Coastal Motor Boat

During the First World War, following a suggestion from three junior officers of the Harwich destroyer force that small motor boats carrying a torpedo might be capable of travelling over the protective minefields and attacking ships of the Imperial German Navy at anchor in their bases, the Admiralty gave tentative approval to the idea and, in the summer of 1915, produced a Staff Requirement requesting designs for a Coastal Motor Boat for service in the North Sea.

These boats were expected to have a high speed, making use of the lightweight and powerful petrol engines then available. The speed of the boat when fully loaded was to be at least 30 knots (56 km/h) and sufficient fuel was to be carried to give a considerable radius of action.

They were to be armed in a variety of ways, with torpedoes, depth charges or for laying mines. Secondary armament would have been provided by light machine guns, such as the Lewis gun. The weight of a fully loaded boat, complete with 18-inch (450 mm) torpedo,[note 1] was to not exceed the weight of the 30-foot (9.1 m) long motor boat then carried in the davits of a light cruiser, i.e. 4.5 tons.

The CMBs were designed by Thornycroft, who had experience in small fast boats. Engines were not proper maritime internal combustion engines (as these were in short supply) but adapted aircraft engines from firms such as Sunbeam and Napier.

IWM Duxford 2017 CMB4
HM Coastal Motor Boat 4 (1916) on display at the Imperial War Museum Duxford. View from the stern showing the torpedo launching ramp.

40-foot Coastal Motor Boats

Class overview
Name: 40 foot CMB
Builders: Thornycroft, Tom Bunn, Taylor & Bates, J W Brooke, Frank Maynard, Salter Bros, Wills & Packham
Operators:  Royal Navy
Completed: 39 +2 not taken into service as CMB
Cancelled: 16
Preserved: 1 (CMB 4)
General characteristics
Length: 45 ft (14 m) o/a
Propulsion: Single screw, various choices of petrol engine
Complement: 2-3
Armament: Single 18" torpedo, 2-4 Lewis guns, depth charges or mines
Notes: Mahogany plank on frame construction, single-step planing round-form hull

In 1910, Thornycroft had designed and built a 25 ft (7.6 m) speedboat called Miranda IV. She was a single-step hydroplane powered by a 120 hp (89 kW) Thornycroft petrol engine and could reach 35 knots (65 km/h).[1]

A 40 ft (12 m) boat based on Miranda IV was accepted by the Admiralty for trials. A number of these boats were built and had a distinguished service history, but in hindsight they were considered to be too small to be ideal, particularly in how their payload was limited to a single 18-inch torpedo.

Several companies were approached, but only Thornycroft considered it possible to meet such a requirement. In January 1916, twelve boats were ordered, all of which were completed by August 1916. Further boats were built, to a total of 39.[2]

The restriction on weight meant the torpedo could not be fired from a torpedo tube, but instead was carried in a rear-facing trough. On firing it was pushed backwards by a cordite firing pistol and a long steel ram, entering the water tail-first. A trip-wire between the torpedo and the ram head would start the torpedo motors once pulled taut during release. The CMB would then turn hard over and get out of its path. There is no record of a CMB ever being hit by its own torpedo, but in one instance the firing pistol was triggered prematurely and the crew had a tense 20 minutes close to the enemy whilst reloading it.[3]

Service history

In December 1916, the 3rd CMB Division proceeded to Dunkirk under the command of Lieutenant W.N.T. Beckett of CMB4 and operated on the Belgian coast. On 7 April 1917, the 3rd CMB Division attacked a group of German destroyers anchored at Zeebrugge. As a result, one destroyer was sunk and one very seriously damaged. For these actions Beckett was mentioned in Despatches and was awarded the Distinguished Service Cross (DSC).[5]
In June 1919 a force of two CMBs attacked Kronstadt and sank the cruiser Oleg. Lt. Augustus Agar of CMB4 won his Victoria Cross in this operation.[3]
In August, a larger combined operation with aircraft managed to damage one battleship and sink a depot ship. There were casualties as the mission came under heavy fire.[6] Lt. Agar won a DSO to accompany his VC.[7]
In January 1919 a force of 12 CMBs was dispatched to the Caspian Sea (travelling by rail from Batumi on the Black Sea coast to Baku) to join a British naval unit supporting the anti-Bolshevik governments of Armenia, Azerbaijan and Georgia.[8]


The hull of CMB 4 in which Augustus Agar won his VC for the attack on Kronstadt naval base in 1919 and sank the cruiser Oleg was, for many years, at the Vosper Thornycroft works on Platt's Eyot on the Thames near Kingston. When these works closed it was restored and can now be seen at the Imperial War Museum, Duxford with details of these boats and the action. Agar’s VC is at the War Museum in London.

CMB 9 has been restored and is based at Avonmouth near Bristol. She took part in the 2014 Remembrance Day events in Bristol. CMB 9 was converted to a Distance Control Boat in 1918, the first CMB so converted and in so doing became DCB1. It is in her DCB outfit that the vessel currently exists.

55 foot Coastal Motor Boats

Class overview
Name: 55 foot CMB
Operators: Royal Navy
Completed: 88[9]
General characteristics
Displacement: 11 tons
Length: 60 ft (18 m) o/a
Beam: 11 ft (3.4 m)
Draught: 3 ft (0.91 m)
  • 750–900 hp (560–670 kW) total power depending on engines
  • 2 shafts
Speed: 34–42 kn (63–78 km/h)
Crew: 3-5
Armament: 2 18" torpedoes or 1 18" torpedo plus 4 depth charges, 4 Lewis guns

Larger versions of the 40-footer were ordered in 1916[9]

In 1917 Thornycroft produced an enlarged 60-foot (18 m) overall version. This allowed a heavier payload, and now two torpedoes could be carried. A mixed warload of a single torpedo and four depth charges could also be carried, the depth charges released from individual cradles over the sides, rather than a stern ramp.[10]

Speeds from 35–41 knots (40–47 mph; 65–76 km/h) were possible, depending on the various petrol engines fitted. At least two unexplained losses due to fires in port are thought to have been caused by a build-up of petrol vapour igniting.

It was these larger boats that entered the harbour during the Kronstadt raid and torpedoed the Soviet ships.

Naval Ensign of the United Kingdom
United Kingdom
Name: MTB 331
Operator: Royal Navy
Builder: Thornycroft
Launched: 1941
Class overview
Name: 55 foot CMBT (1941 class)
Operators: Royal Navy
Completed: 14
Preserved: MTB 331
General characteristics
Displacement: 17 tons
Length: 60 ft (18 m)
Beam: 11.5 ft (3.5 m)
Draught: 4 ft (1.2 m)
Propulsion: Twin screws & twin 650 hp (480 kW) Thornycroft RY12 petrol engines
Speed: 40 knots (74 km/h)
Armament: Twin 18" torpedoes, depth charges or mines
Notes: Mahogany plank on frame construction, single-step planing round-form hull

The design was so successful that more were built during World War II. The last survivor, MTB 331, is of this group, built in 1941.


MTB 331, owned by Hampshire County Council and on-loan to the British Military Powerboat Trust (BMPT) at Marchwood, is the sole surviving 55' CMB.[11] Built in 1941, the penultimate 55' built, her design was based on that of the CMBs of 1917 with two V12 engines. Her post-war history is incomplete, but she was registered as the Jonrey at Teignmouth, then later at Bristol. She was acquired by the Council around 1990. Some restoration after this was carried out at Priddy's Hard, then she was transported by road to BMPT Marchwood in March 2000.[12]

70-foot Coastal Motor Boat

M103 at Chatham Dockyard
CMB 103 at Chatham

Twelve 72 ft long CMBs were ordered in early 1918 for minelaying (7 magnetic mines) or torpedo work (6 torpedoes). Five were cancelled; of the remainder, 3 survived the Second World War,[9] with CMB 103 MT preserved as a museum ship. CMB 103 was restored in August 2011 and is on display at The Historic Dockyard at Chatham.[13][14]

See also


  1. ^ The British "18 inch" torpedoes were 17.72 inches (45.0 cm) in diameter British torpedoes pre WWII


  1. ^ Barrie Griffin (April 2008). "The Thornycroft 55' Coastal Motor Boat". Marine Modelling International.
  2. ^ "WW1 numbers and losses of MTB classes".
  3. ^ a b "A naval operation in the Baltic". sinking of the Russian Cruiser 'Oleg' in 1919
  4. ^ "British Minor Warship Losses - 1914 - 1918".
  5. ^ "Royal Navy (RN) Officers 1939-1945 - B".
  6. ^ History of WWI. Vol. 8. 1969.
  7. ^ Hill, J. R; Ranft, Bryan (17 October 2002). The Oxford Illustrated History of the Royal Navy. Oxford University Press. p. 330. ISBN 978-0-19-860527-0.
  8. ^ "The Royal Navy on the Caspian, 1918-1919". Naval Review, 7/8 1919-20. pp87-99 and 218-240*
  9. ^ a b c Conway's All The World's Fighting Ships 1906-1921. 1985. p. 100.
  10. ^ Air Commodore F. R. Banks (1978). I Kept No Diary. Airlife. p. 29. ISBN 0-9504543-9-7.
  11. ^ "The Preservation of Thornycroft Coastal Motor Boat 331 at Fort Gilkicker". Hampshire County Museums Service. 1991. Archived from the original on 2 January 2005.
  12. ^ "MTB 331 home site and restoration photos". British Military Powerboat Trust (BMPT). Archived from the original on 15 March 2008.
  13. ^ Historic Warships News Sheet: December 2011
  14. ^

Further reading

  • Harald Fox (1978). Fast Fighting Ships 1870-1945.
  • M P Cocker (2006). Coastal Forces: Vessels of the Royal Navy from 1865. National Maritime Museum, Greenwich.
Amenities ship

An amenities ship is a ship outfitted with recreational facilities as part of a mobile naval base. Amenities ships included movie theaters and canteens staffed by mercantile crews of the Royal Fleet Auxiliary service. These ships were intended to provide a place where British Pacific Fleet personnel could relax between operations.

Claude Congreve Dobson

Rear-Admiral Claude Congreve Dobson VC, DSO (1 January 1885 – 26 June 1940) was an English recipient of the Victoria Cross, the highest and most prestigious award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces.

Dobson was born in Clifton, Bristol and was educated at Clifton College. He was an experienced submariner and small motor boat captain who served in World War I. He was 34 years old, and a commander in the Royal Navy serving with the North Russia Relief Force when the following deed took place for which he was awarded the VC:

On 18 August 1919 at Kronstadt, Russia, Commander Dobson was in command of the Coastal Motor Boat Flotilla which he led through the chain of forts to the entrance to Kronstadt harbour. CMB 31BD, a 55 ft boat, from which he directed the general operations then passed in under heavy machine-gun fire and hit the battleship Andrei Pervozvanny with both torpedoes, subsequently returning through heavy fire to the open sea. CMB 31BD was commanded and helmed by Lieutenant Russell Hamilton McBean.His VC is currently displayed at the National Maritime Museum in Greenwich.

Coastal minesweeper

Coastal minesweeper is a term used by the United States Navy to indicate a minesweeper intended for coastal use as opposed to participating in fleet operations at sea.

Because of its small size—usually less than 100 feet in length—and construction—wood as opposed to steel—and slow speed—usually about 9 or 10 knots—the coastal minesweeper was considered too fragile and slow to operate on the high seas with the fleet.

Minesweeping, in conjunction with fleet activities, was usually relegated to the diesel-driven steel-hulled AM-type minesweepers, later to be replaced by the wood-hulled MSO-type minesweeper with aluminum engines.

Coastal submarine

A coastal submarine or littoral submarine is a small, maneuverable submarine with shallow draft well suited to navigation of coastal channels and harbors. Although size is not precisely defined, coastal submarines are larger than midget submarines, but smaller than sea-going submarines designed for longer patrols on the open ocean. Space limitations aboard coastal submarines restrict fuel availability for distant travel, food availability for extended patrol duration, and number of weapons carried. Within those limitations, however, coastal submarines may be able to reach areas inaccessible to larger submarines, and be more difficult to detect.

Dufuna canoe

Dufuna Canoe is a canoe discovered in 1987 by a Fulani cattle herdsman a few kilometers from the village of Dufuna in the Fune Local Government Area, not far from the Komadugu Gana River, in Yobe State, Nigeria. Radiocarbon dating of a sample of charcoal found near the site dates the canoe at 8500 to 8000 years old, linking the site to Lake Mega Chad.It is the oldest boat to be discovered in Africa, and the second oldest known worldwide. The canoe is currently in Damaturu, the state capital.

Fast attack craft

A fast attack craft (FAC) is a small, fast, agile and offensive warship armed with anti-ship missiles, gun or torpedoes. FACs are usually operated in close proximity to land as they lack both the seakeeping and all-round defensive capabilities to survive in blue water. The size of the vessel also limits the fuel, stores and water supplies. In size they are usually between 50–800 tonnes and can reach speeds of 25–50 knots.A fast attack craft's main advantage over other warship types is its affordability. Many FACs can be deployed at a relatively low cost, allowing a navy which is at a disadvantage to effectively defend itself against a larger adversary. A small boat, when equipped with the same weapons as its larger counterpart, can pose a serious threat to even the largest of capital ships. Their major disadvantages are poor seagoing qualities, cramped quarters and poor ability to defend themselves against aerial threat.

General stores issue ship

General stores issue ship is a type of ship used by the United States Navy during World War II and for some time afterwards.

The task of the general stores issue ship was to sail into non-combat, or rear, areas and disburse general stores, such as canned goods, toilet paper, office supplies, etc., to ships and stations.

Guard ship

A guard ship is a warship assigned as a stationary guard in a port or harbour, as opposed to a coastal patrol boat which serves its protective role at sea.

HM Coastal Motor Boat 4

HM Coastal Motor Boat 4 is the torpedo boat used when Lieutenant Augustus Agar earned a Victoria Cross for carrying out a raid on Soviet warships in Kronstadt and sinking the cruiser Oleg

It was one of a large series of small, fast, shallow draught Coastal Motor Boats used during the First World War. She was designed by John I. Thornycroft & Company of Hampton, England, ordered in January 1916, built by them and delivered that summer.

CMB 4 was 45 feet (14 m) long and 8 ft 6 in (2.59 m) in the beam. She displaced 5 tons drawing 2 ft 9 in (0.84 m) of water. Power was a 275 bhp (205 kW) Thornycroft V-12 petrol engine driving a single propeller and achieved a top speed of 24.8 knots (45.9 km/h). The boat was armed with one 18 inch (450 mm) torpedo and four .303 in (7.62 km) Lewis machine guns. It was operated by a crew of three.

In May 1916, Lieutenant W. N. T. Beckett MVO DSC took command of the newly built HM Coastal Motor Boat 4. In December 1916 he proceeded to Dunkirk in charge of the 3rd CMB Division and operated on the Belgian coast. Beckett was in command of a Divisional CMB attack on German destroyers at Zeebrugge on 7 April 1917; as a result one was sunk and one very seriously damaged. For these actions Beckett was mentioned in Despatches and was awarded the Distinguished Service Cross (DSC).The boat, under the command of Lieutenant Augustus Agar, V.C., was made famous by his part in the British operations in the Baltic Sea against the Bolsheviks in 1919, where she operated with her sister ships in activities such as the raid on Kronstadt.After the action the boat was returned to the United Kingdom, where it was on display first at the Imperial War Museum in London and then at the Vosper works on Platt’s Eyot (island) on the River Thames near Kingston for many years with a Victoria Cross painted on the side until the Vosper works there closed. It was then restored and displayed (with details of the action but with the painted VC removed) at the Imperial War Museum’s out-station Imperial War Museum Duxford near Cambridge. In July 2019 the boat was moved to Boathouse 4 in the Portsmouth Historic Dockyard, where she is being displayed alongside a full-size, working replica being constructed by volunteers. CMB 4 remains in the ownership of the Imperial War Museum, and is currently on loan to Boathouse 4 until 2024.

Agar’s VC is held by the War Museum in London.The boat was inscribed on the National Register of Historic Vessels in May 1996, becoming part of the National Historic Fleet.

Holland I

Holland Boat No. I was a prototype submarine designed and operated by John Philip Holland.

Light aircraft carrier

A light aircraft carrier, or light fleet carrier, is an aircraft carrier that is smaller than the standard carriers of a navy. The precise definition of the type varies by country; light carriers typically have a complement of aircraft only one-half to two-thirds the size of a full-sized fleet carrier. A light carrier was similar in concept to an escort carrier in most respects, however light carriers were intended for higher speeds to be deployed alongside fleet carriers, while escort carriers usually defended convoys and provided air support during amphibious operations.

List of Victoria Cross recipients of the Royal Navy

The Victoria Cross (VC) is a naval and military decoration awarded for valour "in the face of the enemy" to members of armed forces of some Commonwealth countries and previous British Empire territories. It takes precedence over all other postnominals and medals. It may be awarded to a person of any rank in any service and civilians under military command, and is presented to the recipient by the British monarch during an investiture held at Buckingham Palace. It is the joint highest award for bravery in the United Kingdom with the George Cross, which is the equivalent honour for valour not "in the face of the enemy." The VC has been awarded on 1356 occasions to 1353 individual recipients.

The VC was introduced on 29 January 1856 by Queen Victoria to reward acts of valour during the Crimean War. The traditional explanation of the source of the gunmetal from which the medals are struck is that it derives from Russian cannon captured at the siege of Sevastopol. Recent research has thrown doubt on this story, suggesting a variety of origins. The original Royal Warrant did not contain a specific clause regarding posthumous awards, although official policy was to not award the VC posthumously. Between 1897 and 1901, several notices were issued in the London Gazette regarding soldiers who would have been awarded the VC had they survived. In a partial reversal of policy in 1902, six of the soldiers mentioned were granted the VC, but not "officially" awarded the medal. In 1907, the posthumous policy was completely reversed and medals were sent to the next of kin of the six officers and men. The Victoria Cross warrant was not officially amended to explicitly allow posthumous awards until 1920 but one quarter of all awards for the First World War were posthumous.Within this list, the date of action listed is the year in which the action took place for which the VC was awarded. The most naval Victoria Crosses awarded in a single conflict were for the First World War, followed by the Second World War and then the Crimean War. There have been a total of 117 recipients of the Victoria Cross who served with the Royal Navy. Sixty-eight awards were to ship-based Royal Navy personnel, with 49 given to those who served with other organisations within the British naval service, such as the Royal Naval Brigade and the Royal Marines. The Royal Marines have received 10 Victoria Crosses, the Royal Naval Reserve and Volunteer Reserve being awarded 22 VCs. Richard Bell-Davies of the Royal Naval Air Service also received an award. Note: this list does not include naval awards of the VC to persons serving in navies other than the British, i.e. Lieut. R.H. ("Hammy") Gray, VC, DSC, Royal Canadian Naval Volunteer Reserve.

Mine countermeasures vessel

A mine countermeasures vessel or MCMV is a type of naval ship designed for the location of and destruction of naval mines which combines the role of a minesweeper and minehunter in one hull. The term MCMV is also applied collectively to minehunters and minesweepers.


A minehunter is a naval vessel that seeks, detects, and destroys individual naval mines. Minesweepers, on the other hand, clear mined areas as a whole, without prior detection of mines. A vessel that combines both of these roles is known as a mine countermeasures vessel (MCMV).

Ocean boarding vessel

Ocean boarding vessels (OBVs) were merchant ships taken over by the Royal Navy for the purpose of enforcing wartime blockades by intercepting and boarding foreign vessels.

Repair ship

A repair ship is a naval auxiliary ship designed to provide maintenance support to warships. Repair ships provide similar services to destroyer, submarine and seaplane tenders or depot ships, but may offer a broader range of repair capability including equipment and personnel for repair of more significant machinery failures or battle damage.

Russell Hamilton McBean

Captain Russell Hamilton McBean DSO DSC (3 March 1894 - 30 September 1963) was an officer in the Royal Navy and was one of the men who took part in the Raid on Kronstadt in August 1919.

McBean was born in 1894, the son of Lieutenant-Commander Thomas McBean RNVR, and his wife Jessie Mouat Russell of Hallow Park, Hallow, Worcestershire, and nephew of Colonel Alexander McBean. He joined the Royal Navy and served in both World Wars. He entered Osborne as a cadet in January 1907. He was a sub-lieutenant of the destroyers HMS Racehorse and HMS Lookout during the first part of the First World War During the First World War he was at Jutland and then became the second young officer to volunteer for service in Coastal Motor Boats (May 1916), and was with the force that led the attack on Zeebrugge and Ostend. At the second Ostend Raid during the night of 9/10 May 1918, Lieutenant McBean commanded and helmed CMB No.25, which escorted HMS Vindictive up to the entrance, torpedoed the western and eastern piers and engaged with enemy machine guns at point blank range. McBean was wounded and Acting-Chief Motor Mechanic Keel was killed. Three officers received the Victoria Cross, seven officers received the Distinguished Service Order, three received bars to their DSOs and Russell McBean was one of nine who received the Distinguished Service Cross. Many others also received decorations for gallantry. His citation reads:

Lieut. Russell H. McBean, R.N. In command of a coastal motor boat. He escorted "Vindictive" close up to the entrance at Ostend, covering her with smokescreen and then assisting her with guiding lights. He torpedoed the eastern and western piers, and finally engaged the machine guns there with his own machine guns at pointblank range with apparently good effect. He most skilfully handled his vessel under a. heavy fire until he was wounded.

The Coastal Motor Boats were used again, successfully, for the Raid on Kronstadt on 18 August 1919. Lieutenant McBean commanded and helmed Coastal Motor Boat (CMB) 31 BD, with the commander of the Flotilla aboard, Commander Claude Dobson. McBean was known to be the best helmsman in the flotilla. CMB 31 led the raid through the chain of forts to the entrance to Kronstadt harbour. CMB 31BD, a 55 ft boat, from which Dobson directed the general operations then passed in under heavy machine-gun fire and hit the battleship Andrei Pervozvanny with both torpedoes, subsequently returning through heavy fire to the open sea. The entry in the London Gazette reads:

Lieut. Russell Hamilton McBean, D.S.C., R.N. For distinguished services in command of H.M. Coastal Motor Boat No. 31 in the attack on Kronstadt Harbour on the 18th August, 1919. Under very heavy fire he entered the harbour, torpedoes the Bolshevik battleship "Andrei Pervozanni:, and returned through the fire of the forts and batteries to the open sea

Two safety pins in presentation cases, from torpedoes fired from McBean's CMBs during the Ostend and Kronstadt raids, were donated to the Imperial War Museum by a member of his family.After the Great War, McBean was promoted to Lieutenant-Commander and held command of HMS Vindictive at Chatham, part of the Reserve Fleet. Since 1926 McBean commanded HMS Liffey and HMS Dee, fishery gunboats, and HMS Mantis, a river gunboat, in China, and the sloop HMS Chrysantheum in the Mediterranean (1935-6). From 1939-1945, McBean held a number of appointments in Europe and India. He is cited in 1941 as Commanding Officer of HMS Beehive (Motor Torpedo Patrol base / coastal forces base at Felixstowe), HMS Woolwich (1941), HMS Mosquito at Alexandria, Egypt (1942), Executive Officer of HMS Bull at Massawa, Eritrea (1942–44) and Assistant Director General of Ship Repairs at HMS Braganza, for duty at Calcutta (1945-6). He retired for the last time as Captain in the Royal Navy. After his retirement, he emigrated to live on his estate of Chattan Lodge, near Nyeri in Kenya. He was a keen fisherman and made good use of the many miles of trout stream which flowed through his land. He was a member of the Muthaiga Club.

Submarine tender

A submarine tender is a type of depot ship that supplies and supports submarines.

W. N. T. Beckett

Captain Walter Napier Thomason Beckett, MVO, DSC (1893 – 1941) was a noted Royal Navy officer in both the First World War and the Second World War. He was known to most people as "Joe" Beckett, after a famous British boxer of the same era, as they shared the same surname. Beckett was also a capable amateur boxer, holding the title of Royal Navy Heavyweight boxing champion for some time.

In Fabulous Admirals and some naval fragments published in 1957, Beckett is described as "an Elizabethan character, who was rough, tough, large and strong, and his words smelt of tar, spunyarn, sound commonsense and humour." The author, Commander Geoffrey Lowis RN, included a chapter on Beckett whom he thought a great character. Much of this article is drawn from that book.


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