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.
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.