Warships and their story

by R. A. Fletcher

Before this, however, Messrs. Dudgeon experimented with a small iron vessel, of 400 tons, called the Flora, which was given two independent engines and screws. The propellers were placed under the counter, and proved the advantage of this position over that of the practice, where two screws were used, of placing one before, and the other behind the rudder. The advantage of placing the screw either in a space cut in the deadwood, or, in the case of twin propellers, under the counter, was much greater than the method at one time adopted of placing the screw behind the rudder. Under the newer method the steering power of the rudder was not impaired; but under the older method, when the screw shaft was carried beyond the rudder, a slit known as a “shark’s mouth” had to be made in the rudder so that the upper and lower portions would be able to pass the screw shaft. The practice of equipping the vessels with wells or recesses into which the screw could be lifted was found to possess but slight advantages for warships, and was ere long abandoned. The best that could be said for it was that when a ship was travelling under sail only, the screw could be lifted from the water and the strain upon the wooden stern caused by dragging the screw, whether of the fixed or folded patterns, through the water, or running loose, was avoided altogether.

The Hebe was the third vessel on this principle built and engined by Messrs. Dudgeon, and the advantages of the twin-screw system over the single screw were again strikingly manifested during a series of manœuvres. The Hebe was an iron vessel of 470 tons, and 165 feet long. The screws were three-bladed, 7 feet 6 inches in diameter, and had a pitch of 15 feet, and were worked by two separate and independent engines each having two cylinders 26 inches in diameter, with a 21-inch stroke of piston, and being collectively of 120 nominal h.p. The tests showed that the vessel with both screws working ahead could made a complete circle in four minutes or less, and in still shorter time with only one screw working and the helm thrown over, or with the two screws working in opposite directions.

The tests were severe, but they proved more effectively than any tests before had done the great superiority of the independent acting twin screw over the single screw; and the results in far greater manœuvring power, speed, and reliability were so satisfactory that the Admiralty was most favourably impressed. The Messrs. Dudgeon, in 1863, built the steamship Far East, and her launch and trial trip took place in the presence of the representatives of the Admiralty. She was fitted with twin screws which had a diameter of 8 feet 2 inches, and a pitch of 16 feet. The shafts of the screws were carried through a wrought-iron tube bolted to a false iron bulkhead clear of the ship’s frame. The Admiralty not long afterwards adopted twin-screw propellers. The advantages of the twin screw were that were one to be disabled, the other could propel the ship without trouble, and that as an aid to steering, one screw could be sent astern and the other worked ahead, so as to turn the vessel in little more than her own length.

The Penelope, launched in 1867, was the first twin-screw ocean-going ironclad belonging to the Navy, and she was, moreover, the first government owned warship in which each screw had its own engine, as compared to the two screws geared to one engine in the floating batteries of the Crimean days. She was of 4,470 tons displacement, and her engines of 4,700 indicated h.p. gave her a speed of between twelve and thirteen knots. Each of her twin screws was fitted to a distinct stern with separate deadwood and rudder, an arrangement which neither added to the steering capabilities of the ship nor increased its structural strength at the stern. The Penelope had recessed ports to allow of increased training of the guns.

Captain Coles, to whom, notwithstanding the sad fate which overtook the Captain, this country is somewhat indebted for his consistent advocacy of the adoption of the turret on sea-going ships, urged upon the Admiralty the superiority of the turret over the broadside system. His contrivance differed from that of Ericsson in the important particular that Ericsson’s turret was supported on a pivot which rested upon bearings at the bottom of the ship, whereas Captain Coles’s turret rested upon bearings supported in a specially constructed room resting upon the beams of the deck, which, in turn, were strongly supported from below. In regard to the thickness of armour there was little to choose between the two. Captain Coles brought his design before the notice of the United Service Institution in 1860, and although it attracted a great deal of attention among naval constructors and manufacturers of naval artillery, only one nation was then of sufficient courage to order an experimental ship. That nation was Denmark, and it is to that country that the honour must be given of having the first ship in which the broadside system of gun-fire was entirely abandoned and the turret system installed instead. This vessel was the Rolf Krake, an iron double-turreted monitor with lowering bulwarks. She was engaged in the war against Prussia, in 1864, when she took part in a fierce duel with the Prussian batteries at Eckernsünde. The batteries fired 24-pounder rifled Krupp guns, and though the ironclad was struck about one hundred and fifty times, her armour was sufficient to withstand the shot, and she certainly inflicted a great deal more damage than she received.

Numerous experiments were made in France and in this country with the object of determining the special characteristics of a vessel which should meet the rapidly altering condition of affairs caused by the increase of the power of the guns and the development of the torpedo from the stationary mine, which was so terrifying in the American War, to the torpedo which could attack a vessel at anchor, or even be directed at one moving slowly. The requirements were a moderate displacement, increased protection, and ability to carry heavier guns capable of fore and aft fire as well as over the broadside. The problem was not an easy one by any means. The cellular double bottom system was extended as a precaution against torpedoes; the number of guns and the extent of the armour were lessened, but the thickness of the armour was increased in order to protect the vital parts and the guns from the fire of the newer and more powerful ordnance, while to compensate for the increased weight in the middle third of the ship, the beam was made greater in proportion to the length.

FOUNDERING OF THE “AFFONDATORE” IN THE HARBOUR OF ANCONA.

Reproduced by permission of the “Illustrated London News.”