Chapter 4
Warship Nomenclature

A. Introduction

4A1. Basic terms. For the young officer going to sea, it is imperative to have a working knowledge of the parts of a naval vessel, as well as the nomenclature which is applied thereto. Prior to discussing any specific part or aspect of a naval vessel, it is necessary to understand the following terms of a general descriptive or designating nature.

B. Hull

4B1. The hull defined. The hull is the framework of a vessel, together with all decks, deck houses, and the inside and outside plating or planking, but exclusive of masts, yards, rigging, all outfit or equipment, and all items generally classed as superstructure. While deck houses are considered part of the hull, they are discussed in connection with the superstructure.

4B2. Exterior. In our preliminary considerations, let us consider the hull as a simple, hollow, watertight shape covered on top with a deck. Reference to Figure 4-1 will enable you to locate readily the bow, waist and stern. It should be noted that the apex of the bow is called the stem, and that the general vicinity of the stem is known as the eyes of the ship. The bow structure above the waterline is called the prow. Slightly abaft the stem is the hawsepipe through which the anchor chain passes and in which the anchor is housed. The deck included in the bow area is generally referred to as the forecastle.

Reference to the after part of the ship in Figure 4-1 will disclose some of the more important details regarding the stern. The general area between the waist and the extreme stern is known as the quarter, either port or starboard. The main stern structure terminates in an upright member fastened to the keel called the sternpost. The rudderpost is the member to which the steering rudder is secured. In certain types of ships, the sternpost and rudderpost are the same member. On some vessels, part of the stern extends over and abaft the point where the rudder is secured; this is the overhand or fantail, although the term fantail is indiscriminately applied to the after part of destroyers and smaller ships regardless of their


Fig. 4-1. The hull.
Fig. 4-1. The hull.


Fig. 4-2. The hull in cross section.
Fig. 4-2. The hull in cross section.

construction. As the hull shapes aft to the sternpost below to overhang, it narrows considerably and this is known as the run of the ship. The propellers or screws are fitted to shafts projecting on either side, and the shafts are braced by propeller struts.

The line to which the water rises on the sides of the hull when the vessel is floated is the waterline. The freeboard is the vertical distance from the waterline to the lowest point of the main deck edge. The draft is the vertical distance from the waterline to the lowest part of the hull at any given reference point. Numbers at the bow and stern provide an easy method of determining the draft. Trim is the relationship between draft forward and aft, above and below the mean waterline. The angle of trim is the angle between the plane of floatation and the mean waterline plane. If the vessel inclines forward so that her plane of flotation is not coincident with her mean waterline plane, the ship is down by the head or trimmed by the head. If the vessel inclines aft, she is down by the stern or trimmed by the stern. Trim may be adjusted by the use of peak tanks which are located in the extreme bow and stern, or forepeak and afterpeak (see Figure 4-4).

Reference to Figure 4-2 will locate the main keel which turns the entire length of the hull from stem to sternpost, and the docking keels which are fitted on some ships to simplify support of the ship when in drydock. Bilge keels are present on the larger ships. These are keels projecting from the hull at the turn of the bilge running fore and aft for approximately two-thirds of the length of the ship, and serving to help reduce the roll of the ship. The turn of the bilge is simply the curved part of a ship's hull, where the sides and flat bottom meet. It should be noted that the plating extends above the deck to form what are known as bulwarks, on the top of which is the rail. Along the edge of the deck, run gutters called waterways for carrying off rain or sea water which is released through scuppers, or holes in the bulwarks.

The hull which we are considering has a flush deck, as it is unbroken, vertically, from bow to stern. If it were stepped in any way, it would be known as a broken deck, and if the waist were lower than bow and stern, it would be called a well deck. This deck is also known as the weather deck, and is cambered or crowned to provide drainage.


Fig. 4-3. Construction of a battleship.
Fig. 4-3. Construction of a battleship.


4B3. Hull construction. Engineering and damage control courses provide detailed discussions of ship construction. A brief discussion at this point, however, provides certain basic information necessary to a study of seamanship. Reference to Figure 4-3 should be made in connection with the discussion which follows.

The interior of the hull is a highly complex structure which must provide: (1) the necessary strength to withstand any stresses encountered; (2) suitable working and living spaces for the efficient functioning of the crew; (3) space necessary for the driving machinery; and (4) a high degree of watertight integrity by means of compartmentation. The hull is designed and constructed with these factors in mind.

As a preliminary step to actual construction of a ship, a platform or cradle conforming to the curvature of the ship's bottom is erected on the building ways, or ship erection site. The outer and inner flat keel plates are first laid on the keel blocks. The keel is the backbone of the ship and consists of 2 main parts: (1) a flat keel which is the external centerline row of plating on the ship's bottom, and (2) the vertical keel which resembles a steel I-beam located just above the flat keel. A common misconception is that the keel extends downward from the bottom of the ship. The is true only on small ships. On large ships, the main keel extends only the thickness of one plate below the bottom plating, and secondary keels, which are known as docking keels and are located outboard of the flat keel, extend down to the level of the flat keel to simplify support of the ship when in dry dock. Also bilge keels, running about two-thirds of the length of the ship, are used on large ships.

After laying down the outer and inner flat keel plates, the bottom plating is laid down on the cradle out to the turn of the bilge. On this plating, transverse frames run from the vertical keel outward, forming a riblike structure with the keel as a backbone. Running fore and aft and secured to the transverse frames to give support to them, are longitudinal frames. On these frames the inner bottom is laid, extending to varying heights up the hull. The space enclosed between the hull or skin of the ship and the inner bottom is known as the double bottom and the spaces therein as double bottom tanks. The transverse bulkheads (athwartship walls) are usually the next members erected, followed by longitudinal bulkheads (fore and aft walls). These bulkheads together with the decks form compartments which provide the necessary working, living, and storage spaces in the ship. Torpedo-defense bulkheads are then erected from inboard out until the one next to the skin of the ship is reached. The framing above the turn of the bilge is secured to the outermost torpedo-defense bulkheads, and the shell plating, or outer skin of the ship, is secured to these frames both by welding and riveting. The construction of the hull thus progresses from the bottom upward, through the successive decks, with framing, bulkheads, and shell plating being fastened in place as the construction advances, and with the ship's heavy machinery being installed as the construction reaches the spaces to which the equipment is allotted.

At about the time the plating is finished up to the third deck, the stem or bow frame forming the apex of the intersection of the forward sides of th3e ship is rigidly connected at its lower end to the keel and secured. The stern frame, or large casting attached to the after end of the keel to form the framework for the ship's stern is also secured, and, on some vessels the stern frame exists as a combined stern and rudderpost. When this is true, the main vertical member of this framework is referred to as the sternpost, or rudderpost.

Thus the basic structure, or hull, of a ship consists of a network of fore and aft and athwartships members. Of the plating secured to the frames, the lowest line of plating adjacent to the keelplates is known as the garboard strake, the highest line adjacent to the main deck beams is known as the sheer strake. The plate at the turn of the bilge is known as the bilge strake. Intermediate lines of plating are known simply as strakes (wales in wooden ships or small boats).

4B4. Divisions of the hull. From forward aft, United States naval vessels are cut by transverse bulkheads into 3 or 4 main divisions labeled A, B, C and D. In a 3-division ship, for example, Division A extends from the stem to the forward transverse bulkhead of the forward machinery compartment. Division B includes the space from that bulkhead to the after bulkhead of the after machinery compartment. DIvision C comprises the remaining space aft. In a 4-division ship, the machinery compartment is divided into 2 parts, Divisions B and C with Division D comprising the remaining spaces aft. The machinery compartment is considered to mean all boiler rooms, engine rooms, and compartments for auxiliary engines. Note that while the ship is considered to have only 3 or 4 main divisions, this does not mean that there are only 3 or 4 transverse bulkheads. There are many others, all lending support to the structure of the vessel and contribution to its compartmentation and watertight integrity. One of the most important of these is the collision bulkhead, located just aft of the forward peak tank. This bulkhead is absolutely watertight, having no openings of any kind.


4B5. Designation of compartments. All compartments aboard ship are designated by various letters and numbers to indicate their location and contents or use.

1. The first symbol in this classification is the letter A, B, C, or D to indicate in which main division of the ship the compartment lies.

Figure 4-4. Decks.
Figure 4-4. Decks.

2. To this letter is added the number of the compartment which indicates (1) the deck and (2) the side of the ship on which it is located. Decks are indicated by the first digit of a 3-digit number. As a general rule, compartments on the main deck are numbered from 101 to 199 from forward aft in each division. Second deck compartments are in the two hundred series, etc. Superstructure decks are numbered from 001 to 099, and double bottom compartments from 901 to 999. The side of the ship on which the compartment is located is indicated by the fact that starboard compartments are given odd numbers, and port compartments are given even numbers. For example, compartment 310 would be located in the third deck, port side, the fifth compartment aft in the division.

3. To further define the contents or main use of a compartment, the number is followed by a designating letter. A list of the more common classification includes:

4B6. Decks. Decks are floors which may or may not extend all the way from stem to stern, and may or may not extend athwartships to the sides of the vessel. They are classified both as to position and as to construction. Reference should be made to Figure 4-4 in connection with the following terms.

  1. Main deck. The highest deck extending from stem to stern and from side to side.

  2. Forecastle deck. A partial deck above the main deck at the bow.

  3. Upper deck. A partial deck above the main deck amidships. The name upper deck is also given to a partial deck above the main deck which begins at the waist and extends either to the bow or stern. The side plating must extend up to the deck for it to be properly considered an upper deck.

  4. Superstructure deck. A partial deck above the main, upper, or forecastle deck which does not extend to the sides of the ship, or one which does extend to the sides but does not have the shell plating carried up to it.

  5. Second deck, third deck, etc. The first complete deck below the main deck is the second deck. Additional complete decks are called third, fourth, etc.

  6. Half deck. A partial deck below the main deck, but above the lowest complete deck.

  7. Platform deck. A partial deck below the lowest complete deck.

  8. Protective or splinter decks. Armored decks. If there is only one deck of this type, it is called


Figure 4-5. The foretop of a modern battleship.
Figure 4-5. The foretop of a modern battleship.

    the protective deck. Where there are two, the heavier one will be the protective deck, the lighter being the splinter deck.

4B7. Hull systems. Through the complex structure of the hull, air and water must be circulated. For circulating the air, there is natural ventilation by means of cowls (bell-shaped funnels capable of being trimmed to the wind), and windsails; and forced-draft ventilation by means of blowers through ducts. Thus, through a supply system, the ventilating system brings air to all parts of the hull; and through an exhaust system, removes foul air.

Prominent also is the system of drainage which involves removal of water from bilges, engine rooms, and boiler rooms by the main circulating pumps through the main drain. A secondary drain of smaller capacity than the main drain is used to remove water from any compartment of the ship. There is also a fire main which is a lead-lined steel pipe running beneath an armored deck almost the length of the ship on which pressure is always maintained. For sanitation purposes, a flushing main is also provided.

Of great importance is the magazine flooding system. In modern vessels the system is connected to the fire main with outlets in the form of flooding plugs or sprinklers. However, many vessels still accomplish flooding by means of sea cocks, which are merely valves that allow entrance of sea water.

4B8. Access. Between decks and compartments is a variety of facilities enabling all hands to move from one part of the ship to another. Companionways (sets of steps or ladders) lead from one deck level to another, the openings to which are called companion hatches. In general, hatches are deck openings providing vertical access to space below, and are usually surrounded by coamings (raised flanges) to prevent entry of water. If the deck is watertight, the hatch providing access through it is a watertight hatch, and is fitted with rubber gaskets and secured by dogs (clamps) to prevent the passage of water. A booby hatch is a hatch on the weather deck protected by a hood. A manhole is simply a round or oval hole cut in tanks, decks, etc., to provide access.

Horizontal movement is facilitated by means of passageways (corridors) and doors. Some doors are watertight doors which means that they are fitted with rubber gaskets and secured by dogs to prevent the passage of water at that opening.


4B9. Typical spaces aboard ship. In all naval vessels, certain spaces are designated for functions which are characteristic of living and working at sea. Chain lockers for stowage of anchor chain are provided well forward, the chain being led into them by means of chain pipes from the forecastle deck. Bunkers are provided for stowage of fuel. Storage compartments are generally called lockers. Magazines are spaces in which ammunition is stowed. A messroom is a space where members of the crew eat their meals. The wardroom is the compartment used by officers for their mess and for social purposes. The ship's kitchen is the galley.

C. Superstructure

4C1. Superstructure defined. A vessel's' superstructure includes all equipment and fittings other than armament extending above the hull. Under superstructure must be grouped masts, stacks, bridge structures, and all housings for equipment and personnel.

4C2. Masts and staffs. Masts were formerly defined as vertical spars erected in ships for setting sail or as supports for cargo booms. Masts in today's naval vessels, however, have many structural differences and serve a great variety of purposes. In modern warships there are either 1 or 2 masts, a high foremast, and sometimes a shorter mainmast. On many battleships and cruisers these masts support heavy structures, known respectively as the foretop and maintop, in which are housed directors, rangefinders, and other equipment for the control of gunfire (see Figure 4-5.) Masts on practically all naval vessels are also used for the suspension of radio aerials and detection and ranging devices, and for the setting of signals.

The yard is a horizontal spar attached to the mast athwartships and equipped with blocks for reaving signal halyards. Various lights which will be described later, are mounted both on masts and yardarms. Masts are supported by the standing rigging, which is permanent in nature and is usually constructed of wire rope set taut by turnbuckles. The standing rigging consists of stays, which lead forward or aft, and shrouds, which lead to the sides. Shrouds are held out from the masts by means of spreaders.

The top of a mast is called the truck. Above the main truck on a naval vessel in commission is mounted a pigstick from which is flown the commission pennant or, if a flagship, the personal flag of the flag officer. Abaft the mainmast, and making an angle of about 40 degrees with it, extends a small spar known as the gaff. The topmost end of the gaff is called the peak, and it is from this oint that the ensign is flown when the ship is underway. The small vertical spars at the bow and stern, from which the union jack and ensign are flown while at anchor, are called the jackstaff and the flagstaff, respectively.

Changes in the design of naval vessels over many years have resulted in a great variety of mast construction. Two older types are illustrated in Figures 4-7 and 4-8. Many of the newer ships of the U.S. Navy combine the bridge and forward fire control tower as an integral part of the foremast (see Figure 4-9).

4C3. Stacks. Pipelike structures, housing the uptakes which convey smoke and gases from the boilers, are called stacks. There are many different varieties--short, high, vertical, raked, single, double, split trunk, and others. On almost all naval vessels, stacks are located on the centerline approximately amidships, a notable exception being on aircraft carriers, whose stacks actually protrude from the sides or are located on the "island" at one side of the flight deck. Stacks are a prominent feature of any ship, and their number, type, and arrangement are important aids to the correct identification of ships at a distance (see Figure 4-10).

4C4. Superstructure bridge assembly. Well forward on most ships is a rather high and prominent structure made up of deck houses, platforms, and ladders, frequently grouped around the foremast. The size of this assembly varies from the tall massive structure on a battleship to the small wheelhouses or pilothouse on the smallest ships. Regardless of size, however, these structures all serve the same purpose--that of providing an adequate housing for the "nerve center" of the ship; for within this network of decks, compartments, and ladders, are the instruments and personnel for the control of the ship, for communication with other parts of the ship and with other ships, and for the control of gunfire.

4C5. The navigating bridge. A major part of the superstructure bridge assembly on all ships is the navigating bridge, the station of the officer conning the ship. From this station, the ship is controlled. The following equipment will be found on the bridge of a modern warship.

  1. The wheel for steering the ship.

  2. The binnacle, a stand which houses the magnetic compass.

  3. A gyro-repeater, operator from the gyrocompass.


Figure 4-6. Masts and staffs.
Figure 4-6. Masts and staff.


Figure 4-7. Cage masts.
Figure 4-7. Cage masts.

Figure 4-8. Tripod masts.
Figure 4-8. Tripod masts.


Figure 4-9. Foremast bridge structure of a modern cruiser.
Figure 4-9. Foremast bridge structure of a modern cruiser.

  1. The engine order telegraph, or annunciator,l by means of which the orders of the conning officer are communicated to the engine room.

  2. The emergency bell pull, a stand-by method for communicating with the engine room.

  3. An engine speed indicator which indicates the number of revolutions per minute the propeller shafts are making.

  4. The change of revolution indicator which transmits to the engine room the number of turns is is desired to have the engines make.

  5. Pulls for both whistle and siren.

  6. A fathometer for measuring the depth of the water by means of sound waves.

  7. A radio direction finder.

  8. Switchboards for operating lights.

  9. The general alarm controller which is used to operate the general alarm system throughout the ship.

  10. The howler controller which is used to operate the system of warning howlers throughout the ship.

  11. Phones. The IJV circuit, which is the maneuvering circuit, is manned in the bridge and has outlets to the engine room, central station, forecastle, etc. Over it orders are given to the engines, for shifting for steering control, for handling of anchor, for handling of lines, among other things. Reports of soundings, condition in the engine room, condition of anchor and chain are likewise received over this circuit. In addition, there are usually intercommunication phones providing communication with any part of the ship by calling through an operator. These may be called IJP, IJL, etc., and are used for damage control, fire control, gun control, maneuvering, etc.

  12. Voice tubes.

  13. Devices for tracking submarines, surface craft, or planes.

Navigational equipment such as sextants, charts, drawing instruments, and reference books may be stowed on the bridge, but more often it is kept in a separate compartment nearby called the chart house.


Around the enclosed bridge, there is usually an open platform where lookouts and the officer in charge may observe the position of other ships, lighthouses, buoys, and other aids to navigation (see Figure 4-13).

Figure 4-10. Various types of stacks.
Figure 4-10. Various types of stacks.

4C6. Other stations. The conning tower, which is located just forward of and slightly below the bridge, is found only on battleships and cruisers. This is a heavily armored structure housing duplicates of all the control apparatus on the bridge. As the primary ship control station, it is the battle station of the Captain. In addition to the conning tower, some ships have a battle bridge, an open platform for the use of the Commanding Officer during engagements with enemy aircraft.

Another distinctive feature of battleships and cruisers is the fire control tower, which may be either a separate structure just aft of the conning tower or actually an integral part of the conning tower. It contains equipment for the control of gunfire and is the battle station of the gunnery officers.

Located near the bridge on practically all ships is another open platform called the signal bridge, from which signalmen maintain visual communication with other ships in the vicinity. A radio room, quickly available to the officer in charge, is also located in the bridge assembly.

4C7. Deck houses. In addition to masts, stacks, and bridge assemblies, the superstructure of a modern warship consists of a variety of workshops, handling rooms, and living spaces enclosed in deck houses. The Captain's cabin is usually located near the bridge, while the engineer and torpedo officers' workshops, and ammunition handling rooms are generally found amidships or in after deck houses.

D. Other Equipment On or Above Decks

4D1. General. No discussion of the topside of a warship would be complete without mention of her ordnance equipment, signal devices and running lights, boats and life rafts, and ground tackle. Although technically not a part of the superstructure, they play such an important part in the function of the ship and their features are no prominent that they will be considered here rather briefly. A complete discussion of boats and ground tackle will be found in Chapter 6.


Figure 4-11. Navigating bridge of a modern battleship.
Figure 4-11. Navigating bridge of a modern battleship.

4D2. Ordnance equipment. Turrets (see Figure 4-14) are found only in armored vessels, such as battleships and cruisers. Essentially they are composed of a heavily armored box topside containing up to four main battery guns, and a structure extending downward through the decks containing the ammunition handling rooms and hoists. The entire structure rotates within a heavily armored cylinder called a barbette, extending from the armored upper part of the turret down to the lowest armored deck. Thus the gun crews and ammunition are completely protected from enemy gunfire.

Enclosed gun mounts are also revolving, box-shaped structures. On destroyers, they provide the housings for the major guns; on larger ships, they contain the secondary battery. Enclosed gun mounts resemble turrets but are not armored and do not have barbettes. Their plating is intended only as a protection from splinters and heavy seas. On battleships and cruisers, the enclosed gun mounts are mounted along each side amidships. Destroyers mount 4 or 5 enclosed gun mounts arranged fore and aft along the] centerline. Latest practice is to mount either one or two 5-inch dual-purpose guns in each enclosed mount.

Many guns are not mounted in turrets or enclosed gun mounts. Almost all antiaircraft guns, such as the .50 caliber, 20 mm., and 40 mm. automatic machine guns are of this type. There are no specified locations for these guns; they are placed wherever they can be of best service and wherever there is room.

Fire control apparatus is that equipment used in the control of a ship's gunfire. The more intricate devices are below decks in a protected position, but much of the equipment must, of necessity, be topside. On the larger ships with heavy masts, some of this equipment is located in the foretop and maintop, some on separate towers built up from the superstructure. On destroyers, however, the gun director is housed on top of the superstructure bridge assembly. This director can be readily identified by the cylindrical-shaped ends of the optical rangefinder extending outboard from both sides of the housing.

Torpedo tube mounts on modern destroyers are usually located amidships on the centerline (see Figure 4-15). They consist of 4 or 5 tubes fitted with breech mechanisms, and are capable of revolving so that torpedoes can be launched on either side of the ship. Some older cruisers have torpedo tubes mounted on the main deck aft, while other destroyers have them on the port and starboard sides amidships.


Figure 4-12. Bridge of a patrol vessel.
Figure 4-12. Bridge of a patrol vessel.


Figure 4-13. Bridge structure of an escort ship.
Figure 4-13. Bridge structure of an escort ship.

Figure 4-14. Battleship armament.
Figure 4-14. Battleship armament.


Figure 4-15. A destroyer, showing torpedo tubes.
Figure 4-15. A destroyer, showing torpedo tubes.

Destroyers and patrol craft are equipped with depth charges for anti-submarine warfare. These charges can be dropped over the stern by rolling them from inclined racks on the fantail. In addition, most anti-submarine vessels have mortarlike Y-guns and K-guns secured to the decks fairly well aft, by means of which the "cans" can be projected outboard by firing charges of black powder.

4D3. Signal devices and lights. Most of the equipment for short-range signaling is located on or near the signal bridge. Light lines, called halyards, are located on this platform and run through signal halyard blocks on the yardarm. Signal flags, stowed in flagbags on the signal bridge, can be "bent to" these halyards and hoisted on the yard (see Figure 4-16). On or near the signal bridge are signal searchlights with manually operated shutters for sending code by flashing light. On the outboard ends of the yardarm are two small lights called the yardarm blinker, and used for sending blinker messages over short distances. Secured to brackets well up on the mast are two red lights, known as the breakdown lights, which are turned on in case a breakdown endangers nearby ships. Sets of colored lights are suspended from the yardarm or halyards or fixed on either side of the bridge structure; these recognition lights furnish instant identification of the ship's nationality, being flashed on at night according to a prearranged system of colors. In addition to these signaling devices, there is the ship's bell, usually secured to the mast above the signal bridge.

Running lights are those lights aboard ship which are turned on at night during peacetime, and which are prescribed by law to be carried by a particular type or class of ship when underway at night. They are fixed lights consisting principally of a white masthead light, usually fixed on the upper part of the bridge superstructure, or on a small shelf extending forward from the foremast; a white range light abaft and above the masthead light, either on the foremast or mainmast; and two side lights, a green one on the starboard side and a red on the port side. The character and position of the running lights are covered in detail in Chapters 9 and 10 on the Rules of the Road.

4D4. Boats and life rafts. Normally a ship carries a number of small boats, either suspended along the side from davits or "nested" one inside the other on the deck in a position to be hoisted over the side. Due to


Figure 4-16. Flagbag.
Figure 4-16. Flagbag.

Figure 4-17. Signal searchlight.
Figure 4-17. Signal searchlight.


Figure 4-18. Signal devices and running lights.
Figure 4-18. Signal devices and running lights.


Figure 4-19. Ground tackle.
Figure 4-19. Ground tackle.


Figure 4-20. Life raft.
Figure 4-20. Life raft.

the fact that these wooden boats create a fire and splinter hazard in wartime, the number now carried has been drastically reduced. Either 1 or 2 is the usual number on ships today. When a ship is in port, her boats are used for the transportation of personnel and supplies; at sea they serve as lifeboats. Many life rafts and floats are in evidence on ships today; they are secured so that they may be released quickly and, on release, drop to the water (see Figure 4-20).

4D5. Ground tackle. Abaft the stem, large tubular openings lead down from the weather deck through both sides of the ship. These are called hawsepipes, and should not be confused with the eyes of the ship which, as has been stated, is a term used to describe the general vicinity of the stem. When the ship is underway, the anchors are housed with their shanks in the hawsepipes and their flukes outside. When an anchor is let go, it drops out of the hawsepipe, and the anchor chain runs freely through it. Just abaft the hawsepipe is a large device called a windlass. The anchor cable passes around a part of the windlass called the wildcat or chain grab, a sprocket wheel with teeth fitting the links of the chain. In heaving in the anchor, the wildcat is rotated by an anchor engine. When the anchor is let go, the wildcat is disconnected from the anchor engine, and the speed with which the chain runs out is then controlled by a friction brake on the wildcat.

A ship is moored to a pier by means of hawsers, or wire ropes. These are secured on the pier to vertical posts called bollards, pass over the ship's side through metal chocks, and are secured on board to pairs of metal heads set vertically and called bitts. Smaller lines may be secured to horned metal castings called cleats, which are found in various places throughout the ship. These hawsers and lines are often heaved in by passing several turns around a smooth concave barrel-like portion of the windlass, called a capstan, gypsy, niggerhead, or winch drum.


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