Cutaway of a Type VIIC submarine (1940)
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Type VIIC submarine (1940)

Internal disposition of the submarine

The internal disposition of the submarine could be divided into six well defined sections from the stern to the prow:

Electric motor room and aft torpedo room (Elektro Maschinenraum und Hecktorpedoraum).

The 500-horsepower electric motors (manufactured by Siemens, AEG or Brown-Boveri) were fed by the huge Diesel engines located in the adjacent room; they occupied little space and provided a speed of 2.5 knots during immersion. The compresor which actuated the refrigerator was directly geared to the starboard engine. The main compressors were after the engines, at larboard side the electric one and at starboard side the smaller Diesel (manufactured by Junkers). In this section they were located as well the electric control panels along with the retractable steering wheel and the mechanisms of the only torpedo tube astern. In the last models it was incorporated a countermeasure system which launched carbide cartridges to disorient the enemy detection systems.

Petty officers room and kitchen (Unteroffizierraum und Küche).

Just before the control room, sealed by a watertight circular hatch, there were a small kitchen, a small fridge, groups of twin bunk beds at each side with their corresponding lockers, habitually crowded with provisions, and the fuel-oil tanks, located between the bunk beds and the pressure hull. The small two-burner electric kitchen was at starboard side, embedded with the sink and the pantry. Salt water was used for washing and cooking, for fresh water was reserved for drinking. In the center of the room there was a small metal ladder which led to the exterior through the aft hatch. At larboard side, two small compartments housed the water closet (used as pantry) and the electric panel. In the lower floor it was located the aft battery room, containing 63 lead-plate elements of the type 33 MAL 800 W and 493 kilograms each, divided in groups mounted over rubber. This prevented that the breaking of one unit affected the rest.

Control room (Zentral).

The control room was the neuralgic center of the submarine where they were housed the guidance controls, valves and all kinds of cranks and stopcocks for the emptying and filling of the ballast tanks. At starboard side there were two steering wheels for maneuvering the hydroplanes, accompanied by depth indicators and, just behind, the table of the navigator with its whole equipment (navigation charts, rulers, drawing compasses, sextant, magnetic compass, etc...). In the center they were located the surveillance periscope and the pit for the large attack periscope. At larboard side they were located the main bilge pump and the motor of the periscope. The little space left was populated by valves, painted in red and green with their respective names molded in brass, to control the immersion and emersion of the submarine. At starboard side it was located the voluminous tank of hydraulic oil. In the lower compartments of the hull they were located the main ballast tank and two fuel-oil tanks of large capacity. From the control room the officers' room was accessed through a second watertight circular hatch.

Attack room (Turm).

Located above the control room, the attack room was accessed by means of a small ladder and a circular hatch. This room, of cylindrical domed shape and less than two meters in height, was the true domain of the commander. Here he gave orders through loudspeakers or air hoses during submarine attacks, assisted by the complex electric attack periscope (manufactured by Karl Zeiss or Goerz), the calculator of courses, the aiming system for arming and guiding the torpedoes, and the repeater compass. In the ceiling, painted in white and red, it was located the watertight hatch which gave access to the bridge.

Officers' room, commander's cabin, radio room and listening room (Offizierraum, Oberfeld webelraum, Horchraum und Funkraum).

Just before the control room it was located the officers' room, the most spacious habitation in the submarine. At larboard side, there was a small room for the electric central panel. Further towards the prow it was located the commander's cabin, the only place which granted a certain degree of privacy, visually separated from the rest of the ship by a thick curtain of garnet color. This lack of privacy was not a mere coincidence, for the commander had to pay attention to everything that happened in the submarine. A desk which served also as sink, a chair, a bed and oak wooden lockers and shelves conferred to the topmost ranked officer onboard the best comfort possible in such circumstances.

In front of the commander's cabin, and on purpose, they were located the radio and listening rooms, the true nexus with the exterior. As the war progressed these rooms were stuffed with diverse devices: the telegraph, the radio, the encryption machine known as Enigma, hydrophones, radar, loudspeakers system, phonograph, typewriter and other electric equipment. The war room further towards the prow at larboard side had a permanent table covered of green linoleum; this place served as dining room, meeting room for the officers and bedroom for the Lieutenant Engineer. At starboard side, there were two bunk beds with their corresponding wooden lockers, similarly as the rooms adjacent to the left and the right, which housed another four officers in twin bunk beds.

At the end of the section, just before the entrance to the fore torpedo room, it was located at larboard side the second toilet and also a salt water shower which sometimes was used as an additional pantry, whereas the main pantry was located at starboard side. At both sides of these rooms, between the pressure hull and the bunk beds, lockers and other furnitures, they were located the fresh water tanks. In the lower floor they were located the fore battery room, which had one element more than its aft counterpart, and a storage room.

Torpedo room (Bugtorpedoraum).

The prow of the submarine was occupied by the fore torpedo room and its four launching tubes which went almost four meters across the room. Among other mechanisms, they were located in this place the launching system and the associated compressed air tanks, the crane and the conveyors to introduce the torpedoes into the launching tubes. The rest of the room was occupied by the twelve bunk beds of the mariners and their corresponding lockers. A total of fourteen torpedoes could be carried onboard the submarine: four inside the fore torpedo tubes, six in the lower floor of the fore torpedo room, one inside the aft torpedo tube, one in the lower floor between the electric motors, and another two outside the pressure hull, housed in watertight compartments located in the stern and the prow, respectively.

The torpedoes

The torpedoes, true purpose of the submarine contraption, were a nightmare for the commanders during the earliest period of the war, as their arming system was excessively sensitive to humidity and prone to failures. The protagonism of torpedoes increased as the war progressed, going from being a simple projectile aimed and launched by the submarine to one which was able to localize and pursue its target. The most basic models were the G7a of compressed air and the G7e of electrical operation, more popular among the crews as it did not generate bubbles along its course. Torpedoes were in constant development until the configuration of the models T3, T4, T5 and T11, which had about seven meters in length and a maximum radius of action of 12 kilometers at 30 knots.

Later they made apparition the models F to T (Flächenab-Suchender Torpedo) and the most perfected version of 1944, the LUT (Lagennunabhängiger Torpedo) of preset course, which navigated following a zigzag course regardless of the angle of launching, passing among the units of a convoy without being possible to know the final destination of the torpedo. The maximum sofistication arrived with the T5 series, Zaunkönig (Wren) acoustic torpedoes capable of detecting at 300 meters the noise of a propeller at 15 knots. The only danger posed by these models was that they could detect as well the noise of an allied propeller, or that of the very submarine which launched the torpedo, turning then against the attacker.

German World War Two torpedoes
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Life onboard the submarine

Life onboard was not a romantic adventure, but one which developed inside a cold enclosure of steel, riddled with a myriad of noisy mechanisms, violent reactions during the navigation in the surface and silent agonies in the cold and impenetrable depths of the ocean. About 44 men comprising mariners, petty officers and officers coexisted during months under extreme conditions. They were crammed in humid cabins crowded with victuals where common actions like shaving, washing or changing clothes seemed unattainable luxuries. In the interior of the submarine the crew had to endure extreme temperatures, either during winter or during summer. The bunks were shared and uncomfortable. Privacy did not exist and aliments soon turned moldy. The noise of the engines was deafening, the air was scarce and rarefied and the changes of pressure caused by the suction of the snorkel caused dizziness. In such circumstances, the guards on the bridge, even if often whipped by a brave sea, were a comforting meeting with the outer world.

The lack of space inside the submarine forced the crew to develop an incredible capability of adaptation. Among officers and mariners a strong camaraderie was created. The mariners enjoyed their communal meal in any place and the coffee could be a good reason for distension. The radio operator used different vinyl records to enliven the travels by transmitting the phonograph's music through the loudspeakers system. Hygiene onboard the submarine was almost a luxury, but the mariners tried to maintain it as much as possible. The work and the leisure in the exterior of the submarine was carried out under any meteorological condition. In the extreme climates the crew had to adapt their attire, which ranged from shorts, shirts or undershirts to waterproof suits or work suits made of linen or leather. The success or the failure of a mission could depend on the condition of the material, so the mariners had to take care of the armament constantly.

At the beginning of the war this life was accepted because of the excitement of taking a new prey from the enemy in which seemed equal combat between knights. This vision was gradually vanishing, giving way to a fight without rules in which technology gradually replaced wit and courage. The mariners no longer put to sea to fight, but to try to survive, dodging a nearly sure death. The hunt was relentless, and no longer was it possible to escape from the efficient detection systems; the sonar waves constantly pealed on the hulls which were often torn by bombs and depth charges. But against any logic, in the crazed world of the 1940s this weapon exerted an inexplicable attraction upon the exalted German youth, who did not hesitate to jump into an hostile world with a wrong eagerness for adventure. Volunteers were always available for the submarine weapon of Admiral Döenitz, which ended the six years of war with a balance of 725 submarines sunk in combat out of the 1155 enlisted, and 28744 lives lost out of a force of 35000 men.

~ The Type VIIC submarine (I) ~

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