SM U-81
Introduction '''SM ''U-81''''' was one of the 329 submarines serving in the Imperial German Navy (''Kaiserliche Marine'') in World War I. ''U-81'' was engaged in naval warfare and took part in the First Battle of the Atlantic. ''U-81'' had one 10.5 cm gun with 140–240 rounds. On 8 February 1917 she torpedoed   off Fastnet, forcing her crew and passengers to abandon her. She then shelled the drifting hulk until being chased away by the  sloop . ''Mantola'' sank the next day. HMS ''E54'' sank ''U-81'' by torpedo west of Ireland on 1 May 1917.31 of ''U-81''s crew were killed; seven survived.
Design German Type U 81 submarines were preceded by the shorter Type UE I submarines. ''U-81'' 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  engines for use while surfaced, and two  engines for use while submerged. She had two propeller shafts. She 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, she could operate for  at ; when surfaced, she could travel  at . ''U-81'' was fitted with four  torpedo tubes (one at the starboard bow and one starboard stern), twelve to sixteen torpedoes, and one  SK L/45 deck gun. She had a complement of thirty-five (thirty-one crew members and four officers).
Summary of raiding history DateNameNationalityTonnageFate1 December 1916''Douglas''1,177Sunk19 December 1916''Nystrand''1,397Sunk2 February 1917''Songdal''2,090Sunk3 February 1917''Port Adelaide''8,181Sunk4 February 1917''Maria''992Sunk5 February 1917''Wartenfels''4,511Sunk7 February 1917''Gravina''1,242Sunk8 February 19178,253Sunk10 February 1917''Netherlee''4,227Sunk12 February 1917''Hugo Hamilton''2,577Sunk10 March 1917''Algol''988Sunk10 March 1917''Skreien''415Sunk13 March 1917''Coronda''2,733Sunk14 March 1917''Paignton''2,017Sunk18 March 1917''Pola''3,061Sunk18 March 1917''Trevose''3,112Sunk19 March 1917''Alnwick Castle''5,900Sunk19 March 1917''Frinton''4,194Sunk22 March 1917''Attika''2,306Sunk25 March 1917''C. Sundt''1,105Sunk25 March 1917''Garant''735Sunk25 March 1917''Laly''1,880Sunk24 April 1917''Amulree''1,145Sunk25 April 1917''Glenesk''1,369Sunk25 April 1917''Heathfield''1,643Sunk25 April 1917''Invermay''1,471Sunk27 April 1917''Uranus''3,978Sunk28 April 1917''Jose De Larrinaga''5,017Sunk28 April 1917''Terence''4,309Sunk30 April 1917''Elisabeth''217Damaged1 May 1917''Dorie''3,264Damaged1 May 1917''San Urbano''6,458Sunk
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