Taking the concept of using civilians in military ships one step further, the U.S. Navy is now using civilian sailors on a command ship. The USS Coronado, a former amphibious ship (LPD) that was converted to a command ship, has cut the size of the crew by about 40 percent by using more experienced civilian sailors in place of younger navy sailors. The Coronados crew size used to be 516, when it was all navy sailors. But now the crew is 153 civilian sailors, and 117 navy ones. Navy personnel handle weapons, command positions and purely military jobs. The more experienced civilian mariners can work much more efficiently than young sailors who only joined the navy a few months ago.
The USS Coronado is also the first warship transferred to the Military Sealift Command (MSC). This was done because the MSC has, for decades, operated navy cargo ships using largely civilian crews. A command ship is basically a non-combat ship that is equipped with powerful communications, lots of computers and space for a fleet commander and his staff to live, and work while afloat. Its not likely that the navy will try and use civilian sailors on regular warships. However, the definition of a warship can become murky, as today it's possible to quickly mount missiles and electronics on a merchant ship, thus turning it into a warship.
The American military has always depended on civilians working with the troops, in combat, because of the need for special skills only the civilians could provide. And these civilians were often more "military" than a lot of the troops (who were often only a few months away from their civilian lives.) It's not really a unique situation. Look at the merchant marine and their navy gun crews during World War II, and the Special Forces use of Montagnard, Laotian and Cambodian mercenaries during Vietnam. These were successful uses of civilians with professional troops. Until about a century ago, most navies made little distinction between civilian and military sailors.