Unarmored Fleets.
ARCHITECTURAL DEVELOPMENTS.
Ever since the introduction of steam propulsion in ships of war, England, France, and the United States have taken the lead in the development of types of naval vessels, and in examining the various methods followed it is necessary to at first fully understand the conditions under which each nation acted and the obstacles against which each had to contend.
In Great Britain the navy has always been considered the main defence. Its support and development have for over two hundred years been considered of the first importance, and, in legislating for its maintenance, expense has seldom been spared. Since the Crimean war, no sudden strain has been imposed upon its administration tending to limit development to certain especial types. Experiments have been carried on with equal profusion in all types, from the line-of-battle ship to the gun-boat, and as each experiment resulted in the addition of a vessel to the fleet whose lifetime could be estimated safely at fifteen years, we find in this immense navy a most heterogeneous collection of ships, which it would be impossible to classify distinctly. Although this heterogeneousness is a certain sign of extravagance, it by no means follows that it is a sign of weakness in the fleet itself. In all this range of liberal experiment there has been but one point where Great Britain has been really hampered, and the true advantage of a certain amount of restraint is well exemplified in the superiority of development brought about by it in this instance. In order to keep the fleet constantly up to the standard in number of vessels, a greater expenditure of timber was required than could be supplied by home production. It was easily foreseen that in case of a foreign war no dependence could be placed upon a constant supply from abroad, and to remedy this evil we find Great Britain the first to utilize iron in ship-construction, and battling against the first and apparently insurmountable obstacles to carry iron ship-building to perfection, making it immeasurably superior to wood, and through its use extending the range of architectural development far beyond the old limits.
In France there has always been a generous system of legislation for the support of the marine, but in this country the navy has never been considered of the vital importance to the safety of the nation that it has in England; consequently naval controllers have always been obliged to exercise a much greater economy in development, and the rigidly mathematical system of the French in the exercise of all control is nowhere better exemplified than in the development of their fleet. The ships of the fleet will be found most rigidly classified, each type being clearly distinct. Reconstruction and development is carried on as it were en masse in accordance with the prescriptions of fleet programmes carefully studied out to meet the exigencies of the time, and once settled upon being rigidly followed to the end. It is on this account that the French are found as a rule backward in introducing radical changes of detail. Whilst keeping to their systems of classification, the French have kept close to the English in the matter of fleet strength. There has been one period in which France fell so far to the rear as almost to take third place in strength of fleet, whilst development ceased entirely. This was caused by the disastrous Franco-Prussian war, from whose effects the navy still suffers, although it has fully regained its former position close to that of Great Britain.
In the United States, naval development has been constantly hampered not only by parsimonious legislation but by a constant legislative meddling, imposing a restraint far more injurious than lack of funds or the distractions of war itself. At no time has the strength of the fleet been sufficient to bear a comparison with that of either England or France, but in the matter of architectural development the United States has repeatedly passed to the front at a single stride. In spite, however, of the advantages gained, parsimoniousness and political meddling have invariably interfered to hold the navy fast at its single stage of advance until its first developments sank into insignificance beside the modifications and perfections applied in Europe. During the Crimean war American architects laid down a programme for an efficient steam fleet and led the world in the development of the steam frigate and corvette. Notwithstanding this start, the outbreak of the civil war in 1861 found the navy with but the nucleus of a steam fleet. Whilst sailing war-vessels had almost disappeared from European navies, giving place to steam types founded mainly upon the principles which had given American architects the lead, the bulk of the United States Navy was still composed of the old sailing frigates and sloops. The turreted iron-clad, the river gun-boat, and the rapid cruiser again showed the way to the world; but the close of the war brought demoralization to all systems of development.
In 1865 the United States possessed a fleet fully able to protect the whole line of its immense sea-coast against foreign aggression; in 1870 the fleet was reduced to a handful of vessels that, whilst showing heterogeneousness equal to the English fleet, did not possess a single element of strength.
At the date of the outbreak of the Crimean war, the building of sailing war-vessels may be said to have ceased throughout the world. Steam corvettes and frigates formed the bulk of the effective fighting fleets, whilst steam line-of-battle ships were being slowly introduced, as yet scarcely beyond the experimental stage. The introduction of steam propulsion and the advancement in the science of naval architecture had given rise not only to improvements in design, strength, and seaworthiness of men-of-war, but also to a gradual increase in dimensions of the different classes. The extent of this advancement is well shown in comparing the English line-of-battle ship Victory, Nelson’s flag-ship at Trafalgar, having a displacement of less than 2900 tons, with the average displacement of English first-class frigates in 1854, which was not less than 2800 tons; the battery power of the frigates being more than twice as effective, steam-power being added, and handiness and speed under sail alone being much superior. Progress in this direction had been made to the extent that in 1854 the French had laid the keel of the Imperatrice Eugènie, a frigate of 3600 tons displacement, designed for a speed of 12 knots and a battery of 56 guns (five and six inch smooth-bores). At the declaration of war with Russia neither the English nor the French navy was in a condition to meet the suddenly created exigencies; both fleets were in a transition state from sail to steam. The necessity for steam-power on all ships was suddenly made forcibly apparent, and architectural development ceased almost entirely in the work of converting all the available line-ships and frigates of the old sailing fleet into steamers.
This total extinction of sailing vessels as fighting war-ships made its effects felt across the ocean, and an attempt was made in the United States to create an efficient steam navy. With but a limited supply of funds for its creation, American architects were forced to study fully the necessities of the fleet before embarking on the new work. Since the foundation of the navy it had been always one of the principles of American construction to build ships whose measurement exceeded those of similar types in Europe. Carrying out this principle in the development of the new fleet, there appeared in 1855 four steam frigates superior in every way to any European vessels of their class that had yet appeared. The importance of these vessels did not lie simply in their excess of measurements over European frigates, but in the combination of all those parts which go to make up the efficient lighting vessel. The Imperatrice Eugènie with her 3600 tons displacement had surpassed previous frigate developments, but had made no impression on other types of vessels. On the contrary, the appearance of the Minnesota, Wabash, Colorado, and Merrimac was the signal for the disappearance of the line-of-battle ship. The displacement of these ships was about 4700 tons, or 1100 tons in excess of the Eugènie. The battery was of the same number of guns as in the French ship, but exceeded by an inch in calibre that of any broadside afloat, the combination of numbers and weight giving these ships superiority even over three-deckers. Whilst the design of the Eugènie called for a speed of 12 knots, her coal supply was sufficient for but 1500 miles. The Americans, with a speed of 9½ knots, carried coal for 2500 miles. The sail-surface of these ships was enormous, ranging as high as thirty times the area of the immersed midship section. In 1858 a fifth vessel was added to this type (Niagara), the displacement in this instance being carried to 5500 tons, speed 12 knots, with a coal capacity for steaming 2500 miles, full sail-power, and a battery in which calibre had been carried to the extreme limit of broadside fire (11 inches).
Whilst the French were engaged on their Eugènie type the English had laid down a type of 3000-ton frigates (Emerald class) which reached a speed of 13 knots. On the appearance of the Wabash in European waters, the English at once designed a type to surpass her, and completely overshot the mark in the Mersey and Orlando, in which displacement was carried to 5600 tons; but in the attempt to realize a speed of 13 knots, they gave the vessels proportions that were unfit for wooden construction. With their profusion of experiments, however, we find between 1857 and 1860 a succession of types ranging from 2500 to 4600 tons, the majority averaging about 3800 tons. In these ships may be seen the constant search to find the one combination that shall possess all the excellences. All of these vessels were thorough cruisers, and in no case except in the Mersey type do we find the experiment resulting in worthlessness; still, an examination of the frigates will show the impossibility of giving a distinct classification to them. Beyond the Crimean war it has been already stated that the development of the line-of-battle ship had scarcely passed the experimental stage, and after 1857 the sudden increase in power of the frigate, combined with the introduction of the sea-going iron-clad, stopped almost entirely the development of this type, although their construction was carried on until 1860.
In France a new fleet programme was laid down in 1857, in which the heavy American and English frigates were entirely ignored, and whilst new frigates of the Eugènie type were built almost without change, the increase in vessels of this class was confined almost exclusively to lengthening and converting the old frigates of 2500 tons into steamers of 3000. Development of wooden ships was found only in the corvette class. The reason for this independent departure was, in all probability, due to the original start made by France in the development of the iron-clad frigate in this same year, combined with a dissatisfaction on the part of the French with the speed realized in the Wabash and Orlando.
In 1858 the United States Navy put forth a type of vessel new in every particular, and one whose value, although not immediately recognized, has by its development become the true standard for effective medium unarmored cruisers. The Hartford, Brooklyn, Richmond, and Pensacola combined all the advantages of both the second-class frigate and the sloop-of-war. With a displacement of 3000 tons, which placed them in a line with light frigates, their steam-power was fully developed, whilst steaming capacity and sail-power were kept at a maximum, and strength of battery combined, in the best manner, calibre and number of guns. In the civil war, which soon followed, no class of vessels proved itself of so much fighting value as this. These vessels formed a distinct class in the navy, and contemporaneously with them appeared a third and lighter class (Iroquois, Wyoming, Mohican, and Narragansett), with a displacement ranging from 1600 to 1900 tons.
In France this latter type had appeared in the navy at the same time, the Cosmao and Dupleix, with a displacement of 1800 tons, realizing a speed of nearly two knots greater (12 knots), whilst steaming capacity and sail-power were the same, and the battery was inferior in about the same proportion as the speed was superior.
In England the development of this class was an extension of the old steam-sloop, realizing in the Challenger and Barossa type a displacement of 2350 tons, with the disadvantages of excessive draught of water, lack of development of speed and steaming capacity. No better evidence of the complete demoralization of architectural development in the United States can be found than in the movement made in 1872, in which the Hartford class, after having established thoroughly its great utility, was by the addition of a spar-deck reduced to the plane of the Challenger, with increased draught, reduced speed and steaming capacity, and in fact a reduction of all the qualities which had rendered it superior, notwithstanding the total disappearance of the type not only in the English but in all foreign navies.
During the Crimean war a great number of gun-boats, ranging between 500 and 800 tons displacement, had been hastily but well constructed, and the type was continued after the war until 1860 almost without change. The same types with but slight modifications were contemporaneously introduced in France, those of the French Navy, as a rule, possessing a superiority in speed of about one knot.
With the Immortalité frigate, the Challenger sloop, and the Britomart gun-boat, the development of wooden war-vessels ceased in England in 1859, giving place to composite and iron construction.
In 1860 a new range of types appeared in the French Navy, the prominent feature throughout being the extreme development of speed and steaming capacity, combined with medium sail-power and a minimum battery-power, although here the French introduced the rifled gun as an offset to the heavier calibres of American smooth-bores, the primitive type of the rifle leaving it inferior to the latter in power. In the first rate appears a development of the English Challenger class.
| Rate. | Name. | Displacement. | Speed. | Battery. |
|---|---|---|---|---|
| Tons. | Knots. | |||
| First | Venus | 2,700 | 12.7 | XIV 6½-inch rifles, VIII 6-inch smooth. |
| Second | Decrès | 1,770 | 12 | II 6½-inch rifles, IV 5¾-inch rifles. |
| Third | Talisman | 1,300 | 12.4 | II 6½-inch rifles, IV 4¾-inch rifles. |
| Gun-boat | Adonis | 730 | 9.3 | IV 4¾-inch rifles |
The corresponding new types of the United States Navy as they appeared in 1862, excluding the frigates, although the Franklin appeared after this date as the last of this type, were:
| Rate. | Name. | Displacement. | Speed. | Battery. |
|---|---|---|---|---|
| Tons. | Knots. | |||
| Second | Hartford | 2,900 | 10.5 | II 11-inch, XVIII 9-inch smooth, I 5¼-inch rifle |
| Shenandoah | 2,100 | 12 | II 11-inch, VIII 9-inch smooth, I 5¼-inch rifle. | |
| Third | Iroquois | 1,575 | 10 | II 11-inch, IV 9-inch smooth, I 4½-inch rifle. |
| Gun-boat | Saco | 900 | 9.5 | IV 6½-inch smooth. |
From these lists the aims of the constructors in France and the United States may be seen. In the former, displacement was kept at a medium whilst speed was developed to the extreme, the balance in battery-power being sought in the introduction of rifles. With the latter, displacement and battery-power were carried to the extreme, speed being sacrificed, although in this respect great attention was paid to retaining fine under-water lines and a maximum of sail-power.
From 1860 to 1873 an interregnum in the development of French wooden types occurs corresponding to the length of time intervening between the fleet programmes.
At the outbreak of the civil war, the Hartford, Shenandoah, and Iroquois types were being built upon slowly, with every prospect of completing a small but compact and efficient cruising fleet. Whilst, however, this fleet had been designed especially for ocean cruising, the unforeseen exigencies of this war demanded the immediate introduction of a type of light-draught gun-boats for river service, as well as an immediate increase in the numbers of vessels for blockade duty. During the first two years blockading and river vessels were extemporized from whatever material could be found in the merchant service. It was this war, however, which gave birth to the Saco type of gun-boats, these vessels being of a greater tonnage and better fitted for blockade duty on the open coast than the gun-boats of foreign types. Although the vessels of this type, hastily constructed and of poor material, were completely worn out in five or six years’ service, the type was renewed and has remained in the service. Two types of river gun-boats, both of which passed out of existence with the war, demand attention from their great usefulness. The first of these was the ordinary river ferry-boat. These vessels, having a displacement of less than 300 tons and a draught of water of seven feet, possessed two valuable qualifications for river fighting. They were built to run either end foremost with equal facility, their speed being moderate and manœuvring qualities excellent. Their decks, intended to carry heavy moving weights, needed no especial bracing to prepare them for heavy batteries. These ferry-boats, without undergoing any transformations except those made necessary for the proper accommodation of the crew and the manœuvring of the guns, carried successfully throughout the war heavier proportional batteries than any vessels afloat before or since. The type itself, enlarged and modified so as to permit the vessel to do cruising duty as well as river service, appeared in 1863 in what was known as the double-ender, a vessel standing between the gun-boat and the second rate, but not to be classed with the regular third-rate cruiser.
The total ruin of American commerce, brought about by the depredations of half a dozen Confederate cruisers, led to the introduction of four new types of ships, and in these types American constructors sought in general to realize the maximum of speed without reducing any of the other qualities.
The first of these (in point of rate) was designed entirely with a view to securing the highest possible speed and steaming capacity, all other qualities being made subordinate. The displacement of this type was between 4800 and 5000 tons, ranging about 300 tons higher than the frigates of 1855, and they were designed for a speed of 17 knots, with a steaming capacity of 5600 miles at 10 knots. The speed alone was realized. The ships themselves being built of white oak rotted almost before they could be launched; the frame was not of sufficient strength to resist the powerful working of the engines or the wear and tear of cruising, failing in this particular as the English frigates Mersey and Orlando had in 1858. The consumption of fuel was beyond the calculations, reducing the steaming power to less than 3500 miles.
The second type was that of a fast frigate, or more properly first-rate (Piscataqua), in which strength of battery and sail-power were raised to their old proportions with regard to the displacement. The displacement of this type was 4000 tons, battery 25 nine-inch smooth-bores, and speed 12 knots, with a steaming capacity of 3000 miles at 10 knots. These ships were also built of white oak and soon rotted, and their general unhandiness combined, with the great expense of keeping them in commission, caused the type to drop out of existence.
The third type (Congress), having a displacement of 3000 tons, came nearer to the requirements of a large fast ocean cruiser than either of the others, proving fast under steam or sail, handy, and carrying a well-proportioned battery. This type died out with the others in the general demoralization following the reduction of the fleet after the war.
The fourth type (Plymouth), having a displacement of 2400 tons, with a battery of 12 guns and a speed of 12 knots, was in reality a development of the Shenandoah class, having for an increase of 300 tons a gain in battery proportional, and a maximum of speed both under steam and sail without any increase of draught. Of the four types, this one alone, which was a development of the Shenandoah class, the latter being modified from the Hartford, was the only real step in advance; but even this type has passed from the active list at present.
Between 1865 and 1873 England was the only country in which real development was carried on. The French, keeping closely within the limits of their programme, were engaged in developing speed and testing subordinate modifications in the lower rates of their vessels. By this is meant such modifications as testing the value of the topgallant forecastle, leading to its adoption in all rates; the suppression of the poop-cabin, the test of the long ram bow for furnishing additional buoyancy forward, the merits of double and single screw propulsion, etc.—particulars which were subordinate to the main architectural development. The United States Navy from 1865 to 1873 passed through a period of uninterrupted decadence. Millions were spent in the futile effort to patch up the fast-rotting fleet of white-oak ships that had been hastily constructed during the war, while not a single attempt was made to benefit by the rapid development of the English.
Between 1860 and 1866 English attention had been almost exclusively turned to the development of the iron-clad fleet; that of the unarmored fleet consisted almost entirely of experiments in composite and iron construction, bringing out no new types, but perfecting constructional development. In the latter year, however, directly following the appearance of the Wampanoag, the same course was followed as with the Wabash ten years before. Before the world had had time to form any judgment with regard to the real value of the type, the lines of the Inconstant were laid down and the ship was pushed rapidly to completion. In this case the development of iron construction saved England from the blunder committed in 1858 with the Orlando. It was the American vessel that had overshot the mark in measurements for wooden construction. The English turned out a seaworthy ship, but her real utility is questionable owing to her unhandiness and the expense of keeping her in service. The displacement of the Inconstant is 5800 tons, battery ten 9-inch and six 7-inch rifles, speed 16 knots, and steaming capacity 2160 miles at 10 knots. The Americans attained superior speed and steaming capacity by a sacrifice of battery-power. The English attempted to realize all the qualities.
At the same time two other fast cruisers approaching the rate of the Congress were built (Volage and Active). Between 1870 and 1873 is seen the same search amongst dimensions to find the ones which will best satisfy the demands of speed, steaming capacity, and battery-power. The Shah, Raleigh, Boadicea, Bacchante, Euryalus, and Rover, ranging in displacement from 3500 to 6000 tons, overshooting the mark at first, and apparently best satisfied with dimensions falling between the Piscataqua and Congress types. All of these ships belong more properly to the Piscataqua than to the Wampanoag type; the latter appearing fully developed in the Iris and Mercury, in which, as in the Wampanoag, all is sacrificed to speed. The modifications in this case consist, first, in the steel construction, giving a strength of frame sufficient to withstand the engine-power; second, the reduction of dimensions, giving a displacement of 3700 tons; third, the increase in speed to 18 knots.
In France is found, on the programme of 1873, provision for first-rate fast cruisers; accepting the necessity for this development of the general frigate type, this country deliberates and studies the birth of the type in 1865 in the United States, its development for six years in England, and finally crowns the English modifications with what to-day must be regarded as the most perfect development of the Piscataqua and Shah type. The Duquesne and Tourville have a displacement of 5400 tons, speed of 17 knots, and steaming capacity of 5000 miles at 10 knots. In these ships France borrows the English constructional development of iron sheathed with wood, while by an excellent arrangement she secures a full battery-power with an almost perfect command.
Next in order of rate in England, but last in development, is what is known as the C class of corvettes. Built of steel, with a displacement of 2380 tons, they truly represent the last development of the type whose foundation was the Hartford, and this type is apparently as great a favorite in the English Navy as the Hartford in her day was in that of the United States. In France the second-rate of the programme of 1873 is a distinctly new type. The Duguay-Trouin in one respect is a departure from French custom, her dimensions being carried to the maximum for this rate, giving her a displacement of 3200 tons, which is an increase over her own immediate predecessors of 1200 tons. Her battery-power is if anything lighter than the proportional French average and below that of the English and American vessels of lighter displacement. She is designed for a speed of 16 knots and a steaming capacity of 3500 miles at 10 knots. The main architectural peculiarity of this vessel is the arrangement for securing great command of fire. Her battery is all carried on the upper deck, whilst she has a clear flush main-deck; the opening of fore-and-aft fire by carrying the gun-platforms beyond the upper-deck rail is also a modification. Contemporaneously with the Duguay-Trouin the Americans introduced a new type which comes nearer a modification of the Raleigh than any other class, although it springs directly from the attempted modification of the Hartford class referred to above by which spar-decks were added to them. The present Hartford, with her spar and main decks, and the development of the type in the Trenton show two ships wherein is well exemplified the absurdity of, as it were, putting new wine into old bottles. The Trenton has a displacement of 3900 tons, a battery of eleven 8-inch rifles, and a speed of 13 knots, with a steaming capacity of 3500 miles at 10 knots. In this ship, as in the Trouin, the dimensions of the second rate are carried to an extreme, although in this case the Americans hold fast to the idea of combining moderate speed with a maximum of battery-power and general cruising qualities. The Hartford, however, having proved herself possessed of all the excellences of her day, and these excellences having been secured by a wise distribution of architectural elements, was sacrificed to the crude development of a new type by the addition of a new deck. Although these two ships belong to the same type and rate, no comparison can be instituted between them, and at the very time that the English perfect the Hartford type in the C class of corvettes a blunder of the Americans disrates the original.
Below the C class in England appeared the Opal class of 1900 tons, a modification of the earlier Blanche type corresponding and following close after the American Plymouth type. At the same time a corresponding type appeared in France and the United States. In the former the Rigault de Genouilly has a displacement of 1640 tons, an increase of 400 tons over her immediate predecessors, a battery of eight 5½-inch guns, and a speed of 15 knots, with a steaming capacity of 4000 miles at 10 knots. In America the Marion has a displacement of 1900 tons, a battery of one 8-inch and seven 5½-inch guns, and a speed of 12 knots, with a steaming capacity of 2500 miles at 10 knots. The French in this class show the same difference in qualities from the English and American types that appeared twenty years before.
The English development closes with the gun-boats whose types come more directly from those commenced during the Crimean war. The displacement of these vessels ranges from 400 to 900 tons, with a diversity that scarcely admits of a distinct classification. The American gun-boats are reductions of the Iroquois class of corvettes, exceeding the English in average displacement, or rather showing no types below 500 tons. The French gun-boats are more closely allied to English than to American types, although there is but little difference between the three, the English showing greater diversity, the Americans greater measurements, and the French greater precision of rating.
Chart of Architectural Development.—
Unarmored Vessels.
CONSTRUCTIONAL DEVELOPMENT.
Previous to 1857 wood construction was universal in the building of war-vessels. About this date England introduced iron frames in her first armored vessels, passing rapidly to the full development of iron construction in armored ships, composite construction in the medium and light classes of unarmored vessels, and iron or steel sheathed with wood in the first and second unarmored rates. By 1867 the old wood construction had been entirely discarded.
French Corvette La Clocheterie.
(Wooden System.)
United States Corvette Plymouth.
(Wooden System.)
In France the wooden construction was almost exclusively used until the development of the programme of 1873. Iron was then introduced in the armored hulls, iron sheathed with wood in the first and second rate unarmored ships, and composite construction in the gun-boats of less than 700 tons, leaving the light second-rates and the third-rates to the old wood construction.
In the United States the wood construction is still invariably followed. There are no composite vessels in the navy, nor has any attempt been made to build one. There are two or three iron vessels of 1000 tons displacement, built during the period of greatest demoralization, and on account of political pressure brought to bear in the interest of iron merchant-ship building. These vessels can scarcely be pointed at with pride, since, throughout the naval world, pure iron construction is found only in transports and troop-ships. In England, where iron ship-building had its birth and development, constructors have never proposed this very excellent type of merchant-ship construction for war-vessels.
Wooden Construction.
The keel in the wooden construction is sided to a certain proportion to the beam of the vessel, the pieces composing it being generally connected by a plain scarf, the stem carrying the form up forward being hook-scarfed to the forward end of the keel and supported by the timbers of the deadwood and apron, forming a solid mass at the fore-foot. The stern boundary is carried up in the main stern-post, which seats with two tenons on the after-end of the keel, being supplemented in some vessels by a rudder-post, but generally in the larger classes of vessels the latter gives way to the equipoise rudder. The angle of the stern-post and keel is made up into a solid supporting mass by the after-deadwood. The junction of stern-post and keel is further strengthened by bronze castings bolted on each side. The keel is rabbeted each side to receive the garboard strake of planking, and the stern-post and apron prolong the rabbet at either end for the hooding-ends of the outside planking. The floor-timbers cross the keel, giving an alternate long and short arm on either side, the frames being carried up by futtocks and top-timbers shifting butts. Over the floor-timbers in the plane of the keel a heavy keelson is laid with, generally, sister-keelsons on each side, the system of keel and keelson forming the rigid back-bone of the ship.
The longitudinal supports of the ship are the boiler-keelsons, parallel to the main-keelson and forming the supports to the boilers; the diagonal bracing, composed of iron ribbons of about three fourths of an inch in thickness, crossing each other at an angle of 45°, and forming a complete lattice-work for the ship extending from the spar-deck to the turn of the bilge. These braces are generally worked on the inner side of the frames, but in certain cases they have been worked on the outside or on both sides. The inner planking, formed of the thick strakes, bilge-strakes, and ceiling; the deck-clamps, ranges of heavy plank for the support of the ends of the beams; water-ways, covering the beam-ends and corresponding to the deck-clamps underneath; and the outside planking.
Diagonal Braces.
The transverse supports are the beams with their connecting systems of knees and carlings, the breast-hooks and transoms, and finally the decks themselves, which furnish both longitudinal and transverse support. Of late years it has been the custom to make the beams, knees, breast-hooks, and transoms of iron, and it is a very general idea amongst those who have not paid especial attention to the subject that this modification, taken in conjunction with the introduction of diagonal braces, constitutes composite construction, which is by no means the case. In the wooden construction the American and the English systems are very closely allied, whilst the French differs from both in many details. These differences are, however, in the detail work, a description of which would be scarcely warranted in the general summarizing of a system.
The outside planking is made up of a series of strakes differing in thickness of plank in accordance with the points at which the greatest strains are brought by the motions of the vessel. Next the keel on each side, and tending to give it thorough support, are ranges of plank firmly secured in the rabbet of the keel and thicker than the planking in general, called the garboard strakes. Outside of the gun-deck beams is another range of heavy planking called the main wales, and in two and three decked vessels other strakes called middle wales are worked abreast the other beams. In the same way a great longitudinal strengthening is gained in the deck-planking by the outer range of planks next to the water-ways, called the thick strakes.
It is considered that all these points are generally understood, and they are simply referred to on account of the necessity of bearing them in mind in following the developments.
Diagonal Construction.
This system of construction is found only in the English royal yachts and in their heavy wooden steam and sailing launches, but it is the opinion of an eminent English naval architect that had it not been for the very general introduction of iron in ship-building it would probably have taken precedence over the ordinary wooden construction. Its only objectionable feature is its expensiveness, while it is much superior in point of lightness and structural strength. Whilst in the ordinary wooden construction the weight of hull ranges between 46 and 54 per cent of the displacement, it is reduced in the diagonal system to between 32 and 40 per cent.
Diagonal Construction.
In this system the keel, keelsons, stern and stern posts, and floor-timbers are similar to the ordinary construction. The heavy frames, however, stop with the floor-timbers, and there is no diagonal iron framework. The outer and inner planking of the ship are the same as in the old construction except that the thick strakes of outer planking forming the wales are done away with, retaining only the heavy garboard-strakes. In place of the futtocks and top-timbers of the old construction a double course of diagonal planking is introduced. That part of the inner planking which covers the floor-timbers is of the ordinary thickness, whilst beyond the timber-heads the planking is increased in thickness to give a smooth turn to the bilge ceiling. These four or five strakes are rabbeted into each other and into the timber-heads. The clamps and water-ways are as in the old type. In order to give transverse strength to this system, the knees are constructed in a peculiar manner. The lower leg of the orlop-deck hanging knee is carried down beyond the head of the floor-timber. Every other knee is forked, giving a housing to the beam-end, the two legs following the curve of the clamps and water-ways and rising with a spread of half the height between decks and beyond the foot of the hanging knee over it.
This system of construction has found great favor in England in the construction of yachts, and it has been very successfully applied to sailing merchant-ships and steamers.
Composite Construction.
Jordan’s Composite Construction.
The object of this construction is to combine, as far as possible, all the advantages of the wooden and the iron ship. There are three main systems of English types ranging from a close approximation to the wooden construction to that of the iron sheathed with wood, which latter forms the connection between composite and iron construction. In McLain’s system, which is the closest approximation to the wood construction, the keel, stem and stern posts, frame, and outer planking are of wood. The ceiling or inner planking, however, is of iron, forming a complete iron inner skin; the beams, knees, stringers, keelsons, transoms, and breast-hooks being also of iron. The wooden frames are of a smaller scantling than in the wooden system, being supplemented by angle-iron frames, by means of which the iron skin is secured to them. The outer planking bolts directly to the wooden frames, being kept entirely clear of the iron inner hull. In Jordan’s system the frames are entirely of iron, inner and outer skins being of wood, whilst the keelsons, stringers, and transverse supports are of iron. In Scott’s system the frames are made of T-iron instead of angle-iron as in Jordan’s system, and a modification is introduced by which the frames are spaced much farther apart. Between the frames oak or teak chocks are fitted, bolted to the frames and calked throughout, thus forming a complete water-tight course. These are the main types as represented in England. In Russia is found another system which, doing away with diagonal braces, which it must be remembered are used with all the systems just described, makes use of the McLain system in connection with Mr. Scott Russell’s method of longitudinal strengthening. In this, the keel, stem and stern posts, and outer planking are of wood, whilst the frame is of iron with an iron skin outside of it, which in general terms would class the type with that of iron ships sheathed with wood. To the outside of this iron skin Z-iron stringers are bolted, the space between them being filled up by chocks to form a complete wooden sheathing. These chocks are made shorter than the spaces, and are wedged in their seats. Outside of this sheathing is run the wooden outer planking in the ordinary way. It will be seen by the descriptions following that this system can scarcely be classed as a true composite.
Scott’s Composite Construction.
McLain’s Composite Construction.
Russian System.
French Gun-boat Crocodile.
(Composite.)
French Transport Annamite.
(Composite.)
The French system as applied in their light gun-boats has the same wooden outer skin, with the ordinary iron frame. The outer planking is double, gaining great longitudinal strength by breaking seams. There is no diagonal bracing. This system of outer planking is the one used in the English Navy. In the French transports of the Annamite class a system of alternate framing is followed, with wooden ceiling and double outside planking. In these vessels additional longitudinal strength is gained by the use of heavy iron box-stringers in place of the ordinary water-ways.
Iron Construction.
In tracing the development of iron construction it is necessary to pass from the consideration of unarmored vessels to the armored types, as the pure iron construction is limited almost exclusively to these vessels. The advantages of iron over wood may be summed up as being, 1st, lightness combined with strength; 2d, durability when properly treated; 3d, ease and cheapness of construction and repair; 4th, safety when properly constructed and subdivided. Its disadvantages are: (1) easy penetration of the bottom by rocks or by other pointed substances; (2) fouling of the bottom and consequent loss of speed; (3) the immense holes made, not only by taking out solid pieces, but, what is worse, the long rents or tears made by a penetrating shot through the thin side-plates and frames. Fast cruisers cannot be built of iron alone on account of the fouling, and the smaller the ship the greater the harm from this cause. War-vessels of any kind are excluded from this construction on account of the vulnerability of the sides, combined with the impossibility to stop a shot-hole which is starred with long rents. In the heavy iron-clad, however, the third disadvantage is done away with by the application of armor. The second is partially overcome by the surplus engine-power, and the first is neutralized by the double bottom, wing passages and compartments which the large roomy hull allows to be introduced.
The Brazilian iron-clad corvette Brazil, although built as late as 1866, is a good example of the primitive iron construction as applied to vessels of war. The keel of this vessel is what is known as the solid-bar type, the plates forming the garboard-strakes turning down on each side of it. The frames, made of upper and lower angle-irons strengthened from the amidship line to the turn of the bilge by a deep web, abut against an interior keel formed of a single plate surmounted by a flat plate-keelson, the frames, keels, and keelson being thoroughly bound together by angle-iron. The stem is scarfed into the keel, rising as a continuation of it and being rabbeted for the reception of the bow-plates. The main longitudinal strengthening consists in an iron bulkhead rising from the bilge to the under side of the main-deck and running fore and aft, forming water-tight wing passages. Just outside of the edges of the plate-keelson is what is called an intercostal longitudinal frame, consisting of short plates between the webs of the frames and secured to them by angle-irons; these frames run fore and aft. In addition to these longitudinal supports, a wide stringer-plate is carried along underneath the water-ways of both decks. In the formation of the armor-shelf, the exterior angle-irons of the frames, turned back along the edge of the web, form the shelf, while the interior angle-irons are carried up unbroken to the plank-sheer. The plating is the system generally applied of every other plate lapping on both edges.
Brazil.
Warrior.
In the Warrior the solid-bar keel gives way to the plate-keel, which in this case is double, the garboard-strakes butting against the edges of the internal plate, while the external one laps well over the joint. The continuous internal keel is found in this ship similar to the Brazil, secured by angle-irons to the inner keel-plate and the broad plate-keelson. The lower angle-irons in this case are continuous, while the upper ones are in short lengths, permitting the upper angle-irons of the frame to pass across and form a continuous length from plank-sheer to plank-sheer. The web of the frame is here shown increased in depth to a maximum, being lightened as far as possible by circular sections cut out. The assemblage of a frame consists of the continuous inner angle-irons, one on each side of a narrow strip to which the deep web-pieces are bolted, and the lower angle-irons bounding the webs. In the Warrior will be noticed six longitudinal frames similar to the continuous inner keel, and it will be noticed that the third of these frames, forming the seat of the wing-passage bulkhead, and the sixth, running along the outer edge of the floor-plates, project beyond the angle-irons of the transverse frame, being slotted to permit these angle-irons to pass them. The wing-passage bulkhead forms another longitudinal support, extending fore and aft from the turn of the bilge to the lower side of the main-deck. The armor shelf-plate in this instance consists simply of a broad plate bent at right angles and secured by angle-irons to the inner plating. This is a noticeable feature, as the extreme strain on the plate in the sharp bend is a plane of weakness.
Bellerophon.
The Bellerophon shows the same arrangement of keel and keelson with the addition of wooden bilge-keels secured lightly to the bottom plates by angle-irons. The framing of this ship, however, is of the type known as the bracket-plate system. The features of this system are the adoption of a double bottom and of angle-irons connected by bracket-plates instead of by solid forged iron-work. The web of the frame in this instance is much deeper, giving a large space between the outer plating and the bottom formed by plating the floor edge of the transverse frames. In the Warrior it will be noticed this plating only extended to the third longitudinal on each side, while in the Bellerophon it reaches to the wing-passage bulkhead. The transverse inner angle-iron is continuous from bulwark to bulwark, the outer one being in short lengths to allow continuous longitudinals. The upper angle-irons of the longitudinal frames notch down over the transverse frames, while the lower ones are continuous. The spaces between the bracket-frames lighten the assemblage a great deal, while the longitudinals, being of continuous plate like the inner keel, are lightened by having holes cut in them. In this manner large water-tight compartments are secured; for the inner keel, the third longitudinal, and the wing-passage bulkhead longitudinal are solid. The web just underneath the armor-shelf is of the old-style solid plate, to give better support than would be gained by bracket-plates. The double-bottom arrangement continues throughout two thirds of the length of the ship, the frames outside of this being reduced in dimensions. The armor-shelf of the Warrior proving a weak construction, that of the Bellerophon was better worked. The outer angle was formed by an angle-iron bolted to the vertical outside plating, and to a flat plate forming the armor-seat, the iron being on the inside of each plate. This left an open joint between the lower edge of the plating and the upper edge of the side-plate, but the joint is one easily calked.
Filled Wing-Passage of Hercules.
Floor of Hercules.
In the Hercules the bracket-plate system is quite similar, and additional strengthening was put in by partially filling the wing-spaces with a strake of heavy teak backing. Two box-keelsons were also run on each side of the main keelson, and the main keelson itself was strengthened by being carried up above the floor and braced by brackets on each side. The armor-shelf in this instance was also slightly modified.
In the Invincible the wing-passage and its bulkhead is done away with, and in place of it the web of the transverse frame is deepened considerably, carrying the double-bottom arrangement up to the armor-shelf; and whilst retaining a good depth as security against the outer skin being broken by ramming, much space is gained in the hold.
These ships, being constructed for ramming, require a firmly braced stem. The stem itself is a solid forging, and attaches to the flat keel by a plain scarf, the outer keel-plate being carried some distance farther along the turn of the fore-foot than the inner one. The whole length of the stem is deeply rabbeted to receive the forward ends of the side-plates and armor, which all house in it. For a distance of forty or forty-five feet from the bow the bottom plates are doubled to give additional stiffness, each plate housing in a separate rabbet. The rear side of the stem is cut square, the breast-hooks seating fairly on it.
Stern-posts are now invariably made in single solid forgings, and are plain scarfed to the keel as with the stem. Compartment bulkheads form an element of great transverse strength. There is no fixed rule for their application in war-vessels, but the usual number is seven. Of these, one is placed well forward, called the collision bulkhead, another is far enough aft to just enclose the screw-shaft stuffing-box, two others are respectively forward of the boilers and abaft the engines, and the others divide the remaining space as is best suited. Above the water-line, doors of a sufficient size to render free passage are worked in the bulkheads and are on hinges having clamps by which they may be screwed up water-tight. Below the water-line the doors slide either horizontally or vertically, being worked by gearing on the main-deck. The wing-passages are provided with small sliding doors generally kept closed. The compartments of the double bottom are connected by sluice-valves worked from the main-deck.
These points constitute the main peculiarities of iron ship-building as it is at present carried on. There are constant modifications made in details, many of which are of the greatest importance, but a description of them would be out of place except in a work on iron ship-construction.
Iron Sheathed with Wood.
It has been stated that in no navy (except that of the United States) are there to be found iron ships of the pure construction. When iron ship-building was first introduced in England, two iron sloops were laid down and experiments were carried on with targets representing their sides, to find out the effect of shot upon them. The frames of these vessels were spaced only one foot apart, and it was found that a very serious amount of splintering took place when a shot penetrated. It was also found that for thicknesses beyond half an inch the projectile was broken to pieces on contact. This advantage for iron was, however, soon counterbalanced by the rapid increase of calibre, change to rifled guns and high velocities, and the introduction of steel and chilled projectiles. The great advantages offered by iron construction, however, rendered its introduction an absolute necessity when it became a question of speed. The rapid fouling of bottoms, with its consequent loss of speed, could only be overcome by coppering, and this necessity introduced another and far more serious difficulty, that of galvanic action. The introduction of the system of sheathing iron with wood is due directly to Mr. Grantham, an English builder. The main principles laid down by him were to have widely spaced transverse frames, and on the exterior of the iron skin to work a system of angle-irons which should in themselves bring up the strength of the hull to the standard, making up for the loss by wide spacing. The iron skin having been covered with pitch, a wooden filling was introduced between the angle-irons, wedged solid so as to form a complete wooden casing. Over this was placed a layer of tarred paper, and then the sheathing proper of the ship was fastened by brass screw-bolts to the wooden filling, completely insulating the iron hull. This sheathing could then be coppered. These exterior angle-iron frames, being worked as a support to the inner ones, take, as a rule, an opposite direction. Thus if the main inner frames are transverse, the exterior ones are longitudinal, and vice versa. Grantham’s method is in reality the one shown in the description of the Russian composite system.
The English Admiralty method is somewhat different. Here the sheathing is in two thicknesses, the inner course being tap-bolted to the iron skin, the bolt-heads being sunk well into the planks and covered with pitch. The outer course shifts seams and butts with the inner one and is secured with brass screw-bolts. Over this course comes the copper. The Admiralty system is the one followed in France in the construction of the first and second rate fast cruisers. The difficulties of insulation are not yet solved by any means. Could the sheathing be absolutely excluded from moisture the system would be perfect, but as yet no means have been devised by which the wood can be prevented from becoming wet and thus serving the part of the porous jar in a voltaic cell.
In examining and discussing different systems of construction it is necessary to always keep in mind the great distinctions between composite, iron, and iron sheathed with wood. Those who cry down the wooden construction, in view of the rapid deterioration of the American unarmored fleet, must bear in mind that this fleet was constructed of the worst possible material. In discussing the advantages of the composite system, those of the diagonal system must not be lost sight of. Above all, it must be remembered that the disadvantages of the pure iron construction, as evidenced by English and French target experiments, have never been overcome. The iron and steel sheathed with wood is an amelioration, but as yet it is by no means a satisfactory one. Although England has totally discarded the wood construction, it must be remembered that France holds her own with but a partial introduction of iron and composite in her highest and lowest rates. The subject of constructional development is still in its experimental stage, and to those nations who, unlike Great Britain, cannot depend upon legislative support and sympathy, nothing is more dangerous to the healthy development of an efficient unarmored fleet than a hasty adoption of a new constructional type.