Ships are the core element of the Navy. There are other important components—aircraft, construction battalions (known as Seabees), commando teams (known as SEALs), and shore installations, to name just a few—but ships have been the centerpiece of navies since ancient times. Because ships have been around in one form or another for thousands of years, they are steeped in tradition, yet modern ships are also prime examples of modern technology. The result is that Sailors must be able to use a very specialized vocabulary that ranges from ancient terms like “forecastle” and “bulkhead” to modern acronyms like “AMRAAM” and “LCAC.”
Navy ships are highly complicated machines with their own propulsion plants, weapons, repair shops, supply spaces, and facilities for living, sleeping, and eating. Although there are great differences in the types and missions of ships, all ships have certain essential characteristics.
TERMINOLOGY
Armament is the combat “punch” of a ship. In some ships, that punch is primarily offensive, such as heavy-caliber guns or long-range missiles. Other ships, whose mission may be supportive, such as oilers or ammunition replenishment ships, carry armament that is primarily defensive in nature. A ship’s armament may consist of guns, missiles, torpedoes, depth charges, rockets, mines, or aircraft. Most ships are armed with more than one type of weapon. An aircraft carrier, for example, uses her airplanes as the primary means of attack and defense, but she also may carry a close-in missile defense system to handle any attackers that may have penetrated her outer defenses.
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[10.1] An Arleigh Burke–class destroyer under way on a distant sea
Survivability refers to those features that help a ship survive the effects of combat. Aside from weapons, a ship’s sturdy construction is her best protection. Compartmentation, double bottoms, and other structural components all make a ship less vulnerable to attack or damage by other means. A ship’s firefighting and flooding-control systems are also important components of her survivability.
Seaworthiness relates to hull design and other features that enable a ship to operate in high winds and heavy seas. A ship’s stability, or the way she recovers from a roll, is an essential part of her seaworthiness. You will sometimes hear a ship referred to by her “sea-keeping abilities,” which refers to how well she is able to perform her mission when the sea and weather conditions are bad.
Maneuverability is the way a ship handles in turning, backing down (going in reverse), moving alongside another ship, or evading enemy attacks. Many factors contribute to a ship’s maneuverability, such as hull design, the size of her rudder, the power of her engines and how quickly they respond to changes, her draft (how much of the ship is under the water), or her sail area (how much of the ship is above the water where the wind can affect her).
Speed determines how quickly a ship can get to a scene of action, overtake an enemy, or avoid being overtaken, and plays a role in a ship’s maneuverability and vulnerability. Key factors are the power of her engines in relation to her size and the shape of her underwater hull.
Endurance is the maximum time a ship can steam at a given speed. Most oil-powered ships can steam for days or even weeks without refueling. The Navy’s nuclear-powered ships can cruise for years, limited only by their need to replenish food and other consumables.
No matter how specialized your professional training, you must still be thoroughly familiar with basic nautical terminology referring to ship construction. You will find that this terminology is used throughout the Navy whether you are on a naval air station, in a Navy school, or aboard ship. So you will need to learn this new vocabulary in order to communicate in your new profession. After a time, such language will become second nature to you, and you will find yourself using these terms naturally.
In some respects a ship is like a building. She has outer walls (forming the hull and superstructure), floors (decks), inner walls (partitions and bulkheads), corridors (passageways), ceilings (overheads), and stairs (ladders). But unlike a building, a ship moves, so you will also have to learn new terms for directions and getting around. For example, when you cross from a pier to a ship you are using the brow to go aboard, and what might be an entrance hall or foyer in a building is the quarterdeck on a ship. The front (forward) part of a ship is the bow; to go toward the bow is to go forward. The back (after) part of the ship is the stern; to go toward the stern is to go aft. Something located farther aft than another object is said to be abaft the other. The uppermost deck that runs the entire length of the ship from bow to stern is the main deck. (An exception to this rule is the aircraft carrier, whose main deck is the hangar deck, not the flight deck, which would seem to fit the normal definition of main deck. This came about because early aircraft carriers were created by starting with an existing ship and adding a flight deck above the main deck.) Above the main deck is the superstructure. “Floors” below the main deck are called lower decks. Those above the main deck are called levels. In a building you would go upstairs or downstairs, in a ship you go topside or below. The forward part of the main deck is the forecastle (pronounced “fohk-sul”) and the after part is the fantail. As you face forward on a ship, the right side is starboard, and the left side is port. An imaginary line running full-length down the middle of the ship is the centerline. The direction from the centerline toward either side is outboard, and from either side toward the centerline is inboard. A line from one side of the ship to the other runs athwartship.
Although an explanation of the term displacement is technically more complicated, for most practical purposes this term refers to the weight of a vessel.
BASIC SHIP STRUCTURE
While you are not expected to be a naval architect, you will need to know some of the basics of ship construction in order to understand how ships work and where things are in relation to each other. This knowledge will not only keep you from getting lost on a ship, it may help you some day to save your ship or yourself should a disaster strike.
Submarines
Submarines are technically ships, but because they are designed to operate under water, they have very few topside features and practically no superstructure. About all that projects above the hull is the “sail,” a streamlined tower that houses the periscopes and certain control stations, and where a few watchstanders can stand when the submarine operates on the surface.
Submarines have long, tub-like hulls with nearly circular cross sections and are built to withstand tremendous pressure. The hull consists of the bow compartment, containing living accommodations; the operations compartment, containing the control room, sonar, and radar rooms, the torpedo room, and some state rooms; the reactor compartment; the missile rooms (on fleet ballistic-missile submarines); and the engineroom. Submarines have special ballast tanks that can be quickly flooded when it is time to submerge, or pumped out when the sub is to surface.
The controls by which a submarine is maneuvered are more like those of an aircraft than those of a surface ship (which merely steers left or right), because a sub also moves up and down. In fact, when operating submerged, she banks in her turns and climbs and dives somewhat like an aircraft. Aside from these basic differences, a submarine is still a ship (although submariners traditionally refer to it as a “boat”) and therefore contains many of the same systems and features found in a surface vessel.
![[10.2] Some...](../images/f0221-01.jpg)
[10.2] Some of the principal parts of a ship
The Hull
The hull is the main body of the ship. Metal shell plating forms the sides and bottom, and the weather deck or main deck forms the top. Where the sides join the main deck is called the gunwale (rhymes with “funnel”). The outermost layer of plating and decking is called the skin of the ship.
The shape and construction of the hull depend on the type of ship. Ships designed for high-speed operations—destroyers and cruisers, for example—have long, narrow hulls with fine lines. Aircraft carriers and auxiliary ships have hulls with square center sections, vertical sides, and flat bottoms for greater carrying capacity. Submarines, designed to operate under water, have hulls that are rounded, like an egg, because that shape withstands great pressure.
The keel is the backbone of the ship. The keel usually looks like an I-beam running the full length of the ship along the bottom at dead center. The forward end of the keel, extended upward, is the stem; the after end, extended upward, is the sternpost. Frames are beamlike structures fastened at right angles to the keel, like ribs, and support the watertight skin or shell plating. Most ships built for the Navy also have longitudinal frames running fore and aft. The longitudinal and athwartships frames form an egg-crate structure in the bottom of the ship, which, when inner-bottom plating is welded to it, creates what is called a double bottom.
What would be interior walls in a building are called bulkheads if they are weight-supporting and watertight, and partitions if they are not. Solid (except for openings such as doors and ventilation ducts) “walls” inside the hull, extending from one side of the ship to the other, are called transverse bulkheads. Deck beams, transverse bulkheads, and stanchions (posts) support the decks and help strengthen the sides against water pressure.
When weight is added to a ship’s inner bottom to balance her topside weight, making her more stable, it is called ballast. Some ships carry permanent concrete ballast; others pump saltwater into tanks to serve as temporary ballast, pumping it out when it is no longer needed.
Where the hull meets the surface of the water on a ship is called the waterline. Any part of the ship that is under water is below the waterline; any part of the ship that is in air is above the waterline.
Vertical extensions of the shell plating above the deck edge, which serve as a kind of solid fence, are called bulwarks. They shield deck areas from the direct effect of waves and keep personnel and equipment from going overboard. Lifelines, which are wire ropes mounted on short stanchions and stretched tight by turnbuckles, also form a kind of safety fence around the edges of the ship’s weather decks (where there are no bulwarks).
The vertical distance from the waterline to the keel determines a ship’s draft. Measured in feet and inches, draft markings are six-inch-high numbers marked on the hull near the stem and stern post. Because these numbers are six inches high and are six inches apart, the bottom of each number indicates foot marks and the top indicates half-foot marks.
That part of the ship’s hull that extends from the waterline to the first weather deck is called freeboard.
To protect the ship’s propellers (also called screws) from damage when coming alongside a pier or mooring next to another ship, steel braces are mounted at the stern directly above the propellers. These are appropriately called propeller guards (sometimes also called screw guards).
When a ship is properly balanced fore and aft (that is, the bow and stern are at the levels they were designed to be), the ship is said to be in trim or trimmed. If the bow is lower than the stern, the ship is said to be down by the head or down by the bow. When her stern is lower, she is said to be down by the stern.
A ship with one side higher out of the water than the other has a starboard or port list. This term is used as both a noun (“the ship has a two-degree list”) and a verb (“she is listing two degrees”). List is a temporary condition caused by uneven loading of the ship. If, for example, fuel is added to the port-side tanks more rapidly than to the starboard-side tanks, the ship will list to port until the weight is balanced. List is measured in degrees by a device called an inclinometer, which is either a liquid-level or pendulum-like device mounted exactly at the ship’s centerline. When the ship is perfectly level, the inclinometer reads “zero”; when she has a list, the inclinometer will tell you by how much.
Superstructure
All structures above the main deck are collectively referred to as the superstructure. Different kinds of ships have different types of superstructure. Often, the superstructure is topped off by one or more masts. At its simplest, a mast is a single pole fitted with a crossbar, called a yardarm, which extends above the ship and carries flag halyards (lines used to hoist the flags), navigational and signal lights, and various electronic devices. If the ship has two masts, the forward one is called the foremast, the after one the mainmast. Modern ships do not normally have three masts, but in the days of sail, when masts also played a role in the propulsion of the ship by supporting her sails, some ships had a third mast, called the mizzen, which was mounted after the mainmast. On single-masted ships, the mast, whether forward or amidships, is usually part of the superstructure and is simply called the mast.
The top of a mast is called the truck. The top of the foremast is the foretruck, while the top of the mainmast is the main truck. The pigstick is a slender vertical extension above the mast from which the ship’s commission pennant or an admiral’s personal flag flies. A pole called a gaff usually extends abaft the mainmast and is used to fly the national ensign when the ship is under way. The vertical spar (short pole) at the bow and the slightly raked (leaning backward) one at the stern are called the jackstaff and flagstaff, respectively. As discussed in Chapter 3: Courtesies, Customs, and Ceremonies, when a Navy ship is at anchor or moored to a pier it flies the “Dont Tread on Me” flag from the jackstaff and the national ensign on the flagstaff from 0800 to sunset. [Note: The jackstaff is so called because for much of the Navy’s history, the union jack (star field portion of the national ensign) was flown at the forward end of the ship while in port; the Secretary of the Navy replaced the jack with the “Dont Tread on Me” flag after the war on terrorism was declared.]
The stack of a ship serves the same purpose as the smokestack on a power plant or the chimney on a house ashore: It carries off gases from the ship’s engines and generators. (Nuclear-powered ships do not need stacks since their reactors produce no smoke or gas.) Some diesel-powered ships release their exhaust from the sides of the ship’s hull rather than through a stack. On some ships, the masts and stacks have been combined to form large towers called macks.
Decks and Levels
Decks divide a ship into tiers or layers of compartments the way floors of a building divide it into stories. The deck normally consists of metal plates strengthened by transverse (athwartships) deck beams and longitudinal (fore and aft) girders. Decks above the waterline are usually cambered (arched) to provide greater strength and drain off water.
Decks are named according to their position and function in the ship. For purposes of compartment identification, decks are also numbered. The main deck is usually the uppermost of the decks that run continuously from bow to stern. The second, third, and fourth decks, continuous decks below the main deck, are numbered in sequence from topside down. A partial deck (that does not run continuously from bow to stern) is called a platform.
A partial deck above the main deck is numbered with a zero in front and called a level to distinguish it from the full decks. So the first partial deck above the main deck would be the 01 level, the next one up would be the 02 level, and so on. The term weather deck means just what it sounds like—a deck that is exposed to weather. Flats are removable plates or gratings installed as working or walking surfaces.
The quarterdeck is not a true deck or a structural part of the ship, but rather a location designated by the commanding officer as a place for ceremonies. Likewise, the word mess deck refers to a specific place where the crew eats and is not actually a deck in the strict sense of the word. A flight deck is the area used by airplanes and helicopters to land and take off.
Compartmentation and Watertight Integrity
Compartments are the rooms of a ship. Some compartments are actually called rooms, such as wardroom, stateroom, and engineroom, but generally speaking “room” is not used. Don’t refer to the area where you sleep as the “bedroom” or the place where you eat as the “dining room.” They are called berthing compartment and mess deck, respectively.
You will also hear the term space used often to describe a compartment or any enclosed area of a ship; for example, “supplies are kept in stowage spaces.”
Each compartment on a ship has a unique identifier as explained in TAB 11-A: Shipboard Compartment Identification.
If a ship were built like a rowboat, one hole below the waterline could sink her. To prevent this from happening, naval ships are built with bulkheads that divide the hull into a series of watertight compartments. The term watertight means that when these compartments are sealed up, water cannot enter or escape. Watertight integrity is the overall quality of being watertight. A ship with good watertight integrity is far more survivable than one with poor watertight integrity. If a ship experiences flooding, the affected spaces can be sealed off and the other watertight spaces will keep the ship afloat. There are limits to this concept, of course. If enough compartments on a ship become flooded, the remaining watertight compartments may not have enough buoyancy (floatability) to keep the ship afloat. The more compartmentation a ship has, the more chance her crew has of confining the flooding to permit the ship to stay afloat (remain buoyant). The tradeoff is, of course, that too much compartmentation would interfere with the arrangement of mechanical equipment and with her operation.
An important bonus is that just as flooding can be isolated through this compartmentation system, so can fire.
Watertight doors allow access through bulkheads when opened but can prevent flooding and the spread of fire when closed. Watertight hatches serve the same purpose by providing sealable access through decks. Be sure to note the difference here. People—even some Sailors—often confuse doors and hatches on a ship. Ships have doors just as buildings ashore do. The difference between shipboard doors and those ashore is that those found on ships can be watertight or nonwatertight. Watertight doors contribute to the compartmentation and overall watertight integrity of the vessel, while nonwatertight doors serve the same kinds of purposes as those ashore—privacy and noise suppression. Watertight doors—set in framework above the deck with latches that can be locked closed—pass through bulkheads and nonwatertight doors pass through partitions. Hatches, on the other hand, are always horizontal—never vertical like a door—and allow passage through decks, not bulkheads or partitions. Technically the “door” used to close the hole in the deck made by a hatch should be called a “hatch cover,” but in actual practice you will hear people referring to the hatch cover as just a hatch. This is acceptable, but you will also hear people refer to doors as hatches, and that is not acceptable.
All watertight fittings (both doors and hatches) are specially marked to tell you when it is all right to open them and when it is not. These markings will be explained in Chapter 15: Damage Control.
Obviously, holes must also be placed in watertight bulkheads and decks to allow ventilation ducts, fluid piping, and electrical and electronic cabling to pass through. These holes are specially constructed to prevent leaking and thereby preserve the watertight integrity of the ship.
Large ships have outer and inner double bottoms. These are divided athwartships and longitudinally into tanks, which are used to stow fuel oil or freshwater. (Note: The nautical term for “store,” when it is used as a verb, is stow. When used as a noun, the correct term remains store. For example: “A load of stores was delivered to the ship and stowed below.” The nautical term for “storage” is stowage.) These tanks can also be used to bring in seawater for ballast (to help keep the ship level).
Tanks at the extreme bow and stern, called the forward peak (or forepeak) tank and the after peak (or aftpeak) tank, are used for trimming (leveling) the ship. Sometimes these tanks are used to carry potable (drinking) water. A strong watertight bulkhead on the after side of the forepeak tank is called the collision bulkhead. If one ship rams another head-on, the bow structure of the latter collapses at a point somewhere forward of the collision bulkhead, thus absorbing some of the shock of the collision and, it is hoped, preventing the flooding of compartments aft of it.
All tanks are connected to a pumping and drainage system so that fuel, water, and ballast can be transferred from one part of the ship to another or pumped overboard.
Ladders, Booms, and Brows
When a ship is not alongside a pier, her freeboard (distance from the water up to her main deck) causes a problem for boarding or leaving the ship. Boats coming alongside a ship will be too low for personnel to get out of the boat and up to the main deck. A special stairway leading from the deck down close to the water is suspended over the side to take care of this problem and is called an accommodation ladder. It has a platform at the bottom that serves as a landing for boats, and a suspended line, called a sea painter (often called merely the painter), to which boats secure themselves when coming alongside.
Some ships have boat booms, which are special spars swung out from the ship’s side when the ship is moored or anchored. These special booms have lines suspended to the water for boats to tie up to, and they also have a Jacob’s ladder (basically a rope ladder, although it can be made of metal or have wood components) that allows boat crews to climb into their boats or to leave their boats and come aboard the mother ship.
Boat booms require some athletic ability and are provided primarily for boat-crew use. Accommodation ladders are used by other ship’s personnel and visitors.
When a ship is alongside a pier (or alongside another ship), boarding and departing are less difficult and can be accomplished by placing a simple crossway, called a brow (not a “gangplank”), to bridge the gap between the ship and pier (or between the two ships).
SHIPS’ VITAL SYSTEMS
A number of systems are essential to every Navy ship. Without these important systems, ships could not carry out their missions. Because they carry out vital functions for the ship similar to functions for the human body, these systems are analogous to our nervous, circulatory, respiratory, and excretion systems.
Propulsion System
A ship is of little use unless it has mobility, and the source of that mobility is the ship’s propulsion plant. In previous centuries, the source of propulsion was oars or sails, but in modern times more sophisticated forms are used.
OIL-FIRED STEAM PLANTS
For the better part of a century, steam has been the primary method of marine propulsion for sizable ships and is still used in many U.S. Navy vessels. Steam plants consist of boilers that transform freshwater into steam and turbines that convert that pressurized steam into usable power that turns the ship’s propellers. Condensers convert the spent steam back into freshwater, which returns to the boilers to be reheated into energy-filled steam again. This “steam cycle,” as it is called, is repeated over and over to provide the energy to propel a ship through the water. Even though this is a closed cycle—meaning that the water and steam are theoretically contained in the system and not allowed to escape—a certain amount of the freshwater is used up, so that a continuous supply of feed water is required for sustained operations. This is generated by distilling plants, which convert sea (salt) water into fresh water. A steam plant also needs a supply of fuel to provide the heat in the boilers, and this must be carried in fuel tanks on board—much as an automobile has a gas tank—and periodically replenished (either in port or from oilers at sea).
NUCLEAR POWER
Nuclear power is a very specialized form of steam propulsion. Instead of using oil-fired boilers, nuclear-powered ships have a reactor that produces the heat to convert freshwater to steam. Nuclear power plants give a ship the advantage of great endurance at high speed. Instead of refueling every few thousand miles like an oil-burning ship, a nuclear-powered ship can operate for years on one reactor core. Because there is no need to replenish oil, nuclear-powered ships can steam almost indefinitely, limited only by their need to replenish food and spare parts, and ammunition in wartime.
Another favorable feature of nuclear power is that, unlike conventional oil-fired systems, the generation of nuclear power does not require oxygen. This makes it particularly useful as a means of submarine propulsion, allowing the vessel to operate completely submerged for extended periods of time.
GAS TURBINES
Gas turbines are very similar to aircraft jet engines, but have been adapted for use on ships. The burning fuel spins turbines in the engines that convert the energy created by the burning fuel into usable power that turns the ship’s propellers.
Although some of the principles are the same, some of the primary differences between these propulsion plants and those that use steam are that the gas turbines combine the functions of the boiler and the turbines into one element and gas turbines have no need of feedwater. This means that they are smaller, more efficient, and easier to maintain. They are also much more quickly “brought on the line” (turned on). A steam-powered vessel requires hours to prepare to get under way, while gas-turbine-powered ships can be ready in minutes.
The obvious advantages of gas-turbine technology have caused the U.S. Navy to build more and more of these ships. Whereas steam was once the main means of naval propulsion, today there are more gas-turbine ships in the Navy than ships with any other kind of propulsion.
DIESEL ENGINES
For relatively small ships that need no more than 5,000 to 6,000 horsepower, diesel engines are frequently used. Diesels take up less space and are more efficient than steam turbines. The diesel can be coupled directly to the shaft through reduction gears and perhaps a clutch, or it can drive a generator that produces current for the main drive.
Diesel engines are preferred over gasoline engines because highly volatile gasoline fumes are heavier than air and tend to collect in low places in a ship, making them very dangerous. Diesel fuel, which does not vaporize as readily, is much safer.
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[10.3] A gas turbine systems technician working on one of the ship’s gas turbines
PROPELLERS
A vital component of a ship’s propulsion system is the propeller(s). Some ships have only one, others have two or more (an aircraft carrier has four giant propellers). Another term you will hear when referring to ships’ propellers is “screw.”
Propeller shafts carry the power generated by the propulsion plant to the propellers. In many ships, shafts run from a set of reduction gears (which change the high-speed spin of the turbines into a more suitable speed for the propellers) through long watertight spaces, called shaft alleys, in the bottom of the ship. These shafts go out through the hull using special watertight sleeves and are often supported outside the hull by struts. More recent technology eliminates the use of reduction gears by using the energy generated by gas turbines to drive electric motors that turn the propellers.
Propellers on some ships are fixed while others are of the controllable-pitch type. Fixed propellers are solid in their construction and change speed by speeding up or slowing down the spin of the whole propeller. Controllable-pitch propellers, on the other hand, pivot their individual blades in such a way as to change the amount of thrust they create and thereby control the speed. For a fixed-type propeller to back down (go in reverse), it must be slowed down, stopped, and then spun in the opposite direction. A controllable-pitch propeller need only change the pitch sufficiently to reverse the thrust. For this reason, the latter type of propeller is much more common in modern naval ships.
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[10.4] A rare look at a destroyer’s propellers
BOW AND STERN THRUSTERS
Although technically not a part of the ship’s propulsion system, some modern vessels have small thrusters mounted at appropriate points on the hull to assist in docking the ship. Usually mounted at or near the bow, these small propulsion units can be turned on to exert an additional force, usually sideways, on the ship’s hull to move the bow in a desired direction. This can be very useful when trying to move a ship alongside a pier when coming into port or to move away from a pier when getting under way. These thrusters can be used for very slow propulsion in an emergency situation. Some vessels also have stern thrusters that essentially do the same for the after part of the ship.
The Steering System
The basic component of nearly every ship’s or boat’s steering system is the rudder. The simplest rudder design is a flat board or blade that extends into the water beneath the vessel’s stern. When it is turned one way or the other while the vessel is moving, flowing water builds up on the front side and pushes the stern of the vessel in the opposite direction. Because the rudder acts by the force of water pushing against one side of it, there is no rudder action when the ship is motionless. And the greater the speed of the vessel through the water, the greater the effect the rudders have. For this reason, the rudder is usually mounted just astern of the screws, where the wash created by the moving propeller pushes directly against it and increases the turning effect.
The rudder is controlled by a tiller in an open boat (such as a motor whaleboat or motor launch) or by a wheel in the cockpit of a larger boat or on the bridge of a ship. This wheel is often called a helm on a ship. In a boat, the motion of the wheel is transmitted to the rudder by a cable or shaft. In a ship, the rudder is turned by an electric or steam engine in the steering-engine room. This electrical or hydraulic engine is controlled by the helm on the bridge. When the helm is turned on the bridge, it transmits a signal to the steering engine, which then moves the rudder.
Ships can have more than one rudder, but in the case of multiple rudders they do not act independently but are controlled together.
To prevent loss of control in case of damage to the bridge, there is usually a second steering wheel mounted elsewhere in the ship. This backup control station is called secondary conn. If that wheel is also disabled, the ship can be hand-steered by several Sailors using special gear in the steering-engine room. There is also a duplicate set of steering engines and connecting cables on naval vessels to serve as backup in the event of damage.
Ships or boats with two screws can be steered fairly well without a rudder by using the engines. If one screw turns faster than the other, the bow will swing toward the slower screw. If one screw goes ahead while the other goes astern, the bow of the ship will swing toward the backing screw. Boats, and even very large ships, can turn within the diameter of their own lengths using this method, which is appropriately called “twisting.”
Mooring Systems
When ships are not under way, they must be secured in some way to keep them in place. A ship is moored when she is held in position by an anchor on the ocean bottom or is made fast either to a mooring buoy or a pier. To moor to a pier, a ship uses her mooring lines. To anchor or to moor to a special mooring buoy, the ship uses her ground tackle (such as anchors, anchor chains, or windlasses). Ground tackle is normally located on the forecastle, but some ships, particularly amphibious craft that run up onto beaches, may also carry a stern anchor, used to help pull them back off the beach when it is time to return to sea.
Electrical System
For ages, ships functioned without electricity, and for many years electrical power provided only a few important services, such as lights and a few motor-driven appliances. But today’s modern ship uses an incredible amount of electrical power to carry out a wide array of functions. A modern ship depends upon its electrical power system to do many things, including powering complex weapon and communications systems, computing the solutions to a vast spectrum of tactical problems, powering ammunition hoists and aircraft elevators, detecting incoming enemy missiles and aircraft, providing lighting and temperature control, and running in-house television systems for entertainment. These and hundreds of other functions make electricity as vital to a modern warship as ropes were to a sailing vessel.
Ships generate their own electricity and all have backup systems to provide power when the primary system fails. Vital electrical circuits are also frequently duplicated so that power can continue to flow after battle damage occurs.
Ventilation System
This system supplies fresh air where it is needed and carries off unwanted exhaust. This system is made up of many subsystems that operate independently of each other.
Supply ventilation brings fresh, external air into the ship and, in the event of cold weather, heats the air by means of a preheater installed in the ducting. Exhaust ventilation carries away the air that has served its purpose and needs to be replaced. In those spaces containing equipment that generates heat or humidity (such as main engineering spaces, galley, or head facilities), the exhaust system is particularly vital. “Recirc” ventilation is provided to spaces containing electronic equipment (which requires a cool environment for proper operation), as well as to berthing, messing, and office spaces. As its name implies, this system recirculates internal air to prevent stagnation and, when necessary, draws the air through a cooling system to maintain the proper temperature.
In the event of fire, flooding, or some other danger requiring the isolation of a space or spaces, ventilation systems can be secured by de-energizing the fan motor and can be segregated by closing valvelike devices in the ducting (often found where the ducting penetrates decks, overheads, and bulkheads).
Potable Water System
Water for drinking, showering, and cooking is provided by the potable water system. Potable water is made in the ship’s distilling units (evaporators) from saltwater taken from the sea and stowed in tanks specifically designated for potable water only. Piping systems carry the water from the tanks to the heads, galleys, and drinking fountains (scuttlebutts) for use.
Because the evaporators can only make so much water at a time, care must be exercised not to waste freshwater while a ship is under way or at anchor. You should never take what is popularly called a “Hollywood shower” while at sea. (This is the kind of shower you probably take at home, where you let the water run for as long as you are in the shower without giving any thought to water conservation.) While at sea, it is important to get in the habit of wetting down (quickly), turning the water off and leaving it off while you soap and scrub, and then turning the water on again just long enough to rinse off.
When moored to a pier where the appropriate connections are available, the ship’s potable water system can be hooked up to receive freshwater. At these times, abundant freshwater is available so that the strict water conservation practices you use at sea are not necessary. The ship’s potable water tanks will all be topped off (filled to capacity) before the ship gets under way.
Saltwater System
Saltwater is drawn out of the sea through underwater intakes and pumped throughout the ship using a different piping system from the one used for potable water. This water is available for firefighting when needed and is used on a routine basis as flushing water for the heads. It also is used as cooling water for certain items of machinery and electronic equipment and can be piped into tanks for ballast to stabilize the ship. Special sprinkler heads mounted all over the outside of the ship can be opened to allow a washdown of the ship to rid her of contaminants in the event of a chemical, biological, or radiological (CBR) attack.
Drainage System
The drainage system includes the piping, valves, and pumps that discharge water from the ship. Its functions include the removal of seawater that has entered the hull because of damage, collision, or heavy weather.
The main drainage system is composed of large piping located in the main engineering spaces and used for pumping their bilges (the lowest parts of the ship’s hull where water collects). The secondary drainage system is composed of smaller piping located in other spaces, such as pump rooms and shaft alleys.
The main and secondary drainage systems are often coupled with the saltwater system to maintain the proper trim of the ship.
Since weather-deck drains collect natural rain and seawater, the drains connected to these areas are piped directly overboard. But internal drains (from sinks, showers, galleys, toilets, and urinals) are carefully controlled for environmental reasons. Drainage from these sources is collected in specially designed tanks for appropriate disposal.
Fuel System
This system includes fuel-stowage tanks, pumps, filling lines, transfer lines, and feed lines to the ship’s boilers or engines. Like the other liquid systems aboard ship (potable water, saltwater, and drainage), the fuel system is also constantly monitored and fuel is moved about to help maintain proper trim.
Compressed Air System
Ships use compressed air for a number of purposes. Ejecting gases from guns after they have fired is one important use of this system. Compressed air is also used for charging torpedoes, operating pneumatic tools, running messages through dispatch tubes, powering automatic boiler controls, and various other uses. Compressors create the compressed air and special piping carries it where it is needed in the ship.
SPECIALIZED SPACES
Just as a building has specialized rooms or areas, such as the lobby, parking garage, heating plant, or boardroom, ships have special spaces with distinct purposes necessary to the operation or utility of the ship. Some ships have very special areas—such as Primary Air Control on an aircraft carrier—not found on all ships, but other special areas are found on most naval ships.
The Bridge
This is the primary control position for the ship when she is under way and the place where all orders and commands affecting the ship’s movements and her routine originate. The captain will be on the bridge a lot of the time under way—especially during most special sea evolutions (such as refueling and rearming) and when the ship is entering and leaving port—but obviously cannot be there twenty-four hours a day. The officer of the deck (OOD)—a rotating watch position manned only by highly qualified personnel—is the captain’s primary assistant in charge of safely running the ship, and is always on the bridge when the ship is under way.
There are various instruments and equipment on the bridge used to control the movements of the ship. The ship’s helm and engine controls are located here, as well as radar repeaters, navigation light switches, wind indicators, radios, speed indicators, and compasses.
The bridge is sometimes referred to as the pilot house.
The Chart House
The chart house is normally just aft of the pilot house and on the same deck, but it can also be on another deck and some distance away. This is where the navigator and his or her team of quartermasters do much of their work. Using navigational equipment and instruments such as sextants, stadimeters, bearing circles, stopwatches, parallel rulers, dividers, protractors, position plotters, electronic devices, and navigational books and tables, the navigational team keeps a constant plot of the ship’s position (location) at any given moment and a plan of where the ship is going.
Signal Bridge
This is an open platform located near (often just above) the navigational bridge and equipped with devices used to communicate visually, such as signal searchlights and signal flags. The signal lights allow ships to communicate with one another by flashing the lights on and off in Morse code. The signal flags are kept in a specially designed stowage locker, known as a flag bag, which allows quick access to the flags. The lower ends of the halyards, on which signal flags are hoisted, are secured here so that the signalmen can quickly attach flags from the flag bag and hoist them into the air where other ships can see them.
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[10.5] The bridge is the primary control position for a ship when she is under way.
Combat Information Center (CIC)
The combat information center is the nerve center of the ship. A lot of electronic equipment is installed in the CIC to process information received from a wide variety of sources, including radio, radar, sonar, electronic-warfare intercept receivers, IFF (identification friend or foe) transponders, visual communications, satellites, fathometers (depth gauges), and computers. All of this information is collected, processed, displayed, evaluated, and sent to other parts of the ship (or to other ships) for use in decision making and in properly employing the ship. CIC is the place where the ship’s tactical operations are controlled. Such operations include the evaluation of targets, weapons firing, the control of friendly aircraft, surveillance operations, navigational assistance, submarine tracking, and many others.
Damage Control Central (DCC)
Damage Control Central serves as the central information site for matters affecting the safety of the ship. By monitoring conditions aboard ship and maintaining control of vital systems such as those used in firefighting and flooding control, and by maintaining careful records, damage-control charts, and liquid-loading diagrams, DCC sees that the ship is functioning efficiently and is prepared for any emergency conditions that may arise.
Storerooms
A ship cannot operate at sea for extended periods of time unless it has adequate stowage for consumable supplies and spare parts. These areas are known as storerooms. Some of these stowage areas are specially configured for a specific type of material.
Magazines
Magazines are used for the stowage of missiles, rockets, bombs, torpedoes, and gun ammunition. For obvious reasons, these important but potentially dangerous areas aboard ship are kept locked and under close control. They also are protected by various alarm and firefighting systems and are usually located in spaces well below the waterline so that, in case of fire, they can be quickly flooded.
Crew Accommodations
The living spaces aboard ship are essential to accommodate the needs of the crew. Berthing (sleeping) compartments, heads (bathrooms), wardrooms (living and dining areas for officers), officers’ cabins (or staterooms), galleys (kitchens), messes (where enlisted personnel eat), laundries, barbershops, and sick bay (medical clinic) are all living areas necessary for the daily routine of the men and women who live aboard ship. Larger ships may have other spaces for the health and comfort of the crew, such as tailor shops, libraries, chapels, weight/aerobic rooms, and crew lounges. Virtually all ships have a ship’s store where you can purchase toiletries, uniform items, gedunk (snacks), and—depending upon the size of the ship and its store—a variety of other items. An added benefit of using your ship’s store is that the profits go to the ship’s Morale, Welfare, and Recreation (MWR) fund.
Shops and Offices
Shops and offices can be found on virtually every Navy ship. The number of each depends upon the size and the purpose of the ship. An aircraft carrier will have hundreds. A patrol craft may have only one or two.
Most Navy ships will have at least an electrical shop and perhaps a machine shop as well. A tender, whose mission is maintenance and repair, will have many shops, including ones that do repairs and specialty work, such as instrument calibration, printing, photography, torpedo overhauls, and pump refurbishment. An aircraft carrier will have a large specialized repair facility called the aircraft intermediate maintenance department (AIMD), which performs a wide variety of maintenance functions to keep aircraft flying while the ship is at sea.
The captain and executive officer will probably have their own offices (or, on smaller ships, they will be combined into one, called the ship’s office). On ships with adequate room, individual departments and divisions will have their own offices.
NAVAL SHIP AND SUBMARINE TYPES
The U.S. Navy operates hundreds of ships. Some of these are active ships, which means they are operational, ready to carry out missions, have a full complement of personnel and, unless they are temporarily undergoing heavy maintenance or repair, are fully capable of carrying out an assigned mission on short notice. The Navy also keeps a number of vessels in reserve status, which means that they are partially manned with active-duty personnel. The rest of the crew is made up of reserve personnel, who only man the ships periodically for training and when called upon in a national emergency.
The many different types of vessels in the Navy have specific functions. Some exist primarily to engage in combat with enemy forces (other vessels, aircraft, or land targets) and are generally referred to as combatants. These include aircraft carriers, cruisers, destroyers, frigates, littoral combat ships, amphibious ships, and patrol craft. Submarines are combatants but are often treated as a separate category from surface combatants because of their differences.
Considered part of the Navy’s expeditionary forces, amphibious ships are often unofficially referred to as the “amphibs” or “gators.” These ships work mainly where sea and land meet, and where assault landings are carried out by Navy–Marine Corps teams. Such operations call for a variety of types of ships. Many are transports of varied designs, used to sealift Marines and their equipment from bases to landing beaches. The differences lie in ship design and the way troops and their gear are moved from ship to shore, which can be done by means of landing craft, helicopters, tilt-wing aircraft, or tracked amphibious vehicles.
Other ships, called auxiliaries, exist to perform supporting functions, such as repairs, salvage operations, delivery of supplies (such as fuel, ammunition, food, and repair parts) needed to keep a ship operating, service as floating hospitals, and so on.
The Navy also operates a number of transport and auxiliary ships under what is called the Military Sealift Command (MSC). These ships usually have only a very small contingent of Navy personnel on board, and the majority of the crews are civilians. MSC ships have a support role and are not used as frontline combatants. They are considered to be “in service” rather than “in commission.” Some ships, such as “roll-on, roll-off” vehicle cargo ships (T-AKRs) and transport oilers (T-AOTs) serve the Army and Air Force as well as the Navy.
Other MSC ships perform special-duty projects, such as laying and repairing of ocean-bottom cables used for detecting enemy submarines. Surveying ships (T-AGSs) and oceanographic research ships (T-AGORs) explore the oceans.
Of special interest is a group of various MSC ships of the Combat Logistics Force (CLF). As with other MSC ships, they have civilian officers and crews. They operate under Navy orders and have a military department of Navy personnel aboard, performing visual and radio communications and otherwise assisting the ship’s civilian master and crew in operations with other naval units. These vessels include a variety of replenishment ships, fleet ocean tugs, and several specialized mission types that directly support the Navy by providing fuel, ammunition, stores, towing services, etc.
The various types of Navy ships currently in service are described in TAB 10-A: Ships and Craft.
Ship Identification
Most Navy ships have both a name and what we call a ship’s designation to identify them. While the name is a convenient and traditional means of identification, there have been Navy ships bearing the same name throughout history, so the ship’s designation—which is unique to that ship—is the only way to identify a specific ship. The ship’s designation tells what type the ship is (such as destroyer, submarine, or cruiser) and assigns a unique hull number to the vessel.
Ships are also grouped into classes to identify those with identical, or nearly identical, characteristics.
NAME
The name is unique to a ship in that there can only be one Navy ship in commission at a time with a given name. But, as already mentioned, there may have been other ships with the same name in the past—in fact, it is fairly common practice in the Navy for ships to carry the name of an earlier ship that served with honor. For example, there have been eight U.S. Navy ships named “Enterprise.” (Note: This count does not include the starship Enterprise of Star Trek fame, but the creator of the hit television and movie series, Gene Roddenberry, recognized the long tradition of passing on ship names and carried it on in his futuristic vision.)
The name of a Navy ship in commission (active or reserve) is preceded by the letters “USS,” which stands for “United States Ship,” for example, USS Enterprise. This practice began in 1907 when President (and former Assistant Secretary of the Navy) Theodore Roosevelt issued an executive order establishing this standard, so when you read about Navy ships before 1907 you may find them referred to differently.
MSC ships are considered to be “in service” rather than “in commission,” and for this reason their names are preceded by the letters “USNS” (for United States Naval Ship) instead of “USS.”
Sailors have traditionally (and unofficially) added nicknames to their seagoing homes. Some of these nicknames apply generally to the type, such as “flat tops” or “bird farms” for aircraft carriers and “tin cans” for destroyers. Specific ships also often have unofficial nicknames; among aircraft carriers, for instance, USS Theodore Roosevelt is known informally as the “Big Stick” (referring to the president’s famous quote “Speak softly but carry a big stick”) and USS Dwight D. Eisenhower is “Ike” because that was the former president’s nickname.
DESIGNATION
While a ship’s name gives her some identity, the ship’s designation—which consists of a combination of letters and numbers—tells you two additional things about a ship: her type and her place in the construction sequence. USS Abraham Lincoln, for instance, has the designation “CVN 72.” CVN is her type classification, CV standing for aircraft carrier and N meaning nuclear propulsion; 72 indicates that she is the 72nd aircraft carrier authorized for construction. The term “hull number” actually refers only to the number part of the ship’s designation, but you will commonly hear this term used instead of “ship’s designation,” as in “The ship’s hull number is CVN 72.” Ships’ hull numbers are frequently painted on their bows and near the stern. Aircraft carriers have their hull numbers painted on the forward part of the flight deck and on the “island” (superstructure).
Since 1920 the Navy has used letter symbols to identify the types of ships and service craft, such as “DDG” for guided-missile destroyer and “CG” for guided-missile cruiser. This is called “type classification” and is used as part of the ship’s designation. These may seem illogical at first (like “CV” for aircraft carrier) but as you become more familiar with these classifications, some patterns will emerge that will make some sense to you. See TAB 10-B: Ship Type Classifications for a list of some of the more common ones that you may encounter.
CLASS
Within a type classification of ships there are classes. Ships belonging to a particular class are built from the same plans and are very much alike; in many cases, they are identical except for the different hull number painted on their bows. The first ship built of a class determines the name of the class. For example, after World War II the United States redesigned its aircraft carriers to accommodate the newly invented jet aircraft then entering the fleet. The first of these new aircraft carriers to be built was commissioned as USS Forrestal (CV 59). She was the fifty-ninth aircraft carrier, but the first of this new class. Satisfied with these new ships, the Navy built three more—USS Saratoga (CV 60), USS Ranger (CV 61), and USS Independence (CV 62)—all of which are referred to as Forrestal-class carriers.
Later, some major improvements were deemed necessary, so the Navy redesigned its aircraft carriers significantly enough that they were considered a new class of carrier. The first of these new and different carriers was named USS Kitty Hawk (CV 63), so the next ship built after her, USS Constellation (CV 64), was considered a Kitty Hawk–class aircraft carrier. Some classes have only a few ships and others have hundreds.
As indicated in the beginning of this chapter, even though the Navy has evolved into a complex organization with various missions and many different kinds of equipment to accomplish them, ships are the core element of the Navy. Even imagined space travel and galactic conflict, such as in Star Trek and Star Wars, usually rely on spaceships as the technological centerpiece. It should come as no surprise that this basic element is so embedded into Navy culture that even at shore installations floors are often referred to as decks, ceilings as overheads, etc. This is a source of pride that Sailors, Marines, and Coast Guardsmen emulate even though it often confuses and amuses civilians and those who serve in non-sea services.