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Saunders Roe 75ft Prototype Motor Torpedo Boat MTB 539 (P1602)
Design and service history:
The Saunders Roe company, operated a factory on the shores of the Menai Straight between the Isle of Anglesey and Caernarfonshire during WW2. Saunders Roe made their name in the design and manufacture of sea planes, but they also operated a ship yard during the war for the production of MTB and MGB boats, but for the most part their focus in the welsh factory was the modification and conversion of Catalina flying boats flown in from Canada to RAF requirements and standards. The reason the work was done in Wales over Canada was in order to keep up with the constantly changing requirements and specifications coming from command, making it simply more convenient to do this locally.
Due to the looming end of the second world war, the company decided to diversify using their prexisting knowledge and began to develop new motor torpedo boats and fast patrol boats for the royal navy. Due to their experience with airframes, their first post-war project would be MTB 539, which would be the first all Aluminium hulled vessel in Royal navy service.
The vessel was of a conventional rivetted design, possessing a hull of 75ft, with a 72ft waterline. The vessel was equipped with a dual Oerlikon 20mm Mk VIIA machine gun mounting on the aft deck, along with 4 forward firing 18-inch torpedo tubes, plus a pair of flare rocket launchers mounted to the sides of the bridge. The boat was powered by three 1500 hp Packard v-12 petrol engines, each driving a separate shaft and propeller. Due to delays from the direct post war period, the ship would not manifest until the early 50s, meaning although during works, it went by the name MTB 539, by the time it reached Navy service, it had adopted the new modern pennant number of p1602.
The design was innovative for the time, and would go on to serve as the basis for the later Gay class of vessels currently represented in game. Even so the design was not without issues, and due to the nature of its experimental Rotol variable pitch propellers it suffered several issues during its short service. A note worth incident occurring when one of the propellers was thrown, suddenly jerking into a reverse pitch whilst operating at full speed, causing the ship to lurch violently to the side, scattering the crew across the deck, and thoroughly knackering the Rotol Vee drive gearbox, requiring the ship to undergo a complete transmission overhaul.
A quick inspection revealed that in order to fix the damage the vessel would need to undergo a large refit back at a suitable drydock, as both the engine and gearbox could not be repaired locally, and were deemed catastrophically damaged. Because of this P1602 was taken under tow by a tug to suitable facilities at Liverpool, as the use of her own propulsion system could potentially further damage the mechanical fittings. Unfortunately this repair would never occur, as a few miles from Fryars Bay, the vessel ran into a storm, and the loose engine shook off its mountings and punched a hole through the lightweight aluminium hull. The gaping breech caused the vessel to sink more or less immediately, though fortunately without loss of life. The wreck currently sits off the east coast of Anglesey in around 40m of water, laying flat on the sandy bottom with only minimum damage. Interestingly due to the aluminium nature of the hull, the tidal currently have polished the hull to a shiny finish, and due to it not being a war grave because no one was lost in the actual sinking, it can be visited by recreational divers.
Vehicle specifications:
Displacement 50 long tons (51 t) (standard), 65 long tons (66 t) (deep)
Length 75 ft 2 in (22.91 m) (72ft waterline)
Beam 20 ft 1 in (6.12 m)
Draught 4 ft 1 in (1.24 m)
Propulsion 3 × American Packard 4M-2500 V12 Type W14 (1,500 hp)
Speed 42 knots (48.3327 mph; 77.784 km/h)
Complement: 18
Armament 1 x dual Oerlikon 20mm Mk VIIA machine gun mounting.
4 x single 18-inch torpedo tubes.
2 x rocket flare launchers
Additional historical photos:
Early photos of MTB 539 undergoing trials and being launched:
P1602 visiting the port of Liege:
P1602 at HMS Hornet, Gosport:
Photos of P1602 in the Minai Strait:
P1602 outside the Saunders Roe factory at Cowes, Isle of Wight:
Promotional photo of MTB 539 (P1602) between two double-decker buses to give an idea of its size
Detailed photos of the deck of MTB 539:
Photos showing her propellers and engine compartment, Cavitation was a serious issue with the design, and would ultimately lead to her undoing:
Blueprints for the ship:
Sources:
- https://dave-mills.yolasite.com/saunders-roe-mtb.php (history and a copious amount of pictures)
- The Motor Torpedo Boat (MTB) 539 was built on the Menai Strait 75 years ago and even featured in a film | North Wales Chronicle (Additional history and pictures)