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 than that suffered by the _Titanic_, the ship came
safely to New York under her own steam.
[Illustration: 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
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:
PARTICULARS OF THE _GREAT EASTERN_
Length between perpendiculars 680 feet
Length on upper deck 692 "
Extreme breadth of hull 83 "
Width over paddle-boxes 120 "
Depth from upper deck to keel 58 "
Draught of water (laden) 28 "
Weight of iron used in construction 10,000 tons
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.
[Illustration: 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 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 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.
[Illustration:
TITANIC BUILT 1912
MAURETANIA BUILT 1906
GREAT EASTERN BUILT 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 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
thus divided by 15 transverse bulkheads into 16 separate watertight
compartments.
[Illustration: From an old photograph, taken in 1860
GREAT 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 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."