View source for HMS M2 (1918)

{{short description| Royal Navy submarine monitor wrecked in Lyme Bay }}
{{other ships|HMS M2}}

{{Use dmy dates|date=December 2016}}
{{Use British English|date=December 2016}}

{|{{Infobox ship begin}}
{{Infobox ship image
|Ship image=[[File:British Submarine HMS M2, 2.jpg|300px|HMS M2]]
|Ship caption=HMS ''M2'' retrieving her [[Parnall Peto]] [[seaplane]].
}}
{{Infobox ship career
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|Ship country= United Kingdom
|Ship flag={{shipboxflag|United Kingdom|naval}}
|Ship name=HMS ''M2''
|Ship ordered=
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|Ship builder=[[Vickers Limited|Vickers]]
|Ship original cost=
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|Ship laid down=1916
|Ship launched=19 October 1918
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|Ship fate=Sank during exercise, 26 January 1932
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}}
{{Infobox ship characteristics
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|Header caption=
|Ship class=[[British M-class submarine|M-class]] [[submarine]]
|Ship displacement=*{{convert|1594|LT|t|0|lk=in|abbr=on}} (surfaced)
*{{convert|1946|LT|t|0|abbr=on}} (submerged)
|Ship length={{convert|295|ft|9|in|m|abbr=on}}
|Ship beam={{convert|24|ft|8|in|m|abbr=on}}
|Ship draught=
|Ship power=*{{convert|2400|hp|kW|lk=in|abbr=on}} ([[diesel engine]]s)
*{{convert|3200|hp|kW|abbr=on}} (electric motors)
|Ship propulsion=*2 × 12-cylinder [[Vickers]] diesel engines
*4 × electric motors
*2 × 3-blade, {{convert|5|ft|10|in|m|abbr=on}} diameter propellers
|Ship speed=*{{convert|15|kn|mph km/h|lk=in|abbr=on}} (surfaced)
*{{convert|8|-|9|kn|mph km/h|abbr=on}} (submerged)
|Ship range=*{{convert|2000|nmi|mi km|lk=in|abbr=on}} at {{convert|15|kn|mph km/h|abbr=on}}
*{{convert|4500|nmi|mi km|abbr=on}} at {{convert|10|kn|mph km/h|abbr=on}} 
|Ship endurance={{convert|80|nmi|mi km|abbr=on}} at {{convert|2|kn|mph km/h|abbr=on}}
|Ship test depth={{convert|200|ft|m|abbr=on}} - accidentally reached {{convert|239|ft|m|abbr=on}} in 1923
|Ship complement=62
|Ship armament=*1 × [[Armstrong Whitworth 12 inch /40 naval gun|12-inch (305mm)/40 cal Mark IX gun]] with 50 rounds (removed 1928)
*1 × [[QF 3 inch 20 cwt|{{convert|3|in|mm|abbr=on}} Mk II HA]] [[Anti-aircraft warfare|anti-aircraft gun]]
*4 × [[British 18 inch torpedo|18 inch (450 mm)]] bow [[torpedo tube]]s with 4 reload [[torpedo]]es
|Ship aircraft=1 × [[Parnall Peto]] [[seaplane]]
|Ship aircraft facilities=[[Hangar]] and [[Aircraft catapult|Hydraulic catapult]] 
|Ship notes=
}}
|}

'''HMS ''M2''''' was a [[Royal Navy]] [[submarine]] [[Monitor (warship)|monitor]] completed in 1919, converted in 1927 into a [[submarine aircraft carrier]]. She was wrecked in [[Lyme Bay]], [[Dorset]], [[United Kingdom|Britain]], on 26 January 1932. She was one of three [[British M-class submarine|M-class]] boats completed.

==Design and career==
Four M-class submarines replaced the order for the last four [[British K-class submarine|K-class]] submarines, ''K17''-''K21''. Although they were similar in size, the M class was an entirely different design from the K class, although it is possible that some material ordered for the K-boats went into them. In any event, the end of the [[World War I|First World War]] meant that only three were completed.

''M2'' was laid down at [[Vickers]] shipyard at [[Barrow in Furness]] in 1916, and launched in 1918. Like the other members of her class, she was armed with a single fixed 12-inch (305mm) gun as well as [[torpedo tube]]s. The Mark IX gun was taken from spares held for the [[Formidable-class battleship|''Formidable''-class]] [[battleship]]s.

[[File:British Submarine HMS M2.jpg|thumb|left|300px|HMS M2 launching her [[Parnall Peto]] [[seaplane]].]]
The M-class submarines were very large for the time at {{convert|296|ft|m}} long. They were designed to operate as submarine [[Monitor (warship)|monitors]] or [[cruiser]]s. They [[Displacement (ship)|displaced]] {{convert|1600|LT|t|0|lk=in|abbr=on}} on the surface and {{convert|1950|LT|t|0|abbr=on}} when submerged. Two 12-cylinder [[diesel engine]]s producing {{convert|2400|hp|kW|abbr=on}} drove them on the surface; underwater, they were driven by electric motors producing {{convert|1500|hp|kW|abbr=on}}.

After the accidental sinking of {{HMS|M1|1917|2}} in 1925, ''M2'' and her sister {{HMS|M3|1918|2}} were taken out of service and reassigned for experimental use. Her 12-inch gun was removed, replaced by a small aircraft [[hangar]], the work being completed in 1927. This could carry a small [[Parnall Peto]] [[seaplane]], specially designed for the ''M2'', which, once its wings had been unfolded, could be lowered onto the sea alongside by a [[derrick]] for take off. On landing, the aircraft was hoisted back onto the deck and replaced into the hangar. In October 1928, a [[hydraulic]] [[aircraft catapult]] was fitted, to enable the seaplane to take off directly from the deck.<ref>[http://www.flightglobal.com/pdfarchive/view/1931/1931%20-%200813.html Flightglobal Archive - Aviation History - Flight, 31 July 1931 (p. 759)]</ref> The submarine was intended to operate ahead of the battle fleet in a [[reconnaissance]] role, flying off her unarmed seaplane as a scout.<ref>[http://www.flightglobal.com/pdfarchive/view/1931/1931%20-%200817.html Flight, 31 July 1931 (pp. 762-3)]</ref>

The concept of a [[submarine cruiser]] was pursued with {{HMS|X1||2}}, but was not a success and was later abandoned.

==Accident==
''M2'' left her base at [[Isle of Portland|Portland]] on 26 January 1932, for an exercise in [[West Bay, Dorset]], carrying [[Parnall Peto]] serial N255. Her last communication was a radio message at 10:11 to her [[submarine depot ship]], {{HMS|Titania||2}}, to announce that she would dive at 10:30. The captain of a passing merchant ship, the [[Newcastle upon Tyne|Newcastle]] [[Coastal trading vessel|coaster]] ''Tynesider'', mentioned that he had seen a large submarine dive stern first at around 11:15. Unaware of the significance of this, he only reported it in passing once he reached port.<ref name="Treadwell p45-6">Treadwell 1999, pp. 45–46.</ref>

Her entire crew of 60 was killed in the accident.<ref name="Treadwell p52">Treadwell 1999, p. 52.</ref> The submarine was found on 3 February, eight days after her loss.<ref name="Treadwell p47,0">Treadwell 1999, pp. 47, 50.</ref> [[Ernest Cox]], the salvage expert who had raised the [[Scuttling of the German fleet in Scapa Flow|German battleships at Scapa Flow]], was hired to salvage the ''M2''. In an operation lasting nearly a year and 1,500 dives, on 8 December 1932, she was lifted to within {{convert|20|ft|m|sigfig=1|abbr=on}} of the surface before a [[gale]] sprang up, sending her down to her final resting place.

The hangar door was found open and the aircraft still in it. The accident was believed to be due to water entering the submarine through the hangar door, which had been opened to launch the aircraft shortly after surfacing.

Two explanations have been advanced;

The first is that since the crew were always trying to beat their record time for launching the aircraft, they had opened the hangar door on surfacing while the deck was still awash.

The other theory is that the flooding of the hangar was due to failure of the stern [[Diving plane|hydroplanes]]. High pressure air tanks were used to bring the boat to the surface in an awash condition, but to conserve compressed air, compressors were then started to completely clear the ballast tanks of water by blowing air into them. This could take as long as 15 minutes to complete. The normal procedure for launching the aircraft was therefore to hold the boat on the surface using the hydroplanes whilst the hangar door was opened and the aircraft launched. Failure of the stern hydroplanes would have sent the stern down as observed by the merchant officers and water would have eventually entered the hangar.

[[Image:M2 submarine wood help message at Royal Navy Submarine Museum, Gosport.jpg|thumb|The help message from ''M2'', written in pencil on a small piece of wood, on display at the [[Royal Navy Submarine Museum]].]]
On 25 February 1932, a help message from ''M2'', written in pencil on a small piece of wood, was discovered by a fisherman on the shore at [[Hallsands]], south [[Devon]]. It read: "Help. ''M2'' gone down. No. 2 hatch open.", with "Help. Lieut." on the back. It was handed over to the naval authorities and is now on display at the [[Royal Navy Submarine Museum]] in [[Gosport]].<ref>{{cite news |title=Message from M2? Strange Discovery on South Devon Coast. |newspaper=Devon & Exeter Gazette |date=26 February 1932 |page=16 |url=https://www.britishnewspaperarchive.co.uk/viewer/bl/0000511/19320226/097/0016 |via=[[British Newspaper Archive]] |url-access=subscription |access-date=17 July 2024}}</ref>

==Aftermath==
The submarine currently lies upright on the sea bed at ({{coord|50|34.6|N|2|33.93|W|}}). Her keel is about {{convert|100|ft|m|abbr=on}} below the surface at low tide, and her highest point at the top of the conning tower at around {{convert|66|ft|m|abbr=on}}. She is a popular dive for [[Scuba diving|scuba]] divers. The wreck is designated as a "protected place" under the [[Protection of Military Remains Act 1986]].

After the loss of ''M2'', the Royal Navy abandoned submarine-launched aircraft, although other navies experimented with the concept in the inter-war years and with Japan producing some [[Submarine aircraft carriers of Japan|42 submarine aircraft carriers]] both before and during the Second World War.<ref>Dorr Carpenter, Dorr B. & Polmar, Norman. ''Submarines of the Imperial Japanese Navy'', Conway Maritime Press, 1986.</ref>

==See also==

[[I-400-class submarine]]

{{portal|Underwater diving}}

==References==
{{Reflist}}

==Bibliography==
*{{cite book |last1=McCartney |first1=Innes |title=Lost patrols : submarine wrecks of the English Channel |date=2002 |publisher=Periscope |location=Penzance |isbn=978-1-90438-104-4}}
* Brown, D.K. (2003) ''The Grand Fleet: Warship Design and Development 1906-1922'', London: Caxton Editions, {{ISBN|1-84067-531-4}}
* Treadwell, T.C. (1999) ''Strike from beneath the Sea: a history of aircraft-carrying submarines'', Stroud, UK: Tempus Publishing. {{ISBN|0-7524-1704-5}}
* [http://www.opsi.gov.uk/si/si2008/uksi_20080950_en_1 SI 2008/0950] Designation under the Protection of Military Remains Act

==External links==
{{commons category|HMS M2}}
* [https://books.google.com/books?id=vuQDAAAAMBAJ&q=flyingboatsdornier&pg=PA532 Gulls of War, October 1931] article [[Popular Mechanics]]
* [https://books.google.com/books?id=CigDAAAAMBAJ&dq=Popular+Mechanics+1931+curtiss&pg=PA48 "Sub Launches Plane With Catapult", October 1931, Popular Science]

{{British M class submarine}}
{{1932 shipwrecks}}
{{Recreational dive sites|wresit}}
{{coord|50|34|34|N|2|32|55|W|display=title|type:landmark_source:dewiki_scale:300000}}

{{DEFAULTSORT:M2}}
[[Category:British M-class submarines]]
[[Category:Ships built in Barrow-in-Furness]]
[[Category:1918 ships]]
[[Category:World War I submarines of the United Kingdom]]
[[Category:Submarine aircraft carriers]]
[[Category:Maritime incidents in 1932]]
[[Category:British submarine accidents]]
[[Category:Warships lost with all hands]]
[[Category:Shipwrecks in the English Channel]]
[[Category:Protected wrecks of the United Kingdom]]
[[Category:Wreck diving sites in the United Kingdom]]
[[Category:1932 disasters in the United Kingdom]]