CHAPTER IVSAFETY LIES IN SUBDIVISION

Provisioning the Boats During a Boat Drill

Courtesy ofScientific AmericanLoading and Lowering Boats, Stowed Athwartships

Courtesy ofScientific American

Loading and Lowering Boats, Stowed Athwartships

In considering the excellent service rendered by the lifeboats of theRepublicand theTitanic, it should be borne in mind that the weather conditionshappened to be very favourable. The launching of lifeboats in rough weather is a difficult and perilous operation. Frequently the sinking ship will have a heavy list; if she lists to starboard, the boats on that side can be launched well clear of the ship, but the boats on the port or higher side cannot be so launched. As they are lowered, they will come in contact with the side of the ship and be damaged or capsized. Furthermore, should the ship be rolling, the boats are liable to be swung violently against the vessel and their sides may be crushed in or heavily strained, rendering them unseaworthy. Had a heavy sea, nay, even a moderate sea, been running at the time of theTitanicdisaster, how long would her heavily loaded boats have survived in water that was infested with ice floes? Their helplessness will be more evident when we remember that they weighed between one and two tons, and thatwhen they were loaded down with sixty-five people, the total weight must have been about six tons. Now a craft of six tons' displacement requires considerable handling, and the two or three sailors allotted to each boat, jammed in, as they were, among crowded passengers, would have been powerless in heavy weather to keep the boat from broaching broadside to the sea and capsizing.

The demand, then, for unsinkable ships is justified by the fact that the lifeboat is at best but a poor makeshift—that to put several thousand people adrift in mid-ocean is to expose them to the risk of ultimate death by starvation or drowning.

Courtesy ofScientific AmericanBoat Deck of Titanic, Showing, in Black, Plan for Stowing Extra Boats, to Bring Total Accommodations Up to 3,100 Persons

Courtesy ofScientific American

Boat Deck of Titanic, Showing, in Black, Plan for Stowing Extra Boats, to Bring Total Accommodations Up to 3,100 Persons

However, in view of the fact that ninety-five passenger ships out of every hundred are built with the single skin, low bulkheads, and non-watertight decks, which characterised theTitanic, it is certain that the cry: "A lifeboat seat for every passenger" is fully justified. The problem of housing the large number that would be required presents no insuperable difficulties, and there are several alternative plans on which the boats might be disposed. On page45will be found a proposed arrangement, reproducedby the courtesy of the "Scientific American," which shows in white the twenty boats actually carried by theTitanic, and in black the additional boats which would be necessary to increase the total accommodation to about 3,100 people. This plan would necessitate the sacrifice of some of the deck-house structures. Between each pair of smoke-stacks two lines of four boats each are stowed athwartships. The boat chocks are provided with gunmetal wheels, which run in transverse tracks sunk in the deck. Along each side of the boat-deck there is a continuous line of boats.

Courtesy ofScientific AmericanThe Elaborate Installation of Telegraphs, Telephones, Voice-tubes, Etc., on the Bridge of an Ocean Liner

Courtesy ofScientific American

The Elaborate Installation of Telegraphs, Telephones, Voice-tubes, Etc., on the Bridge of an Ocean Liner

Another plan would be to take advantage of the full capacity of the Welin davit with which theTitanicwas equipped, which is capable of handling two or even three boats stowed abreast. Three lines of boats carried on each side of the long boat-deck of a modern liner would provide ample accommodation for every person on board.

But we repeat—and the point cannot be too strongly urged—that however complete the lifeboat accommodation may be, it is at the best a makeshift.

The demand that every ship that is launched in the future shall be so far unsinkable as to serve as its own lifeboat in case of serious disaster is perfectly reasonable; for there are certain first-class transatlantic liners in service to-day—notably in certain leading English and German lines—which fulfil this condition. Considerations both of humanity and self-interest should lead to the adoption of similar principles of construction by every passenger steamship company. It is possible that the time will come, and it may indeed be very close at hand, when the most attractive page in the illustrated steamship pamphlet will be one containing plans of the ships, in which the safeguards against sinking—such as side bunkers, high bulkheads, and watertight decks—are clearly delineated.

Other things being equal, the protection of a ship against sinking is exactly proportionate to the number of separate watertight compartments into which the interior of her hull is subdivided. If she contains no watertight partitions whatsoever, her sinking, due to damage below the water-line, is a mere matter of time. If the inflow exceeds the capacity of the pumps, water will flow into the ship until all buoyancy is lost. Protection against sinking is obtained by dividing the interior of the hull into a number of compartments by means of strong, watertight partitions, or bulkheads. Usually, these are placed transversely to the ship, extending from side to side and from the bottom to a height of one or two decks above the water-line. They are built of steel plates, stiffened by vertical I-beams, angle-bars, or other suitable members. The bulkheads are strongly riveted to the bottom, sides, and decks of the ship, and the joints are carefully caulked, soas to secure a perfectly tight connection. In the standard construction for merchant ships, as used in theTitanic, the bulkheads are placed transversely to the length of the ship, and the number of separate compartments is just one more than the number of bulkheads, ten such bulkheads giving eleven compartments, fifteen, as in theTitanic, giving sixteen compartments, and so on. In the case of a few high-class merchant steamers, built to meet special requirements as to safety, bulkheads are run lengthwise through the ship. These longitudinal bulkheads, intersecting the transverse bulkheads, greatly increase the factor of safety due to subdivision; for it is evident that one such, running the full length of the ship, would double, two would treble, and three would quadruple the number of separate compartments.

Hydraulically-operated, Watertight Door in an Engine-room Bulkhead

The bulkhead subdivision above described is all done in vertical planes. Its object is to restrict the water to such compartments as (through collision or grounding) may have been opened to the sea. As the water enters, the ship, because of the loss of buoyancy, will sink until the buoyancy of the undamaged compartments restores equilibrium and the ship assumesa new position, with the water in the damaged compartments at the same level as the sea outside. This position is shown in Fig. 2, page57. It must be carefully noted, however, that this condition can exist only if the bulkheads are carried high enough to prevent the water in the damaged compartments from rising above them and flowing over the tops of the bulkheads into adjoining compartments.

In addition to lateral and longitudinal subdivision by means of vertical bulkheads, the hull may be further subdivided by means of horizontal partitions in the form of watertight decks—a system which is universally adopted in the navies of the world. For it is evident that if the ship shown in Fig. 2, page57, were provided with a watertight deck, say at the level of the water-line, as shown in Fig. 1, page57, the water could rise only to the height of that deck, where it would be arrested. The amount of water entering the vessel would be, say, only one-half to two-thirds of that received in the case of the vessel shown in Fig. 2.

If ships that are damaged below the water-line always settled in the water on an even keel, that is to say without any change of trim, theloss through collisions would be greatly reduced. But for obvious reasons, the damage usually occurs in the forward part of the ship, and the flooding of compartments leads to a change of trim, setting the ship down by the head, as shown in Figs. 3 and 4. If the transverse bulkheads are of limited height, and extend only to about 10 feet above the normal water-line, the settling of the bow may soon bring the bulkhead deck (the deck against which the bulkheads terminate) below the water. If, as is too often the case, this deck is not watertight—that is to say, if it is pierced by hatch openings, stair or ladder-ways, ventilator shafts, etc., which are not provided with watertight casings or hatch covers, the water will flow aft along the deck, and find its way through these openings into successive compartments, gradually destroying the reserve buoyancy of the ship until she goes down. The vessels shown in Figs. 3 and 4 are similar as to their subdivision, each containing thirteen compartments; but in Fig. 3 the bulkheads are shown carried only to the upper deck, say 10 feet above the water, whereas in Fig. 4 they extend to the saloon deck, one deck higher, or,say, 19 feet above the same point. Now, if both ships received the same injury, involving, say, the three forward compartments, a loss of buoyancy which would bring the tops of bulkheads in Fig. 3 below the surface, would leave the bulkheads in Fig. 4, which end at a watertight deck, with a safe margin, and any further settling of the ship would be arrested.

Fig. 1WATERTIGHT DECK AT WATERLINE LIMITS INFLOW OF WATERFig. 2HIGH BULKHEADS, WITHOUT WATERTIGHT DECK WOULD SAVE THE SHIP BUT PERMIT DEEP SUBMERSIONFig. 3SINKING BY THE HEAD; WATER FLOWING ALONG LOW BULKHEAD DECK AND ENTERING COMPARTMENTS THROUGH DOORS OR HATCHWAYSFig. 4DOWN BY THE HEAD, BUT SAVED BY HIGHER BULKHEADS AND WATERTIGHT BULKHEAD DECKFig. 5RELATIVE AREA OF FLOODING FROM SAME DAMAGE IN SHIPS,"A" WITH DOUBLE SKIN; "B" WITH SIDE BUNKERS; "C" WITH A SINGLE SKIN.TRANSVERSE BULKHEADS ON EACH SHIPDiagrams Showing Protective Value of Transverse and Longitudinal Bulkheads, Watertight Decks,and Inner Skin

Fig. 1WATERTIGHT DECK AT WATERLINE LIMITS INFLOW OF WATER

Fig. 2HIGH BULKHEADS, WITHOUT WATERTIGHT DECK WOULD SAVE THE SHIP BUT PERMIT DEEP SUBMERSION

Fig. 3SINKING BY THE HEAD; WATER FLOWING ALONG LOW BULKHEAD DECK AND ENTERING COMPARTMENTS THROUGH DOORS OR HATCHWAYS

Fig. 4DOWN BY THE HEAD, BUT SAVED BY HIGHER BULKHEADS AND WATERTIGHT BULKHEAD DECK

Fig. 5RELATIVE AREA OF FLOODING FROM SAME DAMAGE IN SHIPS,"A" WITH DOUBLE SKIN; "B" WITH SIDE BUNKERS; "C" WITH A SINGLE SKIN.TRANSVERSE BULKHEADS ON EACH SHIP

Diagrams Showing Protective Value of Transverse and Longitudinal Bulkheads, Watertight Decks,and Inner Skin

Ordinarily, it would suffice to carry the first two bulkheads at the bow and the last two at the stern to the shelter deck, terminating the intermediate bulkheads one deck lower. But whatever the deck to which the bulkheads are carried, care should be taken to make it absolutely watertight. Otherwise, as already made clear, the so-called watertight subdivision of the ship may, in time of stress, prove to be a delusion and a snare.

Although the longitudinal bulkhead, which is employed below the water-line, and chiefly in the holds and machinery spaces, is the least used, it is one of the most effective means of subdivision that can be employed. A certain amount of prejudice exists against it, on the ground that it confines the inflowing water to one side of the ship, causing it to list, if notultimately to capsize. But this objection merely points the moral that all things must be used with discretion. A single longitudinal bulkhead, built through the exact centre of a ship, would invite a speedy capsize in the event of extensive injury below the water-line. The loss of the British battleshipVictoriaemphasised that truth many years ago. But longitudinal bulkheads, carried through the engine and boiler spaces, at the sides of the ship, are a most effective protection. Not only is each of the large compartments in the wider central body of the ship divided into three, but along each side is provided a row of comparatively small compartments, several of which could be flooded without causing a serious loss of buoyancy.

These bulkheads, built some 15 to 18 feet in from the side of the ship, not only form an inner skin for the ship, but they serve as the inner wall of the coal bunkers. They extend from the inner bottom to the under side of the lower deck, to both of which they are securely riveted, the joints being carefully caulked, to render them watertight. The space between the ship's side and the bulkhead is subdividedby transverse watertight partitions (see plan ofMauretania, Fig. 3, page129), placed centrally between the main transverse bulkheads of the ship. A further and most effective means for protecting the buoyancy is to construct the ship with a double skin up to and preferably a few feet above the water-line. The inner skin should extend from the first bulkhead abaft the engine-room to the first or collision bulkhead, forward. This construction merely involves carrying the inner floor plating of the double bottom up the sides of the ship to the under side of the lower deck. As all merchant ships are built with a double bottom (see page107), the cost of thus providing a double skin below the water-line is small in proportion to the security against flooding which it affords.

The description of theTitanic, published at the time of her launch, stated that any two of her adjoining compartments could be flooded without endangering the safety of the ship, and the question must frequently have occurred to the lay mind as to why the ability of the ship to sustain flooding of her interior was confined to two, and not extended to include three or even more compartments.

The ability to stand the flooding of two compartments only is not peculiar to theTitanic. It represents the standard practice which is followed in all passenger ships, the spacing and height of whose bulkheads is determined in accordance with certain stipulations of the British Board of Trade. These stipulations, as given by Prof. J. H. Biles of Glasgow University, in his book "Design and Construction of Ships," are as follows:

"A vessel is considered to be safe, even in the event of serious damage, if she is able to keep afloat with two adjoining compartments in free communication with the sea. The vessel must therefore have efficient transverse watertight bulkheads so spaced that when any two adjoining compartments are open to the sea, the uppermost deck to which all the bulkheads extend is not brought nearer to the surface of the water than a certain prescribed margin.

"The watertight deck referred to is called the bulkhead deck. The line past which the vessel may not sink is called the margin of safety line.

"The margin of safety line, as defined in the above report, is a line drawn round the side at a distance amidships of three-one-hundredths of the depth at side at that place below the bulkhead deck, and gradually approaching it toward the aft end, where it may be three-two-hundredths of the same depth below it."

By referring to the diagrams on page66showing the disposition of bulkheads on certain notable ships, it will be seen that, in the case of theTitanic, the application of the Board ofTrade rule called for the extension of the bulkheads amidships only to the upper deck, which, at the loaded draft of 34 feet, was only 10 feet above the water-line! Compare this with the safe construction adopted by Brunel and Scott Russell over fifty-four years ago, who, in constructing theGreat Eastern, extended all the bulkheads (see page83) to the topmost deck, fully 30 feet above the water-line.

Closing, from the Bridge, All Watertight Doors Throughout the Ship by Pulling a Lever

Before leaving the question of bulkheads, the writer would enter a strong protest against the present practice of placing watertight doors in the main bulkheads below the water-line. They are put there generally for the convenience of the engine- and boiler-room forces, whose duties render it necessary for them to pass from compartment to compartment. As at present constructed, these doors are of the sliding type, and they can be closed simultaneously from the bridge, or separately, by hand. The safer plan is to permit no bulkhead doors below the water-line, and provide in their place elevators or ladders, enclosed in watertight trunks. Access from compartment to compartment must then be had by way of the bulkhead deck.

The advantage of lofty bulkheads was admirably illustrated in the case of theCity of Parisand theCity of New York, designed by Mr. Biles in 1888. Although these were small ships compared with theTitanic, their fourteen bulkheads were carried one deck higher. Biles laid down the rule that no doors were to be cut through the bulkheads, and in spite of strenuous objections on the grounds of passenger accommodation and general convenience in the operation of the ship, he carried his point.

COURTESY OF ENGINEERINGOLYMPIC AND TITANIC 1912LUSITANIA 1906GREAT EASTERN 1858CAMPANIA 1893PARIS 1868A Comparison of Bulkhead Protection in Some Notable Ships

COURTESY OF ENGINEERING

OLYMPIC AND TITANIC 1912

LUSITANIA 1906

GREAT EASTERN 1858

CAMPANIA 1893

PARIS 1868

A Comparison of Bulkhead Protection in Some Notable Ships

The wisdom of this construction was demonstratedyears later, when, as a result of an accident to her engines, the two largest adjoining compartments of theCity of Pariswere flooded, at a time when the ship was 150 miles off the coast of Ireland. There was no wireless in those days to send out its call for help, and for three days the ship drifted in a helpless condition. Thanks to her lofty bulkheads, the good ship stood the ordeal and was finally brought into port without the loss of a single passenger.

BULKHEAD SPACING ON NOTABLE SHIPSNAMEDate ofBuildingRegisteredLength,Feet[1]No. ofMainW. T.BulkheadsAverageLengthofCompart-mentsPer cent.ofLengthTitanic1911852.515536.2Lusitania1907762.016455.9George Washington1908699.013507.1Great Eastern1854-59680.096810.0Carmania1905650.015507.8Campania1893601.086711.1New York1888517.014376.7Alma1894270.711238.3[1]Figures in this column represent the length between perpendiculars.

BULKHEAD SPACING ON NOTABLE SHIPS

[1]Figures in this column represent the length between perpendiculars.

An interesting study of bulkhead practice in some notable ships is afforded by the table anddiagrams which are herewith reproduced by the courtesy of "Engineering." In the matter of height of bulkheads above the water-line, theGreat Easternstands first, followed by theParis, theLusitania, theCampania, and theTitanic.

The term "unsinkable," as applied to ships, is used throughout the present work in an accommodated sense. There never was but one unsinkable craft, and for that we must go back to the age of primitive man, who doubtless paddled himself across the rivers and lakes upon a roughly fashioned log of wood.

In the modern sense, an unsinkable ship is one which cannot be sunk by any of the ordinary accidents of the open sea, such as those due to stress of weather, or to collision with icebergs, derelicts, or some other ship.

Can such a ship be built?

Not only is it feasible to construct vessels of this type to-day; but, as far back as the year 1858, there was launched a magnificent ship, theGreat Eastern, in which the provisions against foundering were so admirably worked out that probably she would have survived even the terrific collision which proved the undoing of theTitanic.

TheGreat Easternrepresented the joint labours of the two most distinguished engineers of the middle period of the nineteenth century, I. K. Brunel and John Scott Russell. The former was responsible for the original idea of the ship, and it was he who suggested that it should be built upon the principles adopted in the rectangular, tubular bridge that had recently been built across the Menai Straits. To Scott Russell, as naval architect, were due the lines and dimensions of the ship and the elaborate system of transverse and longitudinal bulkheads.

Those were the days when the engineer was supreme. He worked with a free hand; and these two men set out to build a ship which should be not only the largest and strongest, but also the safest and most unsinkable vessel afloat. How they succeeded is shown by the fact, that on one of her voyages to New York, theGreat Easternran over some submerged rocks off Montauk Point, Long Island, and tore two great rents in her outer skin, whose aggregate area was equivalent to a rupture 10 feet wide and 80 feet long. In spite of this damage, which was probably greater in total areathan that suffered by theTitanic, the ship came safely to New York under her own steam.

Courtesy of Holmes' "Ancient and Modern Ships"Great Eastern, 1858; the Most Completely Protected Passenger Ship Ever Built

Courtesy of Holmes' "Ancient and Modern Ships"

Great Eastern, 1858; the Most Completely Protected Passenger Ship Ever Built

There can be no doubt that in undertaking to build a ship of the then unprecedented length of 692 feet, the designers were as much concerned with the question of her strength as with that of her ability to keep afloat in case of under-water damage. But it so happens that the very forms of construction which conduce to strength are favourable also to flotation—a fact which renders all the more reasonable the demand that, in all future passenger-carrying steamships, a return shall be made to the non-sinkable construction of this remarkable ship of over fifty years ago.

Let it not be supposed, however, that Brunel and Russell were insensible to the risks of foundering through under-water damage, or that the fully protected buoyancy of this vessel was accidental rather than the result of careful planning. For in the technical descriptions of the ship, it is stated that the inner skin was carried forward right up to the bow, as a protection against "collision with an iceberg," and it is further stated that the combination of longitudinal and transverse bulkheads affordedsuch complete subdivision, that "several compartments might be opened to the sea without endangering the ship."

So remarkable in every respect was theGreat Eastern, so admirable a model is she of safe construction, even for the naval architect of to-day, that a somewhat extended description of the construction of the vessel will doubtless be welcome.

It was at the close of the year 1851 that Brunel made a study of the problem of building a vessel of sufficient size to carry enough coal to make a round voyage to Australia and back, and at the same time afford comfortable accommodations for an unusually large number of passengers and carry a large amount of freight. With the thoroughness and frank open-mindedness which distinguished the man, he sought for information and advice from every promising quarter. Sir William White is of the opinion that all the leading features of the design, such as the structure, the arrangement of the propelling machinery, and the determination of dimensions, originated with Brunel, who said at the time: "I never embarked on any one thing to which I have soentirely devoted myself and to which I have devoted so much time, thought, and labour; on the success of which I have staked so much reputation, and to which I have so largely committed myself and those who were supposed to place faith in me." Sir William states that, after going carefully through Brunel's notes and reports, his admiration for the remarkable grasp and foresight therein displayed has been greatly increased. "In regard to the provision of ample structural strength with a minimum of weight, the increase of safety by watertight subdivision and cellular double-bottom, the design of propelling machinery and boilers, with a view to economy of coal and great endurance for long-distance steaming; the selection of forms and dimensions likely to minimise resistance and favour good behaviour at sea, Brunel displayed a knowledge of principles such as no other ship designer of that time seems to have possessed." The value of this tribute will be understood when it is borne in mind that Sir William White is the most widely known architect of the day.

The principal dimensions of theGreat Easternwere as follows:

PARTICULARS OF THEGREAT EASTERNLength between perpendiculars680feetLength on upper deck692"Extreme breadth of hull83"Width over paddle-boxes120"Depth from upper deck to keel58"Draught of water (laden)28"Weight of iron used in construction10,000tons

PARTICULARS OF THEGREAT EASTERN

The ship was propelled by two separate engines, driving respectively paddle-wheels and a single propeller. The engines for the paddle-wheels were of the oscillating type. The cylinders were four in number, 74 inches in diameter, by 14-feet stroke, and each one in the finished condition weighed 28 tons. The paddle-wheels were 56 feet in diameter. Steam for these engines was supplied by four, double-ended, tubular boilers, each 17 feet 9 inches long, 17 feet 6 inches wide, and 13 feet 9 inches high, and weighing, with water, 95 tons. Each boiler contained 10 furnaces. The screw engines, which were placed in the aftermost compartment of the machinery spaces, were of the horizontal, opposed type; there were four cylinders, 84 inches in diameter, by 4-feet stroke, and each one, in the finished condition, weighed 39 tons.The propeller shafting, 150 feet in length, weighed 60 tons. The four-bladed propeller was 24 feet in diameter. Steam was supplied to these engines by six tubular boilers of about the same dimensions as those for the paddle-wheel engines. The working pressure was 25 pounds per square inch.

Length, 692 feet; beam, 83 feet; depth, 58 feet. Subdivision: Double hull; nine main bulkheads, 53 feet high, extending to upper deck, and six sub-bulkheads 35 feet high, extending to lower deck. Two longitudinal bulkheads through machinery spaces.Longitudinal Section and Plan of the Great Eastern, 1858

Longitudinal Section and Plan of the Great Eastern, 1858

The estimated speed of theGreat Easternwas 15 knots; her best actual performance on an extended voyage was an average speed of 14 knots, which was realised on one of her trips to New York. She was designed to carry 4,000 passengers, namely 800 first, 2,000 second, and 1,200 third class, besides a crew of 400. She had a capacity of 5,000 tons of cargo, and 12,000 tons of coal. When fitted up for the accommodation of troops she could carry 10,000. Fully laden with passengers, cargo, and coal, she displaced, on a draft of 30 feet, about 27,000 tons;—her actual draft was from 26 to 28 feet. The accommodations for passengers would have done credit to one of our modern liners. There were five saloons on the upper, and another five on the lower deck. The uppermost deck afforded two unbroken and spacious promenades, one on each side of the ship, eachof which was 20 feet wide and over 600 feet in length.

Because of the great length of the ship it was decided to launch her sideways,—a disastrous experiment which cost the company dear. The launching ways yielded under the great weight, the ship jammed on the ways, and she had to be laboriously forced into the River Thames, inch by inch, by the aid of powerful hydraulic jacks. The great cost of the launching, which occupied two and a half months' time, caused the failure of the original company, and the ship was sold for $900,000 to a new company, who completed her in 1859. She made several voyages to America; and although in this service she was unprofitable, the great ship proved that she was staunch, eminently seaworthy, and fast for a passenger ship of that period. Although theGreat Easternwas never employed on the Australian service, for which she was designed, she was usefully employed in 1865 in laying two of the Atlantic telegraph cables, and, subsequently, in similar service in other parts of the world—a work for which her great strength and size rendered her peculiarly adapted. After serving an inglorious career in the handsof the showman, theGreat Easternwas sold for the value of her metal and was broken up in the autumn of 1888.

The financial failure of this ship was not due to any excessive first cost, resulting from the very thorough character of her construction, but rather to certain economic conditions of her time. Traffic across the Atlantic, both freight and passenger, was as yet in its infancy; and even if full cargoes had been available, the loading facilities of those days were so inadequate, that the ship would have been delayed in port for an unconscionable length of time. Furthermore, fuel consumption, in that early stage of development of the steam engine, was excessive, the coal consumed per horsepower per hour being about three and one-half to four pounds, as compared with a modern consumption of from one and a quarter to one and a half pounds per horsepower.

A careful study of the construction of this remarkable vessel establishes the fact that over fifty years ago Brunel and Scott Russell produced in theGreat Easterna ship which stands as a model for all time. Realising, in the first place, how vulnerable is an iron vessel whichcarries only a single skin, they decided to provide a double skin and construct the ship with two separate hulls, placed one within the other and firmly tied together by a system of continuous longitudinal and lateral web-plates or frames. By reference to the cross-section, published on page83, it will be seen that the double-skin construction extended entirely around the hull, and was carried up to a continuous plate-iron lower deck, which was from 8 to 10 feet above the water-line, the distance varying with the draft of the ship. The two skins were placed 2 feet 10 inches apart and they were tied together by 34 longitudinal web-members, which ran the entire length of the double hull, and divided the space between the two skins into separate watertight compartments. These were themselves further subdivided by a series of transverse webs which intersected the longitudinal webs. The cellular construction thus provided extended from the aftermost bulkhead right through to the bow, to which it was carried for the purpose of protecting the forward part of the ship against the effect of collision with icebergs, which at that early day were recognised as constituting a serious menace to navigation.The inner skin was not continued aft of the aftermost bulkhead, for the reason that at the stern it would have been unnecessary and somewhat inconvenient.

TITANICBUILT 1912MAURETANIABUILT 1906GREAT EASTERNBUILT 1858Two Extremes in Protection, and a Compromise

TITANICBUILT 1912MAURETANIABUILT 1906GREAT EASTERNBUILT 1858

Two Extremes in Protection, and a Compromise

The double hull was closed in by a watertight iron deck (the lower deck), which served to entirely separate the boiler- and engine-rooms and the holds from the passenger quarters. Above the lower deck the hull was built with a single skin, which terminated at a flush, continuous, cellular steel deck, corresponding to the shelter deck of modern steamships, which extended unbroken from stem to stern. This deck was an unusually rigid structure. Its upper and lower surfaces were each one inch in thickness, and each consisted of two layers of half-inch plating riveted together. The double deck thus formed was two feet in depth, and the intervening space was intersected by longitudinal girders, the whole construction forming an unusually stiff and strong watertight deck, which was admirably suited to meet the heavy tensional and compressive stresses, to which a ship of the length of theGreat Easternis subjected when driving through head seas.

The watertight subdivision of theGreat Easternwas more complete than that of any ship that was ever constructed for the merchant service, more thorough even than that of recent passenger ships which have been designed for use as auxiliary cruisers in time of war. In addition to the great protection afforded by her double hull, she was subdivided by nine transverse bulkheads, which extended from the bottom clear through to the upper deck, or to a height of 30 feet above the water-line. Compare this with the practice followed in theTitanicand in all but a very few of the merchant ships of the present day, whose bulkheads are carried up only from one-third to one-half of that height, and too often terminate at a deck which is not, in the proper sense of the term, watertight.

In addition to these main bulkheads, theGreat Easterncontained six additional transverse bulkheads, which extended to the iron lower deck. Five of these were contained in the machinery spaces and one was placed aft of the aftermost main bulkhead. The submerged portion of the hull, or rather all that portion of it lying below the lower deck, wasthus divided by 15 transverse bulkheads into 16 separate watertight compartments.

From an old photograph, taken in 1860Great Eastern, Lying at Foot of Canal Street, North River, New York

Not content with this, however, Brunel ran throughout the whole of the machinery and engine spaces two longitudinal bulkheads, which extended from the bottom of the ship to the top deck. A further subdivision consisted of a curved steel roof which separated the boiler-rooms from the coal-bunkers above them. Altogether the hull of theGreat Easternwas divided up into between 40 and 50 separate watertight compartments. An excellent structural feature, from which later practice has made a wide departure, was the fact that no doors were cut through the bulkheads below the lower deck.

Such was theGreat Eastern, a marvel in her time and an object lesson, even to-day, in safe and unsinkable construction. That her valuable qualities were not obtained at the cost of extravagance in the use of material is one of the most meritorious features of her design and construction. On this point we cannot do better than quote from the address of Sir William White, delivered when he was President of the Institution of Civil Engineers: "I have most thoroughly investigated the question of theweight absorbed in the structure of theGreat Eastern, and my conclusion is that it is considerably less than that of steel-built ships of approximately the same dimensions and of the most recent construction. Of course these vessels are much faster, have more powerful engines, and have superstructures for passenger accommodation towering above the upper deck. These and other features involve additional weight; and theGreat Easternhas the advantage of being deeper in relation to her length than the modern ships. After making full allowance for these differences, my conclusion is that theGreat Easternwas a relatively lighter structure, although at the time she was built only iron plates of very moderate size were available."

In all the long record of disasters involving the loss of human life there is none which appeals so strongly to the imagination as those which have occurred upon the high seas, and among these the loss of theTitanicstands out preëminent as the most stupendous and heartrending tragedy of them all. The ship itself was not only the latest and largest of those magnificent ocean liners which, because of their size and speed and luxurious appointments, have taken such a strong hold upon the public imagination, but it was popularly believed that because of her huge proportions, and the special precautions which had been taken to render her unsinkable, theTitanicwas so far proof against the ordinary accidents of the sea as to survive the severest disaster and bring her passengers safely into port.

The belief that theTitanicstood for the "last word" in naval architecture certainly seemed to be justified by the facts. She wasnot a contract-built ship in the commonly accepted sense of that term. On the contrary, she was built under a system which conduces to high-class workmanship and eliminates the temptations to cheap work, which must always exist when a contract is secured in the face of keen competition.

The famous White Star Company have pointed with pride to the fact that the excellence of their ships was due largely to the fact that they had been built in the same shipbuilding yard and under an arrangement which encouraged the builders to embody in the ships the most careful design and workmanship. Under this arrangement, Messrs. Harland & Wolff, of Belfast, build the White Star vessels without entering into any hard and fast agreement as to the price: the only stipulation of this character being that, when the ship is accepted, they shall be paid for the cost of the ship, plus a certain profit, which is commonly believed to be ten per cent.

GREAT EASTERN 1858FOUR WATERTIGHT COMPARTMENTSTITANIC 1912ONE WATERTIGHT COMPARTMENTTitanicshows omission of inner skin, longitudinal bulkheads, and watertight decks. Transverse bulkheads are lower by 20 feet.Fifty Years' Decline in Safety Construction

GREAT EASTERN 1858FOUR WATERTIGHT COMPARTMENTS

TITANIC 1912ONE WATERTIGHT COMPARTMENT

Titanicshows omission of inner skin, longitudinal bulkheads, and watertight decks. Transverse bulkheads are lower by 20 feet.

Fifty Years' Decline in Safety Construction

Of the strength of theTitanicand the general high character of her construction there can be no doubt whatever. Not only was she built to the requirements of the Board of Trade andthe insurance companies, but, as we have noted, she was constructed by the leading shipbuilding company of the world, under conditions which would inspire them to put into the world's greatest steamship the very best that the long experience and ample facilities of the yard could produce.

The principal dimensions of theTitanic, as furnished by her owners, were as follows:

PARTICULARS OF THETITANICFt.Ins.Length over all8829Length between perpendiculars8500Breadth extreme926Depth moulded to shelter deck643Depth moulded to bridge deck733Total height from keel to navigating bridge1040Load draft346Gross tonnage45,000Displacement in tons60,000Indicated horsepower of reciprocating engines38,000Shaft horsepower of turbine engine22,000

PARTICULARS OF THETITANIC

In this connection the following table, giving the dimensions of the most notable steamships, from theGreat Easternof 1858 to theImperatorof 1913, will be of interest. How rapidly the weight (displacement) increases with the length of these large ships, is shown by the fact that, although in length theTitanicis onlyabout 27 per cent. greater than theGreat Eastern, in displacement she exceeds her by considerably over 100 per cent.

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