U-boat and Submarine Weapons | The Submarine Pen: Your Home for Submarine and U-boat History

What Kind of Weapons did Submarines and U-boats use?


More than anything these boats used the fearsome Torpedo. A weapon packed with explosives and detonates upon impact or proimity to something magnetic. Though torpedoes appear simple, they where complex and many diffferent kinds were employed in submarine warfare.

"The torpedo was a highly sophisticated piece of weapon, which also meant that it was one of the most expensive weapons of its time. In essence, it consisted of the pistol, warhead, depth-keeping device, propulsion and the guidance systems. Early German torpedoes suffered from many problems, particularly with premature or failed detonations and depth keeping which would cause a torpedo to break the surface or run too deep – either of which meant that a perfectly aimed torpedo would fail to sink its target."

*Information in quotes is from here.

Deck Gun Example
"British 4-inch submarine gun in the 'Clandestine Immigration and Naval Museum,' Haifa, Israel. Guns of this type were mounted on INS Tanin and INS Rahav (British S class). This appears to be the post-WWII Mk XXIII variant with short 33-cal barrel." Click here for source and more information.


"Mines were detonated by a passing ship either through contact, magnetic or acoustic signatures. German mines were of two basic types, the torpedo launched TM mines (Torpedomine) and the shaft launched SM mines (Schachtmine). The TM mines were launched from the standard 21 inch torpedo tube, making every attack boat a potential minelayer. Since they displaced mines, thus the torpedo capacity was reduced. The limited mines also meant that any minefield laid was very small. The SM mines were specialized mines designed for maximum effectiveness, and could be laid only by minelayers. They were launched from vertical mineshafts mounted at the foredeck. The minelayer carried many more mines and could lay a more dense pattern of minefield, but carried only a small number of torpedoes."

*Information quoted from "German U-Boat"

Anti-Aircraft Gun Example
U-534's dual barreled anti-aircraft gun. Click here for source and more information.
Torpedo Example
A Torpedo being loaded into a submarine. Click here for more pictures and info.

Deck Guns*

"The deck gun was principally intended as a defensive weapon against small surface vessels, for which the torpedo was not a suitable weapon. During World War I however, it was discovered that deck guns were quite effective when used against stragglers and helped save scarce torpedoes. During World War II, as convoys became better protected, and merchantmen began to be armed with makeshift defensive guns, the deck gun was used less frequently. Eventually, BdU phased them out, though some U-boats still retained the deck guns.

There were two standard deck guns during World War II; the 8.8cm (on Type VII) and the 10.5cm (on Type IX). The U-boat however, was a poor gun platform since it rolled a lot, and ocean waves frequently washed over, making the gun platform slippery and hazardous. To prevent the crews from being washed over, they were fastened with life lines. A further factor was deck guns had no range finders, so engagements had to be done at close range. Depending on sea and weather conditions, it was also not possible man the deck gun at all times. The deck gun also contributed much to hydrodynamic resistance, slowing the underwater speed and increasing crash dive time. Indeed, deck gun engagements made the U-boat very vulnerable; since the gun and ammunition had to be secured and the crew had to get below deck, all of which meant that it took much longer than usual to submerge.

Three men operated the deck gun – gunner, layer and loader, usually under the supervision of the second watch officer. A chain of men were required to bring the ammunition from below the control room floor, then up the conning tower and onto the upper deck. A small watertight locker placed near the gun held a few more rounds ready for use, providing an advantage during the first few vital seconds of engagement. The rate of fire with a good crew was 15 to 18 rounds per minute"

*Information quoted from "German U-Boat"

Mine Example
A Torpedo being loaded into a submarine. Click here for source.

Anti-Aircraft Guns*

"At the start of the war, the standard U-boat antiaircraft armament was a single 20mm Flak (Flugabwehrkanon) gun mounted on the main deck, far from the conning tower. The setback was that the conning tower itself created a large dead zone, and the gun had to be removed and stowed before diving, increasing the amount of time needed to dive. Eventually the weapon was relocated to a special platform just aft of the bridge.

By mid 1942, allied airpower had increased significantly, and it became clear that a heavier air defense armament was required. As a result of this, twin and even quadruple 20mm mountings were installed. But as a result of delays, it was not until the middle of 1943 that the first twin and quadruple mountings appeared. At about the same time, new 20mm shells were also introduced, which not only carried three times more explosive than previous shells, but the explosive itself was new and much more powerful. By late 1943, the new and much more powerful 37mm Flak gun made its debut. This was a navalized version of the German army Flak 37 which was quickly adapted and installed on U-boats. Problems were encountered with the 37mm gun as well, as it was very sensitive to seawater and frequent stoppages meant that it had to be serviced regularly. Finally when this too proved inadequate to thwart air attacks, it was recognized that U-boats were unlikely to win combat engagements with aircraft, and the best defense was to spot an aircraft in time to crash dive to safety."

*Information quoted from "German U-Boat"

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