A surface ship designed primarily for use in warfare, either to operate in direct combat or to provide support to other ships engaged therein. Naval ships can therefore be categorized as either combatants or noncombatants (auxiliaries), both with unique design characteristics.
Combatant ships
This category includes battle ships, cruisers, destroyers, frigates, aircraft carriers, amphibious warfare ships, mine warfare ships, and patrol ships.
After World War II, all the surviving battleships of the U.S. Navy were disposed of except for the four most modern ships, which were retained in a decommissioned (standby or “mothball”) status. In 1995 all four battleships were stricken from the naval register, but Congress later directed that two be retained as mobilization assets.
The primary purpose of modern cruisers is to provide antiair and antisubmarine protection to aircraft carriers and other friendly forces. These highly capable multimission ships can also operate independently. Equipped with antiair, antisubmarine, antiship, and land attack missiles, they are self-contained offensive units in their own right. The dominant cruisers in the world are the U.S. CG 47 Ticonderoga class of Aegis guided-missile cruisers (Fig. 1) designed in the 1970s.
Aegis guided-missile cruiser, Ticonderoga CG 47 class. USS Cape St. George is shown. (U.S. Navy photo)
If battleships and cruisers are the heavyweights and middleweights, then destroyers are the lightweights with a “go-anywhere, do-anything” outlook. They have tremendous firepower for their size and rely on high speed, dash, and maneuverability. Current destroyers tend either to be multipurpose or to emphasize specific warfare areas. An example of a multipurpose destroyer is the U.S. DDG 51 Arleigh Burke class of Aegis guided-missile destroyers. An example of a specialized destroyer is the U.S. DD 963 Spruance class designed primarily to detect and destroy submarines.
The smallest and most numerous surface combatants in the U.S. Navy are the Oliver Hazard Perry (FFG 7) class of multipurpose frigates. Designed in the 1970s, this 50-ship class was expected to protect merchant and military convoys. The speed of FFG-7 is 27–28 knots (13–14 m/s) since carrier operations were not a primary mission. By means of sonars, an embarked ASW helicopter, and shipboard torpedo tubes, it can detect and destroy submarines.
The largest warships in the world are aircraft carriers (Fig. 2), which through the aircraft they support can project power at great distances. An aircraft carrier is a floating mobile air station. Its flight deck provides the runways, its island is the control tower, the large hangar below the flight deck is the garage that contains maintenance and repair shops, and deep in the hull are storage tanks for aviation fuel and magazines for aviation ordnance. These ships, which can operate and maintain up to 80 aircraft, require a length of almost 1100 ft (335 m), a displacement of nearly 100,000 tons (101,600 metric tons), and a crew of 6000.
CVN 68 class. USS Theodore Roosevelt (CVN 71) is shown. (U.S. Navy photo)">
Nuclear-powered aircraft carrier, Nimitz CVN 68 class. USS Theodore Roosevelt (CVN 71) is shown. (U.S. Navy photo)
The ships used to transport, land, support, and control assault troops collectively constitute the amphibious warfare force. Despite the success of Allied amphibious operations in World War II, the need for improvement was recognized. The first major breakthrough came with the advent of the helicopter and its successful adaptation for landing assault troops (called vertical assault). The second was the development of the high-speed (40 knots; 19 m/s) landing craft, air-cushioned (LCAC). The employment of these two new vehicle types permits landing ships to remain offshore, over the horizon, during amphibious assaults. All current United States amphibious warfare ships have both flight decks for operating helicopters and well-decks for operating LCACs and other craft.
Landing craft are used to ferry tanks, vehicles, equipment, ammunition, general cargo, and personnel directly onto the beach from the landing ships offshore.
Amphibious vehicles are capable of being launched directly into the ocean from landing ships, proceeding to the beach, and then moving inland.
Minelayer ships are built in varying sizes, but can be characterized by a mine stowage system, and rails for moving the mines, and dropping them off the stern or side of the ship. Minesweepers can be broadly categorized as having either a hunter role (locate and mark mines) or a hunter/killer role (locate and destroy). Mines can be located by variable-depth sonar and later destroyed by divers or by means of a mine neutralization vehicle (MNV). The MNV is a crewless minisubmarine that lays an explosive charge near the mine, backing off before detonation. Mines can also be located by the minesweeper towing a mechanical sweep that cuts the cable between the bottom anchor and the mine. After the mine surfaces, it is destroyed by divers or gunfire. Mines can also be detonated by towing magnetic and acoustic cables that trigger them. Minesweepers are often built of wood or composite materials to reduce their magnetic signature.
Patrol ships are small ships that augment conventional surface forces in coastal areas and restricted seas. Their primary mission is coastal patrol and interdiction surveillance—an important aspect of littoral operations. These ships also provide full mission support for Navy SEALs and other special operations forces.
Noncombatant ships
Naval auxiliary ships provide services and support naval operations. Floating configurations that provide services but are not ships are called service craft. Service craft include floating dry-docks, harbor tugs, berthing barges, diving support boats, and fuel barges.
Included in the auxiliary category are the tenders for submarines, and the ships that replenish the fleet with supplies of oil, stores, ammunition, and combat support items. Also included are oceangoing salvage rescue ships, acoustic research ships, oceanographic research ships, surveying ships, hospital ships, ocean surveillance ships, cable repair ships, oceangoing tugs, marine prepositioning ships, and even experimental submarines.
