German World War II submarine
German submarine "U-309" was a Type VIIC U-boat of the German Navy ("Kriegsmarine") during World War II. The submarine was laid down on 24 January 1942 at the Flender Werke yard at Lübeck, launched on 5 December 1942, and commissioned on 27 January 1943 under the command of "Oberleutnant zur See" Hans-Gert Mahrholz. She sailed on nine combat patrols, but damaged only one ship, before being sunk off Scotland on 16 February 1945.
Design.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. "U-309" had a displacement of when at the surface and while submerged. She had a total length of , a pressure hull length of , a beam of , a height of , and a draught of . The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of for use while surfaced, two Garbe, Lahmeyer &amp; Co. RP 137/c double-acting electric motors producing a total of for use while submerged. She had two shafts and two propellers. The boat was capable of operating at depths of up to .
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for at ; when surfaced, she could travel at . "U-309" was fitted with five torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one SK C/35 naval gun, 220 rounds, and two twin C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.
Service history.
First patrol.
After training with the "8th U-boat Flotilla" at Königsberg, "U-309" was transferred to the "11th U-boat Flotilla" based in Bergen on 1 August 1943, Norway, for front-line service. The U-boat departed Kiel on 26 August, arriving at Bergen seven days later, on 1 September. From there she sailed out into the Norwegian Sea on 13 September, and arrived in Trondheim six days later on the 18th. As "U-309" was then reassigned to the "9th U-boat Flotilla" based at Brest in France. She left Trondheim on 25 September, and sailed out into the mid-Atlantic to patrol, before arriving at Brest on 7 November. During this patrol, on 30 September, "U-309" suffered her only casualty, when "Mechanikergefreiter" Erich Jungmann was lost overboard while working out on deck.
Second patrol.
"U-309"'s next patrol took her from Brest, on 19 December 1943, out into the Atlantic west of Ireland, then back to Bordeaux on 14 February 1944. In April 1944 the U-boat was fitted with a "Schnorchel" underwater-breathing apparatus.
Third to fifth patrols.
In June and July 1944 "U-309" made two short patrols in the Bay of Biscay, before finally achieving success during her fifth patrol. The U-boat sailed from Brest on 12 July 1944 and into the English Channel. There, at 21:00 on 24 July, she fired three LuT pattern-running torpedoes at Convoy FTM-47, en route from Juno Beach in Normandy to Southend, and hit the 7,219 GRT British Liberty ship "Samneva". Badly damaged, the ship was beached at Southampton, but then broke in two and was declared a total loss. "U-309" returned to Brest on 3 August.
Sixth and seventh patrols.
As the French bases fell to the advancing Allies, "U-309" was transferred again, this time to the "33rd U-boat Flotilla" based at Flensburg. Under her new commander "Oberleutnant zur See" Herbert Loeder she left La Pallice on 29 August 1944, and sailed around the British Isles to Stavanger, Norway, arriving on 13 October. The U-boat left there after only two days, sailing to Flensburg by the 21st. Lothar-Günther Buchheim in 1978 published photos of this patrol in his book "U-Boot-Krieg (U-boat War)," a nonfiction story of his trip on "U-309" and "U-96". Buchheim also wrote the book "Das Boot" in 1973, which has some of his experiences on "U-309" and "U-96".
Eighth and ninth patrols.
"U-309" left Germany on 30 January 1945, sailing to Horten Naval Base in Norway, arriving there on 2 February. She departed on 8 February, and headed into the waters east of Scotland.
Fate.
There, on 16 February 1945, "U-309" was shadowing Convoy WN-74 into the Moray Firth when she was detected by the Canadian with ASDIC (sonar). The first attack on the U-boat produced some oil on the surface. Two further attacks were carried out using the Hedgehog anti-submarine mortar, which produced more oil. The fourth attack using depth charges produced wreckage including charts, signal books and cork insulation material. "U-309" sank in position . All 47 aboard were lost.
Wolfpacks.
"U-309" took part in seven wolfpacks, namely:
Discovery.
The wreck of what is believed to be "U-309" was located on 17 May 2001, 25 miles off Wick in of water. There are no identifying features, but the Type VIIC U-boat is close to the reported position of "U-309"'s sinking, and the damage sustained is consistent with that caused by depth charges. However, there is a possibility that the wreck may be the , which went missing in the North Sea in November 1944 and has never been found. 
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