Of torpedoes on board there were eight "large" and eight "small," as
they called them, which when discharged liberate their own propeller
and shoot along at some ten feet below the surface at a rate of up to
forty knots an hour, occasionally "breaking surface," i.e., coming up
higher and throwing jets of spray in their course and then submerging
again.
It appears that 55 per cent, or more than half, of the torpedoes fired
miss their mark, and with this average they seem satisfied. Once they
let go at a ship two torpedoes at 3,000 yards' range, and both missed,
the range being too long; but they did not care to come any nearer, as
they believed the ship to be well armed.
They prefer to fire at 500 to 700 yards, which means that at this range
the track or "wake" of a projectile would be discernible for, say,
twenty-five to thirty seconds--not much time, indeed, for any ship to
get out of the way. At 100 yards' range or less they do not care to
fire unless compelled to, as the torpedo is nearly always discharged
when the submarine is lying ahead of the object, i.e., to hit the ship
coming up to it; it follows that a gun forward is more useful than
one aft, the gun aft being of real service when a submarine starts
shelling, which she will do for choice from aft the ship rather than
from forward of her, where she would be in danger of being run over and
rammed.
Owing to the big expense of wasted torpedoes it had been planned to
build special larger U-boats, two-deckers carrying larger guns for
shelling purposes--hence the sooner all merchantmen are well armed the
better for them.
Talking one day of the number of submarines lost, the officers declared
that the Allies' reports of their captures and sinkings were much
exaggerated. Naturally they would say so, but the truth is probably
best known at headquarters, where such figures are checked up. Once or
twice when on the surface we were fired at at long range and quickly
submerged, although the U crews recognize they are a difficult target
to aim at, let alone hit, as I, too, knew from experience.
The periscope is about seven inches in diameter and moves up and down
like a piston rod in a cylinder, accompanied by a buzzing kind of
sound, which became familiar after a day or two. If required it can
reach seventeen feet above the surface and may be used as a flagpost
for signals. At its summit is a mirror, three to four inches in
diameter, from which images are reflected to a larger mirror below used
by the observer.
When a ship is first sighted the chief point is to determine her
course, which may be easy if she is going in the same direction, but
more difficult if not. The next point is to determine as near as
possible the speed of the object ship, the size and general lines
being considered, and deductions drawn. Next, the distance away of the
approaching ship has to be noted.
Under ordinary circumstances on board ship the nearer one standing on
deck is to the water the more limited will the horizon be, and likewise
the higher from the water, as in the "crow's nest," the bigger the
horizon. Standing on deck, seventeen feet from the surface of the
water, the horizon, on a clear day, would, roughly speaking, be three
miles. The same rule practically applies in periscope work, which, as
it can extend seventeen feet in the air, will give a three-mile horizon
vision. Therefore, according as is the position on the horizon rays, so
will the distance away of the object ship be gauged.
The course, speed, and distance off being calculated, the U has then to
manoeuvre get into position for firing, taking care to avoid the actual
track of the approaching ship and to get nearly "broadside on" to her.
Hence there is nothing worries them and upsets their calculations more
than when the ship alters her course frequently--this manoeuvre being
called zigzagging--and which accounts largely for the high percentage
of misses registered. The more often the alteration of course takes
place, the bigger and more uneven the zigzag, the better for the ship.
Daylight is most suitable for torpedo firing, but there is nothing to
prevent its being accurate enough during moonlight, even so far as
minor work is concerned. As the torpedo can be discharged from the
surface as well as when submerged, the precaution of having every light
on the ship extinguished is a necessary one. It is remarkable how few
collisions at sea have taken place during the war, even though the
ships are running without any navigation lights and even during fog
no whistle is sounded. The periscope being in those days a "familiar
object," it is believed that some of the later U-boats have another
device in the shape of a small hatch opening upward which can be opened
by the observer on the submarine, enabling him to look around the
surface of the water.
Ordinary navigation on the U-boat is done on usual lines, i.e., sextant
and compass and bearings from landmarks by day and observation by stars
and of lighthouses by night, but the reckoning of distances by dead
reckoning, that is, on the log, has to be dispensed with. The compass
used is a gyroscopic one, so there is no deviation due to magnetic
influence, and the courses are all therefore "true courses."
There were no signs of any soundings being taken while submerged, but
of course they were frequently taken from the surface while approaching
land. While on the surface, if the sea was at all rough, the U rolled
considerably and the officers, in oilskins, were lashed to the nearest
stanchion to prevent being washed overboard. On the for'ard deck on
either side of the bow was a small anchor about the same size as used
on a 500-ton ship.
The personnel of the U-boat consisted of a commander and three
officers, a commander engineer and three officers, several petty
officers and ordinary crew, all of whom were young men. Each department
had its own section to look after, a full log was kept of all that went
on aboard as in peace times, and discipline throughout was excellent.
So much for my cruise in the U-boat, which was satisfactory enough
as an experience and certainly on the lines of all's well that ends
well. With my queer underwater shipmates I parted on quite good terms,
impressed not a little with their general courage and mostly with their
coolness under conditions which required steady head and hands and
observation which called for considerable cunning and resource.
Compared with a small submarine of the early type I found this U-boat
so vastly improved that it was hard to realize so much advance had
been made in so short a time; and if it be true that practice makes
perfection, there is no knowing what further developments are in store
for this class of war craft.
* * * * *
Before concluding I must refer to certain cruises made by U-boats
across the Atlantic to America. Much fuss was made about these and
the performances were called "marvelous," "astounding," and so on.
From experience I fail to see anything wonderful about them. Once the
submarines navigated clear of the north of Scotland, the rest of the
voyage was plain sailing for the modern U-boat as I saw it--and, in
fact, the voyage for those on board must have been simply a restful and
pleasant holiday run.