Dark-class patrol boat

The Dark class, or Admiralty "Type A", were a class of eighteen fast patrol boats that served with the United Kingdom's Royal Navy starting in 1954.[1] All were named with a prefix of 'Dark'. The class could be fitted as either motor gun boats or motor torpedo boats, depending on the type of armament carried. They were the only diesel engined fast patrol boats in the Royal Navy.[2][3] The class was fitted (along with the Nasty class) with the Napier Deltic two-stroke diesel engine.[1] This was of unique layout, an opposed-piston engine with a triangular layout of three banks, 18 cylinders in total.

Class overview
NameDark class
Builders
Operators
Preceded byGay class
Succeeded byBrave class
Built1954–1958
In commission1954–1971
Planned35
Completed26
Cancelled9
Active0
Retired26
General characteristics
TypeFast patrol boat
Displacement
  • 50 long tons (51 t) (standard)
  • 64 long tons (65 t) (deep)
Length71 ft 8 in (21.84 m)
Beam19 ft 5 in (5.92 m)
Draught6 ft 1 in (1.85 m)
Propulsion2 shafts, Napier Deltic 18 cylinder two-stroke opposed-piston diesels
Speed40 knots (46 mph; 74 km/h)
Complement15
Armament
  • Either:
  • 1 × 40 mm guns
  • 4 × 21-inch torpedoes
  • Or:
  • 1 × 40 mm gun
  • 1 × 4.5-inch gun

Construction

The boats were constructed with alloy framing and wooden decks and skin. The exception was Dark Scout which had all aluminium decks, skins and frames.[2] Originally 27 units were ordered by the admiralty from seven builders. Nine were eventually cancelled in 1955, including Dark Horseman which at the time was partially completed and on the stocks in the builders yard.[4]

The all-aluminium version was exported to Burma (five units), Finland (two units), and Japan (one unit) by builders Saunders-Roe.[4]

Design

With no previous experience of using diesel engines in vessels of this size, it was not fully understood how dirty they would get from the exhaust fumes. Originally launched in the normal Royal Navy grey, they eventually had their hulls painted completely black to disguise the staining from exhaust emissions .[2] For a short while, a compromise half grey/half black combination was used.[5]

Fate

An Admiralty decision in 1957 took nearly all fast patrol boats out of commission, with nine of the new Dark-class to be laid up. On 20 December 1960, the Admiralty stated that the Coastal Forces would not be completely abandoned in case it needed to be expanded in the future. A special boat squadron was nominated, but it did not include any of the Dark-class.[6]

Several of the ships were sold to Wessex Power Units for sale onto the Italian Customs Service (8 hulls) in February 1966. Two were used for target practice, with Dark Gladiator sunk by HMS Amazon and HMS Naiad off Portland in December 1975.[7] At least two, Dark Clipper and Dark Fighter, managed to survive up to as recently as June 2001 when they were broken up in Malta.[8][9]

Legacy

The Dark class would be the final commission of this quantity for patrol boats of this size and speed. The following classes had greatly reduced numbers with the Brave class numbering only two vessels and Scimitar class numbering only three.

A similar hull design was used by Saunders-Roe in a prototype, R-103, which led to the development of the experimental hydrofoil, HMCS Bras d'Or, for the Royal Canadian Navy.[10][11]

Ships
Operator Name Pennant Builder Launched Fate
 Royal Navy Dark Adventurer P1101 Saunders-Roe 28 October 1954 Sold January 1970
 Royal Navy Dark Aggressor P1102 Saunders-Roe 9 December 1954 Sold on 3 October 1961
 Royal Navy Dark Antagonist P1103 Saunders-Roe 11 December 1954 Sold February 1966
 Royal Navy Dark Avenger P1105 Saunders-Roe 6 September 1955 Sold February 1966
 Royal Navy Dark Biter P1104 Saunders-Roe 23 June 1955 Sold February 1966
 Royal Navy Dark Buccaneer P1108 Vosper & Company 30 September 1954 Sold February 1966
 Royal Navy Dark Clipper P1109 Vosper & Company 9 February 1955 Sold on 16 March 1967
Broken up June 2001
 Royal Navy Dark Fighter P1113 Taylor (Chertsey) 4 October 1955 Sold on 16 March 1967
Broken up June 2001
 Royal Navy Dark Gladiator P1114 Taylor (Chertsey) 5 December 1956 Used as target and sunk December 1975
 Royal Navy Dark Hero P1115 McGruer (Clynder) 16 March 1957 Used as target 1977
Sold 1985
 Royal Navy Dark Highwayman P1110 Vosper & Company 29 March 1955 Sold on 16 March 1967
 Royal Navy Dark Hunter P1116 Miller (St. Monance) 18 March 1954 [1] Sold on 13 April 1962
 Royal Navy Dark Hussar P1112 Thornycroft 16 May 1957 Sold February 1966
 Royal Navy Dark Intruder P1118 Morgan Giles (Teignmouth) 6 July 1955 Sold February 1966
 Royal Navy Dark Invader P1119 Morgan Giles (Teignmouth) 6 September 1955 Sold February 1966
 Royal Navy Dark Killer P1111 Thornycroft 26 September 1956 Sold February 1966
 Royal Navy Dark Rover P1107 Vosper & Company 30 August 1954 Sold February 1966
 Royal Navy Dark Scout P1116 Saunders-Roe 20 March 1958 Sold on 2 July 1961
 Myanmar Navy T201 Saunders-Roe 24 March 1956[12] Stricken 1975[13]
 Myanmar Navy T202 Saunders-Roe Stricken 1975[13]
 Myanmar Navy T203 Saunders-Roe Stricken 1975[13]
 Myanmar Navy T204 Saunders-Roe Stricken 1975[13]
 Myanmar Navy T205 Saunders-Roe Stricken 1975[13]
 Finnish Navy Vasama I Saunders-Roe Stricken 1977[14]
 Finnish Navy Vasama II Saunders-Roe Stricken 1979[14]
 Japan Maritime Self-Defense Force PT9 Saunders-Roe Stricken 1972[15]
Cancelled ships
Operator Name Builder
 Royal Navy HMS Dark Attacker Saunders-Roe
 Royal Navy HMS Dark Battler Saunders-Roe
 Royal Navy HMS Dark Bowman Saunders-Roe
 Royal Navy HMS Dark Chaser Vosper & Company
 Royal Navy HMS Dark Chieftain Vosper & Company
 Royal Navy HMS Dark Crusader Vosper & Company
 Royal Navy HMS Dark Defender Thornycroft
 Royal Navy HMS Dark Explorer Thornycroft
 Royal Navy HMS Dark Horseman McGruer (Clynder)

Notes
  1. "Here and There: A 2,500 hp Two-stroke" (PDF). Flight: 392. 2 April 1954. Retrieved 23 December 2009. POWERING H.M. fast patrol boat Dark Hunter, launched on March 18th, is a Napier Deltic engine. An opposed-piston two-stroke diesel, it develops 2,500 s.h.p.; its power/weight ratio (4.2 lb/h.p.) is said to be the highest ever achieved in a marine diesel.
  2. Olver, Jeremy. "Dark Class Fast Patrol Boats". Archived from the original on 12 October 2008. Retrieved 9 July 2009.
  3. "Naval Review Vol.67 No.2 April 1979" (PDF). p. Page 113, Paragraph 2. Retrieved 9 July 2009.
  4. Simons, Philip. "Dark Class". British Military Powerboat Trust. Retrieved 9 July 2009.
  5. Else, Ted. "Dark Class Page 2". British Military Powerboat Trust. Retrieved 9 July 2009.
  6. "Coastal Forces of World War II". Coastal Forces Heritage Trust. Archived from the original on 26 December 2009. Retrieved 9 July 2009.
  7. "HMS Dark Gladiator". Oldships.org.uk. Retrieved 9 July 2009.
  8. "HMS Dark Clipper". Oldships.org.uk. Retrieved 9 July 2009.
  9. "BMPT Forum: Dark Identity". British Military Powerboat Trust. Retrieved 9 July 2009.
  10. "Canada Science and Technology Museum". Retrieved 9 July 2009.
  11. Else, Ted. "Dark Class Page 3". British Military Powerboat Trust. Retrieved 9 July 2009.
  12. Blackman 1971, p. 38.
  13. Gardiner and Chumbley 1995, p. 268.
  14. Gardiner and Chumbley 1995, p. 93.
  15. Gardiner and Chumbley 1995, p. 238.

References
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