commissioning was done prior to weapons systems integration, and the ships were placed in the status of "in commission, special" before sailing to San Diego for weapons installation and final acceptance. The first two ships used this approach, while the last one will use the more traditional approach with formal commissioning after final acceptance. Design As of January 2009, the Government Accountability Office (GAO) found that four out of 12 of the critical technologies in the ship's design were fully mature. Six of the critical technologies were "approaching maturity", but five of those would not be fully mature until after installation. Stealth According to a Naval Sea Systems Command spokesman, despite being 40% larger than an Arleigh Burke-class destroyer, the radar cross-section (RCS) is more akin to that of a fishing boat. The tumblehome hull and composite deckhouse reduce radar return. Overall, the destroyer's angular build makes it "50 times harder to spot on radar than an ordinary destroyer." The acoustic signature is comparable to that of the s. Water sleeting along the sides and passive cool air induction in the mack reduces infrared signature. The composite deckhouse encloses many of the sensors and electronics. In 2008, Defense News reported there had been problems sealing the composite construction panels of this area; Northrop Grumman denied this. The U.S. Navy solicited bids for a lower-cost steel deckhouse as an option for DDG-1002, the last Zumwalt destroyer, in January 2013. On 2 August 2013, the U.S. Navy announced it was awarding a $212 million contract to General Dynamics Bath Iron Works to build a steel deckhouse for destroyer Lyndon B. Johnson (DDG-1002). The U.S. Naval Institute stated, "the original design of the ship would have had a much smaller RCS, but cost considerations prompted the Navy over the last several years to make the trades in increasing RCS to save money." To improve detection in non-combat situations by other vessels, such as traversing busy shipping channels or operating in inclement weather, the Navy is testing adding onboard reflectors to improve the design's radar visibility. The usefulness of the stealth features has been questioned. The class's role was to provide Naval Surface Fire Support, which requires the ship to be in typically crowded near-shore waters where such large and distinctive ships can be tracked visually, and any surface ship becomes non-stealthy when it begins firing guns or missiles. Tumblehome wave-piercing hull The Zumwalt-class