We come now to a type of steamship, which, by reason of its peculiar construction, is deserving of more than ordinary consideration. [Opposite page 248] we give the latest example of this type—the s.s. Inland. The “turret-ship,” as the class is called, is of quite modern origin, and no one can come face to face with her without being instantly struck with her unusual appearance. She owes her birth to Messrs. William Doxford and Sons, Limited, of Sunderland, who are the patentees and builders of this kind of ship. It is needless to say that when this novel class of steamship first appeared in the early ’nineties there was aroused the usual prejudice; indeed, having in mind what has been the experience of other inventors in connection with our subject, the reader could hardly expect otherwise. Firstly, let us consider her with regard to her appearance. It will be seen that she differs from the usual cargo and passenger ship in that her sides tumble right in above the water-line. This forms a kind of half turtle deck, and is known as the harbour deck. But the upper deck of the “turret-ship” is extremely narrow. (This will be seen more easily by reference to [the next illustration], which gives a model of the midship section of such a ship.) The harbour deck need not be used except when in port, but it can be employed for stowing long timbers or even iron girders if required. Like the oil-tanker, many of the turret-ships have their engines placed right aft, so that there is a long clear space for stowing the cargo in the hold, an advantage which is especially appreciated in the carrying of certain kinds of cargoes. Just as we saw there was great danger to a ship in the possibility of oil washing about the hull and shifting in a perilous manner, so also there is a danger in such cargoes as rice and grain. With regard to the latter, I remember the case of a big cargo ship which had the misfortune to spring a leak and the water swelled the rice to such an extent that the ship, strong as she was, burst her sides. But in the case of grain the danger is not merely that, but also of shifting. As guarding against this possibility the turret-ship, by reason of her special design, is specially suitable, for any shifting that may take place in the turret matters but little, and whatever shifting may take place in the hold is compensated for by the turret; the cargo can be shot into the hold without needing any trimming. The deck of the “turret” portion will be seen from [the illustration facing page 248] to form a navigating platform.
SECTION OF MODERN OIL-TANK STEAMER.
Photograph from a Model. By permission of Messrs. Sir W. G. Armstrong, Whitworth & Co., Ltd.
THE “SILVERLIP.”
From the Model in the Victoria and Albert Museum.
Some of the modern turret-ships are fitted with twelve or fourteen masts arranged in pairs, each pair being across the ship instead of fore-and-aft-wise. These vessels have proved themselves to be excellent sea-boats, and owing to their high freeboard and the harbour deck, which acts as a kind of breakwater, it has to be a very bad sea indeed that will break over the ship. Furthermore, the harbour deck tends to reduce the rolling of the ship, for when one side of the ship heels over so that one harbour deck is under water, the windward side, when it holds a certain amount of water, actually tends to bring the ship back to her level. Moreover, since these decks are unencumbered with obstructions, they can suffer no damage through the wash of the sea. They are also extremely strong ships, for the sides of the turrets increase the strength of the vessel longitudinally, while the curved formation of the harbour deck augments their strength transversely; their simplicity of construction and their adaptability for almost any cargo still further add to their virtues. But from the view-point of the owners the turret-ship is even still more a welcome type of craft, in that since dues are paid on a ship’s registered tonnage the turret-ship is able to carry far more cargo in proportion to her size than most vessels. On a small registered tonnage the turret-ship has an exceptionally large dead-weight capacity, and those parts of her which are liable to be taxed are diminished as far as is possible, whilst at the same time greater space is allowed to the carrying and handling of the cargo. Economically, then, the turret-ship, with her odd shape, her many masts and derricks, is a very advantageous carrier.
A good deal of interest has recently been aroused by the peculiarities of a steamship named the Monitoria, which, though not a turret-ship, is sufficiently out of the ordinary design to warrant special mention. She is just an ordinary single-deck cargo steamer, but instead of the usual wall-sided shell-plating has two longitudinal corrugations along the outside of her hull. These swellings, so to speak, extend below the water-line and gradually merge into the ship’s lines at bow and stern. The claim made for this novelty is that it is effective in reducing the wave-like irregularities, and allows of more power being available for propulsion, whilst it also lessens the rolling and pitching of the ship. The captain of this ship is reported to have said that these corrugations had a beneficial effect on the steering, whilst the wake of the ship was found to be smooth and about half the width instead of the full breadth of the ship. Very interesting as practical comment on a subject that we have treated elsewhere in this volume, is her commander’s remark that whilst in a diagonal sea, which was running at a height of 9 feet or 10 feet, a ship of ordinary form and the same dimensions as the Monitoria would have been safe proceeding at no higher speed than 6 or 6½ knots, yet the Monitoria was safe going ahead at 7¼ to 7½ knots. The corrugations are said also to increase the ship’s buoyancy, and thus admit of three per cent. more cargo being carried, while the hull is more readily able to resist the strains than vessels of ordinary shape. It is probable that this novel principle will be presently exemplified in a first-class liner, and in a foreign cruiser.
Similar to the turret-type is the “trunk-deck” steamer, which possesses like advantages. She resembles in appearance the former type, but instead of the curves (seen in the Inland) at the gunwale and bases of the turret or “trunk,” the sides of the trunk rise from the main deck nearly at right angles, the harbour deck being really a true deck. This kind of ship owes her birth to Messrs. Ropner and Sons, of Stockton-on-Tees. Such vessels afford even more than the turret-ships the appearance of a kind of up-to-date man-of-war, without the guns which one would almost expect to see protruding from behind some of her steel plates. It should be borne in mind that both the turret and the trunk type possess an absence of sheer, for the height of the lofty turret, or trunk, enables this to be dispensed with, while to make up for this lack of sheer from the bows to the stern, the vessel is given a top-gallant forecastle.