SM UC-42 was a German Type UC II

German Type UC II submarine

Type UC II minelaying submarines were used by the Kaiserliche Marine during the World War I. They displaced 417 tons, carried 7 torpedoes and up to 18 mines...

 minelaying

Minelayer

Minelaying is the act of deploying explosive mines. Historically this has been carried out by ships, submarines and aircraft. Additionally, since World War I the term minelayer refers specifically to a naval ship used for deploying naval mines...

 submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 or U-boat

U-boat

U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

 in the German Imperial Navy  during World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. The U-boat was ordered on 20 November 1915 and was launched on 21 September 1916. She was commissioned into the German Imperial Navy on 18 November 1916 as SM UC-42."SM" stands for "Seiner Majestät" (His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.

Service

In a career that encompassed six patrols, operating from 1 January 1917, UC-42 succeeded in sinking thirteen vessels totaling 9,636 tons, and disabling a warship of 1,210 tons displacement

Displacement (ship)

A ship's displacement is its weight at any given time, generally expressed in metric tons or long tons. The term is often used to mean the ship's weight when it is loaded to its maximum capacity. A number of synonymous terms exist for this maximum weight, such as loaded displacement, full load...

.

Fate

UC-42 sailed on her last patrol on 1 September 1917.

On 31 October 1917 Torpedo Boat TB 055 was accompanying minesweepers operating at the entrance to Cork

Cork (city)

Cork is the second largest city in the Republic of Ireland and the island of Ireland's third most populous city. It is the principal city and administrative centre of County Cork and the largest city in the province of Munster. Cork has a population of 119,418, while the addition of the suburban...

 harbour. At 1500 hours an oil track was seen floating on the surface of the water. Following it to its source, TB 055 used its hydrophone to see if the oil was coming from a submarine. Loud mechanical sounds, of "hammering" and "turbine-like noises" were reported and, believing this to be a U-boat, a marker buoy was dropped, followed shortly after by a depth charge. Following detonation of the charge, TB 055 returned to the area and found that the volume of floating oil had increased, and there were bubbles rising to the surface.

TB 055 signalled the nearby armed minesweeper HMT

Naval trawler

A naval trawler is a vessel built along the lines of a fishing trawler but fitted out for naval purposes. Naval trawlers were widely used during the First and Second world wars. Fishing trawlers were particularly suited for many naval requirements because they were robust boats designed to work...

 Sarba for assistance. Sarba used her hydrophone but detected no sounds from the presumed submarine. A second depth charge was dropped and Sarba remained on station overnight. The following morning HMD Sunshine and TB 058 swept around the spot, to confirm that the incident had not been a false alarm caused by old wreckage. On 2 November oil was still coming to the surface and dockyard drivers arrived to inspect the assumed wreck. The divers reported a German U-boat lying on the seabed with her stern blown off, and a brass plate on her conning tower reading "C42, 1916" identified her as UC-42. No survivors were ever reported even though some of the hatches were found to have been opened. It was thought likely that the submarine had been sunk by one of her own mines detonating under her stern while minelaying.

When the sinking and identification of the submarine was reported, the British Admiralty requested an identifiable item from the vessel for verification purposes, and in December 1917 divers recovered the telephone buoy from the conning tower. The Royal Navy's Naval Intelligence Department were aware of submarine's 1 September departure date from Belgium and were sceptical about the hammering and engine noises reported by TB 055. The Admiralty reported that "The longest known cruise of a UC boat in home waters is 24 days, so UC42 must have been dead long before TB 055 and Sarba dropped the depth charges".

Rediscovery

The wreck was relocated on 6 November 2010 in 27 metres (88.6 ft) of water, just off Roche's Point, by a group of Irish, amateur divers. It was found with "little obvious explosive damage". A serial number stamped on its propeller allowed positive identification of the wreck.

A plaque was placed by the boats stern and under International Maritime Law she is now a War Grave, untouchable and the responsibility of the Deutsche Marine.

External links

• wrecksite.eu
• Cork divers discover WWI U-boat RTÉ
  RTE
  RTÉ is the abbreviation for Raidió Teilifís Éireann, the public broadcasting service of the Republic of Ireland.RTE may also refer to:* Recep Tayyip Erdoğan, 25th Prime Minister of Turkey...
  
  news report of find, January 2011.
• http://www.rte.ie/news/2011/0124/cork.html