The inspector
of the Dutch torpedo service send on 19 June 1912 details about the building of
submarines at Fiume, Hungary to the chief naval staff. At Fiume was the Dutch
navy lieutenant W.C. Bijl de Vroe stationed at Fiume ordered to collect the
details. The details were sent from Fiume on the 12th/ At that
moment was Whitehead&Co. building six similar submarines for Danish account
of which 3 were laid down in Denmark.(1)
The general
technical characteristics were a displacement 160 (surfaced)-210 (submerged )
tons, speed 12 (surfaced contracted)-8 (submerged contracted) miles, range
1.000 miles with a speed of around 10 miles while surfaced and 60 miles while
submerged with a speed of 6 miles. Constant speed while submerged 7 miles
(contracted during 3 hours)-8 miles (contracted during 1 hour). Fitted out with
1-450hp diesel engine and 1-300hp electric engine. Armed with 2-45cm torpedo
tubes in the bow placed above each other, for which 4 torpedoes were carried of
which 2 already in the tubes. There was a possibility to mount a torpedo tube
before the conning tower. There was none artillery armament available. If
wanted was it possible to fit a searchlight at the foreside of the conning
tower. One air press pump with a capacity of 10 litres/minute. Their crew
numbered 12 men. The first submarine named Havmanden just executed with success
her trials in the presence of a Danish commission. She was now docked to
complete her painting after which some new tests were to be executed in the
presence of Danish authorities before the officially transfer. These
authorities were expected to arrive in the second half of June and she was to
be towed on 10 July from Fiume towards Copenhagen, Denmark. At speed trials was
with the electric motor during 3 hours a maximum speed of 8 miles achieved. Both
times exceeded the trial speed the contracted speed with a mile. The diesel
engine manufactured at Nürnberg, Germany was not tested while she was
still not completed. In the plant was around 100hp less developed as
contracted. The chairman of the Danish commission however informed the Dutch
officer that the problems were solved and on short notice the engine would be sent
towards Copenhagen. During the tests was the weight of the lacking diesel
replaced by a comparable weight. The power tests suggested that with the 450hp
horsepower a surfaced speed of 12-12.75 miles was to be achieved. The Dutch
officer was allowed to visit the submarine inside and outside. The hull was
with the use of 5 watertight bulkheads into six compartments, the latter used
as a storage room and accessible via a manhole, the other compartments via
watertight doors. The forward compartment contained the two torpedo tubes
mounted above each other, in the second compartment part of the scupper used
for transporting the torpedoes and in which compartment the two spare torpedoes
were stored. In both compartments were also the accumulators battery placed. The
third compartment contained the central station with all equipment for handling
the boat placed in a good clear manner. When the main ballast tanks in fore and
aft ship were filled was everything handled under direct supervision of her
commanding officer except for the diesel and electric motors. The conning tower
was located above this compartment but used as entrance or exit. In the conning
tower was a engines telegraph, some speaking tubes and so on. The forth
compartment contained the diesel engine with against the sides the compress air
reservoirs. At port side where the engineer handles the diesel engine was also
the control for the electric engine situated. In the fifth compartment was the
electric engine and the air press pump. The Havmanden had 2 short bilge keels
and a safety weight of 3 tons divides into 2 similar halves fitted at starboard
and port although exactly amidships to prevent an increasing draught. With
empty ballast tanks was the draught 2,30 meter. The length of the Havmanden was
large in proportion to her displacement. To prevent disadvantages was aft in
the superstructure a small propulsion engine placed with the shaft
perpendicular on the keel line. It was possible to use this small engine for
the main pump making it easy possible while she was submerged and lying still, to manoeuvre or kept her into
launching position. The engine could also be used for manoeuvring in harbours.
The central station also contained two Zeiss periscopes, hydraulic lifted and
lowered and electrically azimuth. She had a very expensive despite the
simplicity equipment for an underwater clock signal and furthermore an
emergency telephone buoy. Provisions had been made to supply the submarine from
the outside with electricity and compressed air. A barograph in the central
station registered the depth while underway as an extra control and to keep the
wheelsman at the depth rudder attentive. Whitehead was at that moment
experimenting with a carcass tube which could be turned allowing to launch
torpedoes in the broadside. If the tests were successful were the Danish
submarines to be fitted out with such a torpedo tube before the conning tower.
The necessary provisions were already prepared during the building phase. The
searchlight was to be used while navigating in unlit waterways. The second submarine was still on
stocks but nearly complete and scheduled to depart this summer towards Denmark.
With the construction of the third submarine was just begun, just a few
thrushes were ejected.
Nothing could be told about the submarines to be built
for the Austro-Hungarian navy. There was still none agreement about the small type.
Originally desired the Austrian cabinet 600 ton boats. The high building costs
could resulting in a smaller displacement. The negotiations were still going
on.
Finally he
supplied some details how nightly signals by the Danish submarines could be
exchanged. The idea was that some submarines departed together in the night for
a task to execute by daylight. It was possible to place an electric lamp before
the eyepiece of a periscope. After turning the periscope in the direction of a
submarine with which communication was needed was it possible to exchanging
messages with morse code signals.
Note
1. The
Havmanden-class, preceded by the Dykkeren-class and succeeded by the B-class,
built between 1911-1913 and in service until 1932. Havfruen (A2), Najaden (A6)
and Nymfen (A7) built at Copenhagen and Havmanden (A3), Thetis (A5) and
Triton/2nden April (A5) built at Fiume.
Source
Archive
Dutch Naval Staff 1886-1943 (National Archive The Hague Netherlands) inventory
number 293
