The Evolution of Naval Armament

by Frederick Leslie Robertson

This central breastwork, raised above the upper deck and armoured along its sides with 10-inch steel, supported the two turrets and enabled the guns to be carried at a desirable height above the water-line. The upper deck itself was low. The sides, up to its level, were protected by a complete belt of armour 8 inches in thickness.

The abolition of masts and rigging had a striking effect on the design. Compared with the Monarch, of nearly the same tonnage, she carried heavier guns, double the weight of armour, double the amount of fuel, and required little more than half the crew to work her.

The loss of the Captain, confirming the doubts which experts had expressed as to the seaworthiness of rigged turret ships, caused an alarm for the safety of all turret ships, built and building. In the public mind, in consequence of the reported shortcomings of the American monitors and the known deficiencies of our coast-defence vessels, the belief was growing that the turret system was inherently unsafe. It was believed, also, that mastless ships, having no spread of sail to steady their motion, would be liable to excessive and dangerous rolling. To allay the uneasiness as to the safety of the Devastation and her type a Committee on Designs was formed. The Committee, composed of some of the most eminent of naval architects and officers, made a report in the spring of ’71 which, though it met with considerable opposition from one school, nevertheless “formed the groundwork upon which the English Admiralty determined to construct their policy for the future.” The Committee pronounced altogether against fully rigged ships for the line of battle; it was impossible, in their opinion, to combine in the same vessel great offensive and defensive power and a full spread of canvas. They considered the Devastation class as the most suitable type of armoured ship for future service, and found them to have sufficient stability for safety and to be in almost all respects a satisfactory design of warship. As regards the Devastation herself they recommended some minor alterations, the effect of which was to improve the stability of the ship and to give greater accommodation for the crew. The main alteration consisted in the carrying up of the ship’s sides amidships to the level of the central breastwork, and in continuing the breastwork deck outward to the sides, to form unarmoured side superstructures.

Besides the Devastation, two others of the type were laid down shortly afterwards, the Thunderer and the Dreadnought. The three ships differed from each other slightly in dimensions, but embodied the same characteristic features. Of chief interest is the transition of the unarmoured side superstructures, in the Devastation, to an armoured central battery of the same width as the ship, in the Dreadnought. The influence of Sir Edward Reed, who had now given place to Mr. Nathaniel Barnaby as Chief Constructor at the Admiralty, was apparent in this evolution. In ’73 he stated publicly his objections to the carrying up of the Devastation’s sides, and pictured a shell entering the unarmoured superstructure and blowing up all the light iron structure in front of the guns. The result was seen in the Dreadnought, in which the breastwork was made a continuation of the ship’s side and armoured. More freeboard was also given to the forecastle and the after deck than was found in the Devastation and Thunderer, with the desire to make the vessel drier and more comfortable; and, owing to the height at which the turrets were carried, this was found possible without restricting the arcs of fire of the guns. The movement from the monitor type toward the modern battleship in respect of freeboard is clearly traced in these three ships of the Devastation class. Low freeboard, in spite of its effect in rendering inconspicuous the ship in which it was embodied, was gradually being abandoned. High freeboard was foreshadowed for future ships. The loss of the Captain had led to a serious study, by naval architects and mathematicians, of the stability of warships at large angles of rolling, and the advantages of high freeboard were by this time widely appreciated. High freeboard not only made a ship more habitable; by the form of stability curve it gave it allowed a vessel’s beam to be reduced with safety, and thereby contributed to a steadier and more easily propelled ship than would have been obtained without it.

In other respects these three ships show the lines along which progress was being made. In the turrets of the Devastation the twin 35-ton guns had been loaded and worked by hand; but in the forward turret of the Thunderer the new hydraulic system of Messrs. Armstrong was applied with success to two 38-ton 12-inch guns; and this system was adopted for both turrets of the Dreadnought. The guns were loaded externally, the turrets being revolved by steam, after firing, till the guns were on the requisite bearing; they were then depressed by hydraulic power, and the 700-pound projectiles were rammed into their muzzles by a telescopic hydraulic rammer. In 1879 an accident occurred in the Thunderer which helped, it is said, to hasten the return to breech-loading guns. Simultaneous firing was being carried out; one of the guns missed fire without anyone either inside or outside the turret being aware of it. The guns were loaded again, and, on being discharged, one of them burst. Such double-loading, it was clearly seen, would not have obtained with breech-loading guns.

The Devastation had twin screws driven by independent engines, but these were non-compound engines of the trunk type working with a maximum steam pressure of 30 lbs. per square inch. In the Dreadnought an advance had been made to compound the three-cylinder vertical engines, working with 60 lbs. per square inch in engine-rooms divided by a longitudinal watertight bulkhead.

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The evolution of the battleship was being forced along at a hot pace by the evolution of artillery. No sooner had the mastless turret ship received the sanction of the Committee on Designs as the standard type for warfare of the immediate future, than a sudden increase in the power of guns necessitated the consideration of new principles and brought into being a new type.

So far, defence had managed to compete fairly successfully with offence; the naval architect, by devoting as much as 25 per cent of the total of a ship’s weight to protective armour, had been able to keep level with the artillerist. But it was clear that he could not follow much further, by the existing methods. Armour could not be thickened indefinitely. Penetrable armour was no better than none; worse, in fact, since it was a superfluity, and in a ship a superfluity was doubly wasteful, implying a loss of strength in some other direction. Armour might have to go altogether? It seemed that, after all, the predictions of Sir Howard Douglas might well come true; that, just as gunpowder had forced the foot soldier, after burdening him with an ever-increasing weight, to dispense altogether with body-armour, so rifled artillery would render ship armour increasingly ineffectual and, eventually, an altogether useless encumbrance.

The advance in artillery took place in connection with Italian construction. In 1872 Italy laid down the Duilio, and a year later the Dandolo, two mastless turret ships of a novel class, engined by Penn and Maudsley, and equipped with two diagonally placed turrets each designed to carry two 60-ton Armstrong guns; guns which were afterwards changed to 100-ton guns of 17¾ inches bore. In the same ships the Italians introduced a solution of the armour difficulty. They abandoned vertical armour altogether, except for a very thick belt over the central portion of each vessel which was to protect the vital machinery and the gun turrets.