|Selected Extracts from "Famous Ships of the British Navy" |
The "Warrior," and Iron-clad Ships
"It is said that ideas produce revolutions ; and truly they do - not spiritual ideas only, but even mechanical:'-Carlyle.
IN giving a brief notice of the prominent features of the several varieties of iron-cased ships, it will be desirable to divide them into two classes, Sea-going Ships, and Coast-defence Ships.
SEA-GOING SHIPS.-Of these we have built, or are building, the following ships : Warrior, Black Prince, Achilles, Defence, Resistance, Hector, Valiant, Northumberland, Minotaur, Agincourt, Royal Oak, Royal Alfred, Ocean, Prince Consort, Caledonia, Zealous, Favourite, Enterprise.
The COAST-DEFENCE SHIPS are the batteries, Glatton, Trusty, Thunder, Ætna, Terror, Erebus, and Thunderbolt ; and the Shield ships Royal Sovereign, and Prince Albert.
The Warrior (6,039 tons, 1 250 H.P.) is an iron ship of war protected by iron armour. In this respect she is like the batteries Thunderbolt, Terror, and Erebus.
But while these earlier ships are from their slowness and low free-board incapable of warlike operations on the open sea, the Warrior is in every respect an efficient man-of-war.
The main object regarded in her construction was to resist the action of shells, which had long been known to be readily capable of setting ships on fire, and to be frightfully destructive to limb and life when they exploded among the men massed on the fighting decks. It was, however, the startling illustrations of this fact which had been recently given at Sinope and Sebastopol that showed the necessity for a special means of resisting these dangerous missiles.
The mode adopted by the French architects for obtaining
* We are indebted for this chapter to the kind assistance of Mr. N. Barnaby, Member of the Institute of Naval Architects.
Fig. 1.- Sheer of Warrior
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this object, was to cover the exposed parts of the ordinary wooden ships with iron. But it was considered by English architects that, notwithstanding the rapid fouling of iron ships, and their local weakness of bottom, a great advantage might be obtained by the use of iron instead of wood in the whole of the ship. Wood is, under all circumstances, very perishable, and its liability to decay is likely to increase when inclosed within large masses of iron and perforated by numerous iron bolts.
In these ships it was particularly desirable to secure a considerable amount of durability, as they would be necessarily very costly. It was considered, further, that the heavy masses of iron required for plating the bow and stern would make the ship labour in a sea-way, and that by using iron for the construction of the hull, the necessity for armour-casing at the ends of the ship might be avoided.
Iron having for these reasons been adopted as the material for constructing the hull, all danger of destruction by fire from the action of shells was removed.
It would not have been difficult to make the whole of the plating of this hull sufficiently thick to break up common shells, without the use of thick armour at all. But iron plates of moderate thickness, while they will successfully resist such shell, are broken up into innumerable fragments by the blows of shot, which fragments fly about the decks, and do much mischief.
In an iron ship of war it is therefore necessary to protect with shot -proof plating all those portions of the ship in which the crew are engaged during an action.
The portion of the Warrior which is thus protected is shown in fig. 1 (p. 279). It is sufficiently long to enclose a battery of 26 guns, with intervals between the guns of 15 feet 6 inches from centre to centre. It has walls or bulkheads across its extremities, formed of 12 inches of timber and 4-inch iron plates, on a strong frame of iron. These walls extend from the spar deck to 8 feet below the water. The sides are strongly framed with ribs and plating, and have outside these, 18 inches of sound hard teak, and plates of hammered iron 4½ inches thick. Each plate is about 15 feet long and 3 feet wide, and weighs 4 tons. Each plate is fastened by about 30 bolts, two feet long. These bolts are formed with a conical head, sunk into the plate, and a screwed point, on which there are two nuts set up inside the skin of
THE ARMOUR OF THE "WARRIOR."
the ship. This side has been proved to be capable of resisting both 68-pounders fired from a 95-cwt. gun, and 150-pounders from an Armstrong 100-pounder gun, at 200 yards range, the ordinary charges of powder (16 lbs.) being employed.
It was found further that, when a 150-lb. shot was fired from a 300-pounder gun with a charge of 50 lbs. of powder, the side was not perforated until two shots struck in the same place.
For all practical purposes the central battery of the Warrior may therefore be said to be impregnable, except at the ports. In order that these might be reduced in breadth from 3 feet 4 inches to 2 feet, a directing bar has been devised by the Ordnance Department which pivots in the port, and extends under the gun-carriage. by this means greater readiness and precision is obtained in training, and the guns can be made to fire over an arc of 60° through the 2-feet port. The port lids are made of thin iron, and are only musket-proof.
The accompanying figure (p. 282) shows the depth to which the armour extends below the water, in order to make this central tower impenetrable by shot. It shows also an inner water-tight side for additional security, in the event of the ship receiving injury below the armour by the blows of a ram, or by any other means. It has been assumed in the construction of all these ships, that shot cannot be made to penetrate a ship's side more than two or three feet below the surface of the water. This is probably the fact, and will continue to be so while the depression of the guns is limited to 7°. Shot fired at this angle have to pass through 50 feet of water in order to reach a depth of 6 feet below the surface. There is, however, nothing to prevent the construction of ships with lower port-sills, or higher carriages, and an increased height between decks, which shall be able to fire their guns at such an angle of depression as will penetrate the iron-eased ships below their armour. With guns loaded at the muzzle there might be some danger of the shot rolling out, but in breech-loading guns no such fear can be entertained.
Fig. 2 also shows an inner bottom in the middle of the ship, as a security against serious injury in the event of the ship getting aground. This inner or double bottom is 240 feet long, and terminates at each end at one of the transverse watertight bulkheads.
Fig. 3 (p. 283) is a section of the undefended part of the ship
Fig. 2.- Section of Warrior
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Fig. 3.- Section of Warrior
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THE BUOYANCY OF THE " WARRIOR."
in which is a watertight iron deck, 8 feet below the load-water line. The portions of the foremost and after holds lying below this deck are not required for use, and it is intended that the scuttles and the man-holes leading through the deck into them should always be closed. Such being the case, it is assumed that no shot will be able to penetrate the deck, and that the holds below will always remain empty, whatever amount of damage is done to the undefended sides lying above them. The buoyancy of these lower holds, together with that of the impregnable central hull, is sufficient to float the ship, though the remaining upper portions should be completely bilged. These upper portions are divided by numerous bulkheads into a great many compartments, so that it would take a long time to pierce them all. When this is done, the loss of buoyancy will be 1000 tons, and the ship would after the loss steam at about ten knots, and with its ports 6 feet 6 inches out of water. In conjunction with this statement, we may record the facts that the Gloire has at her best an average speed of only 11.8 knots, and swims with her ports within 6 feet of the water.
The total weight of the Warrior is 8,800 tons, of which about 7,000 tons are iron. The armour, of which the greater part is hung upon the sides, weighs 1,000 tons.
The height to which this armour rises above the sea line is so great that fear was entertained by eminent naval officers that the ship would not be able to stand up under her load. It may, therefore, be interesting to show upon what grounds her designers rested their confidence in her stableness.
In fig. 4 (p. 285) the point G marks the position of the centre of gravity of the entire ship and lading. In other words, it is the point about which the ship would balance in any position while the contents of the ship retained their places. B is the position of the centre of gravity of the mass of water displaced. In other words, it is the point about which this body of water would balance in any position if it were congealed or made solid.
If the ship, or rather an exact model of the ship, had to be supported in the upright position by a hand placed beneath it, the hand must be placed at A, and must press upwards in the direction AM, otherwise the ship would fall to one side or the other. And since the ship is supported in the upright position by the upward pressure of the fluid, we see that this fluid acts as if it were a single force equal to the
THE STABILITY OF THE WARRIOR
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weight of the ship applied at A, and pressing upwards in the direction AM. Thus, as the ship weighs 8,800 tons, she sinks into the fluid until she fills the space previously occupied by exactly 8,800 tons of water, and she then receives that amount of support from the surrounding fluid which she requires. There is, then, 8,800 tons of weight pulling the ship downwards, and 8,800 tons of fluid resistance pushing her upwards : the consequence is that she neither rises nor falls, but floats at rest.
Now suppose the ship or model to be pushed over, immersing the right side, and raising the left side out of the water until the line of immersion is changed to that marked inclined line. Since the weight of the ship is unaltered, the size of the hole which she makes in the water must be the same as before, but its shape and position have undergone a change.
While the ship was upright there was the same amount of displaced fluid on both sides of the line A M, but now there is more on the right than on the left side of this line. There
THE STABILITY OF THE "WARRIOR."
is, therefore, an increase in the amount of fluid pressure on the right side, and a decrease in that upon the left; so that if the model were without weight, and it were required to keep it immersed at the inclined line by the pressure of a hand downwards, that hand must be placed somewhere to the right of the position which it would have occupied for this purpose had the vessel been upright, and it would press down perpendicularly to the inclined line. Supposing the exact position of the hand to be at the point a, we should conclude that the fluid forces which support the ship were all pushing upwards as though they were collected in the line b M. Having remarked this from the evidence of our senses in attempting to keep the model immersed by the hand, in the inclined position, we should notice further, that if the model had to be supported by the hand in the inclined position, the hand must be placed at the point W, and must press upwards in the direction of the line W G, because G is the centre of gravity, and it is only about this point that it will balance. From this we should reach our second conclusion, that all the weights in the ship are pushing downwards, as though they were collected in the line G W. But if all the supporting forces act as though they were collected in the line b M, and all the weights as though they were collected in G W, they will, by their joint pushing and pulling, bring the vessel into the upright position again. It is, in fact, only by the application of some other forces, such as the pressure of the wind on the sails, or the blow of a wave, that such a vessel can be made to incline. As soon as she is forced out of her upright position her very weight drags her back again.
To avoid a somewhat difficult proof, the position of the point a was assumed. Its real position is, however, to be found by discovering the point b, which is the centre of gravity of the irregular mass of fluid displaced by the ship in her inclined position, and drawing the line b M vertically upwards. The point M, where this line cuts the middle line of the ship, is for all ordinary angles of rolling practically coincident with what is called the meta-centre. If the weights in the Ship were so disposed that their centre of gravity G were situated at M, then the upward and downward forces would be acting in the same line, and there would be no tendency to pull the ship upright ; in other words, there would be no stability. And if the point G were above M, then, although the upward and downward forces acted in different lines,
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they would so act as to pull her still further from the upright position until she was keel upwards. The stableness of the ship is therefore measured by the height of the point M above G. In order to keep G low, the weights must be kept down; and in order to make M high, the rate at which the point B or b (called the centre of buoyancy; moves towards the inclined side must be great. This may be done by increasing the breadth, or diminishing the depth of the ship. Thus, although the tendency of the armour is to raise the centre of gravity, and make the ship crank, the breadth and form of the ship may be such as will entirely counteract such tendency.
One effect of the armour, hung as it is at a great distance from the middle of the ship, is to make her roll more slowly and deeply than she otherwise would. She would also take a longer time to come to rest than ordinary ships, when rolling once commenced. To obviate this, bilge-pieces, a a, are fitted on the bottom as shown in fig. 2. Their object is simply to increase the friction of the bottom as it rolls through the water, and thus to aid in bringing the vessel to rest. The preceding considerations show us that crankness can in no way be remedied by their use. Stability must be obtained by other means, but they offer a most effectual check to deep and long-continued rolling.
Black Prince and Achilles (6,039 tons, 1,250 H.P.). - All that has been said of the Warrior applies equally to the Black Prince, and most of it to the Achilles also.
The Achilles will however differ from her sister ships in the following respects. She is protected by shot-proof armour, not only in the battery portion, but also in the region of the water line, throughout the entire length of the ship. There is thus a continuous belt of 4½-inch armour on 18 inches of timber extending 8 feet above the water line, and 5 feet below it, as shown in the preceding sketch, fig. 5 (p. 287).
The Achilles differs from her sister vessels also in having four masts, and in an altered form of head and stern. The knee and head are removed, in order to free the ship from what is considered to be a mere useless encumbrance, both when encountering a head sea, and when operating as a ram. The stern is so altered as to afford protection to the head of the rudder and stern-post, both of which are exposed in the other ships. They are, however, so massive in those ships as to promise sufficient resistance to the blows of shot.
THE "MINOTAUR," AND SISTER VESSELS.
The belt of iron employed in this ship, in conjunction with iron plating on the deck, is expected to render her hull secure against the admission of water through shot holes, so that she may go into action without fearing any loss of buoyancy or speed.
Minotaur, Agincourt, and Northumberland (6,621 tons, 1,350 H.P.). - These ships were designed with the view of escaping the objections which were brought by many men of position against such partial protection as that of the Warrior. They contended that the exposed portions of the Warrior would become such a wreck under fire, as to make the ship unmanageable; and they considered that the loss of sea-worthiness which would result from loading the ends of the ship with armour was a less disadvantage than that which might be apprehended from the absence of such armour.
The truth probably lies somewhere between the two positions. It is a great misfortune to have a large portion of the hull capable of being waterlogged, and perhaps a still greater misfortune to have the steering gear exposed to fire. But, on the other hand, the complete plating requires the ship to be increased in size and cost, and it is feared will prove most injurious to its sea-going qualities.
The ships of this latter class are 20 feet longer than the Warrior, 18 inches broader, and have 600 tons more burden. They possess a considerable advantage in the fact, that while the Warrior has only 26 out of her 40 guns under the protection of the armour, they have 40 guns protected. The armour in these ships is omitted from a portion of the fore-end of the top side of the ship, and an athwartship shot-proof bulkhead is erected on the forecastle.
Resistance and Defence (3,668 tons, 600 H.P.). These ships were designed for coast-defence purposes, but there is nothing to prevent their forming part of the line-of-battle in any part of the world.
In comparison with the other ships they are somewhat under-masted, and have a limited supply of coal, but they will perform useful service whenever they are brought into action.
It is to these ships, rather than to the heavier and less manageable frigates, that we must look for active and useful service as rams. They are formed in such a manner as to give them extraordinary strength in the stem and bow. It is to be regretted that their bowsprits are not fitted with a view
to such services; but there can be little doubt that this would speedily be done if a war were to break out.
That the use of the ram will become general, in future naval warfare, is certain.
In a paper read before the Institution of Naval Architects by the writer of this chapter, in March, 1860, he said: "We have seen that one of the ancient modes of fighting was by the use of rams, for piercing the sides of opposing vessels. This mode continued in constant use so long as vessels of war were propelled by oars, i. e., so long as the attacking vessels were perfectly under command for rapid advance in any direction, or for retreat at pleasure. Sailing vessels are not under command in this way, and therefore such a mode of fighting has been, for the last 500 years, impracticable. But steam has again given us this control over our ships, and the opinion is growing that we shall revert to this most ancient mode of warfare. Whether it would be prudent, or even practicable, to use line-of-battle ships as rams is very doubtful; but that a class of vessels for coast defence ought to be, and yet will be, constructed on this principle, I hold to be certain." "And so long as it is possible for a small vessel, at a moderate speed, to penetrate the sides of the strongest ship below the water, as it certainly is, so long will it be imprudent to build large ships of war." Two years after this paper was read, the Merrimac furnished a startling illustration of its truth.
Since it was written the Northumberland class has been designed, but the writer has seen no reason to change his opinions, stated at length in the paper referred to, with regard to the imprudence of building large ships of war.
The Defence and Resistance are armour-plated in the same partial manner as the Warrior, but a somewhat smaller proportion of the hull is defended.
The number of protected guns in these ships is only 14.
In the Hector and Valiant (4,063 tons, 800 H.P.), the plating extends throughout the whole length of the ship at the height of the battery. It is also nearly complete below the battery. There are a few feet left undefended at each end, and the defended part is completed by armour-plated transverse bulkheads, extending from the under side of the battery to a sufficient distance. below the water. These ships are, therefor much less exposed to damage under fire than the Defence and Resistance. They are so constructed as to be able to
WOODEN SHIPS, IRON-CASED.
serve the purpose of rams in case of need, and their bowsprits are made to turn up, about a pivot at the inner end. But their chief advantage as compared with the Defence and Resistance lies in the increase of speed. The average speed of the latter ships will not exceed 11¼ knots, but these may be expected to reach 12¾ knots. They possess a further advantage in having 30 guns protected, or more than twice the number of the other ships; and they have one-fourth more men in the crew.
Prince Consort, Caledonia, and Ocean (4,045 tons, 1,000 H.P.) ; Royal Oak and Royal Alfred (4,045 tons, 800 H.P.).Of these ships, it is only necessary to say that they are ordinary line-of-battle ships, with one deck taken off. They are plated from end to end with iron 4½ inches thick, and have 32 guns on their main deck. They will be much more formidable than they would have been as line-of-battle ships, although greatly inferior to ships of the Warrior class.
Of all the ships we have mentioned, the smallest are the Resistance and Defence, the tonnage of which is 3,668, or nearly twice that of Nelson's flag-ship at Trafalgar. Such large ships are so costly that it becomes important to inquire whether it is not possible to construct smaller vessels, possessing the necessary qualities of an iron-cased ship. If the plating is to extend over the whole of the exposed surface of the ship, and to some 4 or 5 feet under water, then small ships are altogether out of the question. They are almost equally so if the Warrior system is adhered to. Mr. Reed therefore proposes to abandon the idea of protecting a central portion large enough to support the undefended ends after they are bilged, and to adopt instead the belt at the water line, as already shown in the Achilles. The central battery may then be made as short as we please, and the same measure of invulnerability may be obtained in a small vessel as in a large one. With this mode of plating, it also becomes possible, by reducing the number of guns, to use iron armour of any desired thickness without greatly increasing the size of the ship.
Enterprise.- In this ship the principle has been applied with such success that, with a burden of only 990 tons, we have an iron-cased sea-going ship. The great object sought by Mr. Reed in this ship was the reduction of dimensions, for which purpose every possible device has been adopted for lightening the hull without weakening the ship.
Fig. 6. Iron cased sloop of war "Enterprise"
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Fig. 7. Elevation of the Shield ship "Prince Albert."
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THE "ENTERPRISE," AND THE "FAVOURITE."
This vessel will carry four of the heaviest guns, and will be propelled by engines of 160 H.P., at a speed of 9½ knots per hour.
The transverse walls of the central tower are pierced on each side the ship, to allow the guns to fire ahead or astern, a portion of the light topside turning down for the purpose. The guns may be fired within 10° of the fore-and-aft line. The walls are also pierced for musketry for sweeping both the decks.
The upper portions of this ship are of iron, in order that they may be light and incombustible: when the ship is in action these portions of the ship will not be occupied. What portion of the ship's company which is not actually employed at the guns, is accommodated below the deck that is situated at the height of the top of the belt, which deck is bombproof. The whole of the ship below the bomb-proof deck is in communication with the battery, so that the men may readily be collected for boarding or for repelling boarders.
Favourite (8 guns, 400 H.P.) - The same arrangement of armour is being applied in the conversion of the corvettes of the Favourite class into iron-cased ships. But in them, the deck which is made shell-proof is 7 or 8 feet above the water, and the belt is considerably wider.
It will be observed that there is a very great reduction in the number of guns carried, as compared with uncased ships of similar classes. Instead of the 17 guns of the sloop we have only 4 guns, and instead of the 22 guns of the corvette only 8 guns.
This is a startling reduction in the nominal power of the ship, but the increase in the weight of the projectiles thrown goes far towards a complete compensation. And there can be no doubt that the weight and power of naval ordnance will continue to increase until, perhaps, being able to strike with the ship as easily as with the gun, and more effectually, we may dispense with guns in sea fights.
COAST-DEFENCE SHIPS.- The first iron-cased ships which were built in England were those known as the floating batteries. There are seven of them, four built of wood and three of iron. Of the wooden ships three are of the Trusty class, viz., Trusty, Thunder, and Glatton, 14 guns. Their tonnage is 1,469 tons ; and the power of the engines 150 nominal H.P., with which they obtain a speed of 4½ knots per hour.
They swim when loaded, at a draught of 8 feet 8 inches, and
with their ports 3 feet 2 inches out of the water. The average thickness of timber in the ribs and planking at the strongest part of the side is 18 inches, and the average thickness of the armour is 4 inches. The fourth wooden battery is the Ætna, 16 guns. Her tonnage is 1,588, and the nominal H.P. of her engines 200. The load draught of water is 8 feet 6 inches, and the height of port 4 feet 3 inches.
Those which are built of iron are the Erebus, Terror, and Thunderbolt, 16 guns. Their tonnage is 1,954, and H.P. of engines 200. Their mean draught of water is 8 feet 9 inches, and height of port 3 feet 10 inches. They are formed with ribs of iron 6 inches deep, on which is placed the armour and backing.
The Shield Ships.-The revolving shield or cupola of Captain Coles is an engineering device of considerable merit; but its use in naval warfare seems likely to be limited to vessels intended solely for coast defence.
The invention consists, really, in a novel description of gun-carriage, the merits of which are facility of training, and protection of the guns and gunners from the fire of shot and shell. These are advantages which we should suppose to be valuable in a fixed fortress; but when applied to a ship they are greatly reduced in value.
First, with regard to facility of training, it is found that by the use of this invention two 100-pounder guns may be worked by half a dozen men. But of what value is this economy of labour in a ship which must have a large crew to navigate her and defend her against boarding? Thus, the Royal Sovereign was a three-decked line-of-battle ship, of 3,965 tons, with a complement of 1,100 men. Instead of her former armament of 131 guns, she will probably have 8 guns in four shields. Assuming that six men are sufficient for working each shield, there will be twenty-four men employed at the guns. But she will need a crew of at least 200 men, so that only one-eighth of her men will be engaged. This is not of course a disadvantage; but it is so small an advantage as to set off very badly against the serious difficulties introduced by the shields.
Secondly, with regard to the protection which the shields afford to the gunners, it is only necessary to observe that just as much armour is required on the sides of the ship for her protection, in addition to that on the shields, as would be needed if the shields were not used. And while the two
prime advantages of the invention are thus deprived of much of their value when applied to ships, it appears also that the introduction of shields must; necessarily deprive a ship of seagoing qualities.
There are several reasons why this must be so. First, the shield-guns must fire over the highest deck, and all the permanent part of the hull of the ship must lie below the line of fire. If in order to get a good free-board this deck is raised more than six or seven feet out of the water, gun-boats might lie under cover of her sides with impunity while a breach was made in the armour, or while measures were taken for capturing her. It may be said that ordinary ships of war are subject to the same mode of attack; but it must be remembered that these shield-ships have no top-side, under cover of which their own men may assemble, and no tops from which the men may be picked off at the guns of the attacking vessels. Any gun-vessels which should dare to take up a position by the side of the Warrior would be liable to instant capture, and it cannot be conceived possible that their crews would be able to work the guns under the fire of musketry which would be directed against them.
As the shield ships are helpless in these respects, it is indispensable to keep the free-board low. The Royal Sovereign, for example, is only six feet out of the water, and is on that account quite unfit for sea-going purposes.
Again, vessels fitted with shields, must either be without masts, or having masts, must dispense with shrouds to them. With the ordinary masts and rigging, the angle of training of the shield-guns would be as limited as that of guns fired through common broadside ports. Captain Coles proposes to fit tripod masts, which shall not need the support of shrouds and stays. It is not impossible that he may by some such means be able to introduce a light rig into shield-ships; but it must always be of such a character as will tend still further to render the use of shields in seagoing ships undesirable.
In the Prince Albert (2,529 tons, 500 H.P.), fig. 7 (p. 292), the armour and backing extend throughout the entire length of the sides. The upper deck is perfectly straight and level amidships, but slopes down at the sides to form a glacis, to allow the guns to fire with a depression of 6°. The men and officers are berthed on the lower deck, between and beyond the shields.
In this ship the water-tight bulkheads are obliged to stop
at the lower deck. This being the case, if one compartment became filled with water, the water would flow over into the adjoining compartments. In order to give greater security to the compartments, the ship is fitted throughout the greater portion of her length with a complete inner bottom and side.
We have thus described the prominent features of all the iron-cased ships now in existence, and in course of construction.
Of such ships the fleet of the future will be composed.
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