An Unsinkable Titanic/Chapter 5
THE UNSINKABLE GREAT EASTERN OF 1858
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, the Great 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 the Titanic.
The Great Eastern represented 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, the Great Eastern ran 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 area
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Courtesy of Holmes' "Ancient and Modern Ships"
Great Eastern, 1858; The Most Completely Protected Passenger Ship Ever Built
than that suffered by the Titanic, the ship came safely to New York under her own steam.
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 afforded such complete subdivision, that "several compartments might be opened to the sea without endangering the ship."
So remarkable in every respect was the Great 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 so entirely 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 the Great Eastern were as follows:
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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
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.
The estimated speed of the Great Eastern was 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, each of 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 the Great Eastern was 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 hands of the showman, the Great Eastern was 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 the Great Eastern a ship which stands as a model for all time. Realising, in the first place, how vulnerable is an iron vessel which carries 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 page 83, 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
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Two Extremes in Protection, and a Compromise
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.
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 the Great Eastern is subjected when driving through head seas.
The watertight subdivision of the Great Eastern was 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 the Titanic and 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, the Great Eastern contained 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, was
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From an old photograph, taken in 1860
Great Eastern, Lying at Foot of Canal Street, North River, New York
thus divided by 15 transverse bulkheads into 16 separate watertight compartments.
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 the Great Eastern was 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 the Great 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 the weight absorbed in the structure of the Great 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 the Great Eastern has 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 the Great Eastern was a relatively lighter structure, although at the time she was built only iron plates of very moderate size were available."