A GAO report raises worrying questions about the decision to restart production of the Arleigh Burke class destroyer (DDG 51) after nearly a decade and almost $10 billion in development on Zumwalt (DDG 1000) class destroyers.
The new Flight III DDG 51 ships will,in fact, be considerably more complex than previous DDG 51 flights. The report suggests they will almost certainly cost a lot more than once supposed, may face delivery delays and, says GAO, the Navy's choices of system for Flight III "will likely be unsuitable for the most stressful threat environments it expects to face."
The study "ARLEIGH BURKE DESTROYERS: Additional Analysis and Oversight Required to Support the Navy's Future Surface Combatant Plans" (GAO-12-113) is a report to the Ranking Member, Subcommittee on Defense, Committee on Appropriations.
GAO says the Navy relied on its 2009 Radar/Hull Study as the basis to select DDG 51 over DDG 1000 to carry the Air and Missile Defense Radar (AMDR) as its preferred future surface combatant—a decision that may result in a procurement of up to 43 destroyers and cost up to $80 billion over the next several decades. According to GAO, the Radar/Hull Study may not provide a sufficient analytical basis for a decision of this magnitude. Specifically, the Radar/Hull Study:
- focuses on the capability of the radars it evaluated, but does not fully evaluate the capabilities of different shipboard combat systems and ship options under consideration,
- does not include a thorough trade-off analysis that would compare the relative costs and benefits of different solutions under consideration or provide robust insight into all cost alternatives, and
- assumes a significantly reduced threat environment from other Navy analyses, which allowed radar performance to seem
On the costs of the DDG 51 restart, the GAO study says: "The Navy has estimated $2.6 billion in its fiscal year 2012 budget submission for the lead Flight III ship. However, this estimate may not reflect the significant design and construction challenges that the Navy will face in constructing the Flight III DDG 51s—and the lead ship in particular. In fact, the Navy's most current estimates for a range of notional Flight III options are between $400 million and $1 billion more than current budget estimates, depending on the configuration and equipment of the variant selected."
Among other issues, GAO says that, according to Navy analysis, selecting the DDG 51 hullform to carry the Air and Missile Defense Radar (AMDR) requires significant redesign and reduces the ability of these ships to accommodate future systems. This decision also limits the radar size to one that, says GAO "will be at best marginally effective and incapable of meeting the Navy's desired capabilities."
The study says that DDG 51 is already the densest surface combatant class and that, according to a 2005 DOD-sponsored shipbuilding study, the DDG 51 design is about 50 percent more dense and complex than modern international destroyers. High-density ships have spaces that are more difficult to access; this results in added work for the shipbuilder since there is less available space to work efficiently. As a legacy design, the ship's physical dimensions are already fixed, and it will be challenging for the Navy to incorporate AMDRs' arrays and supporting equipment into this already dense hullform. Some deckhouse redesign will be necessary to add the additional radar arrays: a current DDG 51 only carries four SPY radar arrays, while Flight III is envisioned to carry four AMDR-S arrays plus three additional AMDR-X band arrays. The deckhouse will need to be redesigned to ensure that these arrays remain flush with the deckhouse structure. Adding a 14-foot AMDR to DDG 51 will also require significant additional power generating and cooling equipment to power and cool the radar. Navy data show that as a result of adding AMDR the ships will require 66 percent more power and 81 percent more cooling capacity than current DDG 51s. If the Navy elects to use a smaller AMDR for Flight III these impacts may be reduced, but the ship would also have a significant reduction in radar performance.
Adding in all this new equipment will not only add to shipbuilding costs The study says that the addition of equipment to Flight III adds weight to the ship, and adding the large, heavy AMDR arrays to the deckhouse will also change the ship's center of gravity. Weight and center of gravity are closely monitored in ship design due to the impact they can have on ship safety and performance. The Navy has required service life allowances (SLA) for weight and center of gravity for ships to allow for future changes to the ships, such as adding equipment and reasonable growth during the ship's service life—based on historical data—without unacceptable compromises to hull strength, reserve buoyancy, and stability (e.g., tolerance against capsizing). Adding new systems or equipment may require mitigating action such as removing weight (e.g., equipment, combat systems) from the ship to provide enough available weight allowance to add desired new systems or equipment. A reduced center of gravity may require mitigation such as adding additional weight in the bottom of the ship to act as ballast, though this could also reduce the available weight allowance. These changes all require redesign which can increase costs, and this design work and related costs can potentially recur over the life of the ship.
GAO says the Navy is considering a range of design options to deal with adding AMDR and its supporting power and cooling equipment. None of the DDG 51 variants under consideration as part of an ongoing Navy study meet Navy SLA requirements of 10 percent of weight and 1 foot of center of gravity for surface combatants. GAO says that several variants provide less than half of the required amounts.
GAO is making several recommendations to the Secretary of Defense, including requiring the Navy to conduct thorough analyses of alternatives for its future surface combatant program and conduct realistic operational testing of the integrated missile defense capability of the DDG 51's upgrade, ensuring that the Navy does not include the lead Flight III ship in a multiyear procurement request, and raising the level of oversight for this program. DOD agreed with the recommendations to varying degrees, but generally did not offer specific actions to address them. GAO believes all recommendations remain valid and its report includes "matters for congressional consideration to ensure the soundness of the Navy's business case."
Access the GAO report here
January 25, 2012