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STEEL CASKETS - U-Boat Weapons, Men, and Myths
by Jim "Twitch" Tittle
U-Boat Veteran's plaque
ALARM!
Oberleutnant Ottokar Paulssen ordered the U-557 up to periscope depth from her 170 meter deep sanctuary where the destroyers had driven her. The maneuver took twenty careful minutes. The earlier contact had forced the boat to dive with a concert of whining propellers, vibrations and groans from the superstructure.
As night fell Paulssen would use the standard U boat tactic of surface attack. Everyone designated for bridge watch were issued oil-skin clothes to protect against the harsh Atlantic weather. The soundman's speaker in the conning tower filled the space with the sounds of throbbing engines and propellers from the big convoy, exciting everyone.
"Blow all tanks!" ordered the Captain
With decks awash, Paullsen and five men met the howl of the wind and spray as they opened the hatch into a black, moonless night-perfect for a stealthy attack. U-557 surged ahead as the powerful diesels took over from the weak electric motors.
"Shadows bearing three-five-oh" reported a lookout.
"Both engines one-third ahead," countered Paullsen.
The 557 closed to within 400 to 700 meters of the ships as the escorts were far off in the wrong direction.
"The wolf was in the middle of the flock," thought Ensign Herbert Werner who would survive the war with his own command on U-953 and write the excellent U-boat narrative Iron Coffins.
As the Exec confirmed the target values in distance, speed and angle the Captain shouted, "Fire, Exec, let them have it!"
Five torpedoes, including one from the stern tube, began their treks. After the prescribed run times explosions lit the night. Debris rained and two British ship slid beneath the waves.
Soon all tubes were reloaded and the U-557 was ready to attack again when a radio message from H.Q. was relayed. It stated that the Captain was to await arrival of other U-boats to form the infamous wolfpack. He cursed through his teeth at the thought of having to wait and share his prey.
Suddenly, 1,000 yards away a charging destroyer was spotted and the boat was forced to dive back down to the sanctity of 170 meters. The depth charges were not very close.
Upon re-surfacing hours later, the radio commanded them to head for the battleship Bismark's location to assist her in battle. But upon arrival, two days later, nothing marked the fallen giant's grave. U-557 resumed patrol.
THE BOATS
In 1940, German Admiral Donitz said "…the U-boat alone can win this war….nothing is impossible…" He nearly accomplished this goal early in the war. He stated that with 300 U-boats he could strangle Great Britain's supply lines. With but 150 boats on average, Germany gave the Allies their darkest hours between September 1939 and April 1943.
As with other German super weapons, the U-boat (Unterseeboot) was behind in its technical development. As early as 1940 the superb Walter closed-cycle turbine had been proven a success. Why it was not universally adopted early on remains a hindsight mystery like the jet aircraft's development.
Three smaller, 842 ton, single-shaft boats with ten torpedoes were completed and could travel at 22 knots submerged. Though range was short (160 miles) at full speed underwater, it could travel 7,300 miles at 12 knots surfaced. 100 bigger boats in early 1943 would have caused havoc.
The Walter system, in short, would have made outside air unnecessary! No surfacing to charge batteries and no schnorchel. (The "snorkel" broke the water surface like that of a swimmer, allowing air to be ingested by the diesels and exhaust expelled also.) A decomposition of hydrogen peroxide (perhydrol) resulted in the formation of hot gases combusting sufficiently to drive the turbine. But the chemical fuel was eight times as expensive as fuel oil and required clinical cleanliness. Besides, it was volatile. With this closed-circuit system the submarine would have truly been the weapon it was intended to be which was only realized with atomic power of the Nautilus launched in 1955.
The type VII boats were the Bf 109s of the ocean- in wide use everywhere. They began with the VIIA U-27 and ran through the VIIE U-1062. The VIIC model was most plentiful with U-69 through U-2320. There are gaps in the sequences so there were not over 2,000 built. Other types, like the IX and such, filled in the numbering system. The actual first WWII sub so designated was the U-25 and the last, a type XXIII, was the U-4701. A U-5000 was in the Reich's projection. But fully 568 of the U-boat production was the type VIIC.
These boats displacement varied from 769 to 871 tons at 220 1/4 feet in length with a maximum submerged depth of over 700 feet. Power came from 2-shaft diesel/electric motors with B.H.P./S.H.P at 2,800/750 respectively. Speed was 17 knots on the surface and 7 1/2 submerged. With 114 tons of fuel the boats could cruise 6,500 miles at 12 knots and but 80 miles at 4 knots on the electric motors. Offensive armament consisted of four forward torpedo tubes and one aft with fourteen "fish" or fourteen mines. A 3.5 inch deck gun was used to finish off freighters on the surface. Defensive guns originally were a 37mm A.A. and two 20mm A.A. but retrofits sometimes upped the armament to as many as eight 20mms. The schnorchel was added to most type VIICs. Crew compliment was 44-52 officers and men.
Painting by Robert Taylor
A handful of vessels built specifically as depot ships were implemented but other acquired mercantile ships fit the duty quite well. The numerous well-equipped German port bases made little use of these ships necessary.
While depot ships were not extensively used the fabled "milch kuhs," (milk cows) saw some service. Ten of these type XIVs were built being the approximate same length as the VIIC but had greater height and beam to carry the 432 tons of oil fuel for re-supply. Displacing 1,688 tons, the boats cruised for about 10-12,000 miles on their own store of 203 tons of fuel. They could make 14 1/2 knots surfaced and 6 1/4 submerged. Four replenishment torpedoes were toted in an external container though the boats had no tubes themselves, only a 20mm and a 37mm A.A. Usually, 53 officers and men crewed them. No milch kuhs survived the war.
But in 1944, the streamlined type XXI Elektro Boat, U-2501-4000, was THE sub to have. It displaced from 1,621 to 1,819 tons and were 251 3/4 feet in length and able to dive to over 900 feet. Power rating for the 2-shaft diesel/electric motors with B.H.P./S.H.P were 4,000/5,000 equaling 15 1/2 surface knots and a whopping 16 knots submerged on the electrics! The batteries had triple the power of earlier ones. Speed with schnorchel raised was doubled from previous six knot limitations. Added were advanced 226 S.H.P. silent creeping motors good for five knots. Type XXIs could carry 250 tons of fuel for a range of 11,150 miles. The electric motors could propel the boats for 285 miles at six knots, but full speed submerged on electrics was restricted to the same one-hour duration of the type VIIs. The XXIs had six tubes, all forward, and twenty-three 21 inch torpedoes. Usually four 20mm A.A. weapons were mounted but no deck gun. The crew was comprised of 57-60 officers and men. 119 were completed.
The U-boats ranged not only in the North Atlantic, but from the Mediterranean to Africa and South America and on to the Caribbean and the Eastern shores of the U.S.
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