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SM U-9

Diesel-Electric Attack Submarine

Imperial Germany | 1910

"The SM U-9 more than proved the value of the attack submarine for the German Navy in World War 1."

Authored By: JR Potts, AUS 173d AB | Last Edited: 04/11/2022 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site; No A.I. was used in the generation of this content.
World War 1 allowed the "submarine" - essentially an undersea warship - to become as deadly a new weapon as the biplane and the machine gun. SM U-9 was the lead boat of her class, serving in the Imperial German Navy (Kaiserliche Marine), and was constructed by KaiserlicheWerft at the Danzig port in Germany. U-9 was launched on February 22th, 1910 and commissioned on April 18th of that year.

U-9 and her class of four represented only a handful of the 329 submarines involved in World War 1. The U-9 was cylindrically shaped with a pressurized hull that allowed the vessel to force itself underwater. The idea of submarines as viable warships introduced all new crew needs and space requirements as well. The forward torpedo room managed a pair of torpedo tubes that were loaded while the vessel was at port and had storage for only two torpedo reloads. The stern held two torpedo tubes as well and these were also loaded at port with no additional space for any reserve torpedoes. The use of fore and aft torpedo tubes allowed a submarine captain the ability to engage enemy surface targets from both fore and aft facings as opposed to turning his vessel around each time to engage. Aft of the stern torpedo room were quarters for the Captain containing only a small bed, a wardrobe and a curtain as a room divider. Comparatively the Warrant Officers' compartment contained only two small bunks. During action the bunks and clothes cabinets in the Warrant Officers and Captain's cabin had to be moved into the adjacent officers' compartment for required space.

The Watch Officer cabin's bunk was built between the bulkhead and the washing machine. The location of the bunk would only allow the occupant to lie on his side while his feet would push against an electrical box. As one can imagine, sleeping was difficult. Electric cables ran under the bunks to supply current to the electric motors. The passageway through the boat had inserts for the installation of small tables as well as folding camping-style chairs. When the officers were served a meal in the passageway and crew members needed to pass, the tables would need to be removed and folded. As can be expected, the crew would also need to quickly change these living quarters and remove chairs and tables from passageways when enemy ships were sighted - serving as a reminder of the limited space that frayed crew nerves in wartime.

The boat's cooks needed to serve approximately 105 meals a day and had a stove and baking oven located in the crew space. The boats left on patrol with food supplies cramped into every nook and cranny available on the U-boat. This need for using every space available resulted in one of the two toilets being filled to capacity with food. The boat had some small refrigerators but most of the food was stored in the boat at room temperature and spoiled rather quickly, especially in the damp environment that was a U-boat submarine. Within days, fresh bread would sprout white fungi and earned itself the nickname of "Rabbit" due to its white fuzzy appearance. The crew unflatteringly referred to most of the food stores as "diesel food" within time due to its constant exposure to the diesel exhaust fumes rampant among the boat. The stove was unreliable at best and was prone to short circuits on a regular basis, forcing the cook to prepare meals on deck in the dark of night using a paraffin stove that could be used even in strong winds. One is left to wonder just how many cp;d meals were actually being served in one tour alone.

In the engine room were 4 x Korting paraffin (kerosene) engines which could be coupled in tandem, two for each propeller shaft, each having one propeller. The air flow to the engines was drawn in through the open conning tower hatch and the black exhaust was piped from below out through a long removable funnel that looked very much like a conventional smoke stack. When the boat needed to run submerged, normally during the day, the funnel would be collapsed and the hatch would be closed. 2 x AGE electric motors that were fitted astern of the gas engines provided the power for submerged cruising.

The batteries used for submerged propulsion were located under all the living spaces and required constant precautionary maintenance for the systems expelled poisonous hydrogen gas that was removed from the boat through the ventilation system that ran along both sides of the craft. A numberof boats blew up when the ventilation system failed and hydrogen gas filled the insides of the vessel, needing only a spark to light the combustible fumes. To submerge the boat, diving tanks were located in the center of the vessel along with the bilge pumps. Blowers were used to empty the tanks of seawater allowing the boat to surface and, consequently, filling the tanks with seawater allowed it to submerge. This area of the boat also held the gyro compass and hand-operated rudder gear while the nearby toilets were surrounded by nothing more than a simple privacy screen.

For submariners, one of the most vulnerable times in war was when running along the surface of the ocean with the hatch open. However, the airflow to the engines required this hatch to be open. In rough seas, water going into the boat through this hatch soon proved problematic and equally proved a hazard to the men in the conning tower (the conning tower was the "battle station" of the submarine and, on a SM U-9 boat, the station was manned by the Commanding Officer and the Watch Officer - or, in the US Navy, the Officer of the Deck). The conning tower had two periscopes, a seat and space for the Helmsman who steered the boat. This area was also home to the diving station consisting of 24 levers on both sides of the boat that allowed air to be released from the tanks, this in turn allowing the boat to dive to its required depths as decided by the Captain. Other mechanical devices were electrical controls, an indicator of the current depth and the electrical firing devices for the bow and stern torpedo tubes.Voice pipes were used for communication to and from the conning tower and the engine and torpedo rooms as well as crew and the radio room.

Above the conning tower was the "Battle Bridge", a small bridge used by the Watch Officer and the Petty Officer on duty. Using this bridge required the hatch to be open as the Watch Officer sat on the raised edging surrounding the hatch and the Petty Officer sat alongside with his feet hanging down into the hatch area - a tight fit to say the least. A Seaman or lookout stood on a small raised platform and watchcrews wore rain gear and leather trousers while being secured with safety lines to keep them from being washed overboard in rough seas.

Other crew members of a U-9 consisted of basic seamen, two radiomen, multiple torpedo operators, deck gun crew, cooks and machine men (or a rating engineer) who maintained the equipment aboard the U-boat. The seamen worked in three 8-hour shifts with sleeping, general duties and one shift for tasks decided on by the Watch Officer of the day. Trained crewmen such as the radiomen were assigned three 4-hour shifts and two 6-hour shifts at night. They had the longest hours of any other crewmen other than the Captain.

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Fresh water was limited to the crew for drinking and cooking only. To extend their operational range many boats filled one of their fresh water tanks with diesel fuel further limiting their fresh water supply. The crew had the clothes on their backs plus one additional pair of underwear and socks and a small locker for personal items. To remove salt from their body when on deck the crew was issued saltwater soap and, to control body odor, a deodorant was also issued.

Due to the limited water supply washing, shaving, showering and laundry were not allowed. Crew space was at a premium in the forward torpedo room and the six bunks there had to be folded and removed to allow space for two additional torpedoes. Only after the first two torpedoes had been launched and the spare torpedoes were loaded into the torpedo tubes was there room to use the spare bunks. With such limited bunks available, the crew often resorted to "hot-bunking" - when one crewman crawled out, the next crewmember would scramble into the open bunk, a necessity system that is still in use today on many modern naval boats and ships.

There was only one toilet available until the food stuffed in the second toilet had been used. With 35 crewmen sharing the same toilet, waiting times were sure to be long and raw nerves were sure to sour. The flush system consisted of a waste hand pump process that jettisoned into the sea. Using the "head" (toilet) was prohibited during the "battle stations" call so the enemy surface ships prowling for submarines could not hear the metallic noises that could give away the location and depth the U-boat.

World war 1 had begun on July 28th, 1914 and the Imperial Navy was anxious to send U-9 and other submarines against the British Fleet. The U-9 received her first commanding officer on August st1, 1914 as Kapitanleutnant Otto Weddigen. Weddigen's orders were to patrol the southern part of the North Sea by the Broad Fourteens, an area where the water was fairly consistent at fourteen fathoms (26m) deep. The Fourteen's were off the coast of The Netherlands and south of "Dogger Bank". This area of the North Sea had seen many naval engagements throughout history. U-9 was given patrol of this area beginning on September 22th, 1914.

The British Admiralty knew of the German submarine threat but feared her surface fleet more, keeping her oldest capital ships in areas where encountering the German Fleet was less probable. The 7th Cruiser Squadron consisted of the cruisers HMS Cressy, HMS Aboukir, HMS Bacchante, HMS Euryalus and HMS Hogue and supported by destroyers of the Harwich Force. Their mission was to protect ships steaming between Britain and France from German ships operating in the North Sea. They were old and slow, normally making only 12 knots (14 mph; 22 km/h) and were referred to as the "live bait squadron" by British personnel due to their age and untrained crews.

While on her patrol the morning of September 22nd, 1914, the crew on U-9 had a cold breakfast around 5:00am and continued scanning the horizon for her first enemy ship of the war. At 6:00am Weddigen spotted three British Cruisers steaming at 10 knots in battle line. The undetected U-9 submerged and increased speed towards the British cruisers. Moving in close to the HMS Aboukir, a Cressy-class armored cruiser launched in 1899 as a 12,000 ton, 472 foot long vessel. She was armed with 2 x 9.2" main guns, 12 x 6" support guns and 13 x 12-pounder cannons. Her belt armor was 6 inches thick and she was crewed by 760 officers and sailors. At 6:20am Weddigen fired one torpedo into Aboukir, striking her amidships. The ship started sinking and there was little time to lower the life boats. as such, she went down in 20 minutes with 527 of her crew.

While U-9 remained undetected, the British assumed the HMS Cressy and HMS Hogue determined the Aboukir has been struck by a mine. The order was given to stop the fleet and pick up any survivors in the water. Seeing the other two cruisers did not turn and escape but began their rescue mission, the U-9 moved in for a shot at the closest ship - the HMS Hogue. Weddigen ordered the forward torpedo room to reload the empty tube - this marking the first time a torpedo had been reloaded while submerged during a combat action. U-9 fired two torpedoes into the Hogue and felled her where she sat. The captain of the lead ship of her class, the HMS Cressy, now realized the attack was from a submarine and ordered full speed ahead. However the U-9 had the angle on the HMS Cressy and fired two torpedoes, sinking her as well. The U-9 moved away when allied destroyers arrived to lend assistance after receiving the distress code. 837 men were rescued from the three ships that were sunk with a combined loss of life totaling 1,397 seamen and 62 officers.

U-9 returned to Germany to a hero's welcome - the first of the war. Kapitanleutnant Otto Weddigen was awarded the Iron Cross, First Class and each member of his crew received the Iron Cross, Second Class. The sinking of three armored cruisers of the British Navy shocked the British people and the navies of the world despite the age of Cressy-class ships. Churchill was blamed by the British public for the calamity despite his orders that the older ships should not be used. Additionally, the cruisers were not utilizing a "zig-zagging" travel pattern in waters expected to have a submarine threat, furthermore costing Admiral Christian his job. A new rule was made compulsory that ships-of-the-line would never aid sinking ships due to possible enemy submarine attack. Instead, smaller ships would be used for such rescues.

Twenty-one days later, U-9 was operating off Aberdeen and sighted the HMS Hawke, a protected cruiser weighing 7,890 tons with a 360 ft length and a crew of 587 officers and sailors. Captain Weddigen moved U-9 into firing position and torpedoed Hawke. Once again a British cruiser was not zig-zagging in enemy waters and was struck and sunk in minutes, losing her captain and 526 officers and men - leaving only 64 to be saved.

On January 12th, 1915, Johannes Spiess took command of U-9 until April 19th,1916. During this period, U-9 was involved in seven operations andwas credited with sinking a further 13 ships totaling 8,635 tons. However, no capital ships were sunk, just three British steamers (the Don, Queen Wilhelmina and Serbino) along with 10 small fishing vessels. In April of 1916, U-9 was withdrawn from frontline duty and used for training. She survived the war and surrendered on November 26th, 1918 only to be broken up for scrap at Morecambe in 1919.

The need for long cruises lasting months took a toll on the crew when most of the time was spent hunting a target on an empty ocean. The builders provided a built-in record player for the crews to pass the time away and card-playing and chess games were common activities. The living conditions on a U-boat made life on German surface warships something of a "pleasure cruise" in comparison. These war patrols would take several weeks and up to six months in the unforgiving North Sea winters - hard to imagine the conditions these men had to deal with on a daily basis. it begs to wonder why these men would even volunteer for the worst duty in the Imperial Navy with pay being very small. Perhaps it was the glamorization of the role in which the German news proclaimed these undersea boat crews as heroes, laying down the groundwork for the bravery seen in submariners of today.

In Germany, SM U-9's success was regarded as an outstanding heroic deed. The SM U-9 was permitted to carry the Iron Cross medal as the boat's crest on its conning tower - a tradition still in use with all German submarines ever named U-9. Her first voyage record has never been surpassed. Overall, she was credited with the sinking of five warships and another thirteen vessels with a total tonnage of 53,065 tons claimed.

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Power & Performance
Those special qualities that separate one sea-going vessel design from another. Performance specifications presented assume optimal operating conditions for SM U-9.
4 x Korting kerosene paraffin engines developing 480 horsepower each; 2 x AEG electric motors generating 300 horsepower; 2 x shafts.
14.2 kts
16.3 mph
Surface Speed
8.0 kts
9.2 mph
Submerged Speed
3,356 nm
3,862 miles | 6,215 km
The bow-to-stern, port-to-starboard physical qualities of SM U-9.
188.0 ft
57.30 meters
O/A Length
19.6 ft
5.97 meters
11.4 ft
3.47 meters
Displacement (Submerged)
Available supported armament and special-mission equipment featured in the design of SM U-9.
2 x 450mm torpedo tubes at bow.
2 x 450mm torpedo tubes at stern.
1 x 105mm deck gun.
Ships-in-Class (4)
Notable series variants as part of the SM U-9 family line as relating to the U-9 class group.
U-9; U-10; U-11; U-12
Global operator(s) of the SM U-9. Nations are displayed by flag, each linked to their respective national naval warfare listing.
National flag of the German Empire

[ German Empire ]
1 / 1
Image of the SM U-9
Starboard side view of the SM U-9 U-boat

Going Further...
SM U-9 Diesel-Electric Attack Submarine appears in the following collections:
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