Warships and their story

by R. A. Fletcher

The Trident was the first iron steamship of war ordered by the Admiralty, and the first ever built. She was launched from Messrs. Ditchburn and Mare’s yard, at Blackwall, in December, 1845, and in the shape of her hull followed the lines of a sailing ship of the same size. Her length over all was 200 feet, and between the perpendiculars 180 feet; her beam was 31 feet 6 inches, and over the paddle-boxes 52 feet 6 inches, and her burthen was 900 tons. She had engines of 330 h.p., with oscillating cylinders and tubular boilers, so that altogether she was an important vessel in the constructional development of the British navy. She was very strongly put together, as her ribs were double, each rib being composed of two angle irons, 4 inches by 3½ inches by ½ inch thick, riveted together, and in one entire length from the gunwale to the keel she having a total of two hundred and seventy pairs of these double ribs. The iron skin was ¾ inch thick at the keel, and diminished to ½ inch at the gunwale. She was to carry two long swivel guns of 10-inch bore, one fore and one aft, to fire in line of keel, and four 32-pounder guns to fire on the broadside.

In 1846 the Birkenhead was built at Laird’s yard to the order of the Admiralty as the first of a series of steam frigates, and was one of the largest iron steamers belonging to the Government. Her length between perpendiculars was 210 feet, breadth of hull 37½ feet, breadth over paddle-boxes 60½ feet, depth of hold 23 feet, and her tonnage 1,400 tons (carpenter’s measurement). She was followed, in 1849, by the Simoom, launched by Napier, at Glasgow, and by the Megæra, by Fairbairn, at Millwall, all being classed and armed as steam frigates. The Birkenhead was to carry a 96-pounder pivot gun aft, and a similar weapon forward, and four 68-pounders on the broadside, and it was pointed out that her round stern would add to the range of fire of the “Long Tom” aft. However, the Admiralty had serious doubts of the efficacy of these vessels, and having made some experiments with an iron ship called the Ruby, found that the 32-pounder gun at short range could perforate the side of the iron ship, and that the projectile carried its “cloud of langrage” with great velocity into the interior of the ship, so that men could not stand against it. These experiments resulted in the Simoom, Birkenhead, and ten smaller vessels being condemned as warships. Some of them were transformed into transports, and the Admiralty returned to its beloved wooden walls once more. The loss of the transport Birkenhead shortly afterwards is one of the most tragic and heroic episodes in the whole history of the British army. The Admiralty caused other tests to be made with sixteen wrought iron plates superposed, having a total thickness of 6 inches, but these also were perforated by the projectiles of the 32-pounder at 400 yards range.[33] The result was that the adoption of iron for the main structure of a ship was delayed until the discovery was made of the rolling of armour plates, in the time of the Crimean War, but it was not until 1859 that the Admiralty may be said to have definitely adopted rolled armour plates.

In the year 1849 Scott, Sinclair and Co. launched, at Greenock, the first steam frigate built on the Clyde for the British navy, and thus inaugurated that association between the Admiralty and the Clyde iron-ship builders which has been maintained uninterruptedly from that day to this, to the marked advantage of both. The Greenock, for the vessel was named after the port, was 213 feet in length of keel and fore-rake, by 37 feet 4 inches beam, and was of 1,413 tons Admiralty measurement, and had engines of 565 h.p. Her machinery compartment measured 72 feet in length and contained the whole of the machinery, consisting of four rectangular boilers, fitted with brass tubes, and two steam engines, lying flat on the bottom, the whole being so arranged that all parts were several feet lower than the surface of the water. The screw, which weighed 7 tons, and was 14 feet in diameter, could be detached and lifted from the water.

“The funnel also,” says the Illustrated London News of May 12, 1849, in describing the vessel, “is to have some peculiar mode by which its hideous and crater-like physiognomy can be made at once to disappear, and leave the ship devoid at once of this unsightly feature, and of those cumbrous excrescences, paddle-boxes, giving her all the appearance and symmetry of a perfect sailing-ship.”

She carried ten 32-pounder muzzle-loading guns. Her machinery is of special interest as it embodied one of the earliest attempts to drive a screw propeller by gearing. For this purpose it had four sets of massive spur wheels and pinions, in the ratio of 2.35 to 1, so that 42 revolutions of the engines per minute gave 98.7 revolutions per minute to the propeller shaft.

The engines installed in steamers, whether for war or commerce, were of the side-lever type, until they were superseded by the direct-acting type. The former was peculiarly suitable to the paddle-wheel, and in one form or another is in use to the present day. In America, the practice has been to place the beam or lever above the crank, but on this side of the Atlantic the beam was placed below the crank. So far as warships were concerned, this method had the advantage that a great part of the machinery could be placed low down in the vessel. But the very fact that a vessel was propelled by paddle-wheels made it impossible to place the whole of the engine below the water level; it is evident that the greater the diameter of the side-wheels the greater must be the distance between the surface and the crank or shaft upon which the wheels are fastened for rotation. As increased power was required, it became necessary to add to the size and weight of the engines, which in this respect soon reached the profitable limit of their employment. Engineers were not long in foreseeing the extent of the difficulty, and, in seeking means to provide a smaller engine without loss of power, discovered a method of eliminating the lever and causing the engines to act direct upon the crank shaft. One very ingenious method by which the desired result was accomplished was that associated with the name of Mr. Penn, who introduced the oscillating cylinder in 1836. In these engines the connecting rod is done away with altogether, the piston rod works directly on the crank pin, and the cylinder is carried on trunnions which permit of the necessary oscillation, and are themselves made hollow in order that the steam may be admitted to and exhausted from the cylinders through them. The first Admiralty vessel in which they were fitted was the yacht Black Eagle. Another method by which great economy in space was effected was the double cylinder engine invented by Messrs. Maudslay. It consisted of two cylinders of equal size placed side by side, but with a space between them into which the foot of a T-shaped cross-head passed, the foot of the T head being connected by a connecting rod with the crank pin.

With the side-lever engines the difficulty of driving the paddle-wheels at the required speed was overcome by the introduction of the gearing wheel, and this contrivance was applied also to the engines for driving the screw propeller. As the piston speed was increased it became possible to connect the crank shaft direct to the screw shafting. The engines used for driving paddle-wheels were either inclined or vertical, but after the introduction of the screw propeller for warships, the engines were built of the horizontal type and this method remained in vogue for about thirty years. The difficulty of working in the confined space was met by Mr. Penn with the trunk engine, with which he achieved a still greater success. His equipment of the warships Arrogant and Encounter with trunk engines in 1847 so satisfied the Admiralty that engine power for driving screws could be placed so far below the water-line as practically to be safe from an enemy’s shot, that altogether he applied them to no fewer than two hundred and thirty vessels, from a gunboat requiring 20 h.p. to such ships as the Sultan, 8,629 h.p., and the Neptune, 8,800 h.p. This invention, curiously enough, helped in the retention of the sailing power, by leaving the decks unencumbered by engine houses and paddle-boxes, so that when the engines were not in use the vessels could be kept under sail only, to gladden the hearts of the adherents of the old school. It also hastened the abolition of sail, for it showed that the machinery could be placed below the water-line, and when armoured sides and protecting decks were introduced sails were dispensed with altogether.

The trunk engine remained a favourite model until it became impossible to keep the trunks in a steam-tight condition owing to the adoption of high-pressure steam. The use of a geared wheel for multiplying the number of the revolutions of the screw shaft was continued until the crank shaft could be connected direct to the screw shafting. Up to about 1860 horizontal engines were the rule in warships, and though not particularly economical in the matter of fuel, they were a great improvement on the type which had been so useful for paddle engines. Surface condensation became general about 1860, and made possible the introduction of compound engines and cylindrical boilers. The old flat-sided boilers were retained when surface condensation was first introduced, but additional stays were added to enable them to stand the increased steam pressure which had by now advanced from 4 lb. to the square inch, at which it was deemed effective in the early days of the steamship, to 30 to 35 lb. to the square inch.

The warship of the “perfect sailing ship type,” with the engines as little conspicuous as possible, remained in favour until the experiences of the British and French fleets in the Crimea and the Baltic compelled the abandonment of all the theories and practices which had been nursed for years; while the innovations which were made at the time of the American Civil War brought about the introduction of types of vessels which were about as unlike the historical wooden walls, the growth of centuries, as anything could well be.

Some years ago, when visiting the Brooklyn Navy Yard, the writer was discussing with the officers in charge there the effects of the war between the Northern and Southern States, and the expedients tried by the two sides, upon warship construction, irrespective of generally accepted theories and the opinions of the experts.