Warships and their story

by R. A. Fletcher

Photograph by Symonds & Co. Portsmouth.

She was 285 feet in length between perpendiculars, with an inside beam amidships of 58 feet, and an extreme beam of 62 feet 3 inches, with an average draught of 26 feet. The depth from the midship portion of the covering-in deck to the top of the keel was 18 feet. The double bottom contained the water-tanks, and above these were a series of watertight compartments containing the engines and so on, and above these again were another series of watertight compartments used as coal bunkers and lockers, and another series, formed of watertight bulkheads, enclosed the officers’ accommodation. They were said to be as strongly constructed as the strong room of a bank.

The Devastation was probably the first ship in which a built-up keel of steel was introduced. The plates of steel were ⅝-inch in thickness, and the depth of the keel was 4 feet 6 inches, and it was strengthened by an angle-iron 1 inch thick. The stem was a solid forging, the upper deck part being 9 inches thick, and the lower part which formed the ram was 36 inches thick. This immense prow was strengthened by longitudinal iron frames. The stern-post was also forged solid, and was 26 feet in length and weighed 15 tons, and measured 12 inches deep by 8 inches thick. Steel plates riveted vertically over the transverse frames and running longitudinally and crossed by vertical fixed iron plating formed the double bottom. The interior of the hull was divided both longitudinally and transversely into a great number of watertight compartments. The two magazines, one near each end of the ship, were protected from a dropping fire by a bulkhead covered with 5-inch armour plating, and above the magazines again was a strongly constructed deck 4 feet 6 inches below the load water-line. The armoured belt was 9 feet 6 inches broad amidships, but tapered off gradually towards the ends. The armour-plating was 18 inches thick amidships, and gradually reduced to 9 inches towards the extremities. The breastworks or armoured walls built up from the upper deck near the forecastle, and extending to a wall behind the after turret, were 7 feet high, 74 feet long, and had an interior breadth of 50 feet. Their armour-plating varied from 10 to 12 inches, with the usual backing of wood and iron frames, and an inner iron skin. The deck was 2 inches of iron covered with 4 inches of oak. The turrets, which stood at either end of the breastwork, were 31 feet 3 inches in exterior diameter, and 24 feet 1 inch interior diameter; they were built up as follows: Outside, 9 inches of iron plating, then 9 inches of Italian oak set in iron frames, then 6 inches of iron plating, then 6 inches of Italian oak set in iron frames, then two thicknesses of iron plating each ¾-inch thick, to form the inner skin, then iron frames 10 inches in depth, and finally a series of rope mantlets, or nets, to protect the men working the guns from injury through fragments of rivets or bolts being driven in by a shot striking the outside of the turret in battle.

The military mast was introduced in the sea-going turret ships like the Devastation, and a few years later all such masts were given fighting-tops or platforms upon which machine guns or small quick-firing guns were mounted, or were equipped with search-lights. These masts were of steel and hollow, and in some ships the tops could be reached by ratlines and shrouds in the old-fashioned way, and in others by means of internal or external ladders affixed to the masts themselves. Conning-towers were introduced later, but to meet the wishes of naval officers alternative places of control are also provided in all large ships, for use in case the conning-tower should be made the target for the concentration of the fire of a hostile ship.

The experiments with the Glatton’s turret proved the unsuitability of turret armour being made with horizontal joints, as there is always the chance that a projectile may strike the actual line of joining, where the resistance would be less than at any other part. The plates for the Devastation turrets were, therefore, rolled sufficiently broad to cover the faces of the turrets from the breastwork deck to the upper edge, and only vertical joints were exposed to fire. The forward end of the ship was raised to form what was called a sunk forecastle. This considerably added to the freeboard forward and to the buoyancy at that end of the ship, and this was further augmented by the armour belt being reduced as much as possible so as to avoid unnecessary weight. Some critics of this design maintained that the end was too weak, and that the advantage it was sought to gain in sea-going qualities would not materialise; but when the vessel afterwards went to sea and was tested in all sorts of weather, and against heavy seas, in broadside seas, and in following seas, and in seas running a few points off the bow, or on the quarter, she proved herself an admirable sea-boat. An account of the sea trials in which she was accompanied by the Agincourt and Sultan includes a description written by a “scientific observer,” who was on board the Devastation. Her sea trials took place during the summer of 1873. The Sultan was one of the more modern ironclads carrying a two-deck battery on a protected water-line, and the Agincourt was a five-masted ship reminiscent of the steam frigate days.

The scientific observer states:—

“For purposes of comparison in pitching and lifting, etc., the Sultan had the height of the Devastation’s upper deck at side painted on her in a broad white stripe, so that the behaviour of the two ships might be quickly appreciated apart from the records of instruments. The lowness of the extremities of the Devastation gives a great deal of interest to the pitching and lifting (really the longitudinal rolling) of the vessel. Two trials were made, one on the 9th and the other on the 15th of September. On the first of these occasions, she was accompanied by the Sultan only, and on the second she was accompanied by the Agincourt only. The seas met with on the 9th of September were lumpy and irregular, the wind having shifted somewhat suddenly during the previous night. Having got well out to sea, about forty miles off land, the wind was found to be blowing rather north of west with a force of a moderate gale, its speed varying from forty to forty-five miles per hour; and the largest of the waves were found to vary from 300 to 350 feet in length from crest to crest, occasionally reaching 400 feet—the greatest heights from hollow to crest being 15 and 16 feet. Going head to sea, at from six to seven knots, both vessels pitched considerably; the Devastation, however, had the best of it, pitching through smaller angles than the Sultan. The latter vessel was remarkably lively; at one moment she was to be seen with her fore-foot completely out of water, and the next with her bow dipped down to so great an extent that it was difficult to see from the flying deck of the Devastation—although the ships were pretty close together—whether the sea did not really break inboard; and this notwithstanding that the bow of the Sultan rises forward some 30 feet above the surface of the water. On the other hand, the forecastle deck of the Devastation was repeatedly swept by the seas, to each of which she rose with surprising readiness; indeed, it invariably happened that the seas broke upon her during the upward journey of the bow, and there is no doubt it is to this fact that her moderate pitching was mainly due, as the weight of the water on the forecastle-deck during the short period it remained there acted as a retarding force, preventing the bow from lifting as high as it otherwise would, and this, of course, limited the succeeding pitch, and so on. The maximum angle pitched through on this occasion, i.e. the angle between the extreme elevation and depression of the bow, was 7½ degrees. Each vessel behaved extremely well when placed broadside on to the sea, rolling very little. The trial of the ship on the 15th of September, in company with the Agincourt, was by far the most severe of any. Early in the morning the vessel got under weigh and steamed out to sea, accompanied by the Agincourt. The wind was blowing with considerable force from the north-west, while the sea was at times very regular, long, and undulating; just the sort to test the rolling propensities of a ship, but scarcely long enough to be most effective in doing so, either in the case of the Devastation or Agincourt. The largest waves ranged from 400 to 650 feet long, and from 20 to 26 feet high. The ships were tried in almost every position with regard to the direction of the sea, and at various speeds, the result in point of comparison being extremely interesting, and, so far as the Devastation was concerned, very satisfactory. With the sea dead ahead, and proceeding at about seven knots, the Devastation pitched rather more than the Agincourt, although the great length of the latter compared with that of the former caused her bow to rise and fall through a much greater height, giving her the appearance of pitching through a greater angle. The usual angles pitched through by the Devastation, measuring the whole arc from out to out, were from 5 degrees to 8 degrees; the maximum angle pitched through was, however, 11¾ degrees. The scene from the fore end of the frying deck when the vessel was thus going head to sea was very imposing. There was repeatedly a rush of water over the forecastle, the various fittings, riding-bitts, capstan, anchors, etc., churning it up into a beautiful cataract of foam; while occasionally a wall of water would appear to rise up in front of the vessel and, dashing on board in the most threatening style, as though it would carry all before it, rushed aft against the fore turret with great violence, and, after throwing a cloud of heavy spray off the turret into the air, dividing into two, pass overboard on either side. All the hatchways leading below from the upper deck were closed; it was not, however, thought necessary to close the doors in the sides of the trunks leading from the main hatchways to the flying deck, most of the men on deck preferring to remain here under the overhang of the flying deck. It was quite the exception for the water coming over the bow to get much abaft the fore turret; but this, however, occurred occasionally. The foremost turret makes a most perfect breakwater; it receives with impunity the force of the water, which, after spending itself against it, glances off overboard, leaving two-thirds of the deck seldom wetted. There was one sea which came on board, while thus proceeding head to sea, which was much heavier than any other; it rose in front of the vessel some 10 or 12 feet above the forecastle, and broke on the deck with great force, for the moment completely swamping the fore end of the vessel. A mass of broken water swept up over the top of the fore turret, and heavy volumes of spray extended the whole length of the flying deck, some small portion of it even finding its way down the funnel-hatchway—which had been left uncovered—into the fore stokehole. It should be borne in mind that the angles pitched through, given above, do not measure the inclination of the ship to the surface of the water, but only her inclination to the true vertical. Pitching and lifting are produced by the vessel endeavouring to follow the slope of the waves, or, roughly speaking, to keep her displacement the same as in still water, both as to volume and to longitudinal distribution.

“As to the depressing effect of the water on the bow, a layer of water one foot deep over the entire forecastle exerts a pressure of 65 tons; this will produce a change of trim of 11 inches, together with an increase in the mean draught of 1¾ inches; i.e. the draught of water forward will be increased by 7¼ inches, while that aft will be diminished by 3¾ inches. A layer 2 feet deep will have double this effect; one 3 feet thick will have treble this effect; and so on up to a considerable angle. This follows from the fact that the front slope of the longitudinal curve of stability, up to a considerable angle, is very nearly straight. Hence the effect, even of a large body of water passing over the forecastle, tending to make the vessel dive down head foremost, is small, and of no importance. It modifies, however, the transverse stability. When proceeding head to sea there was no appreciable rolling motion. With the wind and sea on the bow she pitched considerably less than when going head to sea, but rolled through 5 degrees or 6 degrees. With the wind and sea abeam, lying passively in the trough of the waves, the maximum angle rolled through was 14 degrees from port to starboard, 6½ degrees to windward, and 7½ degrees to leeward, and this without perceptible pitching. When, however, proceeding at about seven and a half knots, with the wind and sea on her quarter, she rolled through 27½ degrees from port to starboard, 13 degrees off the perpendicular to windward, and 14½ degrees off the perpendicular to leeward, besides also pitching through some 4 or 5 degrees. This is by far the greatest angle she has ever rolled through. It is the apparent period of the waves, i.e. their period relatively to the ship, which operates in making a vessel roll. The motions of the vessel, both as to pitching and lifting and to rolling, were extremely easy. She, indeed, claims to have behaved better than her companion, the Agincourt. Certainly, her rolling motion was somewhat slower, and she rolled less deeply; when the Agincourt was rolling 17 degrees from port to starboard, the Devastation was only rolling 14 degrees. As to pitching, the Devastation may fairly claim to have had the advantage, for, as we have seen, although the Agincourt pitched rather less, her bow moved vertically through a greater distance, so much so that while going head to sea at seven knots she shipped a sea over her high forecastle, showing that she could not be driven under the circumstances at a much higher speed with at least anything like comfort.”[43]

THE OLD “DREADNOUGHT.”