726

carrying capacity of these schooners, the largest of which are engaged almost entirely in the coal-carrying trade, is exceedingly large. Thus, the five-masted schooner is 318 feet in length, 44 feet beam, and 211⁄2 feet in depth. The vessel will carry 4,000 tons of coal on her maximum draft. A six-masted schooner is 330 feet in length, 48 feet in beam, and has 22 feet depth of hold. On her maximum draft of 24 feet she will carry 5,500 tons of cargo. Her lower masts are each 116 feet in length, and her topmasts 58 feet.

The seven-masted steel schooner of modern build has a bar keel of forged steel three and one-half inches in width by 12 inches in depth, which extends from stem to sternpost. There is a cellular double bottom with a continuous, single, vertical, keel plate weighing 22.5 pounds to the square foot. The upper bilge-strake is of 2834-pound plate for two-thirds of the length. The middle bilge-strake is of 30 pounds weight for the same distance and the lower bilge-strake 25 pounds. The bottom strake is of 20-pound plate, while the garboard strake is of 29-pound plate for two-thirds of the length. All of the plating reduces to 1834 pounds at the ends of the vessel, except in the case of the garboard strake, which will reduce to 25 pounds at the ends. There are three complete decks, which are of steel plating, the upper deck, forecastle and poop-deck being woodcovered. A collision bulkhead is worked in at a suitable distance from the stem. The lower masts throughout the vessel are built of steel, with lapped edges, flush butts, and stiffening angles extending inside for the full length. The plates are single-riveted at the edges and doubleriveted at the butts. The plating is double and stiffening double at the mast-partners and at the hounds. The masts are all 135 feet in length from the mast step to the top of the upper band, and they have a uniform diameter throughout of 32 inches. The topmasts are of Oregon pine. They are 58 feet in length over all, tapering from 18 inches in diameter to 10 inches, except the foremast, which is 64 feet in length and 20 inches at its point of greatest diameter. The booms of the first five masts are 45 feet in length by 14 inches in diameter, the spanker boom being 75 feet in length by 18 inches in diameter. The total sail area of the lower sails and topsails is 40,617 square feet. All of the standing rigging, and in special cases the running rigging for the lower sails, are of a high quality of wire rope. Although this vessel is propelled entirely by sails, she carries quite a considerable instalment of machinery, including one 9-inch by 10-inch Hyde double-cylinder ship engine, and five 6-inch by 8-inch Hyde hoisting engines. There are two vertical boilers 56 inches in diameter by 90 inches high, one in the forward house and one in the after house. The boilers were built for a working pressure of 100 pounds to the square inch. There are two 8-inch by 4-inch by 6-inch duplex pumps and two direct-acting steam pumps, with steam and water cylinder, each 12 inches in diameter by 12 inches stroke. As the result of the installation of steam power on board for the purpose of hoisting anchors and sails the number of hands necessary to work this large vessel is considerably reduced, the total number required being only 19 men. The total cost of the vessel delivered was about $250,000.

Steel Steamships. The modern ocean liner for freight and passengers, as built of steel, has a length over all of 630 feet; breadth, 73 feet 6 inches; molded depth from keel to upper deck, 56 feet. On a draft of 33 feet the displacement is 33,000 tons, and on a maximum draft of 361⁄2 feet, to which the vessel can be loaded whenever the depth of the harbors will admit of it, the displacement will be 37,000 tons. The space occupied by machinery is the smallest practicable, so that space for cargo may be as large as possible. In order that cargo may be readily stowed, the ordinary type of hold pillar has been dispensed with, and large boxshaped columns are fitted, supporting heavy girders which run longitudinally under the transverse beams which carry the decks. These columns are widely spaced, and in some cases only one is fitted in a hold, whereas by the older method 10 pillars would be required. A longitudinal bulkhead is fitted the whole length of the ship; this divides each hold into two separate compartments, and, therefore, the hatches are fitted in pairs, one to each hold. Some of the hatches are so large that bulky freight, such as a locomotive or freight car, or large marine or land boilers, can be lowered directly into the hold. Every hatch can be loaded or discharged simultaneously if desired. The cargo-handling plant on such a vessel is very complete, and. designed so as to cut down the number of men to a minimum. Two winches and two booms are fitted to handle cargo at each hatch. The booms, 34 in number, are built of steel. Two heavy booms are fitted to lift weights of from 30 to 50 tons. The winches for cargo handling are 34 in number, all electrically operated. One hold in the ship is devoted to carrying frozen meat, and is completely insulated; its capacity being about 2,500 tons. The insulation is so arranged that ordinary cargo can be carried on return trip. The coal bunkers are located above the boilers; the ends of the bunkers being inclined in such a manner that the bulk of the coal will gravitate through chutes and be deposited on the firing platform. The capacity of the permanent bunker is over 4,000 tons, and a reserve bunker is fitted contiguous to the boiler room, having a capacity for about 2,000 tons of coal. The boilers have a working pressure of 260 pounds per square inch. They will supply steam to two main engines of the tripleexpansion type, arranged side by side, working separate shafts. The propeller wheels are 20 feet in diameter, and revolve 78 times per minute. The horse power of the engines would be about 10,000, and will drive the ship at a speed of about 14 knots per hour. To realize the great size of the ship, one must but recapitulate the various decks, platforms, etc., from the keel to the top-most bridge. First there is the outer bottom of the ship; 6 feet above that is the inner bottom or floor; then within the molded or plated structure of the vessel are the orlop, lower, between, main, and upper decks. All of these decks are of steel plating, and the whole structure of the ship from the bottom to the upper deck is 56 feet in height, the upper deck running in an unbroken sweep the whole 630 feet length of the vessel. Above the upper deck are the promenade deck, the upper promenade deck, and the boat deck, this last being about 80 feet above the keel, while eight

Launching the steel cargo vessel "Pipestone County" at Hog Island shipyard

feet above this, or 88 feet above the keel, is the captain's bridge. Now, since the vessel at her lightest draft draws 17 feet of water, the captain's bridge, when the vessel is running light, will be over 70 feet above the water, and the passengers on the topmost upper deck will be between 60 and 70 feet above the water. See SHIP.

The United States Shipping Board. When the United States entered the World War in 1917 the preponderant demand of the army was for ships to transport men and materials to Europe. The United States Shipping Board was formed to control generally the increase and operation of the necessary ocean-going fleet, and this board established as a subsidiary the Emergency Fleet Corporation. The government advanced $50,000,000 capital to the latter body, taking the entire issue of stock to that amount. The duty laid upon the corporation was the providing of the largest possible ship tonnage in the shortest possible time. It began its labors by taking over a large number of the existing shipyards of the country and entering upon the construction of new ones in all sections of the country whence ships could be brought to deep water. Besides these activities the structural steel works everywhere were set to work fabricating parts of ships which were later to be assembled at the shipyards. In August 1918 the corporation had under its control more than 200 shipyards, half of which it had built. These were distributed over 27 different States, and aggregated nearly 900 ways with a maximum capacity for fabricated ships of 5,400 ships per annum. The actual output was held down to about half of this figure owing to inability to get materials fast enough, and the necessity of training the large forces of unskilled labor. Advantage was taken also of yards formerly in use for the building of wooden ships, especially in the South and on the Pacific Coast, where ship timber was plentiful and within easy reach.

The largest of these new yards was that at Hog Island near Philadelphia where nearly 30,000 men were employed. Efforts were made to celebrate the Fourth of July 1918 by the launching of 100 ships throughout the country. While the goal was not quite reached, more than 90 ships were actually sent into the water on that day. As an instance of the remarkable efficiency attained in some yards the Tuckahoe may be cited. This vessel was a 5,500-ton steel collier of the fabricated type, and was erected in 27 days at a Camden (N.J.) shipyard. On the 40th day from the date the keel was laid this vessel put to sea with a full cargo.

At the yards on the Great Lakes the possible size to which ocean-going ships might be built was limited by the size of the locks in the Welland Canal to a length of not more than 261 feet and a beam not exceeding 42% feet. These limitations were overcome in part by building a ship in two sections and assembling the parts when they reached tidewater in the Saint Lawrence. However, the width of the ship inexorably held them down to a limited length, not exceeding 350 feet and limited the tonnage to about 6,000 tons.

The work accomplished by the United States Shipping Board is best comprehended by comparing the present tonnage of the American

727

merchant marine with that existing immediately previous to the outbreak of the war. In June 1914 the total gross tonnage under the United States' flag, including the coastwise shipping and the fleet on the Great Lakes was 4,287,000 tons. In 1920 the gross tonnage was 12,406,123 tons, an increase of 283 per cent. The larger part of this increase has been in ocean-going vessels. The steam tonnage of the United States is now about 25 per cent of the entire tonnage of the world.

At the close of August 1919 the Shipping Board reported the delivery of 899 steel steamships, of 5,733,622 deadweight tons; 378 wooden steamships of 1,339,103 deadweight tons; and 15 composite ships of 32,500 deadweight tons - a total of 1,292 ships aggregating a deadweight tonnage of 7,125,225 tons. There were fitting out in wet basins 408 steamships aggregating 1,920,000 deadweight tons. There were on the ways in the several yards under the board's control 497 ships, aggregating 3,286,105 deadweight tons, and 227 steel steamships of a combined tonnage of 1,476,610 tons are still under contract but have not been begun.

At the close of August 1919 the Shipping Board had a total fleet of 1,280 ships under its control, with a combined tonnage of 7,706,400 deadweight tons. See, also, AMERICAN SHIPBUILDING; NAVAL ARCHITECTURE.

Ship Construction.- As the first step in the building of a ship' is the designing of it, the use to which it is to be put must first be decided on. What cargo is it to carry and how much? And what speed is desired? The answer to these questions will go far to determining the ship's dimensions-length, beam and depth and to a large extent the shape or "lines" of the under-water body and the horse power of its propelling machinery. The available depth of water in the harbors the ship is designed to visit is another controlling factor.

As the dimensions of the ship are not known, a trial design is first calculated upon the basis of the tonnage required; say, for example, 10,000 tons. The designer makes a calculation of a hull which will afford the space for 10,000 deadweight tons. The displacement of the completed ship will be the deadweight tonnage plus the weight of a hull to contain it. From experience and experiment is has been found that about 64-100ths of the whole carrying capacity (including engines, fuel, stores, etc.) must be added for the vessel itself. The ship carrying 10,000 tons will, therefore, have a displacement of about 16,400 tons. It devolves then upon the designer to determine length, beam and depth for his vessel from this total displacement. Into this problem enters first, if at all, the available depth of water in the harbors where the ship will trade. The shallower the possible draught, the greater, relatively, the beam. Aside from this the desired speed determines the proportion of length to breadth. The longer the ship- and the narrower- the speedier will she move for the same engine power. A trim underwater body with long gently flowing curves will require less horse power for a given speed than a body which is full and roomy well up to the bow and back to the stern.

For all of these calculations "constants" and "coefficients" are available to the constructor,

728

and his ship of 16,000 tons will, in ordinary course, figure out a length of between 450 and 470 feet and a beam of 55 to 60 feet, a draught of 25 to 28 feet, with a total depth of about 40 feet. With engines of 4,000 horse power this vessel should show a speed of about 12 knots.

In the planning of the ship the established rules of the several "Lloyds" and classification committees must be strictly adhered to in order that the vessel may be duly registered.

The chief factor in the hull of the ship is the shell plating. All other constructive parts of the ship, that is, the framing, are to be considered as practically the support and stiffening of the shell. In a large vessel the pressure of the water upon its exterior shell is enormous, the tendency being to cause a collapse. This pressure is tremendously increased by the violent blows of storm waves, and from the pitching and rolling sustained in rough water. Herein lies the demand for the knowledge of the skilled engineer, that the metal of which the ship is constructed shall be so disposed as to afford abundant strength and resistance to every possible stress and strain from without. Another series of strains arises from the load carried by the vessel, and acting from within, of great magnitude when the waves are high and the ship is subjected to a hogging strain when lying across the crest of a great wave, or to a sagging strain when lying across the trough between two waves. It is customary to regard the ship as a section of a tubular bridge, so far as the amidship's part is concerned. The ends of the vessel from their wedge-shaped construction are from that condition relatively stronger and may safely be more lightly built. The art of the shipbuilder is in the skilful adjustment of material to its purpose, so disposing it as to afford abundant strength, without interfering with generous cargo capacity.

In the more recent development of ship construction the system most approved is the longitudinal, as opposed to the transverse; the former having the advantage of stiffening the plating against transverse buckling as well as against fore-and-aft compression, a feat not attained by the transverse method of construction except by an undue and undesirable thickness of the plating and a close placing of the side frames thus adding unprofitable weight and diminishing cargo space.

The division of the hull into watertight compartments is a feature of present shipbuilding regarded as indispensable, particularly as regards the "collision bulkhead," placed near the bow, to keep out the sea in case the bow is broken by collision. The requirements of the Lloyds associations are that the compartments shall be of such a limited size that the vessel may still float safely if two of them are breached. This provision demands at least eight transverse bulkheads in the ordinary passenger liner. The compartments are connected by water-tight sliding doors which are operated by compressed air from the bridge, in case of emergency.

Given the hull, the remaining problem is its propulsion. A certain model of hull will be found to have a definite economic speed. Above this speed the engines labor without corre

sponding effect. This economic speed can be very closely calculated by the shipbuilder from the under-water lines of his model for the load of cargo it is to carry. He is thus able to decide upon the size of the propeller or propellers needed their diameter and pitch, and the number of revolutions they must make per minute to drive the ship at the desired rate. Engines powerful enough to turn the propeller easily and without strain the calculated number of revolutions may then be designed. One more problem remains, that of so attaching the engines to the ship that they actually form an integral part of its construction. The whole problem of propulsion is one of delicate adjustment. The engine will run best at a certain speed, and the vessel will run best at a certain speed. The closer these two conditions can be matched, the more successful and the more durable the ship. In most vessels nothing better than a compromise is reached. The instances in which hull and engines are really mated are so rare as to excite admiration - and incidentally to mark the possibilities to be achieved.

The reciprocating engine is of satisfactory efficiency for moderate speeds, ranging up to 0.88 for triple expansion and 0.92 for quadruple expansion engines. The latter are more economical of fuel, but require so much more engine room that little if any advantage is gained on the average voyage. The steam turbine is equal in efficiency to the quadruple expansion reciprocating engine, and does equal work with considerably less fuel, but, as it cannot be run astern, a second turbine must be provided for this purpose, or a transformer employed. Furthermore the turbine is of great efficiency only at high speeds too high to allow of its being connected directly to the propeller shaft. A combination of reciprocating engines and the turbine has worked well, where the turbine has been of the low pressure type and runs by the exhaust steam of the reciprocating cylinders. With triple screws on large vessels (20,000 tons and upward) the two wing shafts are operated by reciprocating engines and the centre shaft by the turbine. Turbines of the high speed type are successfully utilized when employed to run electric generators which, in turn, operate the shafts by electric drive.

It is quite impossible in the limits of space available in this work to even touch upon the multitudinous details of practical ship construction. For this information the student is referred to the excellent and complete treatises named below. See SHIP; SHIPBUILDING TERMS.

Bibliography.- Baker, G. S., 'Ship Form, Resistance and Screw Propulsion' (New York 1915); Biles, J. H., The Design and Construction of Ships (2 vols., London 1919); Holms, A. C., Practical Shipbuilding' (2 vols., London 1916); Kelly, R. W., and Allen, F. J., The Shipbuilding Industry) (Boston and New York 1918); Marvin, W L., The American Merchant Marine (New York 1902); Nelson's Encyclopedic Library, 'Ships and Shipping' (London 1914); Simpson, G., "The Naval Constructor' (New York 1918); Taylor, D. W., The Speed and Power of Ships' (New York 1910); Tompkins, A. E., Marine Engineering) (London 1908).