Francis Lieber.

Library of universal knowledge. A reprint of the last (1880) Edinburgh and London edition of Chambers' encyclopaedia, with copious additions by American editors (Volume 13) online

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Online LibraryFrancis LieberLibrary of universal knowledge. A reprint of the last (1880) Edinburgh and London edition of Chambers' encyclopaedia, with copious additions by American editors (Volume 13) → online text (page 103 of 203)
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some of the long ships with which he invaded Britain could only approach the shore to
uch a point that the soldiers in disembarking were breaat-high iu water. The Roman*



built their vessels of pine, cedar, and other light woods; but their ships of war were of
oak at the bows, clamped strongly with iron or brass, for use as rains a custom now
curiously revived after 2,000 years of disuse. According to Cfesar, the Veneti tirst built
entirely of oak. The speedy oxidation of iron bolts and fastenings led to their super-
session by copper and brass about the time of Nero. Before this time, the planks had
been calked with flax, and the beams had been pitched. There is evidence to .show that
in Trajan's reign sheathing of lead fastened on with copper nails had been used as a pro-
tection for the timbers from the devastating insects of the Mediterranean, With the
decline of Roman greatness came a new era for ship-building. The hardy ^Norsemen
had chopping seas and Atlantic swells to fight with; their ships differed much from the
stately galleys and quinqueremes of the empire. Far smaller, they were built more
stoutly, with bluff bows, and a lug-sail which could be braced well up to the wind.
The Norse ships must have been of considerable power, for there ie good evidence that
they had visited the coasts of the new world at an early period. We have, however,
very little knowledge of the construction of these vessels, except that they had high
prows and sterns to resist the waves, and that they were calculated for sailing in oppo-
sition to the galleys, which were for rowing. The introduction of galleys by Alfred,
pulled by 40 and 60 oars, and twice as long, deep, nimble, and stc;,dy as the Danish
ships, keep the latter in check; but it also checked the development of ocean-navigation,
for the galleys were only tit for shore-service. The ships gradually increased in size.
Harricauute had a galley pulled by 80 oars; and contemporaneously, the Venetians are
said to have built ships of 1200 to 2,000 tons. William invaded England in miserably
small sailing vessels; but large indeed very large vessels appeared to have existed in
the time of Richard I. John systematized ship-building by establishing a royal dock-
yard at Portsmouth. Large ships constructed for sailing only seem to have come into
general use, together with the mariner's compass, in the beginning of the 14th century.
One hundred and fifty years later, the addition of the bowsprit added much to the sailing-
powers of vessels.

In Ellis's collection of letters there is one, dated 1419 from John AlcOtre to king
Henry V., concerning a ship building at Bayonne for that monarch. This letter is
curious, as showing how many of the present terms then existed, and also that the
" Kynges schyppeo " were of considerable dimensions (e.g., " the stcrnme is in hithe 96
fete; and the post 48 fete; and kele ys yn leynlhe 112 fete"). Before this period, ships
had been built strong enough to encounter ice in the whale-fishery. From this period
the history of ship-building is resolved into the history of individual parts, for the main
principles of wooden ships were already established. In Henry Vll.'s reign, the cum-
brous fourth mast began to be dispensed with; in that of his successors, shifting top-
masts came into fashion, the lofty steins and sterns (which must have precluded sailing
on a wind) fell gradually into disuse. Port-holes were invented at least as earyas 1500.
In 1567, there were cutter-rigged vessels in the British seas. In the century ensuing,
naval architecture was much improved by Mr. Phineas Pott, his son Peter, and by sir
Anthony Deane; but the best naval architects were not in England. Within the present
century, the introduction of steam has led to the building of ships with finer lines, both
for bow and stern. About 186, iron was introduced as a material for ship-building, and
Las now (1878) so far superseded wood, that, taking steamers and sailing ships together,
10 iron vessels are built for 1 wooden one.

Adverting now to the actual art and practice of ship-building, the subject is divisible
into two distinct portions the theoretical, known as naval architecture; and the practi-
cal, called thip-buildiny. The r.aval architect designs the form of a ship with reference
to the objects intended in her construction, to the speed required, powers of stowage,
etc.; while the ship-builder works from his drawings, and gives practical effect to the
theoretical designs.

Natal architecture on a theoretic basis is of recent date, for, as in all cases, practical
efforts, more or less in the dark, have preceded by many ages the theorems of the man
of science; nor is it at present by any means an exact science: some most successful
ships have been but happy experfmcnts. Our present knowledge of naval architecture
we owe mostly to the researches of such men as the late prof. Kankine, Mr. Scott Rus-
sell, Mr. Fronde, and others. All ships have to possess certain qualities, the principal of
which are buoyancy, stability, handiness, and speed; but it is not possible for any ship
to possess at the same time the maximum of all these, as to some extent they neutralize
each other. The skill of the naval architect is shown in duly proportioning them to one
another, ascertaining which are the more important in each particular case, and provid-
ing these without unduly impairing the others. In some vessels, it is essential that the
greatest possible speed should he attained; while, as they are to work only in smooth
water, their degree of stability (~v freedom from excessive rolling, and tendency to right
themselves when heeled over by a wave) is only secondary. In others, which have to
weather long-continued storms in mid-ocean, speed may have to be sacrificed to attain
gpeater steadiness. In sailing-vessels, where the means of propulsion is not under con-
trol of the crew as in steamers, handiness the property of answering quickly to their
helms, and of rciidity performing various maneuvers (such as tacking) tinder all conditions
of weather is often the quality to w r hich most attention has to be paid. Along with all
these things, the ship has to be made so as to nave the largest possible amount of cargo



443



Ship.



or passenger space consistent with the proper degree of buoyancy. The degree in which
a ship possesses the various qualities named depends chiefly upon her external form and
dimensions, about which the following general statements may be given:

An increase of length gives an increase of displacement of water, and therefore of
carrying power; if this be not desired, it allows of finer lines forward and aft, and con-
sequently greater speed. It also increases the resistance to lee-way. The greater fric-
tion of the water on the longer sides does not appear to be material. Against the increase
is to beset a diminished power of turning, tacking, and wearing. It also involves a
more careful balancing of weights in the fore and after portions of the ship, for the
moment of inertia of a small weight may become large in a long vessel, from being such
weight multiplied into the square of its distance from the ship's center of gravity.

The increase of breadth gives greater stability to the ship, and by allowing of more
sail, indirectly greater speed; but directly, it increases the resistance to the water. Of
course, greater breadth enables greater bulk to be carried. Depth is a question depend-
ent on the seas to be navigated, the object for which the ship is intended, and many other
reasons. It is to be borne always in mind that the consumption of stores on a long voy-
age will change the draught of a ship considerably. Practice has proved unequivocally
that ships sail better for drawing more water aft than forward.

Passing now to the actual designing of vessels: the architect works on paper only;
he has therefore to show on a flat surface, for the builder's guidance, the exact position,
curvature, and relief of every line and point in his proposed structure. He accordingly
draws three plans, on each of which every point of the ship is traceable; the sheer-plan,
showing all lines of length and height; the half-breadth plfi,n, lines of length and breadth;
and the body-plan, which shows 'breadth and height. From these combination^, the
exact position of every point is determinate. Figs. 1 to 3 show those plans, called
construction drawings, on. the same scale for the Great Eastern steamship. The sheer-



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plan represents, in its outside line, a vertical plane through the keel. The dotted lines
1, 2, 3, are the edges of supposed horizontal planes drawn at various heights. The
curved lines, i, n, m, are the edges, as they would appear on the outer covering of the
ship, of vertical planes drawn parallel to the central plane through the keel. The
uprights, A, B, etc., A,, B,, etc., are the edges of supposed planes drawn at given dis-
tances from the line of greatest breadth X, at right angles to the plane through the keel.
The half breadth plan represents one-half of the ship's upper deck, as regards the black
outer line; the horizontal, vertical, and cross sections of the sheer-plan appearing again
under different conditions. The vertical longitudinal sections become
straight lines parallel to the keel; the horizontal sections appear as
curves taken at different heights on the vessel's sides. The body-plan
is the ship looked at end-on; the outer line, being her cross section at
the line of greatest breadth, and the horizontal and vertical sectional
lines appearing at right angles to each other. The lines on the left
side correspond to the cross sections of the after-body (that is, the por-
tion of the ship nearer the stern than the line of greatest width), and Pm. s. Great East-
ehow the curvature of the ship's sides toward the ste.n; while in a ern Body-plan, k
similar manner those on the right side show the curvature \ip to the bow. Of course, in
working-drawings from which ships are to be actually built, thj scale employed would be
very large; and instead of three or four sectional lines in each direction, a great number
would be inserted for the guidance of the builder. With these three plans in hand, the
workman has the exact position of every point in the ship's exterior coating exactly
defined. Even the unprofessional observer need not strain his imagination greatly to
clothe these flat plans with their dimensions of length, breadth, and depth, and to con-
jure up before his eyes the precise form of the goodly ship represented.

With the completion of the construction drawings the work of the naval architect




hip.



444



ceases, but in most cases the two professions of naval architect and ship-builder are com-
bined in one firm, if not in one man. It is then to be decided of what material the ship
shall be constructed. The choice lies between iron, steel, wood, and a combination of
wood and iron. Of the many woods employed, oak, teak, and fir are those most com-
monly used. The building of a wooden and of an iron ship are quite distinct operations,
the requisite strength being obtained in a different manner in each case. It is necessary,
therefore, to consider separately the principles of wooden ship-building and iron ship-
building; and as the older and most time-honored process, we will first deal with the art
of the ship-wright who forms the vessel of timber.

In addition to the construction drawings which we have described, it is usual also to
construct a small wooden model of the ship upon a scale very often of inch to the
foot which shows the designer what his ship is going to look like better than the flat
paper can do. This model is made of a number of horizontal layers of wood, and upon
it the whole arrangement of the plating of the ship is marked, with the position of all the
joints, etc.

Wooden SMp-buildinff. The first process is to develop or " lay off," on the mold-loft
Jloor, certain full-size working sections of the required ship. These are taken from the

construction drawings and the model,
and are built up of planks. The com-
binations of these pieces of plank show
the shape in which the several timbers
will have to be cut, to impart the neces-
sary curvature aud strength.

The next step in actual construction
is to prepare the slipway by raising a
number of strong blocks of timber a
short distance apart, on which the keel
shall rest, and which shall sustain the,
entire s4iip when built. These blocks
are composed of several pieces, and it
is of the utmost importance that their
upper surface be in an exact line. That
line is made at an inclination of of
an inch to a foot; and the keel of the
ship, and the ship itself, have conse-
quently that slope to the horizon while
building. This inclination is for the
facility it affords in launching the com-
pleted vessel. On the blocks is laid the
keel, which may be called the back-
bone, and is certainly by far the most
important timber in the ship. From it
start the ribs, the stem, and the stern-
post; so that any serious accident hap-
pening to the keel involves the break-
ing up of the whole structure. It is,
therefore, made of great strength, being,
in a first-rate, no less than 20 in. square.
The material is usually elm, on account
of its toughness, its non-liability to split,
A, keel: B. keelson; C, false keel: D. floor; EE, fut- and tue fact that immersion in sea-water
tocks; F, top-timber: G, lengthening piece; HH, preserves it. The pieces of which it 19
wales; I, diminishing planks; K. bottom planks; L, composed are united by the Strongest
garboard strakes; M. beam; N. deck; O, shelf; P, ki j r * <,,.* ^ n : nt /, r An ppKTRvf
waterwav; Q, spirketing; R. clamps: S, knees; T, klI ML, , J , V CARPE>TRY).
side-keelsons; V, limber strakes; \V, rough-tree What the keel is to the bottom, the
rail; X, mast. gtem and the stern-post are to the bow

and stern of the ship, forming the keys

from which the ends of the planking (technically called the " butts") and all longitudinal
eupports start. Each is, of necessity, of great strength, and they rise from the respective
extremities of the keel. The stern-pout has to bear the rudder, and is usually made, when
possible, of one piece of timber; it is united to the keel by a mortise and tenon joint.
In screw-steamers there is a second stern-post, forming the forward support for th
screw.

The extreme outlines of the ship being now established, the builder proceeds with
the timbers to form the bottom and sides, which together constitute the frame, corre-
sponding to the ribs in an animal. The ribs form the sides of the ship, and are placed
at from 2 ft. 6 in. to 3 ft. 9 in. from center to center. Up to the water-line the spaces
between them are filled in solid with timbers of equal thickness. For this purpose in
the midship-body the keel is crossed at right angles, or nearly so, hy certain timbers
which form tlie floor. The keel is let about three-fourths of an inch into a groove run-
ning along the bottom of the floor, while above the floor the keelson is a massive timber,
parallel to the keel. The keel and keelson are bolted firmly together by long copper bolts,




Fio. 4. Ribs and Decks In section:



445



Ship.



which pass through the timbers of the floor, and completely fix the latter. As an addi-
tional strengthening to the frame in large vessels, side or sister keelsons are bolted on to
the floor or futtocks, a short distance on each side of the principal keelson. Fig. 4 is a
cross section of a three-decked wooden vessel, showing a complete rib, with the principal
parts as they are commonly arranged amidships. Near the ends of the ship the frames
no longer stand at right angles to the keel, but are necessarily bent or canted round.

After the main skeleton, as it were, of the ship is built, the skin is the only thing
remaining to complete its exterior. This is represented by thick wooden planking,
fastened on to the ribs, the lowest layer pressing into the rabbet of the keel, and the
highest reaching to the uppermost bulwark. The thickest planking is at the bends or
wales, marked H in tig. 4, where it varies from 4} in. in small vessels to 10 in. in ships
of the first class. Every complete line of planking from stem to stern is styled a
trake. Oak and fir are the woods mostly used for the skin, and elm for the planks
nearest the keel. The planks are generally fastened to the ribs by copper bolts, but
wooden treenails are frequently employed, as less in weight than copper, and less liable
to split the wood. The comparative utility of wood and copper fastenings for the
strakes is still a disputed point.

In a well-constructed ship the filling in of the timbers to a level above the water-line
should be so accurately formed that she would float without her planking; but when
the latter has been well calked, it is certain that it adds greatly to the dryness of the
ship, while it aids materially in binding her several parts together.

At frequent intervals across the ship, and at the heights of the several decks, are
inserted the beams, which are solid masses of timber, either in one piece or scarfed.
These prevent the ship from collapsing, and at the same time support the decks. The
beams and decks are shown at M and N respectively in Fig 4. The beams are always
made convex upward, principally for the sake of preventing water lodging on the
decks. When the beams are well established, the hatchways and mast-holes are traced
out. This done, the deck is laid down of straight-grained hard wood, and the planks
are calked and pitched between, until the deck or platform becomes perfectly water-tight.

Along the inside of the bottom are laid the sister keelsons or fide keelsons, if the ship
be large, and all spaces are filled up with planking, except the width of one plank next
the keelson on each side, which is left for a drain to carry all refuse-water to the foot of
the pumps.

Iron Ship-buMing. Iron affords, in many respects, a better material for ships than
wood. In the first place, the same strength may be obtained with less weight; secondly,
iron plates can be bent to any curve, so that the combinations necessary for strength in
wooden vessels can be avoided. The Laying off
the lines of the vessel full size upon the mold-
loft floor is the first process in iron as in wooden
ship-building. Rough wooden templates are here
made of the cross sections of the ship, one template
to every cross section.

The slip-way is prepared in much the same
way as in the ca'se of a wooden ship. The keel is
generally of flat bar-iron sometimes in several
thicknesses the different lengths being scarfed
at the ends and riveted together, or sometimes
welded. In the cross section of a 2,000-ton iron
vessel given in Fig. 5, the keel is in five thick-
nesses; in the mtddle a center-plate, which is
carried upward through the floors, and forms a
keelson; on either side of this a thick bar, and
outside these again the two lowermost plates of
the skin bent downward. The whole five thick-
nesses are riveted together.

The ribs in an iron ship are called "frames."
They are always made of angle-iron, and are
placed from 18 in. to 2 ft. apart. They are bent,
while red-hot, upon a large flat cast-iron plate,
into the proper curve, fixed by the templates
already mentioned. The frames, when thus bent
to the right shape, are set up in place upon the
keel. To them are fastened at the bottom the
floors, which are narrow plates running across the
ship; and frequently additional stiffness is gained
by running "reverse" angle-irons along the top of




Fio. 6. Section of Iron Ship:



the floors, throughout at least a considerable por- o, frames; 6, reverse angle irons; c, floors;
tion of the ship's length. The beams which support
the deck are convex upwards as in wooden ships.
After the frames, floors, and beams are in place,



t, i, bilge keelsons; k, ce ling.



the plating commences, each particular plate being of a si?.e and shape exactly 88
determined by the model. The lowest plates of all are called the " garboard strake,"



snip.

Shipping.

and are usually bent downward and riveted to the sides of the keel, as in fig. 5. The
thickness of the plates gradually diminishes upward, till the " sheer strake" the strake
at the level of the main deck is reached, and this is always made very strong. The deck
beams are further secured and stiffened by longitudinal and diagonal plates called
"stringers." All the iron-work of a ship is fastened together by rivets. Holes are first
punched or drilled in the plates and angle-ironsin most cases before they are put
together. The holes having been made exactly to overlap, a red-hot rivet is inserted
through them. A man, called a " holder-up," holds the head of the rivet forcibly in
its place with an iron tool, while two riveters on the other side of the plate strike
its end rapidly with their hammers until it is all hammered down. The contraction of
the rivet when it cools causes it to hold the two plates still more tightly together. Iron
ships are always divided into a number of compartments by transverse partitions called
"bulkheads." These partitions can easily be made water-tight, and then afford great
additional security to the vessel, as, in the event of a leak occurring, it will often be pos-
sible to confine the water to the space between two bulkheads, and there will be sufficient
buoyancv in the other compartments to keep the vessel afloat. The bulkheads are fitted
with water-tight doors, and hesides being a source of safety, they are also the cause of
groat additional transverse strength.

By the time that the external plating of the ship is finished, and the beams and bulk-
heads all in their places, she is ready for launching; much, however, still remains to be
done to her. Most frequently, the greater part of the decks has to be laid, and the
whole of the cabin fittings to be put up; the rudder and steering gear have to be fitted;
the wooden "ceiling" (which lines the hold) to be put in; the masts have to be set, and
all the spars, sails, and rigging put up; and lastly, in a steam vessel, the engines and
boilers have to be placed and properly secured on the seating.} provided for them.

Steel has as yet been but little -used in the construction of ships. As it possesses
much greater strength than iron, all the various parts of a steel ship may be made much
lighter for the same strains than in an iron one. There has been, however, a very wide-
spread distrust of this material among ship-builders, based, to some extent justly, oa
the difficulty of getting really reliable steel plates and bars; and this has been the prin-
cipal cause of its non-use. With greater facilities for the manufacture of steel, and
consequent reduction in its price and improvement in its quality, we may still expect to
see it largely used as a material for ship construction.

8Mpi of Iron and Wood conjointly, or "composite" vessels. It was at one time thought
that various advantages would be obtained by the use both of iron and of wood in the
same ship, the frame and beams being made of the former material, and the skin of
the latter. Composite vessels were always more used by the French than among our-
selves, but although Lloyd's committee have thought this class of vessels of sufficient
importance to publish special rules in reference to it, very few composite ships are now
constructed. During 1873 only 7 such vessels (of a gross tonnage of 1069 tons) were
launched, and 6 more (of a gross tonnage of 1430 tons) were in course of construction
at the close of the year.

In some recent ships of war (e.g., the Tnumpli and Stmftsurc), the vessels, after being
built of iron in the usual way, and heavily armored, have been covered all over with
planking, and copper-sheathed. The object of this has been to insure that the ship's
bottom shall not be fouled with weeds and barnacles, which so easily happens with iron
vessels, as these frigates are intended for very high speeds.

Internal Arrangements of a Ship. Whether the vessel be of iron or wood, her inter-
nal design must follow the purposes for which she may be required. As a general prin-
ciple, the ship is divided into a greater or less number of platforms, floors, or decks
(q.v.), devoted to various purposes. In a ship-of-war a large portion is required for the
men, the remainder being occupied by warlike stores, provisions, and coal. In a mer-



Online LibraryFrancis LieberLibrary of universal knowledge. A reprint of the last (1880) Edinburgh and London edition of Chambers' encyclopaedia, with copious additions by American editors (Volume 13) → online text (page 103 of 203)