VI. ELEMENTARY ELECTRIC CIRCUITS

A. General information

Electric current: (The Ampere) All matter is said to be composed of positive and negative charges of electricity. The positive charge, or PROTON, is the neucleus of the smallest particle of matter around which revolves in continuous motion the electrons. The electrons are negative charges of electricity. Molecules of different materials differ in the number and the arrangement of the electrons and protons. Some materials have more or less free electrons in their molecules; that is, electrons which are free to move from one molecule to another under an electrical pressure. These materials are said to be conductors of electricity.

There are also materials that have no free electrons in their molecules, and an electrical pressure will not cause them to move from their molecules. Such materials are said to be nonconductors of electricity or INSULATORS.

Gold, silver, platinum, and copper are conductors of electricity. Copper, due to its relatively low cost and good conductivity, is the material most used for conductors of electricity. Porcelain, rubber, oiled paper, mica, and glass are some of the best insulators or non-conductors of electricity.

When electrons move along a conductor under an electrical pressure, their movement is said to constitute the flow of an electric current. When a certain number pass a given point in one second of time, one AMPERE of current is said to flow along the conductor.

As previously stated, it takes an electrical pressure to cause the electrons to flow along the conductor. One such source of electrical pressure is a battery. Another is the electric generator. The battery, by chemical actions, separates the electrons from the protons. The electrons going to one plate of the battery leave the other plate with just the protons, since they are not free to move. The plate having the excess of electrons is said to be the negative plate, and the plate which has the deficiency of electrons, is said to be the positive plate.

THE LAW OF ELECTRICAL CHARGES states that unlike charges attract one another, and like charges repel one another. Since by chemical action the battery has separated the positive and negative charges (electrons and protons), there is a continuous effort being exerted by them to get back together again. This effort to get back together is called the electro-motive-force. It can readily be seen that the more electrons which have been separated from their protons, the greater will be the effort to get together again; hence a greater electro-motive-force or pressure is exerted.

If the two plates of the battery--the negatively-charged plate and the positively-charged plate--are connected together by a good conductor, the electrons will find a path by which they can get together. As the electrons flow along this conductor from the negative plate to the positive plate, their flow constitutes the flow of an electric current.

A conductor is run between one pole of the battery to the bell. Another wire is run from the other pole of the battery to the push button. (The push button is a device for making or breaking the circuit.) Then another wire is run from the push button to the bell. When the push button is pushed in, it makes contact and completes the path by which the electrons can go from the negative plate of the battery to the positive plate. This current, going through the bell, causes it to ring. It should be noted that the push button can be placed in either wire from the battery to the bell. It breaks the path in either wire and interrupts the flow of current to the bell.

Electric current is not "used up" in the bell. The same amount returns to the positive plate of the battery as left the negative plate. This electric current must be thought of as a medium for transferring power from one place to another, much in the same manner as an endless belt transfers power from the source of power to the load. In transferring that energy, the belt is not "used up." The same amount of belt returns to the driving pulley as went away from the driving pulley. Thus, electric current (thought of in this way) goes out from its driving source (the battery or generator), does its work, and returns to its source again.

In the foregoing discussion you should have learned:

1. Negative charges of electricity are called ELECTRONS. Positive charges of electricity are called PROTONS.

2. Negative charges are the ones that move.

3. The movement of electrons through a circuit constitutes the flow of electric current.

4. Unlike charges attract one another, and like charges repel one another.

5. The attraction between unlike charges separated from one another produce an ELECTRO-MOTIVE-FORCE or electrical pressure.

6. In order that electric current may flow, there must be a continuous path of some conducting material from the source of supply to the load, and from the load back to the source again.

7. A conducting material is a material having free electrons in its molecules.

8. Electric current flows from the NEGATIVE pole, around through the CIRCUIT, and returns to the POSITIVE pole.

9. Electric current is not used up in doing its work but returns to its source.

B. Ohm's Law

1. General information

We have learned that an electrical pressure was necessary to cause electrons (electric current) to flow in a circuit. This pressure, or electro-motive-force, is measured in volts. The VOLT, then, is the unit of electrical pressure. In every circuit there is some opposition to the flow of electric current. This opposition or resistance to the flow of electric current is measured in OHMS. The OHM, then, is the unit of resistance. When a certain number of electrons flow past a certain point in one second, we say that one ampere of current flows through the circuit. Now let us consider the relationship between volts (pressure), ohms (resistance), and amperes (current).

If the pressure is increased across an electrical circuit and the resistance of the circuit remains the same, it is natural to suppose that the current will be increased. If the electrical pressure is doubled, the current will also be doubled. On the other hand, if the resistance of the current is increased, the flow of the current under the same electrical pressure will decrease. Let us try to put this down as a single statement.

The current (amperes) flowing in a circuit is directly proportional to the electrical pressure (volts) and inversely proportional to the resistance (ohms) of the circuit. This is Ohm's Law. In the form of an equation it would be stated as follows:

Amperes = Volts / Ohms

PROBLEM: How much current will flow in a circuit which has a resistance of 2 ohms across which there is an electrical pressure of 50 volts?

SOLUTION: Amperes = 50/2 or 25 amps.

If the pressure (volts) is the unknown quantity and the current and resistance are known, this formula can be transposed to read:

Volts = Amperes x Ohms

PROBLEM; What pressure (volts) is required to force 7 amperes of current through 10 ohms of resistance?

SOLUTION; Volts = 7 x 10, or 70 volts

If the resistance of the circuit is the unknown quantity and the current and the pressure are known, the formula is transposed to read;

Ohms = Volts / Amperes

C. The parallel circuit

1. General information

First, let us connect one bell to a battery. The bell requires 2 amperes of current to make it operate properly. In order to get this current, it must be connected directly to a 6-volt battery. If we were to connect another bell to this same battery, we would extend the two wires from the first bell to the second bell. Since the battery maintains a pressure of 6 volts across the two-line wires, both bells have a pressure of 6 volts across their terminals. We have already stated that each bell requires 2 amperes to operate it; therefore the battery must supply 4 amperes of current to the 2 bells. Thus, 4 amperes flow out from the battery to the first bell where the current divides, 2 amperes going through the first bell and 2 amperes going on to the second bell.

On the return wire, 2 amperes flow from the second bell to the first bell where it is joined with the 2 amperes coming through it, and 4 amperes now flow between the first bell and the battery. This is called a PARALLEL circuit.

Summary; The voltage across a parallel circuit is the same across all parts of the circuit.

The current flowing in a parallel circuit is the sum of the currents flowing in each part of the circuit.

PROBLEM; Four bells requiring the same voltage but different amounts of current are connected in a parallel circuit. Bell No. 1 requires 2 amperes, bell No. 2 requires 4 amperes, bell No. 3 requires 4-1/2 amperes, and bell No. 4 requires 6 amperes.

(1) What is the voltage across each bell?

(2) What current must the battery supply to the 4 bells?

SOLUTION: (1) In a parallel circuit the voltage is the same across all 4 bells.

(2) The total current taken by all 4 bells is the sum of the current taken by each bell or a total of 2 plus 4 plus 4-1/2 plus 6 = 16-1/2 amperes.

PROBLEM FOR SOLUTION: Draw a circuit of the above problem and indicate the amount of current flowing on each wire between the battery and bell No. 1; bell No. 1 and bell No. 2; etc.

C. The series circuit

1. General information

In a series circuit, the current must flow through one piece of electrical apparatus in order to get to another one. As previously explained, the current that goes to the bell must also go through the push button. It does not matter which wire the push button is in; the fact to be remembered is that in order to flow through one, the current must also flow through the other. If the current cannot flow through the push button, it cannot flow through the bell either. The bell and push button are said to be connected in series.

Let us consider a more complicated series circuit where 2 bells, each requiring 6 volts pressure and 2 amperes of current, are connected in such a manner that the same current going through one must also go through the other. (See accompanying illustration.)

Since each bell requires 6 volts, the battery must produce a total pressure of 12 volts. We have already stated that each bell requires 2 amperes of current. Since they are connected so that the same current flows through each bell, the battery must put out just 2 amperes.

Summary: (1) The total voltage across pieces of electrical apparatus connected in series is the sum of the voltages across each piece.

(2) The current flowing in a series circuit is the same in all parts of the circuit.

PROBLEM: Four pieces of electrical apparatus, each requiring 10 volts pressure and 4 amperes of current, are connected in series.

(1) How much current flows in the circuit?

(2) What is the total voltage across the circuit?

SOLUTION: (1) In a series circuit the current is the same in all parts of the circuit; therefore the total amount of current flowing is 4 amperes.

(2) The total voltage across a series circuit is the sum of the voltage across each piece; therefore the total voltage across this circuit would be 10 x 4, or 40 volts.

PROBLEM FOR THOUGHT: Could pieces of electrical apparatus requiring different amounts of current be connected in a series?

VII. ELEMENTARY LIGHTING CIRCUITS

A. Installation of lighting circuit, Job No. 1

1. Objectives

2. Introductory information

These circuits are to be installed on a practice board and should be done in a neat and workmanlike manner. Sockets and cutout are to be screwed to the board with wood screws. Where wires are necessary, they should be fastened securely with saddle tacks. All bends are to be square bends. Wires should be run parallel, either vertically or horizontally.

3. Supplies, tools, and equipment

4. Procedure

a. ASSEMBLE ALL WIRES AND TOOLS LISTED.

b. INSTALL CUTOUT AND LAMP SOCKETS AS SHOWN IN DRAWING. (TOP TERMINAL SHALL BE THE CONNECTION TO SHELL OF SOCKET.)

c. HAVE INSTRUCTOR INSPECT THE JOB.

B. Two switches controlling two lights each, Job No. 2

1. Objectives

2. Introductory information

In a PARALLEL circuit the voltage or electrical pressure is the same across all parts of the circuit. Lamps of the same voltage rating, therefore, must be connected in parallel.

In a SERIES circuit the current (amperes) is the same in all parts of the circuit. The switch, therefore, must be placed in a series with the lamp or lamps which it is to control, so that it will control all the current going to the lamps.

B. TWO switches controlling two lights each, Job No. 2 (continued)

3. Supplies, tools, and equipment

C. Three switches controlling one light, Job No. 3

1. Objective

2. Introductory information

As in previous jobs, the white wire is run to the lamps and the black wire is run to the switches. A three-way switch is always considered as a single pole switch because it breaks only one side of the circuit. A white wire should never be run to a single pole switch. Study the construction of the three-way switch. Notice that it has only three terminal screws--two on one end and one on the other. The black line wire is connected to the side having only one screw.

3. Supplies, tools, and equipment

4. Procedure

a. INSTALL CUTOUT, SWITCHES, AND RECEPTACLES AS SHOWN IN DRAWING.

VIII. FIXTURES AND FITTINGS

A. Objectives

B. General information

The use of fixtures in marine electrical work and industrial work is governed by the same principles; the only difference is in the materials used, methods of construction, and conditions for which they are used. Conditions which severely affect marine work are salt water and dampness; the greatest care must be taken, therefore, when installing marine fixtures, as uninterrupted service on a ship is far more important than in an industrial plant. A ship at sea is entirely dependent upon her own resources.

Fixtures that are used in marine work are subjected to severe conditions, such as jarring and vibration. It is necessary that they be constructed and installed so that connections will not be loosened, small coils will not become displaced, and relays will not be affected.

Fittings may be divided into two classes; watertight (WT) and non-watertight (NWT). The difference between a watertight and non-watertight circuit box or compartment is that the former must be drilled and tapped for installation of a packing or terminal tube for entry of the cable, whereas only a cable clamp is necessary in a non-watertight fitting. (See following illustrations of various types of fixtures.)

Fittings used in marine work are generally furnished by manufacturers, and a large assortment of parts for replacement are always available or can be quickly obtained. If a piece of equipment becomes defective while a ship is at sea, an order may be sent by radio to port for replacement and can be installed upon arrival of the ship to port. (A number of fittings used in marine work are illustrated on the following pages.)

Ceiling Fixtures

Bulkhead Fixtures

Bow, Masthead, Stern, Range, or Towing Lights

Anchor or Riding Lights

Marine Searchlight

Switches

Watertight Plug Receptacles

Junction Boxes

Special fixtures and fittings are made for magazines, handling rooms, and similar compartments. All electrical devices in these rooms must be absolutely sealed when completed.

Identifying fixtures and fittings. See illustrations of the various fixtures and fittings. Refer also to catalogues of the various companies which supply marine electrical supplies and equipment.

Installations. Illustrations Nos. 1, 3, 4, 5, and 6 show the methods of installing fixtures to watertight and non-watertight decks and bulkheads of aluminum and steel as well. The methods used in illustrations Nos. 2, 7, 8, and 9 are for installing fixtures to decks or bulkheads of steel only, both watertight and non-watertight. Illustration No. 10 shows the installation of fixtures to non-watertight bulkheads only.

Locations. Fixtures should be placed in the most convenient places. Switches should be placed 48 inches from the deck to center, and phones and other means of communication should be placed 58 inches from deck to center of instrument. Whistle pulls and control devices measure 36 inches to the handle or key. Convenient outlets or plug receptacles are placed 72 inches from the deck, while radio and fan outlets are placed 15 inches from the finished ceiling unless otherwise indicated. Connection or junction boxes (other than fuse boxes), that are seldom opened should be placed to evenly distribute the light. Usually the plans give the location of all fixtures. To locate the center of the room, measure half the distance from one side and half the distance from one end. The two lines cross in the center.

Note: Porcelain should never be used on shipboard. Bakelite, hard rubber, fiber, or synthetic plastic are preferable because they are more rugged and durable.

IX. SIMPLE SKETCHES

A. General information

In the reading of ordinary freehand sketches or drawings, there are certain minimum measurements and related information necessary for a comprehensive understanding. In studying an illustration, special attention should be given to the following: (1) over-all length, (2) over-all width, (3) thickness, (4) inside measurements, (5) distance between centers of holes, (6) alignment of holes in respect to a given line, (7) specific types of material, such as flat bar, angle bar, channel bar, plate, galvanized or plain sheet metal, and the number of pieces required for the job.

For a plain flat plate, the following is sufficient:

For a plate with an opening cut in it, the following information should be given:

For an angle bar, the following dimensions are needed: over-all length, thickness of metal, and width of each side of angle bar.

For channel iron, the dimensions of over-all length, thickness of material, and depth and breadth of channel are needed.

For a plate that is to be drilled, the holes should be designated as to size or purpose and location.

A box to be made of sheet metal should show inside measurements of box, size of opening, and how cover is to fasten.

Top and Perspective Views of Box

Cover of Box

1. Supplies, tools, and equipment

Blueprints
Paper
Pencil
Rule

2. Procedure

a. SECURE MATERIALS FROM SHOP BLUEPRINT MAN.

b. CLASSIFY CABLES SHOWN ON PRINTS AND CHECK THEIR RUN.

c. STUDY ARRANGEMENT PRINT AND CHECK COMPARTMENT ARRANGEMENT

d. DRAW LINES ON PAPER TO REPRESENT EACH CABLE IN COMPARTMENT AND CHECK WITH PRINT.

e. DRAW SYMBOLS SHOWING LIGHTS, BOXES, SWITCHES, OUTLETS, ETC., AS SHOWN ON ARRANGEMENT PRINT AND CABLES FEEDING THESE UNITS.

f. CHECK ALL UNITS AND CABLES WITH PRINTS FOR ERRORS OR OMISSIONS.

g. INFORM LAYOUT BOSS THAT YOUR SKETCH IS COMPLETE AND READY FOR HIS CHECK AND APPROVAL.

h. RETURN BLUEPRINTS TO SHOP BLUEPRINT MAN AND RECEIVE SIGNED SLIP.

i. TURN SKETCH OVER TO THE FOREMAN.

Note: The job of making a sketch varies in man-hours, due to size of compartment on boat and to number and size of cables located in compartment. The time would range from 3 hours to 120 hours for this job. The more experience the man gets on layout, the bigger sketches he is given to do.

X. CABLE TESTING FOR CONTINUITY AND IDENTIFICATION

A. Objective 1. To demonstrate one method of testing a multiple conductor cable for continuity and identification of conductors.

B. Introductory information

The requirement is to test a 16-conductor cable and identify the various conductors. The cable we have chosen is one run between the steering gear motor and the rudder angle indicator on the bridge. This cable is not in one continuous length. A junction box is cut in somewhere along its length.

It is necessary to test the cable between the steering gear, therefore, and also from the rudder angle indicator on the bridge to the junction box. This is a new installation and the conductors are not color-coded or otherwise identified.

C. Supplies, tools, and equipment

2 headphone test sets
Screw driver
Knife
Pliers

D. Procedure

1. SKIN AND CLEAN BOTH ENDS OF ALL CONDUCTORS PREPARATORY TO TESTING.

2. FAN OUT ALL CONDUCTORS AT BOTH ENDS SO THAT THEY DO NOT TOUCH EACH OTHER OR GROUND.

3. IDENTIFY EACH CONDUCTOR AT ONE END OF CABLE WITH IDENTIFICATION TAGS.

Note: These identifications may be terminals, either soldered to the wire or put on the conductor with solderless connection. One man (usually the helper) will put on one head set and connect one of the test leads to a good ground.

A test should be made by tapping the other test lead to another part of the ship to determine whether or not it is a good ground. If a click is heard in the phones, it is a good ground.

The free test lead of the phones should be connected to the first conductor to be tested.

4. BEGIN THE TEST.

Note: The journeyman goes to the other end of the cable, puts on his test phones, and connects one lead to the ground. He now begins by touching the free test prong to each individual conductor in turn, until a click is heard in the test phones. This click will also be heard in the phones at the other end. The helper should immediately reply by giving the number of the conductor.

As soon as the journeyman has repeated the number, the helper should connect the next conductor to be tested. This operation is repeated until all conductors in that cable are identified. If for any reason a click is heard in the test phones and communication cannot be established, it usually means a grounded conductor. It may be an accidental ground and should be cleared. If a helper waits a considerable length of time without getting a click in his phones, it may be best to test again to make sure his phones are still grounded. If the ground is all right, move test lead to another conductor, leaving the dead one on until the last. There may be an opening in that particular wire.

The helper should stay at his station with his test phones on until relieved by the journeyman.

The headphones should be tested for polarity before starting the test. Each headphone has its own battery. The proper lead of each headphone must be grounded or they will not work. The phones should be connected together and the proper ground lead for each phone determined before attempting to test the cable.

XI. SHIP LOCATIONS AND NOMENCLATURE

ABOARD--On or in a ship.

AFT--In the direction of or toward the stern.

AMIDSHIPS--In the vicinity of the middle portion of a vessel, as distinguished from her ends. The term is used to convey the idea of general locality, but not that of definite extent.

ASTERN--Signifying position, in the rear of, or abaft the stern; in regards motion, the opposite of going ahead; backwards.

ATHWARTSHIP--In a transverse direction; from side to side at right angles to the fore and aft centerline of a vessel.

BATTERY BOX--A lead-lined box which holds the storage batteries.

BELOW--Underneath the surface of the water. Underneath a deck or decks.

BETWEEN DECKS--The space between any two, not necessarily adjacent, decks. Frequently expressed as "'Tween Decks."

BILGE--The rounded portion of the hull between the side and bottom.

BINNACLE--A stand or case for housing a compass so that it may be conveniently consulted. Binnacles differ in shape and size, according to where used and the size of compass to be accommodated.

BOOBY HATCH--The hatch covering the escape trunk from the propeller shaft tunnel.

BOW--The forward end of the ship.

BRIDGE--The athwartship platform above the weather deck from which the ship is steered.

BRIDGE, NAVIGATING OR FLYING--The uppermost platform erected at the level of the top of pilot house. It generally consists of a narrow walkway supported by stanchions, running from one side of the ship to the other and the space over the top of the pilot house. A duplicate set of navigating instruments and controls for the steering gear and engine room signals are installed on the flying bridge so that the ship may be navigated in good weather from this platform.

BULKHEAD--A term applied to any of the partition walls used for subdividing the interior of a ship into the various compartments. The main partition walls also serve as strength members of the ship's structure and as a. protection against water passing from one compartment to another.

BULKHEAD, WATERTIGHT--A partition of planking or plating reinforced where necessary with stiffening bars and capable of preventing the flow of water under pressure from one compartment to another.

CABIN--The interior of a deck house, usually the space set aside for the use of officers and passengers.

CAPSTAN--A revolving device, with axis vertical, used for heaving in lines.

CARGO HATCH--Large opening in a deck to permit loading of cargo.

CHAIN LOCKER--Compartment in forward lower portion of ship in which anchor chain is stowed.

CHART ROOM--Small room under bridge used for charts and navigational instruments.

COAMING, HATCH--A frame bounding a hatch for the purpose of stiffening the edges of the opening and forming the support for the covers.

COFFERDAM-The space between two bulkheads located very close together.

COMPANION WAY--A passageway or hatchway.

COMPASS, MAGNETIC--The compass is the most important instrument of navigation in use on board ship, the path of a ship through the waters depending upon the efficient working and use of this instrument.

CROW'S-NEST--A lookout station attached to or near the head of the mast.

DAVIT--Heavy vertical pillar, of which the upper end is bent to a curve, used to support a small boat.

DECK--A deck in a ship corresponds to the floor in a building. It is the plating, planking, or reinforced concrete covering, or any tier of beams above the inner bottom, forming a floor, either in the hull or superstructure of a ship.

DECK, QUARTER--A term applied to the after portion of a weather deck. In a warship that portion allotted to the use of the officers.

DOOR, WATERTIGHT--A door so constructed that when closed it will prevent water under pressure from passing through.

DOUBLE BOTTOM--Compartments at bottom of the ship between inner and outer bottoms, used for ballast tanks, water, or fuel oil.

ENGINE ORDER TELEGRAPH--Transmits the engine orders from the bridge to the engine room.

EXHAUST TRUNK--An outlet for engine exhaust from diesel-driven boats.

FIDLEY HATCH--Hatch around smokestack and uptake.

FIRE DETECTOR AND I. C. TRUNK--Cable rack for fire detector and interior communicative cables.

FLAGSTAFF--Flag pole at stern of ship.

FLAT--Part of deck of a ship.

FOREWARD-A term used in indicating portions or that part of a ship at, or adjacent to, the bow. Also applied to that portion and parts of the ship lying between the midship section and stem; as fore body, fore hold, and foremast.

FORE PEAK--A large compartment or tank just aft of the bow in the lower part of the ship.

FORE AND AFT--Parallel to the ship's centerline.

FORECASTLE--The forward upper portion of the hull, usually used for crew's quarters, lamp room, boatswain's stores, or paint locker.

FORWARD--In the direction of the stem or bow.

FRAME--A term generally used to designate one of the transverse ribs that make up the skeleton of a ship. The frames act as stiffeners, holding the outside plating in shape and maintaining the transverse form of the ship.

GALLEY--The space on a ship where the food is prepared; ship's kitchen.

GANGPLANK--A term applied to boards or a movable platform used in transferring passengers or cargo from a vessel to or from a deck.

GANGWAY--A term applied to a place of exit from a vessel. Gangways are fitted in the sides of a vessel or may be movable portions of bulwarks or railing on the weather decks.

GASKETS--Packing materials, by which air, water, oil, or steam tightness is secured in such places as on doors, hatches, steam cylinder, manhole covers, or in valves, between the flanges of pipes, etc. Such materials as rubber, canvas, asbestos, paper, sheet lead, and copper, soft iron, and commercial products are extensively used.

GRATINGS--A structure of metal bars so arranged as to give a support or footing over an opening, while still providing spaces between the members for the passage of light and the circulation of air.

HAWSE PIPE--A large fitting attached to the bow of a ship through which the anchor chain passes.

HEADS--Toilets.

HELM--A term applied to the tiller, wheel, or steering gear, and also the rudder.

HOLDS--Spaces or compartments between the lower-most decks and the bottom of the ship; or top of the inner bottom, if one is fitted. The spaces below decks allotted for the storage of cargo.

HYDROPHONE--Submarine telegraph which transmits by sound vibrations through water.

INBOARD--Toward the center; within the vessel's shell and below the weather decks.

IMPACT OSCILLATOR--The oscillator which produces sound for depth sounding.

JACKSTAFF--Flag pole at bow of ship.

LADDER--A framework consisting of two parallel sides connected by bars or steps which are spaced at intervals suitable for ascending or descending. On shipboard, the term ladder is also applied to staircases and to other contrivances used in ascending or descending to or from a higher or lower level.

LIGHTENING HOLE--A large hole cut in a floor plate, or longitudinal to reduce its weight.

MAGAZINE--Spaces or compartments devoted to the stowing of ammunition.

MAIN DECK--The highest continuous deck running from bow to stern, which is in general the upper strength member of the ship's girder. This term is especially applicable to warships.

MANHOLE--A round or oval hole cut in decks, tanks, boilers, etc., for the purpose of providing access.

MANIFOLD--A casting or chest containing several valves. Suction or discharge pipes from or to the various compartments, tanks, and pumps are led to it, making it possible for several pumps to draw from or deliver to a given place through one pipe line.

OUTBOARD--Away from the center toward the outside; with the hull.

PILOT HOUSE--A house designed for navigational purposes. It is usually located forward of the midship section and should command an unobstructed view in all directions except directly aft.

PLATFORM DECK--A partial deck below the main deck. Platform decks generally have neither camber nor sheer.

POOP--The after, upper portion of the hull, usually containing the steering gear.

PORT, AIR--An opening in the side or deckhouse of a vessel, usually round in shape, and fitted with a hinged frame in which a thick glass light is secured.

POWER TRUNK--Cable rack for power cables.

QUARTER DECK--That space on a naval vessel so designated by the commanding officer where all ceremonies are held and where officers come on board.

QUARTERS--Living spaces for passengers or personnel. It includes staterooms, dining saloons, mess rooms, lounging place, passages connected with the foregoing, etc.; individual stations for personnel for fire or boat drill, etc.

RANGE, GALLEY--The stove, situated in the galley, which is used to cook the meals. The heat may be generated by coal, fuel oil, or electricity.

RUDDER--A device used in steering or maneuvering a vessel.

SAMSON POST OR KING POST--A heavy vertical post that supports the cargo booms.

SCUPPER--A drain from the edge of a deck discharging overboard.

SCUTTLE BUTT--A drinking fountain.

SHAFT TUNNEL OR ALLEY--Enclosed alleyway around the shaft extending from engine room to after peak tank.

SHEER--Fore and aft curvature of a deck.

SOUNDING--Measuring the depth of water or other liquid.

SMOKE STACK--A metal chimney or passage through which the smoke and gases are led from the uptakes to the open air.

SPLINTER PROTECTION--Light armor used exclusively for protecting personnel.

STARBOARD SIDE--That side of a vessel to the right hand when looking from the stern toward the bow.

STEERING GEAR--A term applied to the steering wheels, leads, steering engine, and fittings by which the rudder is turned.

STEM--The bow frame forming the apex of the triangular intersection of the forward sides of the ship.

STERN--The after end of a vessel; the farthest distant part from the bow.

STIFFENER--An angle bar, T-bar, channel, or bulb angle used to stiffen plating of a bulkhead.

STRINGER--A fore and aft continuous member used to give longitudinal strength; as for example, hold stringers, bilge stringers, side stringers, or deck stringers.

SUPERSTRUCTURE--A structure built above the uppermost complete deck; a pilot house, bridge, galley house, etc.

TANKS--Compartments for liquids or gases. They may be formed by the ship's structure, as double-bottom tanks, peak tanks, deep tanks, etc., or they may be independent of ship's structure and installed on special supports.

TEMPLATE--A mold or pattern made to the exact size of a piece of work that is to be laid out or formed, on which such information as the position of rivet holes, size of laps, etc., is indicated.

TOPSIDE--That portion of the side of the hull which is above the designed waterline.

TRANSOM--The aftermost transverse frame.

TRUNK--A vertical or inclined shaft formed by bulkheads or casings extending one or more deck heights, around openings in the decks, through which access can be obtained, cargo stored, and handled, or ventilation provided without disturbing or interfering with the contents or arrangements of the adjoining spaces.

TURRETS--Structures designed for the mounting and handling of the guns and accessories (usually main battery guns) of a war vessel.

UPTAKE--A sheet metal conduit connecting the boiler smoke box with the base of the smokestack. It conveys the smoke and hot gases from the boiler to the stack and should be made double thickness with an air space between to prevent radiation.

VOICE TUBE--A tube designed for the carriage of the human voice from one part of, or station in the ship, to another.

WARDROOM--A room or space on shipboard set aside for use of the officers for social purposes, and also used as their mess or dining room.

WATERTIGHT COMPARTMENT--A space or compartment within a ship having its top, bottom, and sides constructed in such a manner as to prevent leakage.

WEATHER DECK--Decks above, including the highest continuous deck running from bow to stern, which are partially or entirely exposed to the weather.

WINCH--A hoisting or pulling machine fitted with a horizontal single or double drum. A winch is used principally for the purpose of handling, hoisting, and lowering cargo from a dock or lighter to the hold of a ship, and vice versa.

WINDLASS, STEAM--An apparatus in which horizontal drums or gypsies and wildcats are operated by means of a steam engine for the purpose of handling heavy anchor chains, hawsers, etc.

YARD--A term applied to a spar attached at its middle portion to a mast and running athwartship across a vessel as a support for a square sail.

YARD-ARM--A term applied to the outer end of a yard.