sound like building a skyscraper on a foundation of paper, but NNS uses
The close tolerances in the construction of a
Now a thirty-three-month countdown clock starts. From this day forward to the launch date, the construction process is a race to determine the milestone bonuses and resulting profits for NNS stockholders. Meanwhile, Navy officials plan dates for commissioning and first deployments, select the 'plankowner' officers and crew who will first man the new carrier, and assemble the 'pre-commissioning unit' (PCU). These are the sailors who will report on board the ship while it is still under construction, in order to learn every detail of maintenance and operation.
Back at Dry Dock 12, the thirty-three-month construction moves forward rapidly. The secret to staying on schedule is 'modular construction,' a technique originally pioneered by Litton-Ingalls Shipbuilding in Mississippi. Rather than constructing a ship like a building, from the bottom up, the ship's designers break the design down into a series of modules. Each module is completed alongside the construction dock, with piping, fixtures, and heavy equipment already installed. Then it is lifted into place and 'stacked' with other modules to form the hull. When that is done, the modules are 'joined' (welded together). Pipes, ducts, and electric wiring bundles are connected into a mostly finished configuration, and the ship is 'floated' out of the dock (or launched), with final work done alongside a 'fitting-out' dock elsewhere in the yard. This mode of construction has many advantages. For one thing, the ship can be launched at a more advanced stage of construction than used to be the custom, which reduces costs considerably. Work that takes an hour to do in an NNS workshop usually takes three hours out in the yard, or eight hours in the ship once it is floating in the water. So anything that can be built in the shops or installed in the yard before it is assembled reduces costs; it is money in the bank.
Though modular military shipbuilding was pioneered by Litton-Ingalls, the scale at NNS is far greater. At NNS, they call this the 'Superlift' concept. By way of comparison, Litton's largest module weighs around 500 tons/ 453.6 metric tons, while NNS utilizes modules up to 900 tons/816.6 metric tons lugged in place by the huge bridge crane. NNS can build a
A Superlift starts as a small mountain of steel plates, brought by rail and truck to NNS. Flame-cut to exact tolerances in the shops just south of Dry Dock 12, the plates are tack welded together by spot welds, then permanently joined by robotic welders along a pair of side-by-side production lines. These are then linked into the structural assemblies that form each Superlift. Once the basic structure is completed, cranes move it to the large assembly area next to Dry Dock 12. Then NNS yard workers crawl over and inside it to 'stuff' electrical, steam, fuel, sewage, and other lines, fittings, and gear into place. Sometimes Superlifts are turned upside down, to make 'stuffing' easier. When a Superlift is ready for joining, the nine-hundred-ton bridge crane is moved into position overhead, the lift cables are fastened, and the assembly in Dry Dock 12 made ready. Despite a Superlift's gigantic size and weight, this is a precision operation, with tolerances frequently dictated by the relative temperatures of the ship assembly and the Superlift. Depending on temperature, the metal structure of a Superlift can easily expand or contract over an inch during a given day on the Tidewater.
Around the assembly yard, several dozen Superlifts are in various stages of preparation at any given time. Some interior and exterior painting is done on Superlifts, to make this nasty and environmentally sensitive job a little safer. Because power, water, and air-conditioning can be installed in a Superlift while it is being assembled, the construction process is considerably facilitated. This is particularly helpful in the hot, muggy summers and cold, wet winters of the Tidewater region. There is a particular order to how Superlifts are stacked. The initial Superlifts- including the double bottom, reactors, steam power plants, ammunition magazines, and heavy machinery-are laid around the keel structure. In general, these items (making up the bottom of the middle third of the carrier) are the heaviest and most deeply buried components, and cannot be accessed or installed easily later on. They take some four months to assemble.
At twenty-two months to launch, everything aft to the fantail and up to the main/hangar deck is in place. Many of the living and habitation spaces are also included in this phase, as well as the majority of the carrier's protection systems (double bottoms, heavy plating, and voids-hollow spaces like fuel tanks, etc.). Now the assembly is beginning to look like a ship. At eighteen months to launch, the hangar deck is taking shape, along with the great overhanging 'sponson' structures that extend out to port and starboard. Assembly of the bow is beginning. The flag (admiral's staff) and air wing spaces are fitted out, as well the offices for the various ship's departments. By fourteen months to launch, the hangar deck, sponson, and bow structures are in place, and the first parts of the flight deck are filling in amidships. After four more months, the hangar and flight decks are almost finished. Meanwhile, the lower bow has been completed, as well as the entire fantail structure. At two months before launch, the entire island structure-an eight-story building-is lifted onto the deck of the ship. This final Superlift represents the completion of major construction.
While the NNS yard workers seal up the hull and make it watertight, the managers and planners get ready for the actual launching of the ship. The launching ceremony is similar in many ways to the keel-laying just over two-and-a-half years earlier. Again, the Secretary of the Navy and the Chief of Naval Operations are present, as is the carrier's sponsor. She gets to break the traditional bottle of champagne over the new carrier's bow. A hint, though: Scratch the bottle first with a diamond-tipped scribe to ensure a clean break. Long-winded speeches, prayers, and benedictions complete the launching ritual. Then things get deadly serious and precise.
Since Dry Dock 12 is not deep enough to float off a finished
Before this can begin, any other ships in Dry Dock 12 are floated out and the movable cofferdam is removed. Then the dock is carefully flooded, with hundreds of NNS and Navy personnel monitoring tidal conditions and the watertight integrity of the carrier. When the dock is fully flooded and the ship has lifted off the keel blocks, the gate is opened. Now things happen fast. As a small tugboat pulls the carrier out of the dry dock, other tugboats wait just outside in the river to take control of the massive hulk. When the carrier is finally clear of the gate and safely into the deep channel of the river, it is turned and towed downstream to the fitting-out wharf on the southern end of the NNS property. Here it will be moored until it is turned over to the Navy, approximately two years later.
While it is an impressive sight sitting at the fitting-out dock, the mass of metal floating there is hardly a ship of war. It is still, in naval terminology, just a 'hulk.' Making it into a habitable vessel is the job of almost 2,600 NNS yard workers-everything from nuclear-reactor engineers to diesel-engine mechanics, computer specialists to roughneck welders. Building a modern warship takes almost every technology and tradecraft known. Imagine a skyscraper with offices, restaurants, workshops, stores, and apartments that can steam at more than thirty knots, with a four-and-a-half-acre airfield on the roof. That is a fair description of a
During a visit to NNS in the fall of 1997, I spent some time aboard the USS
