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Part five of the Journal of Submarine Commander von Forstner.
This is a LibriVox recording. All LibriVox recordings are in
the public domain. For more information or to volunteer, please
visit LibriVox dot org. Recording by Sue Anderson. The Journal
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of Submarine Commander von Forstner by Georg Gunter Fraher von Forstner,
translated by Anna Krafts Codmen, with commentary by John Hays
Hammond Junior. The Journal, Part five, Chapter eight, The method
of Sinking and raising Ships. During the present naval warfare,
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we have had the opportunity to watch the sinking of
ships of every type and size. Shortly after receiving their
death wound. The vessels usually disappeared totally beneath the surface.
It takes even big steamers only between four war and
ten minutes to sink after being hit by a torpedo
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or shell beneath the water line, and yet occasionally a
ship may float several hours before going down to the
bottom of the sea. It is clearly evident that the
slow or rapid sinking of a ship depends on the
distribution of its bulkheads and water tight compartments. A man
of war built on the latest models has a great
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many small, water tight compartments, for she is meant to
be able to continue fighting even after several of these
compartments have been destroyed. Whereas an ocean steamer is so
constructed that she will remain afloat only a short time
after a collision with another ship, or if she runs
into an iceberg or a derelict, she can endure a
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certain intake of water and lists at a moderate angle,
far more readily than a warship, whose guns are rendered
nearly useless if the ship is heavily canting. A warship
must be built so as to withstand without sinking the
injury caused by a number of gun holes, even beneath
the water line, where the inner part of the ship
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must necessarily be subdivided into many parts. A warship is
built at great cost, but so is an ocean steamer.
The sunken Lusitania was worth thirty five million marks nearly
nine million dollars, and the mammoth steamers of the Hamburg
American Line, the Imperatore and the Waterland, were still more
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expensive to build. The ordinary commercial steamer often has in
her inner construction only athwart ship bulkheads through the double
bottom that run from one side to another and form
large partitions and in proportion to her height. A steamer
is again subdivided horizontally into several decks, but these are
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not usually water tight, and the cross bulkheads already mentioned
form the only water tight divisions in the hold. In
the big cargo spaces, these divisions practically do not exist,
and the ship throughout almost its whole interior is open
from keel to deck. This arrangement, of course, facilitates the
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rapid loading and unloading of the cargo. Therefore, in this
type of ship, the engine rooms and boilers, surrounded and
protected by coal bunkers, are the only really water tight
portions of the ship. Whoever has gazed down into the
capacious hold of such as steamer will readily understand that
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if the water should pour into one of these spaces
at either end of the ship, the other end of
the vessel would rise steadily upwards. In nearly every case,
even the largest steamer, just before sinking, tilts abruptly its
bow or stern straight up out of the sea, until
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the water rushing into the hold draws the vessel downwards,
and with a mighty roar, it plunges forever into the deep.
We have repeatedly noticed at this moment that the air
within the boat escapes with a shrill whistle from every
possible aperture, and the sound resembles the shriek of a
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steam siren. This is a wonderful spectacle to behold. The
velocity with which a ship sinks depends on the size
of the hold and its distance from the ship's center
of gravity, For the suction occurs more rapidly if the
ship is struck at either end than if the blow
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is delivered amidships. We are seldom concerned with ships having
empty holds. Those we pursue usually carry heavy cargoes, and
therefore the water can only penetrate within where space and
air exists. Whatever air is left around loosely packed bales
and boxes must be driven out before the water can
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stream in. Certain exceptional cargoes like wool and cereals, absorb
a given amount of water, but these can be discounted accordingly.
The air must escape through existing holes as the water
pouring in drives the air into the hold. The pressure
with which the water comes in is equal to the
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air pressure in the hold. It is quite conceivable that
a cargo may be so closely packed that there will
be no space left for air to escape, but this
is hardly ever the case. Frequently, however, the cross sections
of the air vents are so small that the air
escapes only very slowly and the water enters very slowly
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in the same ratio. Under these conditions, it would take
a long time for a ship to sink. This undoubtedly
is very desirable in peace time, but in time of
war the un is not at all agreeable to our purpose. First,
if the foundering of the vessel is prolonged, we are
prevented from accomplishing other work. And secondly, warships may come
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to the assistance of a sinking steamer whenever possible. We
found it expedient to break open with an axe big
holes in the lockers. In case the hatch could not
be quickly enough removed, or if circumstances did not permit
of our doing this, we shot holes with our cannon
into the upper part of the steamer above the hold,
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so that the air might conveniently escape and the water
rush in. We employed with excellent results this method in
the sinking of many steamers, which otherwise would have settled
too slowly. It happens sometimes that a ship may carry
a cargo that floats and that is not porous, such
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as wood. It is impossible to sink a vessel with
such a cargo by admitting water into the hold. Shots
therefore must be fired at the engine and boiler rooms
to force this kind of a steamer to sink. In general,
this is a safe rule to follow, for these are
always the most vulnerable portions of every heavily laden vessel,
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and this mode of attack is nearly invariably successful. A
warship is usually equipped with cross or lateral bulkheads in
addition to the longitudinal bulkhead that runs from stem to
stern through the middle of the ship, dividing it into halves,
and other bulkheads separate these two longitudinal sections into further subdivisions.
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With the exception of the great fast passenger steamers, these
divisions by means of longitudinal bulkheads seldom exist on vessels
of commerce, although exceptions are to be found. The sinking
of a steamer with a multitude of partitions is effected
by by its gradually listing more and more on the
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side in which the water is penetrating, until it capsizes
completely and founders with the keel uppermost. A ship can
also roll over on its side as it plunges downward
with stem or stern erect. Theoretically, a vessel might sink
on a parallel keel, descending horizontally deeper and deeper into
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the sea, but it never occurs in reality. This hypothesis
assumes that a ship has taken in at the bow
exactly the same amount of water as at the stern,
at exactly the same distance from the center of gravity. This,
of course, is impossible. Besides, the holes through which the
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water is pouring in must be at precisely the same level,
or else the water pressure would be greater at one
end than at the other, and the slightest alteration of
level would occasion a greater intake of water and upset
the equilibrium of the boat. There is one other point
I will touch upon. It has often been asserted, especially
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in romances of the ocean, that as a ship sinks,
the suction creates a tremendous whirlpool which engulfs all things
in its vicinity. This statement is naturally very much exaggerated,
people swimming about may be drawn down by the suction
of the foundering ship. But in my opinion, no lifeboat
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which is well manned is in danger of this whirlpool.
Even old sailors, diluted by the superstition, have rowed away
in haste from a sinking ship, when they might have
stood by and saved many lives. The question is now
often being put whether it will be possible to raise
the vessels that have been sunk during the war. The
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raising of a ship depends, above all, upon whether the
depth at which it lies is so great that it
precludes the work of a diver. I have already stated
that the water pressure augments at the rate of one
atmosphere one kilogram to the square centimeter to ten meters
increase of depth. If a diver working at ten meters
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depth is under a pressure of one atmosphere. At fifty meters,
he will be under the tremendous pressure of five atmospheres.
This is the greatest depth to which a diver can attain,
And if by chance a diver has gone a few
meters beyond fifty meters, no man, to my knowledge, has
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attained sixty meters. The work of divers at a depth
of forty or fifty meters is even then not very effective,
as they are unable to perform heavy tasks, nor can
they remain more than half an hour at a time
under such a pressure. And I am speaking now only
of experts. Therefore, or only light and easy work can
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be performed by most divers at a great depth, and
the appliance of ponderous chains for lifting purposes can only
be accomplished under unusually favorable conditions. To raise any ship
at a depth beyond thirty meters must be considered as
a very efficient job, whereas if this is attempted at
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a depth below thirty meters, it can be done only
by salvage companies where neither unfavorable bottom obstacles nor currents intervene.
A strong current renders a diver's work impossible, for it
carries him off his feet. On the high seas, the
currents change with the ebb and flood at the precise
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moment of the turn of the tide, the undercurrent is
supposed to be nil, and the diver must take advantage
of this moment to perform his task. Another difficulty arises
from the sand being shifted by the currents, and settling
on the prominent parts of a wreck, it often envelops
them to such a degree that the ship becomes so
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deeply embedded in the sand that it is no longer salvageable.
According to my estimation, eighty percent of our enemy's sunken
ships lie from fifty to one hundred meters below the
surface of the sea, so that all possibility of their
being raised is excluded. The largest ships nowadays have a
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draft of less than ten meters, and as the vessels
sunk lie at far greater depths, they are no source
of danger to shipping in time of peace. Of the
remaining twenty percent of sunken ships, half of them are unreclaimable,
either owing to their position or owing to the high
cost of salvage, or because it is not even known
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where they lie. The other half or last ten percent,
have probably for the greater been sunk in channels where
the currents are so swift that they are covered with sand,
and diving enterprises are out of the question. In time
of war, such work cannot be thought of. After the war,
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the ships will long since have been completely buried by
the sand. Maybe off the east coast, of England, one
or two ships may be raised, for they lie at
a lesser depth and are exposed to slighter currents than
on the south coast of England. But in that district
only the smaller and more insignificant vessels have been sunk,
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and it would hardly pay to raise them, especially as
they are so damaged by torpedoes and mines that they
would probably fall apart on being raised to the surface. Therefore,
hardly a single ship will be salvaged, and the sea
will retain all those ships it has swallowed in the
course of this war carried on by all the nations
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of the Earth. End of Part five of the Journal.
End of the Journal of Submarine Commander von Forstner by
Georg Gunter flihirvon Forstner, translated by Anna Kraftskodman, with commentary
by John Hayes Hammond Junior,