural changes that increase weight. “Either you want a ship that goes 40 knots or you don’t.” Murdoch said LCS 2 construction required too many labor hours. The Austal ships now feature a more modular and economic construction process. Large blocks of the ship are built with all the installed piping and wiring, and are mostly complete and tested when fitted to the other parts of the ship. In addition, the LCS 4 centerline waterjets are larger so as to take full advantage of the General Electric LM2500 gas turbines. The Austal ship has also experienced corrosion problems. Both designs need more cathodic protection, he says. The Navy and the builders are installing both additional sacrificial anodes known as zincs and an impressed current system, “An Impressed Current Cathodic Protection System (ICCP) will be installed in both the cone assemblies and the water jet tunnels on Austal variant ships to reduce the effects of galvanic corrosion,” says Naval Sea Systems Command spokesman Chris Johnson. “The General Dynamics and Austal USA approach to prevent corrosion on LCS 2 was based on commercial practices and included a coating system on the exposed metal, electrical insulation of dissimilar metals and cathodic protection via sacrificial zinc anodes in the water jet tunnels. This design proved to be less effective than intended due to multiple factors including improper electrical insulation during installation. To provide more comprehensive protection, an ICCP system and additional sacrificial protection design is being finalized and will be implemented on LCS 2 during its Post Shakedown Availability (PSA); has already been installed on LCS 4; and will be included on LCS 6 and follow as a baseline change prior to the start of construction.” With the changes, Murdoch says both production lines should now be quite stable. The key to keeping costs down, he says, is avoiding changes. “We don’t introduce any changes we don’t absolutely have to,” he says. From: Marine Link |
Lessons Learned from First Littoral Combat Ships Lead to Improvements in Follow-on Ships
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