Kriegsmarine Issue G7a Torpedo

From my novel, An Honorable German:


A twist of his body and Max was through the hatch into the forward torpedo room, which also served as the crew’s quarters. Blood covered the starboard bulkhead where the torpedo had come loose and pulped two sailors, breaking the arm of a third. Each torpedo was seven meters long and weighed a ton and a half. When they came loose of their moorings the result was always the same: men died.

One of the things hard to grasp about U-Boats in World War Two is how big the torpedoes were. In length alone, the standard German issue G7a torpedo was almost 24 feet long. It had a diameter of 21 inches. The torpedo was actually a miniature submarine of its own. And damn finicky, too. Torpedo mechanics, or “mixers” as they were called on the boat, spent hours each day tending to their torpedoes.

Sailors loading a German Torpedo into a U-Boat

Once fired the torpedo could not be steered in any way (with exceptions later in the war) and it ran at an average speed of about 35 knots though it could go faster or slower depending on the circumstances. But the window of speed was relatively narrow: 30 knots to 40 knots for torpedoes fired from a U-Boat, 44 knots for torpedoes fired from Schnellboote.

Trail of Bubbles Common on G7a Torpedoes

Water and gasoline were mixed together in a combustion chamber and ignited. This produced superheated steam which powered a four cylinder engine. The torpedo had two propellers which rotated in different directions. The G7a torpedo’s biggest problem was it left a trail of bubbles. U-Boat Kommandants typically fired it at night.

But U-Boats and Schnellboote weren’t the only craft to use torpedoes. Although we think of torpedoes as mainly a weapon used by submarines, almost all capital ships of the navies of the era carried torpedoes. They were usually in tubes mounted on the deck and trained by hand. Every large ship had a torpedo officer, often more than one, and they were the ones who kept the tubes trained outboard and ready to fire during battle. In addition to shellfire during a battle, the captain of a warship had to constantly be aware of the danger posed by torpedoes fired by the enemy. Many a captain saved his ship by turning into oncoming torpedoes and “combing the tracks”, that is, steering between the torpedoes and allowing them to run down either side of the ship without striking. Sort of tense as you might imagine.

USS Dunlap (DD-384) During exercises on 3 July 1942, she fires torpedoes from both starboard (pic on left) and port (pic on right) torpedo tubes. Both pics are looking aft from the forward superstructure with the center-line torpedo tubes and midships 20mm gun platform just beyond. The left pic also shows a torpedo davit beyond the gun platform.

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Charles McCain

Charles McCain is a Washington DC based freelance journalist and novelist. He is the author of "An Honorable German," a World War Two naval epic. You can read more of his work on his website: http://charlesmccain.com/

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