ANGUS KONSTAM, Illustrated by TONY BRYAN
BRITISH MOTOR TORPEDO BOAT 1939-45
Although Vosper, Thornycroft and the British Power Boat Company remained the main suppliers of British MTBs throughout the war, several smaller yards produced their own designs. Of these, the J. Samuel White Yard of Cowes in the Isle of Wight and the Camper & Nicholson Yard at Gosport were the most important. Vosper issued sub-contracts to White's Yard for the construction of MTBs 41 to 48, 201 to 212 and 246 to 257 between 1940 and 1944. All were built according to the standard Vosper design, although modified slightly to incorporate existing White construction facilities. These varied in length, the initial batch having 72-foot hulls (MTBs 41 to 48), while the later boats were slightly increased to 72 feet, 10 inches. The designation '72-foot MTB' was given to all of these boats. They were initially powered by three Hall-Scott engines, but were later 'retro-fitted' with the more powerful Stirling Admiral engines. The armament was slightly different from conventional Vosper boats: two 21-inch torpedo tubes, a twin .5-inch Vickers machine gun in a turret amidships, two single .303-inch machine guns and up to four depth charges per side. Later in the war, White-designed boats were provided with additional armament, usually a single or twin Oerlikon in place of the Vickers mount.
J.S. White also produced their own design, a 73-foot boat which the company considered an improvement on the Vosper designs they had been producing for three years. The Admiralty contracted for six 73-foot White boats (MTBs 424 to 429) in June 1943, and these entered service the following year. Soon after entering service in late 1944 they were transferred to the Polish Navy and were re-designated S5 to S10. They were heavily armed, mounting a 6-pounder gun forward, a twin 20mm Oerlikon amidships, two twin .303-inch machine guns and two 18-inch torpedo tubes.
Experience gained during the early part of the war led to a demand for MTBs with the firepower to stand up to German S-Boats (E-Boats) in combat. There was also a growing need for a rugged, longer-hulled MTB capable of operating further from its home base and enduring heavier weather. While MGBs were becoming increasingly powerful, their lack of any torpedo armament meant that they could often miss the opportunity of inflicting damage on the enemy. The answer was the creation of the combined MGB/MTB. Two companies specialised in the production of these craft; Camper & Nicholson and the Fairmile Marine Company.
Under the guidance of Norman Hart, Fairmile produced a range of Motor Launches (MLs), culminating in the versatile 115-foot Fairmile TV boat which combined the characteristics of an MTB and an MGB. Nicknamed 'dog boats', they were designed to combat the E-boat threat in home waters and in the Mediterranean. The prototype entered service in February 1942, by which time the First dual-purpose MGB/MTBs (MGB/MTBs 601 to 616) had already been ordered, designed to carry two 18-inch torpedo tubes. MGB/MTBs 617 to 632 were fitted with 21-inch tubes, while in the following batch (MGB/MTBs 633 to 696) the armament varied, and many were never actually fitted with torpedo tubes. While most of the following batch (MGB/MTBs 697 to 800) were designed to carry four 18-inch torpedo tubes, a handful of the class were fitted with only a pair of 21-inch tubes. Of the final batch of Fairmile TV combined MGB/MTBs (designated 5001 to 5029), only 11 boats were designated as MTBs (MTBs 5001 to 5003, 5005, 5007 to 5010, 5015 and 5020), carrying a powerful deck armament and two 21-inch torpedo tubes. The designation MGB or MTB varied depending on the actual fit of the individual Fairmile boat, causing some degree of confusion in contemporary accounts. Of the earlier boats, while 616 to 640, 649 to 656, 664 to 673 and 675 to 700 were considered primarily MTBs, the remaining numbers in the sequence were designated MGBs. After that, there was no clear designation, although most appear to have been designated as MGBs rather than MTBs or even MGB/MTBs. The first of the combined Fairmile boats entered service in June 1942, and production continued until the end of the war. Standard deck armament consisted either of two 6-pounder guns or one 6-pounder and a 2-pounder Hotchkiss pom-pom in addition to a variety of 20mm Oerlikons, Vickers and Lewis machine guns and depth charges.
In 1940-41 Camper & Nicholson built eight vessels for the Turkish Navy, but these were requisitioned by the Admiralty, who designated them MGB/MTBs 502 to 509. These 117-foot boats displaced 95 tons, and unlike short-hulled MTBs they were round-bilged, their mahogany hulls built around a steel frame. The original armament of MGB/MTBs 502, 503 and 509 consisted of two 21-inch torpedo tubes, two twin .5-inch Vickers machine guns mounted amidships, and a 2-pounder mounted on the quarterdeck. The remaining five were converted into blockade runners before their completion, designed to run 45-ton cargoes of ball bearings and machine tools from Sweden to Britain. Their armament consisted of a twin Oerlikon and two twin .303-inch machine guns. In late 1944 the blockade runners were redesigned as MGRs. A second group of Camper 8c Nicholson MGB/MTBs were built in 1944, designed to carry four 18-inch torpedo tubes, a 6-pounder, a twin Oerlikon and two single Oerlikons, None of these formidable second-batch vessels saw service before the war ended. Although all these Camper & Nicholson craft carried torpedoes as a means of attacking targets of opportunity, they were not true MTBs, despite their official title. Consequently the Royal Navy tended to classify them its MGBs. To a lesser extent the same was true of the Fairmile MGB/MTBs: when the Admiralty wished to refer to a particular vessel, it tended to use one or other of the designations (although MGB was the more common form). A detailed study of these important craft is beyond the scope of this book, except to discuss their relevance to thoroughbred MTBs. Both MGBs and combined boats warrant their own study, so consequently only the basic information about these craft is supplied in this volume.
MTB 365 was a 72-foot 6-inch Vosper boat built under license at the Annapolis Yacht Yard, Maryland. In 1943 it was one of eight Vosper boats (MTBs 363 to 370) that were transferred to Russia. (Stratford Archive)
During the terms of the Lend-Lease arrangement, 38 American boats were acquired by the Admiralty, helping to bridge the gap before British-built boats could enter service and help turn the tide of the coastal war, Of these, 21 saw service in the Royal Navy. In addition, Vosper arranged for the construction of its own design of boats in American yards at a time when British boatyards were still expanding their facilities to cope with increased wartime demand. The Lend-Lease arrangement also meant that boats could be produced in yards that were not subject to frequent bombing attacks by German aircraft, and where the latest design innovations developed in the United States could be examined and in some cases incorporated into British designs. This was not always an easy process. For example, when British Admiralty officials inspected their new Elco boats, they tried to modify them to conform to the standards of contemporary British designs. This involved removing electric fridges, replacing safe electrical galley stoves with volatile paraffin versions (a standard fit on British boats), and replacing bunks with far less stable hammocks!
The Electric Boat Company (Elco) of Bayonne, New Jersey, produced a 70-foot PT (Patrol Torpedo) which entered British service under the Lend-Lease programme in 1940-41. Although this photograph shows MGB 89, it was identical to the MTB counterparts 259 to 268 apart from the lack of two 21-inch torpedo tubes. (Private collection, Museum of Naval Firepower, Gosport)
The power-driven mount of a twin .5-inch Vickers machine gun mounted amidships on a 70-foot Elco boat in the Mediterranean. The bin itself remained stationary, and the gun and mounting ring rotated inside the turret. (Imperial War Museum)
Of the Lend-Lease boats, 26 were supplied by the Electric Boat Company (Elco) of Bayonne, New Jersey, five by Higgins Industries Inc. of New Orleans, Louisiana, and the remainder by the US Navy. American interest in Motor Torpedo Boats (or Patrol Torpedo Boats) dated from the mid-1930s, although the US Navy had some experience of Thornycroft CMBs during and immediately after the First World War. Several prototypes were authorised during 1938-39, and some of these formed part of the initial Lend-Lease package. Of the US Navy craft, all were prototype craft of limited value to the Royal Navy. PT 3 (designated MTB 273) and PT 4 (MTB 274) were 58-foot boats displacing 25 tons each, produced by the Fisher Roatworks of Detroit, Michigan. PT 5 to 8 (designated MTBs 269 to 272) were all 81-foot Higgins boats displacing 34 tons each. PT 7/MTB 271 and PT 8/MTB 272 were constructed from aluminium, while the remaining two boats were of all-wood construction. After some discussion it was decided that the US Navy should retain PT 8, which was redesignated YP 110. Likewise the two smaller boats never entered operational service, so only MTBs 269, 270 and 271 were actually commissioned into the Royal Navy. PT 9 was another prototype: the British Power Boat Company 70-foot MTB that Scott-Paine took to America, and which was subsequently purchased for evaluation by the US Navy. Like the other three prototype vessels, this boat (which became MTB 258) spent the war in Canadian waters, serving as a Canadian Navy air-sea rescue craft.
Ten 70-foot Elco boats (PTs 10 to 19) were also transferred, becoming MTBs 259 to 268. All were completed in November and December 1940, and, like the other US Navy craft, were transferred to the Royal Navy in April 1941. A second batch of ten Elco boats (PTs 49 to 58) became MTBs 307 to 316 in February-March 1942, but unlike their predecessors were 77-foot Elco boats. They never actually saw service its PT boats before their transfer, but they all saw heavy action in Royal Navy service. Ten more 77-foot Elco boats were designated MTBs 317 to 326 at the same time, but never saw service, being diverted into the Soviet Lend-Lease programme before they could serve in the Royal Navy. A year later in April 1943 the US Navy transferred six more 77-foot Elco boats (PTs 88 and 90 to 94 becoming MTBs 419, 420 to 424). The origins of the 70-foot Elco boat can be traced to Hubert Scott-Paine's BPB prototype of 1938. A sleek enclosed pilothouse tapered back to a low cabin, which was surmounted by two machine gun turrets. These Dewandre turrets could be protected by plexiglass (perspex) domes, similar to those used in bomber aircraft. Power was supplied by three Packard VI2 1,200hp engines. The British versions were armed with two 21-inch torpedo tubes, two twin .5-inch Browning machine guns in the Dewandre turrets, two twin .303-inch machine guns and a single 20mm Oerlikon mounted on the stern. Two depth charges could also be carried. The 77-foot boat was an improvement on the earlier design, having improved Packard 1,350hp engines, but these later boats carried a smaller armament (a single twin .5-inch turret, a single 20mm Oerlikon and two 21-inch torpedo tubes).
The American-built 72-foot 6-inch Vosper boat MTB 378, viewed from the stern of a 78-foot Higgins MTB during operations in the Mediterranean. The Higgins was equipped with a Canadian-built 40mm Bofors gun on its quarterdeck. (Imperial War Museum)
The five 78-foot Higgins PT Boats that entered Royal Navy service in April 1943 were originally designed as a US Lend-Lease contribution to the Soviet Union (formerly being designated PTs 88, and 90 to 93). Instead the boats were sent to the Mediterranean, where they became MTBs 419 to 423. Unlike other British MTBs, they were armed with 40mm Bofors guns supplied from Canada, together with twin Oerlikon guns and two 21-inch torpedo tubes.
The basic shape of a Motor Torpedo Boat was dominated by the hard-chine hull. The design had come about through virtually simultaneous research by both the British Power Boat Company and Vosper, and both rivals developed the concept through the use of water test tanks and small-scale models. Although the boats were short, wide-beamed and prone to rolling badly at slow speeds, they came into their own when their commanders pulled down on the throttle. At speed the hulls lifted clear of the water, creating a minimum amount of water resistance, and increasing the speed through the water. In effect the only portion of the boat that remained in the water was the stern.
A group of six 70-foot Vosper boats under construction in the Vosper Yard in Portsmouth in 1942. This photograph shows the way pre-fabricated pieces were used in construction. (Vosper Thornycroft (UK) Ltd)
The hulls themselves (with a few exceptions) used a frame system that in its most basic form was similar to that used in wooden ship construction for centuries. The aim was to create a lightweight hull which was as robust as possible, and which could absorb damage without falling apart. First an oak keel was laid, then stem and stern posts were positioned. The transom (stern) framing and a series of TV-shaped birch or mahogany frames were then put into place, providing the outer shape of the hull and delineating the upper deck. Diagonal supporting knees were also added to improve strength, and elm hogs (beams designed to prevent the hull from warping) were also added. A typical 70-foot Vosper boat had 67 such frames. Four of these were then reinforced, extending from keel to upper deck, forming watertight mahogany bulkheads dividing the crew's quarters, engine room, forepeak and fuel tank portions of the lower hull. The outer edges of the frames were then joined by an oak gunwale running around the hull, then the gaps for major hatch callings and crew areas were created by adding fore-and-aft running stringers between the frames. Extra support was provided in the engine room, where zinc-coated steel engine bearers and deck plates were laid on top of the keel and lower frame structure to distribute the weight of the engines across the whole stern area of the boat. Wooden box-like frames were added to provide stable lower-deck areas above the bilges, then a similar prefabricated box system was used to establish the shape of the upper-deck, While most of these non-supporting boxes were glued and then pinned in place, all major joints were strengthened by birch knees and brackets, then reinforced by heavy bolts. Pre-war experiments with less robust fastenings demonstrated a tendency for them to fracture under stress when the boat rose out of the water; hence the need for secure joints. Extra support was provided to the chine brackets, where the extremities of the hull would take the full force of any pounding of the boat while it was propelled at speed.
Hull strength combined with light weight was an important part of MTB design. The closely spaced frames provided hull strength and gave the craft some chance of surviving multiple hits by machine gun or auto-cannon rounds. (Vosper Thornycroft (UK) Ltd)
Next the lower hull (from keel to waterline) was planked using triple diagonal mahogany planking. This involved laying a series of mahogany planks at a 45° angle to the horizontal. A caulking compound was used (known as 'Seamflex'), then a layer of oiled cotton fabric was stretched over the planking to improve water resistance. Next, a second layer was placed on top, but the diagonals ran the opposite way, creating a sort of herringbone effect. After another cotton coat, a third layer was then fastened on top, running fore and aft. The upper hull (from waterline to deck) was covered with double diagonal mahogany planking, as was the upper deck of the boat. In these cases the lower planking was laid at a 45° angle, but the upper planking was laid fore and aft. The wheelhouse and bridge structure and any hatch combings were then added using plywood and mahogany, the structure supported by 2-inch square columns that ran down to the keel. Finally a steel sheeting was used to provide some protection for the bridge and wheelhouse.
Alter construction, the fitting-out process involved the addition of engines, weaponry; crew quarters, ventilators and all the other features needed to transform a small wooden hull into a functional MTB. Average construction time varied, particularly in Britain where bombing raids, shortages of materials and outdated production methods meant slightly longer building times than in the United States, The necessities of wartime also meant that builders in both countries were prepared to work longer hours to complete a project. MTB 22 was ordered from Vosper in August 1938, laid down two months later, and launched in April 1939. Its fitting-out took ten months, and it was delivered in June 1939. The 72-foot 6-inch Vosper MTB 81 was laid down in March 1942, launched five months later and was fitted out by January 1943. By contrast the 77-foot Elco boat MTB 314 was laid down in July 1941 and launched just over two months later. By February 1942 it was in service.