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Class overview
Name:
Steam Gun Boat (SGB)
In service:
Nov 1941
Completed:
7
Active:
none
Lost:
1
General characteristics
Displacement:
175 tons (standard), 255 tons (deep load)
Length:
44.3 m (145 ft 8 in) overall
Beam:
7.1 m (20 ft)
Draught:
1.68 m (5.5ft)
Propulsion:
twin Metrovick geared steam turbines, 1 boiler delivering 5965 kW (8,000 shp) to two shafts
Speed:
35 kts maximum
Range:
200 n.miles at full speed; 900 n.miles @ 12 knots
Complement:
27 initially (3 officers and 24 men), later rising to 34 as a result of changes in armament.
Armament:
(final arrangement) one 76.2-mm (3-in) gun, two single 6-pdr guns, two twin 20-mm cannon, and two 21-in torpedo tubes
The Steam Gun Boat (SGB) was a class of steam gun boats built during 1940 - 1942 for the Coastal Forces of the Royal Navy.
They were developed in parallel with the Fairmile D motor torpedo boats ("Dog boats"), specifically as a response to the need to hunt down German E-boats and also as a response to the scarcity of suitable diesel engines. While sixty were planned only an initial batch of nine were ordered on 8 November 1940, of which seven were completed.
Contents
1 Design
2 Service
3 Boats
4 Notes and references
5 See also
6 External links
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Design
The Steam Gun Boats were conceived to answer the seeming need for a craft which was large enough to put to sea in rough weather and which could operate both as a 'super-gunboat' and a torpedo carrier, combining the functions of the MGB (Motor Gun Boat) and MTB (Motor Torpedo Boat) in the same fashion as did the German S-boats. They were the largest of the Coastal forces vessels, and were the only ones to be built of steel (all other Coastal Forces craft were of wood). They resembled a miniature destroyer, and were perhaps the most graceful of all the craft produced during WW2. However their comparatively large silhouette was a drawback, making them too easy a target for the faster German craft.
They were 145 feet 8 inches long and had a displacement of 172 tons (202 tons fully fueled). They were powered by two 4,000hp steam turbines using special flash boilers. These boilers proved to be particularly vulnerable to attack and - once the vessel had broken down - it required a major effort to repair it. Steam had the advantage of quietness but demanded a large hull. Large wooden hulls were not feasible for mass production so steel was used. This meant hulls and machinery were beyond the scope of the small yards engaged in the rapid expansion of the coastal forces, and the SGB thus competed for berths in yards hard put to produce urgently required convoy escorts. Also they competed in the demand for mild steel and steam power plants against the more urgently demanded destroyers; accordingly the planned 51 further vessels were never ordered, while the two units ordered from Thornycroft were never begun due to enemy action. The seven vessels actually completed were built by Yarrow, Hawthorn Leslie, J. Samuel White and William Denny and Brothers, entering service by the middle of 1942.
Fuel consumption was heavy with the added disadvantage that, where a petrol boat could start from cold and get away immediately, the SGB had to remain in steam. Over time the addition of 18mm (0.7 in) protective plate over the sides of the boiler and engine rooms, together with the extra armament and crew, increased the displacement to 260 tons and their service speed was consequentially reduced to 30 kts.
Veritable battleships of the coastal forces, the Steam Gun Boats were heavily-armed and could maintain high speed in a seaway. In action E-boat commanders respected the SGBs almost as much as destroyers.
Service
The nine boats ordered initially received the designation SGB 1 to 9 (of which numbers 1 and 2 were cancelled). The 1st SGB Flotilla was formed at Portsmouth by mid-June 1942, under the command of Lt-Cmdr. Peter Scott, son of the Antarctic explorer Captain Robert Scott and later a noted ornithologist, conservationist and broadcaster. Their first fleet action took place in the Baie de Seine (the Seine Estuary) shortly after midnight on 19 June, when two vessels - SGB 7 and 8, under the joint command of Lt. J. D. Ritchie, in company with the Hunt class destroyer HMS Albrighton encountered several E-boats escorting two German merchantmen. SGB 7 was sunk in this action; as a consequence the Admiralty noted their vulnerability and refitted them with the additional armour over their engine and boiler rooms, as mentioned above. At the same time the six survivors were renamed after wildlife in the form "SGB Grey...." .
Boats
Nine vessels below were all ordered on 8 November 1940.
Ship
Builder
Laid down
Launched
Commissioned
Fate
SGB1
Thornycroft, Woolston
Cancelled
SGB2
Thornycroft, Woolston
Cancelled
SGB3/Grey Seal
Yarrow, Scotstoun
24 January 1941
29 August 1941
21 February 1942
For sale 20 August 1949
SGB4/Grey Fox
Yarrow, Scotstoun
24 January 1941
25 September 1941
15 March 1942
For sale October 1947
SGB5/Grey Owl
Hawthorn Leslie, Hebburn
17 April 1941
27 August 1941
1 April 1942
Sold to British Iron & Steel and scrapped 15 December 1949
SGB6/Grey Shark
Hawthorn Leslie, Hebburn
28 March 1941
17 November 1941
30 April 1942
Sold 13 October 1947. Houseboat in 1949
SGB7
Denny, Dunbarton
3 February 1941
25 September 1941
11 March 1942
Sunk by gunfire from German surface vessels in the Seine Estuary 19 June 1942
SGB8/Grey Wolf
Denny, Dunbarton
3 February 1941
3 November 1941
17 April 1942
Sold 3 February 1948
SGB9/Grey Goose
J. Samuel White, Cowes
23 January 1941
14 February 1942
4 July 1942
Sold about 1957
These boats formed the 1st SGB Flotilla which was initially formed at Portsmouth, but later based at HMS Aggressive, Newhaven, Sussex on the south coast of England.
SGB 5 was damaged in the Dieppe raid after meeting a German convoy of R boats.
In 1944 the six survivors were all converted to fast minesweepers and all (except SGB9/Grey Goose) were sold off in the years after the war. SGB9 remained in service as a trials vessel from 1952 to 1956, and was sold off subsequently, becoming a mercantile repair hulk from 1958, being renamed Anserava.
Notes and references
^ BBC WW2 Peoples War accessed 11th December 2007
The Encyclopedia of Weapons of World War II by Chris Bishop, 2002 ISBN 978-1586637620
Coastal Forces SGBs at unithistories.com accessed 11th December 2007
David K. Brown, The Design and Construction of British Warships 1939-1945, Volume 3, Conway Maritime Press, ISBN 0-85177-674-4.
George L Moore, The Steam Gunboats - in Warship 1999-2000, Conways Maritime Press, ISBN 0 85177 7244.
See also
Coastal Forces of the Royal Navy
External links
Picture of a steam gun boat
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