WMSL-750 Legends Class
In December 2002, the Coast Guard's technical experts first briefed senior Deepwater Program management and ICGS representatives of concerns about the NSC's structural design that they had been unable to resolve through the IPT process. In September 2003, Systems Directorate personnel informed the Coast Guard's Office of Acquisition and Deepwater Program management that there were "very significant problems" with the NSC's design. In January 2004, the Systems Directorate received the results of independent technical reviews conducted by two renowned naval vessel subject matter experts to assess the structural adequacy of the NSC design. Both studies corroborated the Systems Directorate's initial technical concerns.
In March 2005, two months after receipt of the System Directorate's latest recommendation, but more than 27 months after first being advised of the design deficiencies, the Deepwater Program Office contracted with the U.S. Navy to conduct a fatigue assessment of the NSC's design, emphasizing the Coast Guard technical experts' specific areas of concern. Final results of the Navy's assessment that were published in August 2006 validated most of the Systems Directorate's concerns by determining that, "there are several areas of concern that have insufficient fatigue strength to endure 30 years of operation in the General Atlantic."
In December 2006, the New York Times published an article on the Deepwater program that stated that the new National Security Cutter (NSC) (formerly called High Endurance Cutters) has "structural weaknesses that some Coast Guard engineers believe may threaten its safety and limits its life span, unless costly repairs are made." The contract with ICGS states that a cutter should have a 30 year life-span. The Coast Guard believed that these engineering concerns were based on different assumptions regarding structural weaknesses in the welding and cutting techniques as well as assumptions about the amount of time the NSC will operate in the rough marine environment of the North Pacific Ocean. It is not that the vessels won't be able to operate for 30 years - but that they may require more maintenance if structural cracks appear during that period.
By early 2007 it appeared that the NSC, as designed and constructed, will not meet performance specifications described in the original Deepwater contract. Specifically, due to design deficiencies, the NSC's structure provides insufficient fatigue strength to be deployed underway for 230 days per year over its 30-year operational service life under Caribbean (General Atlantic) and Gulf of Alaska (North Pacific) sea conditions. These design deficiencies include: (1) vent penetration openings in the strength deck stringer plates; (2) large door openings in longitudinal bulkheads near their supports; (3) weakness in the shell fashion plate; and (4) an abrupt discontinuity in deckhouse superstructure.
Operating in the North Pacific adds additional strain to a ship due to the rough weather. The more a vessel operates in that environment, the more structural fatigue the ship must endure. The Coast Guard believes that some of these cutters will operate much of the year the North Pacific - and therefore have a greater rate of structural fatigue than the rate assumed by ICGS.
Regarding the construction techniques used by ICGS, and their subsidiary Northrup Grumman Shipyard in Pascagoula, MS, the Coast Guard uses 2 examples. Coast Guard engineers prefer a welding technique in which an individual follows up after a welder and hits the weld with a ball-penne hammer. They said that this strengthens the weld. Ingalls Shipyard does not use this welding technique when building ships for the Navy at that shipyard and did not do it when building the first 2 NSCs. The Coast Guard is concerned that this could increase chance of having cracking in the weld over the 30-year lifespan of the cutter. When Ingalls cuts a hole in a structural support member of a ship (i.e. to run plumbing or electrical systems) they cut a square hole. Coast Guard engineers believe that a square hole increases the risk of having a stress fracture at one of the 4 corners of that square hole over the 30 year life of the cutter. The Coast Guard believes that the hold should have rounded corners. Again, Ingalls shipyard has made square holes when building Navy ships.
Coast Guard technical experts believed the NSC's design deficiencies will also increase the cutter's maintenance costs and reduce its service life. To mitigate the effects of these deficiencies, according to the DHS Inspector General, the Coast Guard modified the NSC's design to support an operational profile of 170 to 180 days underway per year in the North Pacific region, lower than the 230- day performance standard required by the Deepwater contract. Assuming a 30-year service life for each of the eight planned cutters, if the Coast Guard's plan to operate the NSC for 180 days per year in the North Pacific is implemented, the operational capability of the entire NSC fleet could be reduced by up to 12,000 underway days. This is more than 52 underway years, representing a loss of approximately 1.7 cutters over the course of 30 years.
The Coast Guard took the view that it had not lowered performance standards. Fatigue issues identified and addressed by the Coast Guard do not and will not, according to the Coast Guard, impact the NSC's operational performance, nor will they require operational restrictions of any kind. The NSC performance standard is in accordance with Commandant's Instruction (COMDTINST 3100.5A), bywhich all cutters are managed. This instruction specifically dictates what is meant by Underway Days versus Days Away From Home Port (DAFHP). The DAFHP requirement for the NSC is 230 days. The 230 days consists of: 185 days underway (165 Mission Days and 20 Average Transit Days) and 45 in-port logistics DAFHP. It is understood by all parties that the 230-day requirement is Days Away From Home Port (DAFHP), not Underway Days.
The NSC's design and performance deficiencies were fundamentally the result of the Coast Guard's failure to exercise technical oversight over the design and construction of its Deepwater assets. The Coast Guard's technical experts first identified and presented their concerns about the NSC's structural design to senior Deepwater Program management in December 2002, but this did not dissuade the Coast Guard from authorizing production of the NSC in June 2004 or from awarding ICGS a contract extension in May 2006.
The NSC, as designed as of late 2006, had several key structural components with a calculated service life of less than 3 years that required immediate remediation. This is especially true with regard to NSCs 1 and 2. It was not clear whether NSCs 1 and 2 can be fixed given their stage in construction. Structural enhancements to improve the NSC's fatigue life need not be done immediately. Hulls #1 and #2 will have much of the work done after delivery. NSC hulls #3 through #8 will incorporate design changes during construction. Any known or suspected fatigue concerns will be addressed when this design change is incorporated on the NSC. In the end, the NSC will be designed to achieve a 30-year service life.
ICGS agreed to make these changes in NSC hull #3 which hasn't been built yet (at an added cost of approximately $15 million). The Coast Guard is evaluating the cost of having NSC hulls # 1 and 2 modified - and depending upon the cost of the modification - may make some of these changes now. If the weld or square hole is in a fairly inaccessible place - they may choose to just pay more attention to the location during maintenance inspections over the life of the vessel.
|Join the GlobalSecurity.org mailing list|