SHIP DESIGN, CONSTRUCTION, AND REPAIR
Ship design, prior to the opening of the 19th Century, was based very
largely on rule-of-thumb methods. In ancient times, before Greece
became a sea power, this was particularly true. Shipwrights and sailors
came to know from experience what qualities were good and what were
bad, and after many years at their work were able to construct ships
with some understanding of what the ship could be expected to do.
It took only a little while for them to learn that narrow ships were
easier to propel than broad ones but that broad ships possessed
carrying power superior to that of narrow ones. Thus the merchant
ships were “tubby” while warships were narrow. If a ship proved to be
unseaworthy in heavy weather shipwrights naturally did not build other
ships like her if they were looking particularly for seaworthiness. If
a ship was able, it was only natural that her characteristics should
be incorporated in other ships. If a ship otherwise satisfactory
permitted seas to come aboard over bow or sides or stern, the sailors
and shipwrights tried to correct the difficulty without losing her good
qualities. Thus from generation to generation ships improved, although
the process was slow.
When Greece was at her zenith there seems to have been a more thorough
study made of structural design, and many things about ships were more
or less standardized. Just how far the Greeks carried their study of
ships it is impossible to say, but crude methods gave way to finer
ones, and Greece passed its understanding of ships on to Carthage, and
from the Carthaginians it went to Rome. But the Middle Ages lost this
information, as it seems to have lost almost everything else, and a new
beginning had to be made.
[Illustration: A SHIP ON THE WAYS
_While a ship may look large on the water, she looks gigantic when on
land. The great hulls and the collection of scaffolds and machinery
in a shipyard are always a source of surprise to the visitor who is
unfamiliar with the construction of ships._
]
The Norsemen went through a similar development. The seas their ships
were called upon to sail were almost always boisterous. The principal
use to which their ships were put was war. They had, then, need to be
both seaworthy and fast. The early crude attempts of the Norsemen,
therefore, grew slowly into those beautiful ships for which they are
famous. To-day the seaworthy whaleboat is very similar to the finest
examples of the old Norse “serpents.” These old ships were long,
narrow, pointed at bow and stern, and had both ends raised, while
amidships they were low. The sheer, that is, the line from the high
bow to the low section amidships, and from there up again to the
stern, was a beautiful sweeping curve. Such ships readily rode rough
seas, while their low “freeboard” amidships permitted the oars to be
used to good advantage, and their narrow hulls presented a minimum of
resistance to the water. This refinement, however, can hardly be said
to have resulted from thought so much as from experience. By that I
mean that these ships at the highest stage of their development were
not consciously designed, but were outgrowths from experience, and that
the shipwrights, only after many generations, had learned that such a
design combined the advantages they particularly desired.
It was with the Crusades, as I have said before, that ships began to
improve more rapidly. This was due to the broadening spheres of travel
of western European sailors. They visited the Mediterranean and Asia
Minor, and found in that part of the world ships that were strange to
them. But in these strange ships they found characteristics that they
deemed desirable, and, combining these desirable points with those of
their own ships that were equally desirable, they produced improved
types. Thus they profited by the experiences of others who, in their
own little spheres of activity, had gradually developed ships that
answered, at least to a considerable extent, the requirements of their
own localities.
It hardly needs to be pointed out that the British, who sailed the
rough waters of the North and Irish seas and the English Channel,
developed ships far different from those developed by the peoples of
Mediterranean countries, where the distances sailed were shorter and
the weather conditions were so radically different.
After the Crusades had introduced the peoples of western Europe to
those of the Mediterranean, trade between the two increased, and, so
far as ships were concerned, each learned from the other. Thus it was
that by the time Columbus sailed on his famous voyage, the sea-going
ships of all the European countries had grown somewhat similar in
design and appearance.
[Illustration: A FLOATING DRY DOCK
_And a ship undergoing repairs._]
A few glimmerings of the complicated subject of naval architecture
became evident in the years that included and followed “the age of
discovery,” and ships, or at least _some_ ships, were “designed” by
men who made a study of them. The designs, however, were largely
little more than the transfer of rule-of-thumb methods to paper, and
a real understanding of the subject was still far distant. Phineas
Pett, during the 17th Century, designed many ships for the British
Navy, and from these designs the ponderous ships of later days
developed. In France, however, naval architecture seems to have been a
better-understood art than in England, for many times British designers
improved their ships after studying captured French ships.
The designers in England for many years were guilty of one error in
particular which, while later corrected, proved to be the cause of
the loss of several of their very greatest ships. This fault was the
placing of the lowest tier of gunports so close to the water that when
the ships were under a press of sail the ports on one side or the
other, and they were not watertight even when closed, were under water.
During the reign of Henry VIII, a British ship named the _Marie Rose_
heeled over when getting under way, and the ports, which were open and
were only sixteen inches above the water when she was on an even keel,
permitted the water to enter in such quantities that she sank. Years
later Sir Walter Raleigh wrote that this defect was being corrected,
yet later still the _Royal George_ was lost because of the same fault.
It is interesting to quote a few lines of Raleigh’s writings on ship
design. Commenting on improvements in lines he said that ships with
these improvements “never fall into the sea after the head and shake
the whole body, nor sinck a sterne, nor stoope upon a wind.” He also
suggested that the lowest tier of gunports should not be less than four
feet above the water. Furthermore, he objected to the high sterncastles
which made the ships of the time both unseaworthy and ridiculous.
Modern scientific naval architecture can properly be said to date from
the latter part of the 17th Century, for it was then that the first
studies were made of the passage through the water of various shaped
hulls. Before this, ships were built and if they were successful were
copied; if unsuccessful they had less influence on later design. Now
began a study that has been carried down to to-day, and scientific
deductions began to be made, and upon these investigations and the
results of them an important part of naval architecture has been
founded.
Still, however, this new science was crude. One reason for this was
that ships depended upon the wind for power, and it was a slow task
to compile comparative data. That this was not impossible, though,
is proved by the brilliant American designers of the first half of
the 19th Century, who suddenly evolved the clipper ships that so far
surpassed all previous sailing ships that comparison became mere
contrast.
But it was steam that made it possible for naval architects to develop
their profession to so high a point as it has reached. It was during
the 19th Century, then, that naval architecture made its greatest
progress. Since the 19th Century great improvements have been made, it
is true, and many facts have been discovered, and naval architecture
still is progressing, but the 19th Century made a profession of it, and
the 20th Century is only continuing its development.
The profession of the naval architect is one that is not widely
recognized or understood. When Cass Gilbert designs a Woolworth
Building we recognize him as a great architect, and realize, to some
extent, the great task he has so successfully completed. When the
building is built we view it with interest, perhaps with awe, and
comment on the brilliance of the architect and the ability of the
constructor. And they deserve all the credit they get—and more.
But how often have you ever heard mention made of the architects from
whose brains were evolved the _Mauretania_ and the _Leviathan_, the
_Belgenland_ and the _Majestic_? True, it is commonplace to marvel
at their size. But who thinks of the titanic task that faced their
designers?
And now imagine a Woolworth Building being built on a sloping
runway, and, when completed, slid bodily into the water, across
thousands of miles of which mighty engines placed inside could drive
her at express-train speed. Imagine such a structure, with all the
magnificence of appointments that are to be found in the Woolworth
Building, forcing its way through winter storms with waves pounding
madly at its sides—waves which, striking the ironbound coasts of Maine
or Wales, sometimes tear away tons of the living rock and hurl it
about in a smother of foam. And then compare such a structure with
the greatest ships of to-day. There are several far longer than the
Woolworth Building is tall, but these vast steel hulls do not rest on
foundations of steel and concrete—immovable. They float in the water,
and may pitch and roll in the giant swells of the deep sea, but still
their huge steel frames easily bear the strain, and while a tremor
of the earth might dash skyscrapers disastrously about our ears, the
almost constant motion of the sea, whether violent or weak, affects
them little. For such work as this the architects of ships deserve all
praise.
In such huge and complicated structures as ships have grown to be,
repairs, naturally, are frequent and vital. The ordinary wear to which
the machinery is subjected necessitates constant adjustments and
replacements. Improved mechanical apparatus sometimes is installed
to take the place of less reliable or less economical apparatus. The
action of sea water on the exposed metal and the collection below the
water line of barnacles and other marine growths require periodic
attention, while paint seems for ever necessary and, at least on
warships, wet paint is omnipresent.
Before the introduction of iron and steel, ships were comparatively
small, and consequently it was a simpler job to haul them out of water
or ground them at high tide in order that, when the tide had gone out,
their underbodies could be examined and repaired. Sometimes, again,
tackle made fast to their masts and led to anchors dropped well away
from their sides or to points ashore made it possible for ships to be
hauled over to one side or the other, bringing a large part of their
underbodies above water, where their crews could make the necessary
repairs, or scrape off most of the accumulation of marine growth.
[Illustration: THE _OLYMPIC_
_A sister ship of the ill-fated_ Titanic, _and operated by the White
Star Line._]
Nowadays, however, when the very smallest of our ocean-going steamers
is many times the size of Columbus’s largest ship, such methods avail
little. Sometimes, still, in harbours where there is a large rise
and fall of tide the smaller ships avail themselves of it for minor
repairs, but for most modern ships such methods are impossible and
dangerous.
Yet even the greatest ships must from time to time be taken out of the
water for repairs and for the inspection of the hulls, and for this
purpose dry docks, or, as they are sometimes called, graving docks,
came to be designed.
Dry docks are long narrow basins, the dimensions of which are slightly
larger than the largest ships they can accommodate. Nowadays they are
usually built of reenforced concrete, although brick and stone are
sometimes used, and formerly timber dry docks were not uncommon in the
United States. The entrances to these basins are equipped with hinged
gates, or a floating or sliding caisson. Dry docks in the United States
ordinarily use the floating caisson. European dry docks commonly use
the other two. These seal the mouths of the dry docks, preventing the
entrance of water from the outside as powerful engines pump the water
from the dock itself.
The sides of dry docks are usually built in steps, so that at the top
they are wider than at the bottom. The bottom is very nearly level, but
there are careful arrangements made for draining all the water into
pits from which it is pumped out.
Extending almost the length of the centre of a modern dry dock is a
row of large wooden blocks, called keel blocks. These can be moved and
are made fast when they are put in place. Often this row of blocks is
paralleled on each side by a row of somewhat similar blocks called
bilge blocks which run along tracks laid at right angles to the line
of keel blocks. The bilge blocks can be moved individually along these
tracks by means of ropes and pulleys. These ropes are extended up the
sides of the dock so that, even when the dock is filled with water,
each individual bilge block, and there are scores of them in each row,
can be moved back and forth by men beside the dock.
When it is necessary for a ship to be docked her docking plans are
given to the man in charge of the dock. He then arranges the keel
blocks so that the line along their tops is the same as the line along
the keel of the ship. Certain marks are then made at the top of the
dock’s side walls to show just how far the ship is to be hauled into
the dock. When these arrangements are completed the dock is flooded,
the gates are opened, or the caisson is floated out and the ship is
very carefully and very slowly hauled into the dock. She never goes in
under power, for the clearance between her sides and the sides of the
dock is often very small, and the greatest of care must be taken to
keep her from coming in contact with the masonry.
When she has been hauled up to the point marked on the dock side she
is carefully made fast with cables, and the entrance to the dock
is closed. The ship must be riding on an even keel, for if she is
listing—that is, leaning to one side or the other—she may damage
herself when the water is pumped out and she comes to rest on the keel
blocks.
As the water level is reduced her keel slowly settles on the keel
blocks which support the whole weight of the ship, but in order to
prevent the ship from toppling over sideways the bilge blocks are
pulled carefully under her. As they are slightly higher than the keel
blocks they touch her bottom at some distance from the keel, and as
there is a row of them on each side they keep her securely upright.
Care must be taken that none of these bilge blocks come in contact with
the ship where any of her numerous underwater valves project, for if
that happened the valves would be damaged. The docking plan referred
to, however, shows where such protuberances are and such accidents need
not occur.
In dry docks where bilge blocks are not used, the ship is supported
instead by “shores.” A “shore” is a long timber which is placed with
one end against the ship and the other against the side of the dock. In
order to make them fit snugly great numbers of varying lengths are kept
on hand and are chosen so that they come within a few inches of filling
the space between the ship’s sides and the dock wall. Then large wooden
wedges are driven in between the dock wall and the end of each shore.
Dozens of these are placed about a ship and serve the same purpose as
is served by the bilge blocks.
A ship I was on some years ago was rammed by a coal barge while at
anchor in the harbour of Brest, France, and was forced to go into dry
dock for repairs. Being familiar with dry-dock procedure only in the
United States I was unprepared for what has always since seemed to me
to be a thoroughly picturesque method of placing the shores.
Our ship was hauled into the dock, the gates were closed, and the pumps
began to lower the water. Finally she settled on to the keel blocks and
the shores were floated into place, each end being held from above by
a line. As the water sank lower the wedges were inserted between the
shores and the dock walls, and a man with a large wooden mallet took
his place at each wedge. Then the foreman, standing at the head of the
dock began a song which the mallet bearers took up, singing beautifully
in unison, their voices booming upward from the dry dock, halfway down
the sides of which they stood. And as they sang they kept time with
great strokes of their mallets on the wooden wedges, the musical wooden
sound ringing in unison with their song as every man drove his crashing
blows with every other man.
I stood on the bridge of the ship listening to the lilting song, and
the great musical crashes that punctuated it, every man striking at
exactly the same instant that every other man struck. Never before or
since have I seen a more practical demonstration of the uses of song
or heard so beautiful a song of industry. It was an “Anvil Chorus” with
a different setting.
There is another type of dry dock that is widely used and is of great
importance where it is too expensive or difficult to build the type to
which I have just referred. This other type is the floating dry dock.
In principle it is a huge barge, rectangular in shape, and with highly
raised and very thick sides and open ends. Its bottom is built up of
many compartments and its “reserve buoyancy” must be at least a little
greater than the total weight of the largest ship it is designed to
accommodate. That is, it must be able to float while carrying a load of
15,000 tons if it is meant to be used by ships up to that displacement.
[Illustration: THE _AQUITANIA_
_A British built ship operated by the Cunard Line._]
These floating dry docks need only to be placed in a sheltered spot
where the water is deep enough for the dock to be sunk so that the dock
floor is a little farther beneath the surface than is the keel of the
ship that is to be docked. When everything is in readiness—that is,
when the keel blocks are properly placed and the incoming ship has been
otherwise prepared for—water is allowed to enter the inner compartments
of the dry dock. Gradually the whole thing sinks until only the two
high sides are visible above the water. When it has sunk until there
is enough water over the dock floor for the incoming ship to float in,
the valves are closed and the ship is hauled in and made fast. Then
giant pumps begin to expel the water that has been allowed to enter
the compartments. This causes the dry dock to come once more to the
surface, and as it rises beneath the ship the keel blocks press up on
the ship’s keel, shores or bilge blocks are put in place, and when the
ponderous float regains the surface there is the ship, high and dry,
where men can scrape and paint and repair her or accomplish the other
tasks assigned to them.
It is interesting to watch the labours of a crew of workmen in a
dry dock. If a ship looks large in the water, it looks startlingly
gigantic in a dry dock, especially if one walks down to the dock floor
and views the high bow or the overhanging stern from the level of the
keel. Propellers from a distance look small, but with half-a-dozen men
realigning their blades or working about them, they look huge indeed.
[Illustration: THE _PARIS_
_The greatest French Merchant ship, operated by the French Line._]
A hundred men may be swinging on scaffolds which are hung over the
ship’s side by lines from the deck, and they remind one who is watching
from a distance of flies or ants on a wall. A regiment of workmen may
disappear beneath the huge bulge of the ship’s underbody in order to
scrape or paint or repair. Fathoms of cable may follow an anchor from
the hawse pipes to the dock floor as the “ground tackle”—that is, the
anchors and cables—is cleaned, painted, and examined. Propellers or
sections of propeller shafts may be swung over the yawning dock and
lowered into it by great cranes, to take the places of others lost or
damaged. Sections of the ship bent or cut by collision may be replaced
to the raucous tune of nerve-shattering riveting hammers. Rivets
loosened by the “working” of the plates or by galvanic action may be
renewed. Plates damaged by any of a hundred causes may be replaced, and
great piles of barnacles scraped from the steel skin of a ship that has
been overlong between dockings may accumulate on the dock floor. Sea
valves are reground, the rudder is examined, propeller-shaft supports
are looked over, and, when the work on the ship’s great underbody is
completed, the workmen take their tools and depart, great valves are
opened in the dry dock walls, the water enters, and once more the great
ship floats. The dock gate or the caisson is removed, and carefully the
monster of the sea is backed from her gigantic hospital, fit, so far
as her underwater parts are concerned, for another round of duty at sea.
But dry docks are not necessary for all the repairs a ship might need
to undergo. To replace or repair engines she may go alongside a quay or
a pier, and for any of a thousand jobs she need never stop her regular
voyages. But repairs or changes are always under way. To the voyager on
a handsome liner little of this is apparent, but it is always known to
the crew, and rare indeed is the time on a steamship when repairs are
neither under way nor contemplated.
This continuous round of repairs does not mean, though, that the
steamships of to-day are not properly designed and built. It only means
that a great ship is so vastly complicated that some part of it is
always just a bit below par. A small town needs repair men to keep its
electric-light system properly working. Its water system is similarly
under constant supervision. Its gas, its paving, and a dozen other
parts of its equipment are always being repaired, renewed, or extended.
The same is true on board ship, except that, at least on the giant
liners, the ship’s equipment is more complicated than the town’s.
This wandering discussion presents a few of the difficulties that face
the designer, the builder, and the operator of ships. Such difficulties
are all but infinite in number, and constant vigilance is vital to
the efficient operation of the ships of to-day. But so reliable have
these great structures grown to be that one of the greatest—the
_Mauretania_—while launched in 1907, was able after fifteen years of
constant and efficient service consistently to defeat newer ships of
greater size and greater power in her constant voyages to and fro
across the Atlantic. Such results as this must be credited to the
designer, the builder, and the officers and crews of these complicated
structures of the sea.