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Pacific Iron. A fitting consisting of a Y-shaped piece hinged to a bearing pin. The inner end of a cargo boom is secured between the prongs of the Y and the bearing pin is passed through a pad eye on the mast, an eye on a mast ring or inserted through a hole in a pedestal. The cargo boom can be raised or lowered by means of the hinge and rotated by means of the pin. Also called Gooseneck.

Packers. Men who fit lamp wicking, tarred felt or other material between parts of the structure to insure water or oil tightness.

Packet Bunkers. A ready service bunker of small dimensions.

Packing, Gland. Packing for use in a stuffing box and against which the gland is forced. Packing material varies in character according to its use.

Packing, Metallic. Metal rings fitted in cylinders, cylinder stuffing boxes, etc., also bronze or white metal segments assembled in the form of an internal and external cone, fitting into each other and held in place by springs, thus floating them on the rod, to eliminate friction.

Pad Eye. A fitting having an eye integral with a plate or base in order to distribute the strain over a greater area and to provide ample means of securing. The pad may have either a "worked" or a "shackle" eye or more than one of either or both. The principal uses of such a fitting is that it affords means for attaching rigging, stoppers, blocks, and other movable or portable objects. Pad eyes are also known as lug pads, the two terms being practically synonymous.

Paddle Beams. Athwartship supporting girder at each end of the paddle box.

Paddle Box. A semicircular structure, placed at the stern or one on each side of a vessel, for the purpose of housing the paddle wheel.

Paddle Box Annex. A continuation of the paddle box structure faired into the sides of the ship and generally used for staterooms, toilets, etc.

Paddle Box Cabin. Staterooms or other living quarters built into the prolongation of a paddle box.

Paddle Box Stays. Inclined struts running from the planking or plating of a vessel to the sponson and spur beams supporting a paddle box structure.

Paddle Wheel. A large wheel consisting of two or more sets of arms and rims with radial boards or floats attached to the outer ends of the arms and running between the rims. The floats may be fixed in position, or feathered so that they enter and leave the water at the most efficient angles.

Paddle Wheel, Feathered. A paddle wheel having floats that are controlled by a mechanism so that they enter and leave the water at the proper angle.

Paint. A viscous or plastic mixture of solids and liquid applied in thin coats for protection or decoration or both. Paint may be defined as a close union of solids or pigments and liquids or binder.

Aluminum Paint

Consists of a mixture of finely divided aluminum powder and a special vehicle containing hard varnish resin, raw linseed oil and turpentine. This paint has very good heat resisting properties and when applied to iron and subjected to a dull red heat is only slightly affected.

Anti-Corrosive Ship’s Bottom Paint

This paint is generally made of metallic zinc, zinc oxide, shellac, alcohol, pine tar and turpentine and is designed to insulate the metal in the anti-fouling coat from the steel plating, preventing corrosion and pitting. Anti-corrosive and anti-fouling ship’s bottom paints differ radically from oil paints in that the vehicle portion consists of shellac, alcohol, and pine tar solution. This produces a very rapid drying paint which can be submerged a few hours after application. Anti-corrosive ship’s bottom paint is designed to prevent corrosion from electrolysis. This coat does not offer resistance to the flow of electric current but contains a metal which is electropositive to iron. Electrolysis decomposes this metal and deposits it on the steel hull. Insulation or protection from electrolysis is not obtained by paint which offers resistance to the flow of electric current since abrasion and movement of the plates will prevent the maintenance of a continuous film necessary to prevent the passage of current. A number of proprietary paints are on the market and are reported as giving satisfactory service. Anti-corrosive paint also provides a solid base for the anti-fouling paint.

Anti-Fouling Ship’s Bottom Paint

This paint is intended to prevent marine growth from adhering to the underwater surface of the hull. This is effected by the presence of a poisonous compound in the film, usually mercuric oxide, copper oxide, copper cyanide, etc. An efficient antifouling paint is so designed that it will exfoliate, thereby presenting new surfaces at regular intervals, In this class falls the so-called copper paint for wooden hulls. This paint usually contains a substantial percentage of copper oxide ground in a special vehicle.

Asphalt Solution

Is a viscous asphaltic solution in mineral spirit or turpentine substitute and is applied to metal surfaces as a priming coat for the bituminous cement and enamels. The enamel is solid and is applied hot ranging in thickness from 1/l6" to 1/4". Asphaltic compounds are specially prepared to resist fairly high temperatures without running or sagging, and low temperatures without being unduly brittle. Asphalt enamels made of a properly balanced mixture of asphalts or tars having various melting points and other specific characteristics, admixed with rosin, Portland cement and mineral spirits produce compositions which have been found to give excellent service. Bituminous compositions are usually applied to places with difficult access upon completion of new construction

Boottopping Paint

Boottopping paint is generally a mixture of zinc oxide, lamp black and a special varnish. This paint is applied at the waterline of steel vessels, and will last for several months, whereas an ordinary oil paint would be washed off or destroyed in a few days by the alternate action of the water and the air. The special varnish used in the preparation of boottopping paint requires careful consideration and should be tested for its suitability in the manufacture of this type of paint. Tung oil varnishes are very water resistant but have a tendency to thicken up or "liver" when mixed or ground in zinc oxide.

Canvas Preservatives

White and tinted – is usually a mixture of crude paraffine, paraffine oil, turpentine substitute and kerosene; if a tinted preservative is desired a quantity of zinc oxide and sufficient tinting material to produce the desired color is added. This type of preservative can be applied by painting with a brush, spraying with an air gun or by dipping the fabric.

Cork Paint

Known also as under cork, consists of varnish, a small quantity of linseed oil and drier and a good grade of whiting. This mixture is painted on the surface to be corked and allowed to become tacky. Ground cork of fairly large grain is blown or pressed on and the paint allowed to set hard. Cork paint is usually applied to interior surfaces in living quarters, store rooms, etc., which become chilled by the conduction through the metal, and sweating occurs due to the extremes in temperature; over the cork the usual interior finishing paint is applied.

Deck Paint

This type of paint is usually prepared with spar varnish, turpentine drier and coloring pigment, which dries rapidly forming a hard water resisting coating.

Linoleum Cement

Is usually a mixture of shellac, crude rubber, whiting, alcohol and gasoline and in some respects is similar to certain brands of marine glue on the market. This cement is used to bind the linoleum to the deck or other surfaces without the use of fastening appliances. It is of such a character that it allows the linoleum to spread without buckling or injury.

Metallic Oxide of Iron Paints

Are dark in color, usually red or brown, and when properly prepared are extremely durable. Red lead or zinc chromate or both of these pigments when added to an iron oxide base produces an excellent metal preservative paint which will give service equal to red lead. In connection with the application of paints intended for use as metal preservatives, it will readily be seen that an ordinary paint giving good protective service on wood will not be satisfactory to iron and steel, since the characters of the two surfaces are entirely different, steel presenting a relatively smooth, non-porous surface which makes it necessary for the excess oil or other vehicle to harden by oxidation or evaporation, whereas wood, having many pores, absorbs the excess oil which amalgamates with the fibers of the wood forming an inseparable bond. In this connection it is recommended that skilled labor be employed for the application of paint, and especially paint intended or designed for metal surfaces. Many failures of paint can be traced to careless handling or improper application.

Priming Paint

Red lead, free from coarse vitrified particles mixed with pure linseed oil makes the best priming coat for iron and steel. Consumers are cautioned, however, not to purchase or use red lead paste which has been ground sufficiently long enough to over oxidize the oil. When pure dry red lead (containing a substantial amount of litharge as a natural constituent) is mixed with pure raw linseed oil within l8 hours before application it can be applied to iron and steel without the addition of a thinner or drier. This practice is not recommended, however, since the drying conditions usually encountered in marine painting are not very favorable and the addition of a thinner and drier will enable the operator to apply a thin uniform coat which will dry rapidly, forming a very tenacious, hard, elastic weather resisting film. Rust resisting or preservative coatings are usually dark in color, since the white pigments (basic carbonate, basic sulphate white lead and zinc oxide) have certain physical and chemical characteristics which make them unsatisfactory for priming paints for iron and steel.

Smoke Stack Paint

Smoke Stack Paint is usually made of zinc oxide, white lead, litharge and Damar varnish thinned with kerosene and a substantial amount of dryer added. This paint is very resistant to high temperatures. Another type of smoke stack paint is made as follows: white lead, silica, litharge, boiled linseed oil and mineral spirits. This mixture is tinted to the desired shade and applied in the usual manner.

Spar Varnish

It is pale in color, very rapid drying, water resistant, elastic and durable; it is used to coat the "bright work" of ships and due to its rapid drying qualities it is frequently used on repair work. This varnish can be brushed on a surface and spread out to a very thin film which accounts for its rapid drying properties. It is somewhat deficient in durability, however, owing to the thinness of the film.


The solid portion of paint usually white lead, red lead, oxide of zinc, oxide of iron, Van Dyke brown, Venetian red, Indian red, vermilion, Prussian and Chinese blue, ultramarine blue, blacks and lakes. In addition to the above mentioned pigments, the following Extenders are used: Barytes, silica, Asbestine, aluminum silicate, calcium carbonate, etc. Extenders have specific value and are used to reduce the spreading power and increase the thickness of the paint film.

Pigments – Color

Color pigments are used for tinting the base pigment and are usually as follows:

(a) Natural Earth Colors: Ochers, siennas, umbers, metallic brown, Indian red and mineral blacks.

(b) Chemical colors: Prussian and Chinese blue, lead chromate, chrome green, ultramarine blue, vermilion, etc.

(c) Carbon blacks made by carbonizing animal and vegetable substances.

Basic Carbonate – White Lead

Corroded white lead was first commercially produced in the United States about l00 years ago. This pigment is manufactured by two principal processes, known as the Dutch process, or stack method, and the chamber process, or quick method. The Dutch process probably produces about 75 per cent. of the corroded white lead used in the United States. Briefly described, this method is as follows:

A series of clay pots surrounded with tan bark and containing dilute acetic acid (vinegar) are filled with discs of metallic lead. Carbonic acid from the fermenting tan bark acts on the lead, converting it into hydrated carbonate of lead. This process requires about 90 days. In the Chamber process the dilute acetic acid acts on the finely divided metallic lead in the presence of carbon dioxide gas, producing a white pigment similar in every respect to the Dutch process white lead.. This process requires from one to two weeks.

Basic Sulphate – White Lead

Sublimed white lead or basic sulphate white lead is obtained from Galena, a lead sulphide ore. The mined ore is roasted and the fumes given off combine with the oxygen of the air and form a white powder. Basic sulphate white lead, a product of sublimation, exceeds the basic carbonate in fineness. It is considered by some to be superior to basic carbonate white lead in that it is relatively non-poisonous and resists the darkening action of sulphur gas to a great extent.

Zinc Oxide

This pigment has been commercially used as a paint pigment for a short time. It has, however, assumed a very important position in the paint industry and is a pigment of exceptional merit. Paints containing zinc oxide in appreciable quantities dry with a hard enamel-like surface, which is highly impervious to water. It is therefore very desirable in the manufacture of marine paints. In the manufacture of zinc oxide, the mineral is first mixed with powdered coal and spread on a bed of glowing coal. Air is blown through the charge volatilizing the zinc in the ore. This vapor is carried into the upper part of the furnace and converted into oxide of zinc by contact with the atmosphere. This oxide is drawn through cooling pipes, being finally deposited as an extremely fine powder in fabric bags.

Red Lead

This pigment is prepared by heating litharge to approximately 700 degrees Fahr. in contact with the air. It then takes up more oxygen and turns red. The composition of red lead varies from 65 per cent practically pure red lead, little or no litharge being present. The latter type is more expensive to make and is therefore sold at a higher price. Red lead is used extensively for the protection of metal and is usually applied as a priming coat.

Venetian Red

A brick colored pigment in which the ferric oxide content varies from 20 per cent to 40 per cent, the balance being calcium sulphate, also used in the manufacture of metal paints.

Indian Red

An earth pigment analyzing from 75 per cent to 90 per cent, the remainder being silica. Indian red when mixed with pure raw linseed oil and drier produces an excellent paint and tinting pigment.


A precipitated dye on a lithol barium or orange mineral base used for striping and tinting purposes, being one of the so-called permanent reds.


This is a natural earth pigment, which contains as high as 70 per cent ferric oxide, the remainder being silicate of aluminum, or clay. The best grades are obtained from Italy, and are used largely for tinting purposes and in the making of stains.


This is a natural earth pigment very much darker than sienna. This pigment is obtainable in commercial quantities in the United States, but the best grade comes from the Isle of Cyprus. It is used for tinting and staining purposes.

Ultramarine Blue

Ultramarine blue in its natural state (lapis-lazuli) is found in Tibet, Prussia, China and in the Andes of South America. It is usually found in the form of pebbles. This natural pigment is not used in the paint industry on account of its harsh granular texture. Artificial ultramarine blue is a chemical color and has great tinting power, is soft in texture and relatively opaque.

Prussian or Chinese Blue

This is a dark blue pigment which is a ferro-cyanide of iron and is prepared by chemical precipitation. This blue cannot be used in the tinting of white lead paints successfully. When Prussian blue is used for tinting white lead paints, it is acted upon and a chemical change in its composition takes place.

Chrome Green

This color is a mixture of Prussian blue and Chrome Yellow (lead chromate) and unless chemically pure is found mixed with an inert base such as barytes. Chrome green contains Prussian blue which under goes a chemical change when used for tinting white lead paints. Salt atmosphere attacks chrome green and bleaches it.

Chromium Oxide

This is a permanent green but is seldom used in the manufacture of commercial paints. It is used in special marine and railway paints and is unaffected by salt atmosphere or the white lead pigments. It is used on vessels in repainting the receptacle on which the port light rests.

Lamp Black

Lamp black is the condensed smoke of petroleum oils and is considered one of the most permanent blacks used.

Carbon Black

Carbon black is similar to lamp black in that it is intensely black in color. Its staining power is very great and due to its extreme fineness fairly large amounts of pigment have a tendency to separate from the paint and rise to the top of the liquid thereby making it difficult to incorporate and produce a uniform tint.

Metallic Zinc

Metallic zinc used in the paint industry is in finely divided form and is used in the manufacture of anti-corrosive ship’s bottom paint.


Shellac is the exudation deposited by a lac bug; it is soluble in alcohol and when cut in this solvent in the proportion of 2½ lbs. of gum shellac to one gallon of alcohol a good working shellac varnish is produced. Shellac varnish is applied to furniture, and to cover decks where the application of paint or varnish is not practical on account of the length of time required in drying. The use of shellac on woodwork exposed to the water is not recommended since the heat of the sun’s rays will soften shellac and form blisters.


The spreading medium or liquid portion of a paint which combines or holds in close union the solids or pigment portion. Linseed Oil is usually used as a base to which is added turpentine mineral spirits (or turpentine substitute) and a liquid drier.

Linseed Oil

Linseed Oil is obtained from the flaxseed, which grows in practically all parts of the world. It is of interest to know, however, that oil extracted from the flaxseed from the various sources varies greatly in quality. South American flaxseed produces a slow drying oil which forms a relatively soft film; North American flaxseed yields a higher percentage of oil, which dries more rapidly, forming a very tough, elastic, hard film. Oil obtained from India flaxseed varies in its drying properties, but is more desirable than South American oil and is generally preferred to North American oil for varnish making, since it resists discoloration on prolonged heating.


Turpentine is obtained from the pine tree by direct or steam distillation of the sap collected from the growing tree. Wood turpentine is produced by steam distillation of finely cut or macerated pine wood. The lower grades of wood turpentine have an objectionable, sharp odor and are not desirable in the manufacture of interior paints. Turpentine has a high oxidizing value which causes the rapid drying of paints and varnishes. Turpentine is used to reduce the consistency of the oil paint so as to allow it to be spread in thin fine coats.


In most cases the drying effect of the pigment is not sufficient and liquid dryers are added to accelerate the drying. The most commonly used dryers are composed of lead, manganese and cobalt or a mixture of these metals combined with pure linseed oil and a hydrocarbon solvent.

Painter. A length of rope secured at the bow of a small boat for use in towing or for making it fast. It is sometimes termed a bow-fast.

Painters. Inside workmen who mix paint, also those who paint, varnish and polish joiner work in the shop. Outside, workmen who apply the paint aboard ship.

Pall, Pawl. A term applied to a short piece of metal hinged to engage in a revolving mechanism for the purpose of preventing recoil. Usually fitted to capstans, winches and windlasses.

Palm. The fluke, or more exactly, the flat inner face of the fluke, of an anchor; a sailmaker’s protector for the hand used when sewing canvas. It consists of a strong canvas or leather strap to which is secured a flat metal disc thimble to drive the needle through the canvas; a flat surface at the extremity of a strut or stanchion for attachment to plating, beam or other structural member.

Panel. The part of a door or bulkhead, the edges of which are inserted in the stiles and rails.

Panel, Flush. A panel, the surface of which is flush with the surface of the stiles and rails.

Panel, Molded. A panel which is set in and the stiles and rails projecting beyond the surface.

Panel, Raised. A panel, the surface of which projects above the surface of the stiles and rails.

Panel Raiser. A wood working machine designed to dress down the edges of the work so as to leave a raised panel.

Panting. The in and out vibrations of the frames and plating. Most noticeable in the bow and stern.

Panting Beams. See Beams, Panting.

Panting Stringer. See Stringer, Panting.

Parallel Middle Body. That portion of a vessel’s body throughout the extent of which the cross sections retain the same area and shape as the midship section.

Parallel Ruler. This was used for plotting a course on a sea chart with a compass card.

Parbuckle. An improvised purchase used in hoisting and lowering casks or other cylindrical objects where a tackle or crane is not available. The middle of a rope is secured above the object to be hoisted or lowered, the two ends passed over and under it and then brought back again. Hauling on the two ends raises or lowers the object as desired. This method is extensively used in handling shells in the turrets of men-of-war. The shells being stowed upright, base downward, on the turret floor are easily parbuckled horizontally in the bight of a single rope.

Parceling. Narrow widths of canvas which when tarred are wound around ropes, following the lay and overlapping in order to shed water. The parceling is applied after worming preparatory to serving.

Parent Form. A ship’s form from which a series of forms are derived by the systematic variation of certain characteristic features.

Parrel. A rope or metal collar attached to a band on either side of a yard near its middle and encircling the mast. By this means the yard is attached to the mast though allowed a vertical movement.

Part Double Bottom. Descriptive of a vessel which is fitted with a double bottom extending throughout a portion of her length only.

Partial Bulkhead. See Bulkhead, Partial.

Parting Strip, Window Frame. The narrow strip fastened to the inside of the stiles for the purpose of dividing the paths of the outer and inner sashes or blinds.

Partner, Mast. See Mast Partner.

Partner Plate, Rudder. A term applied to plates fitted around the rudder stock where it pierces a deck.

Passers. Usually boys who receive the heated rivets from the heaters and deliver them to the holders-on.

Passing Tongs. Long handled tongs used by rivet passers to handle the heated rivets.

Pattern Makers. Workmen who fashion the wood forms or patterns for the use of the foundrymen in setting up molds. Inside pattern makers prepare those patterns which can be made from plans such as machinery parts. Outside pattern makers prepare patterns for those castings which are to be fitted to the hull such as stems, stern posts, and hawse pipes.

Paulin. See Tarpaulin.

Pawl. A small part or member of a mechanism used to prevent overhauling. Pawls engaging ratchet wheels are fitted on windlasses, capstans, etc.

Paying. A term applied to the operation of filling the seams between planks, after the calking has been inserted, with pitch, marine glue, etc. Also applied to the operation of slackening away on rope or chain.

Peak. A term applied to the outer and upper end of a gaff.

Peak, Fore or After. The space at the extreme bow or stern below the decks.

Peak, Purchase. A tackle applied to the peak halyards to haul them taut and straighten the leech of the sail.

Peak Tank. A tank or tank space built into or formed in the extreme forward or after lower portion of a vessel’s hull.

Pelican Hook. A type of quick releasing hook used at the lower ends of shrouds, boat gripes, etc.

Pelorus. A navigational instrument similar to a binnacle and mariner’s compass but without a magnetic needle. The instrument is used for taking bearings, especially when the object to be sighted is not visible from the ship’s compass. Also known as a Dumb Compass.

Pendant. A length of rope usually having a thimble or block spliced into the lower end for hooking on a tackle, and when suspended from a masthead, yard, or gaff, is known as a mast head pendant, brace pendant, etc.

Pendants, Rudder. See Rudder Pendants.

Perfect Fluid. A theoretical fluid without viscosity or surface tension and incapable of internal friction or of friction against any object.

Period of Roll. The time occupied in performing one double oscillation.

Permeability. The percentage of a given space which can be occupied by water. The value of this factor is of great importance in all considerations of the effect of damage upon floatability and stability.

Permissible Length. That length of a vessel which may be flooded without causing her to sink below the margin line.

Perpendicular, After. See After Perpendicular.

Perpendicular, Forward. See Forward Perpendicular.

Pet Cock. See Cock, Pet.

Photostat. A machine for making photographic reproductions of tracings, blueprints, etc. The reproduction may be to the same, a greater or a smaller scale. The term is also applied to the photographic reductions made on these machines.

Picklers. Men who put steel plates through an acid bath in order to remove the mill scale preparatory to laying out and working the material into the ship.

Pier. A structure of iron, wood, or concrete, resting on piles built out into the water for use as a landing place for vessels, pleasure resorts, etc.

Pieces of Eight. This Spanish silver coin (dollar) was romantically the currency of Caribbean pirates, but was more important as the bullion which financed Spanish expansionism in the Americas from the l5th century on. It was the currency of the Hispano-American colonies, and remained coin of the realm in places such as Peru and Chile, Guatemala and Mexico, Honduras and Colombia long after they had wrested independence from their decaying conquerors. Pieces of eight were even used in the early settlements of Australia from 1788 onwards and in the North American colonies, where they were current until as late as 1857. In 1792 the Americans passed legislation to introduce their own currency, which was called the dollar after the old Spanish version, but there were so many Spanish silver dollars around that they had to be used for a long time after. Other countries would use pieces of eight that had been counter-stamped with their own design. They were even used in Britain during the silver shortage of 1797; the head of George III was overstamped on these. Firms in Birmingham and elsewhere in the 19th century would sometimes overstamp old pieces of eight with their name or device and circulate them as TRADE TOKENS. A hoard of pieces of eight recovered from the wreck of the Dutch ship Hollandia contained some splendid coins that had been newly minted at Mexico City for the Spaniards before the ship sunk after striking the Gunner rock in the Scilly Isles in 1743. They bear on one side the Imperial Crown of Spain surmounting the Spanish Royal Family’s coat of arms, surrounded by the legend "Philip V of Spain and the Indies, by the Grace of God", and with a figure eight to indicate the coin’s value of eight reales. The reverse has two globes representing the Old and New Worlds, above which is the Spanish Imperial crown. On each side of the globes are pillars representing the Pillars of Hercules at the entrance to the Mediterranean, and under the globes are lines to indicate the sea that divided the Old and New Worlds with, finally, the date 1741. On some pieces of eight the Pillars of Hercules indicated that these showed the limit of the Old World: such would have the motto "Nothing Beyond". Such coins found in submerged wrecks are often badly worn if loose, but can be in almost mint condition when cemented in a conglomerate of sand and gravel, which can be carefully dissolved.

Pig Iron. Iron cast in the form of a rough oblong or bar.

Pigment. See Paint.

Pilaster. An ornamental column or false stanchion on a light bulkhead. It usually extends out from the bulkhead for a distance of about one half its diameter.

Pile. A pole or post generally of wood, though sometimes of metal or concrete, driven into the earth along the bank or in the bed of a body of water for the support or protection of bridges, piers, etc.

Pillar. A post constructed of wood or steel and used as an intermediate support for girders and deck beams. Also used as reinforcement under decks in the way of guns and heavy foundations, thus helping to distribute the load to the lower structural members.

Pillar, Built-up. A term applied to a column that is constructed by riveting plates and shapes together.

Pillar Crane. See Crane, Pillar.

Pillar, Deck. A term applied to a pillar supporting a deck. It is usually given the name of the deck that it supports, as Upper or Main Deck Pillar.

Pillar Head. A term applied to the upper end of a pillar.

Pillar Heel. A term applied to the lower end of a pillar.

Pillar, Hold. A column fitted in the hold of a ship for the purpose of supporting the lowermost deck. They are generally much longer and of greater sectional area than the pillars fitted between decks.

Pillar, Middle Line. A term applied to a column erected on the center line of the ship.

Pillar, Movable. A term applied to a portable pillar that can be easily shifted.

Pillar, Pipe. A term applied to a column constructed of piping or tubing.

Pillar, Portable. A term applied where the pillars are removable. A disadvantage of this type of pillar in a hold is, that if it is taken out while the cargo is being stowed, that is difficult to get back in the proper position.

Pillar, Quarter. A term applied to a column fitted from about one third to about one half the distance from the center line to the side of a vessel and to columns in the way of the sides of hatches.

Pillar Socket. A receptacle, usually a casting, for taking the end of a pillar. A common type consists of a hollow cylindrical piece set up on and connected to a flat base piece by triangular shaped webs.

Pillow. A block of timber used as a rest piece for the lower end of a mast or the inner end of a bowsprit.

Pilot Bridge. See Bridge, Navigating or Flying.

Pilot House. A house designed for navigational purposes. It is usually located forward of the midship section and so constructed as to command an unobstructed view in all directions except directly aft along the center line of the vessel where the smoke stack usually interferes.

Pilot Lamp. See Lamp, Pilot.

Pin, Marking. A short piece of pipe of approximately the same diameter as the rivet holes in a template. The pin is dipped in whiting and then thrust through the holes in the template to mark their location on a plate or shape.

Pintle, Heel. A term applied to the lower pintle.

Pintle, Locking. A term applied to a pintle having a head turned on the bottom end to prevent the rudder from unshipping. It is well to place this pintle at the top so that the rudder may be unshipped without dry docking, by trimming the vessel by the bow.

Pintles. A term applied to the pins or bolts which hinge the rudder to the gudgeons on the stern post. These pins are cylindrical in shape in the way of the gudgeons up to the rudder lug. Through the rudder lug they are given a conical taper and above the lug a thread is cut for a nut. The taper provides a shoulder which, by tightening on the nut, firmly fixes the pintle to the rudder lug. It is to be noted that the weight of the rudder should be carried by the rudder stock to a bearing above, and that the pintles should serve as a hinge and as a bearing only for the side pressure of the water. The pintles are often fitted with a brass sleeve in the way of the gudgeon which is provided with a white metal bearing surface. The upper pintle sometimes has a head turned on the bottom for the purpose of preventing the rudder from moving upward and unshipping itself.

Pipe, Auxiliary Steam. A steam pipe leading from the steam down to auxiliary engines.

Pipe Berths. See Berth.

Pipe Bending Machine. A machine designed for bending pipe or conduit. Pipe bending machines are similar to bending presses except that special dies are used to suit the size of pipe being bent.

Pipe, Bilge Suction. A pipe leading from the well, which collects bilge water, to the bilge pump.

Pipe Coverers. Workmen who fit the insulating material on pipes. They also fit insulating material wherever necessary, as on boilers and engines.

Pipe Cutting Machine. A machine designed for cutting pipe.

Pipe Cutting and Threading Machine. A combination machine designed for both cutting and threading pipe.

Pipe Down. The signal on board a naval ship for the crew to sling their hammocks preparatory to retiring for the night. Used as a slang phrase, meaning to stop some annoying act.

Pipe, Jacket Steam. A pipe by which steam is led from the main steam pipe to a steam jacket.

Pipe, Main Exhaust. The principal steam lead from the engine to the atmosphere or condenser.

Pipe, Main Feed. A pipe by which water supplied by the feed pump is led from the hot well to the boilers.

Pipe, Oil Lubricating. A small oil supply pipe leading from a lubricator to some working part.

Pipe, Outboard Delivery. A term applied to the pipe leading from the outboard delivery valve to the shell or sea chest.

Pipe, Sea Injection. A term applied to the pipe leading from the sea chest to the outboard valve controlling the intake of water.

Pipe, Smoke. See Smoke Stack.

Pipe, Standard. A term applied to a pipe having a thickness equal to the standard adopted by the Wrought Pipe makers.

Pipe, Steam Escape or Waste. A pipe attached to and leading nearly to the top of the smoke stack from the upper deck. The steam from the safety valve is led into this pipe and escapes through it into the atmosphere.

Pipe, Suction. A pipe connected to the suction side of a pump and led to the compartment to be pumped.

Pipes, Scupper. See Scupper Pipes.

Piping, Oil. Systems of piping for loading, discharging, supplying, transferring, etc., fuel, cargo and lubricating oil.

Piping, Steam. Piping designed to carry live steam from the boilers to the main engines and to the various steam driven auxiliaries.

Piping System. Any system of pipes such as bilge and ballast, steam and exhaust, water, sanitary, steam heating and cargo and fuel oil systems that is installed aboard a ship for conveying water, oil, steam, etc.

Piping, Water. Systems of piping installed aboard ship for supplying, draining and transferring fresh and salt water. The sanitary, bilge and ballast, fire, condenser circulating and feed water systems, etc., come under this head.

Piragua. A term applied to a large canoe-shaped boat used by the Indians. Made by hollowing out a log.

Piston. The movable part upon which the steam in the cylinder exerts its pressure to produce rectilinear motion in alternate directions. It consists in general of a central disc with a heavy circumferential portion for the reception of the piston rings and a central boss to take the shouldered end of the piston rod.

Piston or Packing Rings. Rings fitted into annular channels in the cylindrical surface of the piston and designed to secure steam tightness between piston and cylinder barrel.

Piston Rod. That member which, being at one end securely attached to the piston, transmits the motion of the piston to the other moving parts of the engine. The piston rod projects through the cylinder stuffing box and terminates at its lower end in the cross head.

Piston Valve. See Valve, Piston.

Pitch. A term applied to the distance a propeller will advance during one revolution, the distance between centers of the teeth of a gear wheel, the spacing of rivets, etc.

Pitch Chain. See Sprocket Chain.

Pitch, Coal Tar. The residue obtained from the redistillation of coal tar.

Pitch, Hard Wood. The residue obtained by the redistillation of a hard wood tar.

Pitch, Pine. The black or dark-colored viscous residue from the distillation of resin oil or the residue after distilling the oils from crude pine tar.

Pitch Pockets. A pitch pocket is an accumulation of pitch occurring between the annular growth at any place in the timber.

Pitch, Propeller. See Propeller, Pitch.

Pitch of Rivets. See Rivet Spacing.

Pitching. The alternate rising and falling motion of a vessel’s bow in a nearly vertical plane as she meets the crests and troughs of the waves.

Pitting. The rapid corrosion of iron and steel in certain spots, thereby producing small indentations.

Pitting, Boiler. See Boiler Pitting.

Pivoting Point. That point during the progress of a vessel’s launch at which the moment of buoyancy about the fore poppets becomes equal to the moment of the vessel’s weight. At this point the stern begins to lift the vessel pivoting about the fore poppet.

Plain-laid Rope. See Rope, Plain-laid.

Plan Lines. See Lines, Plan.

Plane of Flotation. The water plane at which a vessel is floating.

Planer, Wood. A machine designed to dress or plane wood. The table of the machine is divided and a rotating shaft, carrying the knives or cutters, is carried between the two halves of the table.

Planer, Wood Portable. A wood planing machine power operated, used for the dressing down wood decks.

Plank, Margin or Nibbing. The extreme out plank of wood deck generally fitted just inboard of the waterways and sometimes notched out to revive the ends of the deck planks. Also placed around the outside of coaming of hatches, and around manhole frames where wood decks are fitted.

Planking. A term applied to wood decks and to the outside planking in wood or composite ships.

Planking, Bottom. A term applied to the outside planking between the garboard plank and the side planking.

Planks, Parting. The centerline planks of the deck near the bow.

Planksheer. A term applied to the plank fitted horizontally on top of the sheerstrake in wooden vessels. It generally has a rounded edge on the outboard side projecting a little beyond the planking and giving a finished appearance to the vessel.

Plate. Steel of other metal rolled or cast into form such that it has in general a consistent thickness which is small relative to its length and breadth. In ship work mild steel plates cut to proper form are used for the shell, decks and bulkheads. Plate is generally referred to by thickness only.

Plate, Apron. A plate fitted in continuation of the shell plating above the forecastle sheerstrake as the stem. These plates are sometimes fitted, one on each side of the stem, and serve as a foundation for the bow mooring pipes.

Plate, Bolted, Portable or Detachable. A plate fitted to a deck, tank top or bulkhead with the bolts permitting its removal. These plates are used for the purpose of preserving water-tightness and at the same time providing for occasional access.

Plate, Boss. A term applied to the plate fitted around the boss of a propeller post or around the curved frames in way of stern tubes. These plates usually require furnacing and are thicker than the adjoining plating.

Plate, Bow. Any shell plate fitted in the bow of a ship.

Plate, Bracket. See Bracket, Plate.

Plate, Butt. A plate used for end connections between the ends of planking on a composite ship.

Plate, Doubling. A term applied where an extra plate is fitted over the regular plating either for extra strength or to compensate for opening in the structure.

Plate, Face. See Face Plate.

Plate Flanged. A term applied where one or more edges of a plate are bent over to more a less of an angle. It also applies where an aperture is made in a plate with its edges stiffened by bending them at right angles to the plate.

Plate Furnace. See Furnace, Plate.

Plate, Furnaced. A plate that requires heating in order to mold it into shape. The most common types are the oxter and boss plates.

Plate, Garboard. See Keel, Flat Plate.

Plate, Keel. See Keel, Flat Plate.

Plate, Margin. See Margin Plate.

Plate, Oxter. The plate that is riveted to the stern from immediately below or on the transom. On account of the shape of the ship at this it usually requires furnacing and molding into shape. The oxter plate is given extra thickness to compensate for the stretching and heating necessary in bringing it to shape.

Plate, Rider. See Rider, Plate.

Plate Scarphing Machine. A machine for scarphing or tapering the corner of a plate. Shell plates are often scarphed where a seam crosses a butt lap to reduce the thickness of metal that the rivets penetrate and make a better job for water-tightness.

Plate, Sheerstrake. A plate forming part of a sheer-strake.

Plate, Stealer. A term applied to a plate taking the end of a drop strake or a plate combining two strakes into one. Stealer plates occur at the bow and stern, where the narrowing girth compels a reduction in the number of strakes.

Plate Straightener. A workman who removes from sheet metal any kinks, bumps or bulges so they will present a smooth even surface.

Plate, Stringer. See Stringer Plate.

Plate, Swash. See Swash Plate.

Plate, Tuck. A flat plate riveted to the arch piece and stern post of a stern frame, and having its forward edge flanged out to take the stern plating. It is advantageous when the propeller aperture is low, making the sides of the ship above the arch piece approximately flat.

Plate, Web. A wide girder plate as in a web frame or hatch beam. Angle bars are usually fitted on each edge.

Plate, Wood. The horizontal timbers which are fitted above the studding and which run parallel with the sill forming a part of the framing of a deck house.

Platen. A work bench or table the upper surface of which lies in a true plane,

Plates, Intercostal. The plates in an intercostal member. Where the plates are cut and attached to each continuous structural member that lies in their path. The continuous members are usually at or nearly at right angles to the intercostal members, and in order to pass each other one or the other of the girders must be composed of a range of short plates attached by angle bars or other means to the continuous members.

Platform, Deck. See Deck, Platform.

Plating, Clinker System. Where the edges of outside plating form lap joints so that one edge of a plate is inside while the other is outside. In this case tapered frame liners are used.

Plating, Flush System. Where the edges of the outside plating form butt joints so that a flush surface is formed. The connections between plates are made by seam straps and butt straps.

Plating, In and Out System. Where the edges of the outside plating form lap joints so that both edges of the plates are alternately inside and outside. In order to do this, the frames have to be joggled in the way of the outside strakes or frame liners of the thickness of the plating have to be fitted between the frames and outside strakes.

Plating, Rounded Gunwale. Plates bent to fit a rounded gunwale and connecting the side and deck plating.

Plating, Shell. The plating forming the outer skin of a vessel. In addition to keeping the water out of the hold, it contributes largely to the strength of the vessel.

Plating, Side. See Side Plating.

Plating Stern. The shell or outside plating covering the stern frames.

Plating, Tank Top. The plating forming the top of the double bottom. It is fitted to the tops of the floor plates, longitudinals and center keelson, and makes a complete inner skin extending over the bottom and sometimes up the sides of a vessel.

Plimsoll Mark. A mark stenciled in and painted on the side of a vessel designating the depth to which the ship may be loaded. Lord Plimsoll originated the idea of so marking vessels.

Plug, Fusible. See Fusible Plug.

Plug, Watertight Electric. An electric device for connecting an extension circuit with the main circuit and so arranged that the connection is watertight.

Plugs, Drain Hole. Plugs sometimes of wood but usually of special design with screwed ends for closing drains from tanks and other compartments.

Plumber Block. See Spring Bearings.

Plumbers. Workmen who install the water closets, urinals, baths, lavatories and other sanitary fixtures and their connections to the mains installed by the pipe fitters.

Plummet, Plumet. A sounding lead or weight attached to a plumb-line, also a weight attached to a fishing line to keep the float in position. Also used by fishermen to plumb the water’s depth.

Pneumatic Hoist. A hoist actuated by compressed air. A direct hoist may consist of a cylinder in which a piston travels up and down lifting the weight by means of a piston rod. A compact and more powerful type consists of cylinders actuating the hoist through gears. Steam can be used as well as air.

Pole Mast. A term applied where the lower and top-mast is in one piece.

Pontoon. A scow-shaped boat used in connection with engineering and military operations for the transportation of men and equipment or for the construction of bridges, etc. The term is sometimes applied to cylindrical airtight floats and ordinary scows used in salvage operations.

Poop Bulkhead. See Bulkhead, Poop.

Poop Deck. See Deck, Poop.

Poop Deck Stringer. See Stringer, Poop Deck.

Poop Deck Stringer Bar. See Stringer, Bar.

Poop Gunwale. See Gunwale, Poop.

Poop Sheerstrake. The strake of outside plating adjacent to the poop deck.

Poop or Poop House Frame. See Frame, Poop or Poop House.

Pooped. A term descriptive of a vessel which has shipped a wave over the stern.

Port. An opening in the plating or planking of a vessel for the purpose of providing access for passengers, loading and discharging cargo, taking on coal, discharging ashes and water, etc.

Port, Air. An opening in the side or deck house of a vessel, usually round in shape, and fitted with a hinged frame in which a thick glass light is secured. The purpose of the air port is to provide light and ventilation to the interior.

Port, Ballast. An opening in the side of a vessel provided for the purpose of loading and unloading ballast. A watertight cover or door should be provided.

Port, Bar. A strongback fitted on the inside of a port to hold the cover or door in position.

Port, Bow. An opening cut in the bow plating or planking to provide means of loading long timbers, piles, rails, etc. This opening must have a watertight cover as it is constantly under the pressure of head seas.

Port, Bulwark, Clearing or Freeing. A rectangular or oval opening in the bulwark just above the deck. These ports are necessary when seas break over the deck so that the ship can clear itself quickly. As these openings are about the size of a manhole, rods or bars are generally fitted across them. Flap doors are sometimes fitted on the outside hinging outboard.

Port, Cargo. An opening in the side plating or planking provided with a watertight cover or door and used for loading and unloading cargo.

Port, Coaling. An opening in the side of a vessel provided with a watertight cover used for loading coal aboard a vessel.

Port Flap or Lid. A cover or door hinged over a part so that it can only open outboard.

Port Frame. A term applied to the bars fitted around the edges of a port to compensate for the aperture and to hold the opening in shape.

Port, Gangway. An opening in the side plating, planking or bulwark for the purposes of providing access through which people may board or leave the ship or through which cargo may be handled.

Port, Hawser. An opening in the bulwark through which a hawser may be passed.

Port Lid. A cover hinged on the inboard side of an air port. It can be closed when the glass in the air port is broken or in danger of being broken.

Port, Raft. See Port, Bow or Stern.

Port Side. That side of a vessel to the left hand when looking from the stern toward the bow.

Port Sills. The horizontal members of a port frame.

Port, Stern. An opening in the stern plating or planking to provide means of loading long timbers, piles, rails, etc. This opening must have a watertight cover.

Port the Helm. A term originally applied to the operation of putting the tiller over to the left or port side, causing the rudder and ship to turn to the right or starboard. The operation of turning a steering wheel to port may cause the vessel to turn to either the right or left according to whether the leads are open or crossed or otherwise mechanically arranged. Different localities and countries and also different branches of the marine in the same locality have their own rules as to whether the ship turns with or against the wheel. Thus an order to port the helm on a vessel plying the inland waters or harbors or on the ship of a foreign country might he interpreted in the opposite direction from the same orders issued on board some deep sea and naval vessels.

Portable Pillars. See Pillars, Portable.

Portable Scarphing Machine. A scarphing machine designed to permit its being moved around to suit the work instead of requiring the work to be brought to the machine.

Post Crane. See Crane, post.

Post, Propeller. See Propeller Post.

Post, Stern. See Stern Tube.

Power Factor. The ratio of the electric power in Watts to the apparent power in volt amperes in an alternating current circuit.

Precession. See Gyroscope.

Press. A machine designed to exert pressure on a given area for purposes such as drawing, embossing, trimming, punching, forging, etc.

Press, Bending. A vertical press with two supports located below and equi-distant each side of a pressing head. Used for bending or straightening bars, shafts, pipes, etc. Horizontal types of bending presses are also used.

Press, Embossing. A machine designed to produce raised figures or letters on name plates, label plates, etc.

Press, Flanging. A press for flanging plate metal. The flanging may be done hot or cold.

Press, Inclinable. A press designed to be used in a vertical or inclined position.

Pressure Gage Glass. The glass forming a cover over the face of a pressure gage.

Pressure, Hydrostatic. Pressure induced by a liquid. Usually hydrostatic pressure is due to and in direct proportion to the difference in elevation between the free surface of the liquid and the point at which the pressure is indicated, the difference in atmospheric pressure at the two points being neglected. The difference in atmospheric pressure may, however, be appreciable, especially in cases of enclosed vessels in which the pressure may be increased by mechanical means. Hydrostatic pressure may be measured in pounds per square foot, but is also often measured in "feet" or "inches of water" or "inches- of mercury," in which cases a pressure is signified equal to the pressure induced by a column of water (or mercury) at the stated height. One foot head of water is equivalent to 62.4 pounds per square foot or .43 pounds per square inch.

Preventer. A supernumerary member, such as a stay, shroud, or any rope, chain, etc., whose only function is to assist or be substituted for another when under unusual stress or when damaged or lost.

Preventer Bolts. Bolts used to secure the preventer plates.

Preventer Plates. Metal plates secured to the lower ends of the chain plates in large sailing vessels to assist in taking the stress.

Preventer Stay, or Preventer Backstay. An additional stay so secured as to be easily slacked away to allow a beam to swing around. Usually attached to the deck on or near the center line.

Pricker. A cone shaped tool used to make holes in canvas or to spread eyelet holes for working.

Prismatic Coefficient. See Coefficient, Prismatic.

Profile Plan. See Lines Plan.

Progressman. A man assigned to follow up work in a shipyard and make reports concerning the progress of the same.

Progressive Rupture. A rupture or break which starts at the point of maximum unit stress and then spreads with the recurrence of the strain. Progressive rupture may occur in such members as plates which are stressed to rupture at one point only. When failure occurs at this point the total stress is then perforce concentrated over a smaller area of cross section which naturally increases the unit stress resulting.

Progressive Speed Trials. A series of speed trials over a measured course, successive trials being run at varying speeds.

Promenade Deck. See Deck, Promenade.

Promenade Deck Stringer. See Stringer, Promenade Deck.

Promenade Deck Stringer Bar. See Stringer Bar.

Pro-Metacenter. A term used by some authors to designate a point on the metacentric involute directly above the center of buoyancy for any inclined position of the vessel.

Proof Strain. The test load applied to anchors, chain or other parts, fittings or structure to demonstrate proper design and construction and satisfactory material.

Proof Strength. The proof strength of a material, part or structure is the strength which it has been proved by tests to possess. The term is often used in referring to chain cable, wire rope and the like.

Propeller. A propulsive device consisting of a boss or hub carrying radial blades, from two to four in number, the rear or driving faces of which form portions of an approximately helical surface, the axis of which is the center-line of the propeller shaft. The propeller is ordinarily located at the after end of the propeller shaft. The rotary motion imparted to this shaft by the engine turns the propeller, thereby exerting a rearward thrust upon the water which reacts to force the ship ahead. The selection of proper characteristics, such as diameter, revolutions, pitch, etc., the accurate determination of blade thickness, shape, etc., and the great care in construction and finish are essential to the securing of the best results from the propeller in service.

Propeller Aperture. See Aperture.

Propeller Blade, Back of. The forward side of the propeller blade.

Propeller Blade, Developed Area of. The actual area of the surface of the blade.

Propeller Blade, Projected Area of. The area enclosed by the trace on an athwartship plane of the perpendiculars drawn from the edge of the propeller blade.

Propeller Blade, Rake. The sloping aft from a position at right angles on the axis of propeller shaft of the propeller blades.

Propeller Blade, Root of. That portion of the blade closest to the hub or boss.

Propeller Blade Tip. The outermost portion of the propeller blade.

Propeller Blade Tip Clearance. Generally the shortest distance between the skin of a vessel and the circle swept by the propeller tips.

Propeller Blades, Screw. The radial arms, attached to the propeller hub, the faces of which form portions of an approximately helical surface the axis of which coincides with that of the propeller shaft. Blades are either cast in one piece with the hub or cast separately and designed to be attached to the hub with bolts. In this latter case provision is usually made for a slight adjustment in pitch by means of the shape of the bolt holes.

Propeller Boss. The central portion of the screw propeller which carries the blades and forms the medium of attachment to the propeller shaft. It is taper bored for the reception of the propeller shaft and slotted for the key. When properly placed upon the shaft it is forced home and secured in its final position by means of the propeller lock nut.

Propeller Cavitation. That condition of screw performance in which increase of torque fails to produce a corresponding or reasonable increase in thrust.

Propeller Diameter. The diameter of the circle tangent to the tips of the propeller blades.

Propeller Disc Area. The area of the circle swept by the blade tips of a propeller.

Propeller Driving Face or Face. The after face of the propeller blade; that face which acts directly upon the water when driving the vessel ahead.

Propeller Efficiency. The ratio of the thrust horsepower delivered by the propeller to the shaft horsepower as delivered by the engine to the propeller.

Propeller Following Edge. The after edge of a propeller blade.

Propeller Frame. See Stern Frame.

Propeller Guard. A frame work fitted somewhat below the deck line of narrow, high speed vessels with large screws and so designed as to overhang or house the projecting propeller tips.

Propeller Leading Edge. The forward edge of a propeller blade.

Propeller Pitch, Nominal. The distance (measured parallel to the axis of rotation) between similar positions of appoint of the driving face of a propeller blade in successive revolutions. When the driving face of a propeller blade lies entirely in a true helical surface the blade is said to have uniform pitch. When the pitch at the following edge is greater than that at the leading edge, the blade is said to have axially increasing pitch. When the pitch near the tip is greater than that near the hub the blade is said to have radially increasing pitch.

Propeller Pitch, Virtual. The pitch of a theoretically perfect blade of no thickness which would act as does the actual blade. The pitch of the back of a propeller blade varies greatly from that of the face of the blade. Inasmuch as the back exercises a material influence upon propeller performance, correct conclusions are impossible unless proper allowance is made therefore. The virtual pitch as above defined meets this requirement.

Propeller Post. The forward post of a stern frame on vessels having a center line propeller. It provides a support for the stern tube and propeller shaft as well as a joining frame for the converging sides of the ship at the stern.

Propeller Racing. The sudden increase in the number of revolutions made by the engine when the propeller blades or paddle wheels are lifted clear of the water, or nearly so, due to the roll or pitch of the ship.

Propeller Shaft. That length of shafting in a screw steamship which carries the propeller. It is the after-most piece of shafting and at its outermost end is coned, slotted and threaded for the attachment and proper securing of the propeller itself. This piece of shafting is carried directly by the propeller strut or stern bearing and is made slightly larger than the line shafting as a precaution against corrosion and shock. It is generally encased in a brass sleeve to provide proper bearing surface and to protect the shaft from corrosion.

Propeller Slip Angle. The angle between plane of blade face and its direction of motion.

Propeller Slip, Apparent. The value of the fraction Propeller speed – speed of ship

Propeller Slip or Slip Ration; Apparent True Slip. The ratio of speed of slip to speed of propeller.

Propeller Speed Ratio. The speed of advance divided by the speed of propeller.

Propeller Sweeping Up. The process of preparing molds for the casting of a screw propeller in the foundry. It ordinarily consists of the generation of a helical surface by the revolution of a horizontal straight edge, called a sweep, about a central vertical column to which the sweep is so attached as to permit of vertical motion. At its outer end the sweep follows the helical edge of a guide board erected at the proper radial distance from the central column. The foregoing applies to propellers having a vertical generatrix. For those having an inclined generatrix, the straight edge is set at an angle other than 90° to the central column.

Propeller Thrust. The effort delivered by a propeller in pushing a vessel ahead. The power resulting from the propeller effort is termed thrust horsepower. It is equal to the actual thrust in pounds multiplied by the distance in feet moved by the ship per minute divided by 33,000.

Propeller Thrust, Deduction. The actual thrust of the propeller minus the tow rope resistance of the ship or the net thrust of the propeller. In driving a ship ahead the screw exerts a suction upon the afterbody of the ship, thereby virtually increasing its resistance over what it would be without the screw. The wake created by the ship’s hull in moving through the water affects the action of the screw favorably. These two factors work against and partially offset each other.

Propeller Tip Speed. The speed in feet per minute swept by the propeller tips generally used as that corresponding to the maximum designed revolutions of the machinery.

Propulsive Coefficient. See Coefficient, Propulsive.

Propulsive Efficiency. The ratio of effective to indicated (or shaft) horsepower.

Protection Plate. A term applied to the plate fitted in the way of the hawse pipe for protection against blows from the flukes of the anchor.

Protractor. An instrument with graduated scales, for measuring angles or setting them out, and for other measurements.

Prussian Blue. See Paint.

Puddening, Pudding. Pads constructed of old rope, canvas, oakum, etc., in any desired shape and used on rigging to prevent chafing or on the stem of a boat to lessen the force of a shock.

Puddling. Described under Steel and Iron.

Pulley or Sheave. See Sheave.

Pulsometer. An apparatus for pumping water consisting of chambers in pairs, wherein steam is condensed, making a vacuum in alternate chambers. The water drawn into a chamber is forced out by the admission of steam under pressure.

Pump. A machine actuated by hand or power for raising and transferring fluids or gases and for inducing a vacuum.

Pump, Admiralty. A direct acting simplex or duplex pump with the piston and plunger on a vertical rod. In this type of pump the valves for the admission and discharge of water are easily examined and removed.

Pump, Air. The main air pump is for the purpose of reducing the back pressure in the low pressure cylinders or turbines and also for removing the condensed steam and vapor from the condenser. These pumps are driven either by a connection with a cross-head (usually the low pressure) on the main engine or by an independent engine. They are also made single and double acting. The single acting, direct driven type is the most common. As the vacuum in the condenser with the above described pump is dependent on the temperature of the hot well and as water will absorb only about 1/20 of its volume of air, dry vacuum pumps, augmenters, rotary and air ejector systems are being installed where a high vacuum is desired.

Pump, Air and Circulating, Auxiliary. This pump is composed of three cylinders: a steam cylinder for power, a water cylinder for circulating water through the auxiliary condenser, and a water cylinder for extracting the condensed steam in the auxiliary condenser and delivering it to the feed tank. This pump is an extravagant user of steam.

Pump, Air, Bucket Valves. Non-return valves placed in the moving bucket of the air pump and providing communication for the air, water and vapor from the suction to the discharge end of the pump cylinder. purpose of delivering the condensate to the hot well and allowing the air and vapor to escape.

Pump, Air, Discharge Valves. See Pump, Air, Head Valves.

Pump, Air, Dry Vacuum. A pump for discharging the air and vapor from a condenser into the atmosphere. The suction from this pump is located as high as possible on the suction line to the condensate pump or to a dry suction pad on the condenser. These pumps may be operated at a high speed, and they also keep a uniform head of water to the condensate pump.

Pump, Air, Dual. A combined wet and dry pump. A wet cylinder takes care of the condensate, and a dry air cylinder, which has an independent cooling system, densifies the air and vapor. This keeps the temperature of the hot well close to the temperature of the vacuum.

Pump, Air Ejector. A steam ejector connected to the condenser dry suction for the purpose of discharging the air and vapor into the atmosphere. A condensate pump handles the condensed steam.

Pump, Air, Foot Valves. Air foot valve. Non-return valves placed at the suction end of the cylinder.

Pump, Air, Head Valves. Non-return valve placed in the discharge end of the air pump cylinder for the purpose of delivering the condensate to the hot well and allowing the air and vapor escape.

Pump, Air, Suction Valves. See Pump, Air, Foot Valves.

Pump, Auxiliary Circulating. A pump to force water through the tubes of the auxiliary condenser. It is often combined with the auxiliary air pump. These pumps deliver to the main feed line only.

Pump, Auxiliary Feed. A pump with the following suctions: From the main feed tank, the reserve feed tank, the sea, the bilge, and from the bottom of the condenser. It can deliver to the boilers, the reserve feed tank or overboard. On account of the number of leads to and from this pump great care should be taken that fresh water is not pumped overboard, salt or bilge water pumped into the boilers, unless it is an emergency and so intended, or that the pump is used at all for boiler feed after pumping the bilge unless it has been thoroughly washed by a salt water circulation.

Pump, Ballast. A pump used for filling and emptying the ballast tanks. It has by-passes so that it can work the bilges and fire system either alone or in conjunction with the other pumps.

Pump, Bilge. A pump used aboard ship to remove accumulations of water in the vessel’s bottom tanks, hold and other compartments and discharge it overboard.

Pump, Bilge and Fire. See Pump, Fire and Bilge.

Pump Booster. See Pump, Transfer.

Pump Bucket. This term is sometimes used synonymously with the plunger. More correctly it is the cylindrical piston in vertical single acting pumps where the water is lifted from the bottom to the top of the cylinder. The term bucket should be used only when both top and bottom sides of piston come into operation in the performance of the function of the pump. Where one side of the piston only comes into operation, the term plunger should be used.

Pump Bucket Valve. A non-return valve placed in the moving bucket of a pump.

Pump, Centrifugal. This pump consists of a shaft to which vanes are attached and which rotates in a circular shape casing. Water enters the casing near the center or rotating shaft and moves outward along the vanes by centrifugal force. There is a discharge pipe at the circumference of the casing through which the water escapes. The pump may require priming to start it and is more efficient with low heads.

Pump, Condensate. The function of this pump is to deliver condensate to the hot well or feed tank.

Pump, Crank. A pump that, hand-cranked with a cast-iron wheel, was used for expelling water from the ship. It would be sited near the main mast. Rotation of the wheel drove long crank-shafts that descended into the pump-well at the bottom of the hold.

Pump, Direct Acting. A pump in which the piston and plunger are on the same rod but that does not require a fly wheel to carry it over the dead points.

Pump, Direct Driven. A pump whose plunger is actuated from the main engine.

Pump Discharge Head. The distance from the pump up to the point of delivery including frictional resistance.

Pump, Distiller. A pump used for transferring the distillate to the culinary and supply tanks.

Pump, Distiller Circulating. A pump for forcing circulating water through the distiller tubes to condense the vapor into water. It should have a by-pass to the flushing system.

Pump, Donkey. This pump has the same suction and discharge leads as the bilge pump has, and in addition is usually connected to the donkey boiler. Thus is can work when the main boilers are cold.

Pump, Double Acting. A pump that delivers on each stroke and from both ends of the cylinder.

Pump, Downtown. A hand pump that is also a force pump. It is worked by cranks on each side of the pump chamber or if placed on a lowerdeck the cranks may work through shafting gears. It is arranged to draw from all compartments and from the sea and discharges overboard and to the fire main.

Pump, Dredging. A heavily built pump of the centrifugal type used on dredges and sand suckers for removing sand, gravel, etc. from the bottom of rivers and harbors when building or deepening channels.

Pump, Duplex. A pair of pumps so placed that the piston rod of one pump actuates the valve of the other. ashes and such refuse as are liable to collect in the bottom of a ship, it becomes of great value when a large quantity of water is admitted to the ship through the hatches or by accident.

Pump, Evaporator Feed. This pump supplies the evaporator with salt water for vaporization.

Pump, Fire and Bilge. A pump used for keeping the bilges free of water, washing decks and for putting out fires. It has a sea suction and an overboard delivery of its own. It is more or less constantly in operation, keeping the bilges free of water and when used for washing decks should be cleaned by pumping salt water overboard. This pump has a suction to the bilge, drains, and inner bottom.

Pump, Flushing. See Pump, Sanitary.

Pump, Force. One that in addition to lifting the water also forces it out through piping to a point of delivery.

Pump Foundation. A term applied to a foundation supporting a pump and given the name of the pump as Ballast Pump foundation, Feed Pump foundation, etc.

Pump, Fresh Water. This pump delivers fresh water that moves back and forth or up and down in the from the culinary or supply tanks to a gravity tank, which is called the daily supply tank. The gravity tank feeds the fresh water supply lines to the quarters, galleys, pantries, lavatories, etc.

Pump, Fuel Oil Service. A pump for feeding the oil burner in a boiler.

Pump, General Service. A term applied to the main fire and bilge pump.

Pump Governor. See Governor, Pump.

Pump, Hand. A pump worked by hand. They are located in the upper decks and consequently have a high suction and are difficult to operate by hand. The amount of water that they will handle is so small that these pumps are not of much use in ships of any size.

Pump, Handy Billy. A portable hand pump.

Pump, Hydraulic Pressure. A pump designed to deliver against a heavy pressure. The pump and its parts must be extra heavy and strong.

Pump, Independent. A pump with its own engine. The piston and plunger are usually on the same rod, the valve gear being actuated from the crosshead.

Pump, Lift. A pump that lifts only and does not discharge against a head.

Pump, Lubricating Oil. The function of this pump is to force lubricating oil to the shaft and engine bearings and crossheads.

Pump, Main Circulating. The function of this pump is to take water in large quantities from the sea, force it through the main condenser tubes and then overboard. On account of the low head to be overcome and the large capacity required, it is usually of the centrifugal type. In addition to a suction line, sea injection valve, it has a by-pass to the bilge which may at any time be used in pumping water overboard either directly of through the condenser. As a centrifugal pump will handle ashes and such refuse as are liable to collect in the bottom of a ship, it becomes of great value when a large quantity of water is admitted to the ship through the hatches or by accident.

Pump, Main Feed. The function of this pump is to keep the water at the proper level in the boilers. It takes fresh water either from the main or reserve feed tanks. Some types are driven from a connection to the main engine and others have independent engines. The number and location of these pumps depends on the size of the ship and the design.

Pump, Oil. Oil pumps on shipboard are used for feeding the lubricating system, feeding oil burners on boilers, transferring fuel oil from one tank to another and to the settling tanks, and for handling cargo oil.

Pump, Oil Service. A pump for the circulation of lubricating oil.

Pump, Plunger. A solid or hollow cylindrical piston that moves back and fourth or up and down in the water cylinder of a pump. The plunger retains its full diameter when it passes through a stuffing box.

Pump, Reciprocating. A pump composed of one or more cylinders in which a piston or bucket moves back and fourth or up and down. The power is obtained from steam cylinders and depends on the area of the piston and steam pressure.

Pump Rose Box. See Pump, Strainer.

Pump, Rotary. This pump discharges through the action of a rotating cam or plunger and does not rely on centrifugal force.

Pump, Rotary Air. One form of rotary pump consists of a waterwheel which throws thin films of spray into a discharge pipe in which a steam ejector is installed. It removes air and vapor only while a condensate pump handles the condensed steam.

Pump, Sanitary. The function of this pump is to supply salt water to the flushing system and for baths. It may deliver directly but commonly discharges into a gravity tank, the overflow of which is carried to the water closets and troughs. It also supplies a tank in which a steam coil is installed for the purpose of providing for hot sea water baths.

Pump, Single Acting. A pump that delivers from one end of the cylinder only and on alternate strokes.

Pump Strainer. A galvanized iron box with the sides perforated by small holes, the combined area of which equals at least twice the area of the suction pipe. The object is to prevent refuse from clogging the pumps.

Pump Strum. See Pump Strainer.

Pump Suctions. In the midship and dead flat sections of a ship and where there is not a sharp rise in the floor or bottom three suctions are required, one at the keel and one on each side to make sure of clearing the ship when she has taken a heavy list. In the ends of the ship and where there is a sharp deadrise only one suction need be installed near the keel.

Pump, Transfer. An oil pump used for transferring oil from one tank to another and from the oil tanks to the settling tanks.

Pump, Water Service. A pump for circulating cooling water through shaft bearings, crosshead, slides, etc. The delivery should also by-pass to the fire main and to the distiller.

Pump Wells. A tank formed either independently or by the structural members of the ship in which the pump strainer on the end of a suction line is installed. The hot well may be an independent tank and is used to collect the condensate water.

Punch and Shear, Combination. A double ended machine designed for punching at one end and shearing at the other. Each end is controlled independently and may be operated simultaneously on two pieces of work.

Punch, Double End. A double ended punching machine, designed for punching holes in metal plates or shapes at both ends. The punches at each end are controlled independently and may be operated simultaneously on two pieces of work.

Punch, Horizontal. A punching machine in which the punch moves in a horizontal direction. This type is generally used for punching holes in shapes such as angles, zee bars, etc.

Punch, Multiple. A punching machine designed for punching more than one hole in a single operation.

Punch, Vertical. A punching machine in which the punch moves in a vertical direction. This type of punch is generally used for punching holes in plates.

Punching Machine. A machine used for punching rivet and bolt holes in metal plates, angles, I-beams, channels, etc.

Punt. A heavily built boat of rectangular shape used by workmen employed in painting, cleaning or repairing a ship’s topsides when in sheltered water’s.

Purchase. Any mechanical advantage which increases the power applied.

Purser. A ship’s officer who has charge of provision accounts, is head of the steward’s department, handles mail, etc.

Putty, Rust. A putty made from the cast iron filings or borings and sal ammoniac, used as a luting between the flanges of iron pipe, etc.

Pyrometer. An instrument for measuring the temperatures of the hot gases and steam in a boiler.


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