The construction of a ship is a highly technical and complicated process.
It involves the blending of many skilled trades and contract employees working under the control of a primary contractor.
Shipbuilding is performed for both military and commercial purposes.
It is an international business, with major shipyards around the globe competing for a fairly limited amount of work.
Shipbuilding has changed radically since the 1980s. Formerly, most construction took place in a building or graving dock, with the ship constructed almost piece by piece from the ground up. However, advances in technology and more detailed planning have made it possible to construct the vessel in subunits or modules that have utilities and systems integrated within.
Thus, the modules may be relatively easily connected. This process is faster, less expensive and provides better quality control. Further, this type of construction lends itself towards automation and robotics, not only saving money, but reducing exposures to chemical and physical hazards.
Overview of the Ship Construction Process
Figure 1 gives an overview of shipbuilding. The initial step is design. The design considerations for various types of ships vary widely. Ships may transport materials or people, may be surface ships or subsurface, may be military or commercial and may be nuclear or non-nuclear powered. In the design phase, not only should normal construction parameters be considered, but the safety and health hazards associated with the construction or repair process must be considered. In addition, environmental issues must be addressed.
Figure 1. Shipbuilding flow chart.
Newport News Shipbuilding
The basic component of ship building is steel plate. The plates are cut, shaped, bent or otherwise manufactured to the desired configuration specified by the design (see figure 2 and figure 3). Typically the plates are cut by an automatic flame cutting process to various shapes. These shapes may be then welded together to form I and T beams and other structural members (see figure 4).
Figure 2. Automatic flame cutting of steel plate in fabrication shop.
Eileen Mirsch
Figure 3. Bending of steel sheet.
Newport News Shipbuilding
Figure 4. Welded steel plate forming part of a ship's hull.
Newport News Shipbuilding
The plates are then sent to fabrication shops, where they are joined into various units and subassemblies (see figure 5). At this juncture, piping, electrical and other utility systems are assembled and integrated into the units. The units are assembled using automatic or manual welding or a combination of the two. Several types of welding processes are employed. The most common is stick welding, in which a consumable electrode is used to join the steel. Other welding processes use inert gas shielded arcs and even non-consumable electrodes.
Figure 5. Working on a ship subassembly
Newport News Shipbuilding
The units or subassemblies are usually then transferred to an open-air platen or lay down area where erection, or joining of assemblies, occurs to form even larger units or blocks (see figure 6) Here, additional welding and fitting occurs. Further, the units and welds must undergo quality-control inspections and testing such as radiography, ultrasonic and other destructive or non-destructive tests. Those welds found defective must be removed by grinding, arc-air grouping or chiseling and then replaced. At this stage the units are abrasive blasted to ensure proper profiling, and painted (see figure 7. Paint may be applied by brush, roller or spray gun. Spraying is most commonly utilized. The paints may be flammable or toxic or pose an environmental threat. Control of abrasive blasting and painting operations must be performed at this time.
Figure 6. Combining of ship subassemblies into larger blocks
Newport News Shipbuilding
Figure 7. Abrasive blasting of ship units prior to painting.
Judi Baldwin
The completed larger units are then moved to the graving dock, shipway or final assembly area. Here, the larger units are joined together to form the vessel (see figure 8) Again, much welding and fitting occur. Once the hull is structurally complete and watertight, the vessel is launched. This may involve sliding it into the water from the shipway on which it was constructed, flooding of the dock in which it was constructed or lowering the vessel into the water. Launchings are almost always accompanied by great celebration and fanfare.
Figure 8. Adding ship's bow to the rest of the vessel.
Newport News Shipbuilding
After the ship is launched, it enters the outfitting phase. A large amount of time and equipment are required. The work includes the fitting of cabling and piping, the furnishing of galleys and accommodations, insulation work, installation of electronic equipment and navigation aids and installation of propulsion and ancillary machinery. This work is performed by a wide variety of skilled trades.
After completion of the outfitting phase, the ship undergoes both dock and sea trials, during which all the ship’s systems are proved to be fully functional and operational. Finally, after all testing and associated repair work is performed, the ship is delivered to the customer.
