- Denis, A.L.E., Commander, RNR (Rtd)
- Ship design and development, Ship histories and stories, History - WW1, WWI operations, History - Between the wars
- None noted.
- RAN Ships
- None noted.
- March 1980 edition of the Naval Historical Review (all rights reserved)
In the early summer of 1915 three young Naval Officers from the Harwich Destroyer Force (Lieutenants Hampden, Bremner and Anson) conceived the idea of a small fast motor boat, capable of firing a ‘Whitehead’ torpedo, that could be carried in the davits of a light cruiser; such boat to be taken as near as possible to the enemy coast and then launched so that it could carry on under its own power through the enemy minefields to attack their bases.
The Commodore of the Force authorised these three officers to approach the well known shipbuilding firm of Thornycrofts with their plan. They explained that they wanted a boat that would discharge its torpedo over the stern without having to turn for the attack.
Experiments were accordingly carried out by Thornycrofts and the result was a motor boat that could work up to a speed of thirty-four knots in a matter of minutes and discharge its eighteen inch torpedo over the stern whilst steering directly for its objective. On the success of this experiment the British Admiralty ordered twelve boats to be built as soon as possible.
A base was established on the South Eastern Railway Company’s pier at Queenborough, Kent, and the first three boats were ready for service in April 1916.
In order to preserve the utmost secrecy during the training period the boats were run only at night.
The crew of each boat consisted of two officers and a mechanic (ERA) and in order that they could be thoroughly conversant with the new type of engine they spent several weeks at the Basingstoke works to see the engines and boats built and the trials run.
Under Lieutenant Hampden’s direction the newly joined crews were able to perform the most complicated operations at night without difficulty.
Lieutenant Erskine Childers, RNVR, joined the flotilla as Navigator, in view of his exceptional knowledge of the German coast. (He was author of the book Riddle of the Sands).
Before proceeding further with this narrative I must give some details of the construction of a CMB. It was forty feet long by eight feet beam with a draught of about two feet. The hull was of double skin of mahogany and the frames and knees were of American Elm; stringers were of Oregon Pine. The hull was resilient so that it could withstand the slamming in a choppy sea. When travelling at full speed the middle part of the hull was lifted clear of the water to reduce resistance. This was achieved by means of a ‘step’. A spiral propeller was fitted for jumping booms. The torpedo sight, which consisted of a metal triangle somewhat resembling a sextant in a horizontal plane, was fitted at the forepart of the cockpit.
A special design of lifting gear was fitted to the forward engine bearer and to the torpedo trough aft, for slinging under davits.
The boat was propelled by a twelve-cylinder engine of the aviation type but modified for sea work and this developed 250 hp at 1,600 revolutions, giving a maximum speed of thirty-four knots.
A fuel tank with a capacity of 100 gallons of aviation spirit was installed in the cockpit amidships and beneath the Commanding Officer’s seat. A ‘Whitehead’ torpedo was carried in a cradle in the after centreline trough, and was launched by a bell-head ram which was impelled by a cordite charge exploded in a steel bottle. 1,500 grains of No. 37 cordite were used for this charge giving a pressure in the explosion bottle of four tons, but reduced to 1,000 lbs. pressure on reaching the ram. The torpedo firing lever was conveniently to the right hand of the Commanding Officer. Lewis guns on portable swivel mountings were also installed in the cockpit for use against attack by enemy aircraft.
The eighteen-inch torpedo weighed three quarters of a ton and when being launched its initial speed was thirteen knots. In place of a torpedo, depth charges could, if necessary, be launched from the after trough.
Another fitting to the CMB was the Stoke’s mortar, for bombardment purposes. Chlor-sulphonic acid was employed in the exhaust when the boats were required to lay a smokescreen to afford cover to larger vessels, such as the blockships for Zeebrugge Harbour.
The forty foot CMBs were so successful in their operations that larger and faster boats were built to carry two torpedoes each. These were the fifty-five footers which attained a speed of forty-five knots and they were propelled by two engines of 375 hp each. Over one hundred of these boats were built and they were followed up by seventy-footers which were employed for minelaying.
Some tens of thousands of miles were covered in patrols which had been carried out between the minefields off the entrances to Zeebrugge and Ostend and they had many opportunities of action with the German patrol boats (PMBs) and destroyers.
The officers of Coastal Motor Boats wore kit similar to that of the Air Force in those days and the leather helmet and goggles were the only means of protection against the ice-cold and blinding spray that swept continually across the cockpit.
After the successful training at Queenborough a larger base was established at Dover and the flotilla then became part of the famous Dover Patrol.
At the end of 1916, when twelve boats were available, four of them were sent over to an advanced base at Dunkirk where they were kept in readiness for a suitable opportunity of making an attack on the enemy. There was no prepared base for the boats so they were berthed alongside a large steel barge on which the officers and ratings lived through the winter months. A bathing box served as a charthouse and office for Lieut. Childers. Day and night patrols were carried out constantly between the minefields along the coast between Zeebrugge and Ostend, and during these patrols the boats were frequently fired at by the shore batteries and unfortunately more than one was lost, having apparently received a direct hit at short range.
The CMB’s worst enemy was the seaplane which, with its superior speed, would swoop down on the flotilla and spray the open cockpit with machine-gun fire. These sudden attacks resulted in many casualties among the boats’ crews and on one occasion the mechanic brought his boat back single-handed, his two officers lying dead in the cockpit. On another occasion the patrol encountered five German destroyers returning from their dash through the Dover Straits. They attacked and succeeded in torpedoing one of them and causing another to run aground. One of the CMBs ran in close when launching her attack and the blast from the enemy’s four inch gun actually blew the Commanding Officer’s cap off his head without damage to the boat or injury to himself.
For North Sea work another base was established at Osea Island, which is situated up the river Blackwater in Essex. From this base some of the boats joined the Harwich Light Cruiser Force and it was a familiar sight to the residents of Harwich and Felixstowe when the cruisers put to sea with a couple of forty-footers hanging from their cutter davits.
The quickness with which these boats could work up to maximum speed in favourable weather conditions, which was more than the majority of destroyers could do, enabled them to get away successfully after an attack, but the aeroplane or seaplane having greater speed proved a formidable adversary when met with in daylight. CMBs were at their best during night operations.
In the summer of 1917 six of the CMBs were attacked by aircraft in the North Sea and two were lost; the other four managed to make their way into Holland but not until they had accounted for several of the aircraft which had attacked them in great numbers and used up all the ammunition for their machine guns.
The four boats were interned in Holland until the end of the war.
There have been many cases of pluck and heroism in the numerous fights which the CMBs have had and in this particular North Sea action, after the boats had all been riddled and most of the officers hit, Lieutenant Lewis – who was himself wounded – succeeded in keeping another officer afloat on a large mattress fender for over two hours, thereby saving his life.
It is not generally known what a leading part the CMBs played in the blocking actions at Zeebrugge and Ostend.
In the Zeebrugge action the Coastal Motor Boats were responsible for making the smoke screen, which they effected by running ahead of other vessels at high speed and emitting smoke clouds from their exhaust by a special contrivance; they also had to mark certain positions with flares to indicate the right turning points for the blocking ships.
The CMBs entered the harbour in the early stages of the operation to torpedo a vessel alongside the mole while others were fitted with Stokes trench mortars to throw bombs over the mole on to the aeroplane sheds.
In the second action, at Ostend, when the Vindictive was placed in position, two of the CMBs were specially told off to torpedo the ends of the piers to put the guns on them out of action. While others made the smoke screen, one of them went in ahead of the Vindictive burning flares to indicate the exact position of the entrance.
Admiral Keyes, in his official report of the blocking action, referred to the highly efficient handling of his flotilla by Lieutenant Welman, the officer in charge of them and the Dover Base.
The high speed and small size of these boats may, to some extent, be a source of safety, but there is no question that the duties they have undertaken have made this service one of the most risky in the Royal Navy. It is a remarkable fact that with one exception, all the CMBs which took part in the blocking action succeeded in getting away; although they were in many cases very battered and warworn with numerous officers and ratings wounded. Perhaps I should mention that I joined the CMB Service at Dover and served in the boats at Dunkirk, Osea and the Caspian Sea.
Minelaying hardly sounds the work which would be expected of these little craft, but they have nevertheless been utilised very effectively to lay mines where the ordinary mine-laying vessels could not go, their shallow draught enabling them to take short cuts over the enemy minefields safely and their high speed to approach enemy waters unexpectedly.
CMBs had their amusing side and what is looked upon as one of the best jokes occurred when one of the Portsmouth boats patrolling the English Channel was mistaken by a ‘P’ boat for a submarine on the surface. Having missed in her attempt to ram, the ‘P’ boat swung her stern round and fired her depth-charge thrower, which performed splendidly, but it was not quite close enough to finish off the CMB The latter was not seriously damaged and returned at full speed to the base to await the return of the ‘P’ boat. In the morning she duly returned and reported that she had either sunk a submarine or a CMB
After the Armistice the Admiralty decided to send out expeditions to north and south Russia to assist the White Armies against the Bolsheviks. I will first of all tell you about the southern expedition to the Caspian Sea as I was a member of the party and eventually took command of one of the CMBs.
With the opening of the Dardanelles twelve Coastal Motor Boats were sent out by the cruiser Diamond and the Admiralty transport War Stag to Batoum. From Batoum they were put on rail and taken overland to Baku (on the Western shore of the Caspian Sea) to augment the fleet which had been improvised by fitting out some of the Russian merchant vessels as gunboats. Commander E. Robinson, VC, RN, was in command of this expedition and after an adventurous six hundred-mile railway journey from Batoum, during which we had to work the train ourselves, we arrived at Baku. At the time of the journey it was difficult to discover which of the Russians were friends and which enemies, but all were equally determined to take possession of the gear and stores belonging to the boats.
Two of the merchant vessels in the Caspian Sea were fitted out as carriers with the boats on their foredeck and they were kept at sea in readiness for an attack on the Bolshevik Fleet.
The first stroke of luck came our way when four destroyers surrendered after witnessing the effect of the explosion of a depth-charge in their vicinity. The Russians were really afraid of the CMBs and spoke of them as ‘Eestrabeety’ meaning ‘Devil Boats’.
Towards the end of April, when the ice broke up in the northern Caspian, the remainder of the Bolshevik fleet ventured out of the River Volga and established a base at Fort Alexandrovsk on the eastern shore of the Caspian Sea. All through the winter months the ‘Bolshie’ fleet had been bottled up in the river port of Astrakhan.
On the 21st of May 1919, when Commodore Norris’s gunboats and Commander Robinson’s CMB carriers were cruising south of Alexandrovsk, Colonel Bowhill (now Air Chief Marshal of the RAF) sent up one of his ‘Short’ seaplanes on a reconnaissance flight. The plane eventually returned with the information that a fleet of destroyers, two submarines and several barges and small armed craft were at anchor in the harbour. This was good news for Eric Robinson and Ginger Bowhill so they combined in their efforts to raid the port. The six CMBs were launched and sent into the harbour and two of them each torpedoed and sank a destroyer while the latter were still at anchor. One CMB was put out of action and all hands killed by gunfire during an engine breakdown. The remaining boats attacked small craft and caused them to surrender.
Some of the destroyers got clear of the harbour and were met by Norris’s fleet, which was lying-in-wait on the south side of the promontory.
The Emil Nobel, which was armed with six inch guns, was in danger of being sunk by a Bolshevik submarine when one of the CMBs successfully attacked the latter with depth-charges and so put a quick end to her commission.
Although we suffered many casualties, we regarded the raid as being a very successful one and commemorate it to this day by holding a Caspian Naval Force Dinner at the Trocadero in London, on the 21st of May each year. I will mention that I arrived home last leave on the day of the dinner and the boat-train from Plymouth got me in to London in time to meet some of the old brigade for the first time in twenty years. It may interest you to know that one senior member of the party is now an Admiral and Commander-in-Chief, South Atlantic, at Freetown. Having told you my experiences with the CMBs in the Caspian Sea I will now switch over to events in north Russia.
The First Cruiser Squadron and destroyers under the command of Sir Walter Cowan were based on Biorko Sound in the Baltic Sea. One of the original CMBs with Lieut. A. W. Agar, VC, DSO, in command was attached to this squadron, but operated alone.
One morning in the early part of 1919 Agar set out at crack of dawn in his CMB No. 4 and succeeded in breaking through a screen of destroyers and torpedoing the Bolshevik cruiser Oleg. This cruiser was acting as guard ship to the naval base at Kronstadt.
After Agar’s success in sinking the Oleg, Commander Dobson arrived with his flotilla of CMBs and joined up with the First Cruiser Squadron.
The shallow water and minefields made navigation difficult for the British cruisers and destroyers and it was impossible for them to attack Kronstadt, but it was an easy matter for the CMBs to run in and attack, more so since the guard ship was sunk.
At 10 o’clock on the night of the 17th of August 1919, eight boats of the fifty-five-footer class cast off from the new cruiser Vindictive and headed for Kronstadt harbour. Weather conditions were ideal – a dark night and a flat calm. The aerial attack had been planned to coincide with the CMB attack. The flotilla of eight boats ran the gauntlet of gunfire from the forts and succeeded in getting into the harbour. One CMB torpedoed the submarine-depot ship Pamiat Azov and then turned her attention to other ships in the harbour. Lieutenant Dayrell-Reed, RNR, in command of CMB No. 88, was shot through the head and Lieut. Steele took over command and torpedoed the two battle cruisers Andrei Pervqzanni and Petropavlovsk. For this gallant deed Gordon Steele was awarded the Victoria Cross. I will mention that just prior to the outbreak of the present war he was in command of the cadet ship Worcester at the port of London, but has been called up once again for active service.
There were many exciting incidents but I have no time to give a full account of the raid; however, I must tell you how an aeroplane helped the CMBs to get past the forts when they retired from their raid on Kronstadt. The forts were fully prepared for them with searchlight beams on the water and the boats’ crew feared there was little chance of their getting through, but one of the airmen who appreciated the position flew down into the beam of light from the particular fort they were passing and then climbed rapidly. Those in charge of the searchlight could not resist following him with their beam and the boats passed through invisible to the gunners. The crews of these boats are convinced that they owe their lives to this airman.