BATH, Maine — A defense industry expert said Tuesday that a Navy decision to award a contract for the third Zumwalt-class “stealth destroyer” deckhouse to Bath Iron Works may have saved money, but could come at the expense of increased stealth.

Meanwhile, the decision prompted officials at BIW’s chief competitor, Ingalls Shipbuilding — which built the first two Zumwalt-class deckhouses of composite — to say they would examine the future of the Mississippi shipyard’s composite center.

The hulls of the three Zumwalt-class destroyers — a line of stealth warships since discontinued because of their cost — are being built at BIW. Ingalls Shipbuilding’s Composite Center for Excellence facility in Gulfport, Miss., was awarded contracts to build the deckhouses, helicopter hangar and launch missile shields for the first two Zumwalt-class ships out of composite.

But on Aug. 2, the Navy announced that BIW had secured a $212 million contract modification to build the third deckhouse — for the future USS Lyndon Johnson — out of steel.

Chris Johnson of Naval Sea Systems Command said Tuesday that the Navy turned to Ingalls for the first two deckhouses because during the initial design, “we needed a lower weight alternative to steel, and the composites met that requirement.”

As the Navy built the first ship, however, studies indicated that steel deckhouses were feasible, and the Navy asked both companies to continue studying and submit proposals. Bath Iron Works submitted the lowest-cost proposal, for a steel deckhouse, and was awarded the contract.

But Loren Thompson of the Arlington, Va.-based Lexington Institute said Tuesday that although the steel deckhouse may come at a lower price, it could prove to offer fewer tactical advantages than a composite deckhouse.

“If an enemy is searching the surface with radar, it’s likely to get a stronger return signal from a steel deckhouse,” he said. “If you shoot a signal to it from radar, it will bounce back and the enemy will know it has found something.”

Thompson said that because the Navy limited the Zumwalt class to three warships, “it probably thinks that using steel will save money on a class of warships that will be of limited use. When the Zumwalt was conceived, it held a very ambitious design at a hefty price tag. The class was prematurely terminated, and at this point, I think the Navy wants to get the work done at the lowest possible price so it can move on to other priorities.”

Johnson, however, said studies showed that steel and composites meet the exact same requirements — including radar return — although he said he couldn’t say whether they would return a radar hit with exactly the same strength, or which deckhouse met those requirements better. But he added, “Neither is stealthier than the other.”

Weight was certainly a factor, Johnson said, as well as some technical criteria, but he said changes to the ship design since work started on the first Zumwalt-class destroyer accommodated the heavier steel deckhouse.

The deckhouse and hangar for the DDG 1000, made of composite, already was delivered to BIW, and Bill Glenn, public affairs manager at Ingalls, said the composites center — which employs about 650 people — continues work on the deckhouse and hangar for the DDG 1001.

In a statement, Glenn said officials at Ingalls “are disappointed” in the Navy’s decision to award the third deckhouse to BIW, despite “considerable improvement from the first set of class products to the second set, and we are confident this trend would have continued on DDG 1002.”

As a result of the decision, he said, Ingalls ”is currently evaluating the future utilization of this facility.”

Thompson said that while composites “are the wave of the future in aircraft design, they don’t deliver the same value on warships that they do on planes.”

Of the Ingalls’ statement, he said, “Unless there’s a demand for those specialized facilities and skills, it’s kind of obvious the center would be in jeopardy.”