Motor Torpedo Boat

Motor Torpedo Boat

Motor Torpedo Boat

The British motor torpedo boats (English: Motor Torpedo Boat) were known by the acronym MTB.
There were mostly wooden speedboat of around 20 to 24 meters in length and 40 to 50 tons displacement, with a few exceptions that were powered by gasoline engine. Designed primarily as speedboats, they could in calm part of speeds of more than 40 knots (kn) (≈74 km / h). The armament consisted of up to four torpedo, machine gun (MG) ​​and partially automatic cannon.

The first motor torpedo boat putBritainin the First World War under the name CMB, was the concept of inter-war period. During the Second World War, then over 400 MTBs came in different versions around the British Isles and theMediterraneanwere used. They were also behind the development of the American so-called PT-boats, whose production number was even higher during the war. After the war, the number of MTB was drastically reduced in the 1950s and built only about 35 new boats. In the late 1960s, the Royal Navy then triggered on the last MTB Flotilla.

Description

The Royal Navy developed fast boats in World War under the name Coastal Motor Boat (English for coastal motor boat) abbreviated CMB managed this but after the war again. Only with the resumption of the speedboat concept from 1932 for boats with torpedoes and only weak secondary armament was the designation as Motor Torpedo Boats or MTB introduced and those of the Motor Gun Boats (English for motor gunboats) or MGB armament of artillery, but without torpedoes, distinction. MTB also identify as such As the Canadian, Norwegian and U.S. Navy comparable boats.
Within this type classes the division was mixed, also boats changed by upgrading the assignment and the “Fairmile boats” (see below) resulted in a mixture that has been assigned almost randomly. As it before the Second World War the small boats, especially zudachte a task in securing the coasts, all the boats were an identifier with the letter P on Patrol.

The bike did not receive names, but sequential numbers, mainly from P1 – P539. Here, the numbers were but one manufacturer for each assigned a configured number of boats that were processed partly in parallel, but that have whole number sequences were never used. Therefore, the numbering is no chronology.

The most widespread is the classification according to length and manufacturer of boats. To some version information came in the form of 72 foot Vosper Type I or 72 Foot British Power Boat Mark V. Length specified in feet (ft) is often rounded. The exact equipment with engines and weapons then hung from the time of manufacturing. Overall, this results in a variety of versions.

The postwar classes had to be designed from the start as a multi-purpose vehicles and designed to be converted as MGB, as well as fast minelayer or U-hunters and used, so that the designation as MTB no longer clearly possible.

History

Development

Manufacturer

The development of British speedboats was mainly supported by three manufacturers, but many other shipyards inCanadaand theUnited States, acted as a supplier of parts orders or made ​​for these licenses.

During World War I was the only producer John I. Thornycroft & Company Limited. Although the shipyard production in the inter-war period continued for export, they missed the boat developing new concepts and was involved in World War II only to a small extent. The company Thornycroft built during World War CMB for the Royal Navy at 40 and 55 feet (ft), and later with MTB 72 and75 ft in length.

The British Power Boat Company (BPB), established the first impetus to the revitalization of the speedboat designs before the Second World War, but then fell apparently back due to personal differences between decision-makers in the shipyard and the Admiralty in importance as MTB producer. However, the yard was even more involved in the production of MGB. BPB built before the war boats of60 ft and during the war, only those with72 ft length.

Vosper & Company was the last of the three companies in the race for orders, but was the main supplier of motor torpedo boats and finally delivered over two-thirds of all boats. After World War II Vosper remained the only supplier. In 1966, the merger with Thornycroft, but was pursued at a time when the MTB concept any more. Vosper built boats with 60, 70, 72 and73 ft in length.

Another producer was the Fairmile Marine Company, which first appeared in Schnellbootbau active as a subcontractor by Vosper. Fairmile produced independently coast guard boats especially, then brought out as my own design called “Fairmile ‘D’” boats, which have been classified mainly as MGB. Some boats also produced similar Camper & Nicholson. Moreover, in small quantities, came to own boats designed by JS White and prototypes of other yards are used. The boats (PT boats), which were donated by the U.S. Navy, were produced by the manufacturers Electric Launch Company (Elco) and Higgins Industries.

CMB

The development of British MTB goes back to 1915, when officers drew up a plan to move them through fast motorboats shallow draft German minefields to attack the German coastal shipping. Assuming the specified requirements of the Admiralty to the effect that the boats have a 18 – inch torpedo wear (≈ 45.72 cm), while over 30 knots should reach (kn).
As was planned to bring the boats in the davit s of light cruisers to its location, it should not weigh more than 4.5 tons and not more than40 ft (12.2 m ≈).

Also known for building luxury motor yachts Thornycroft shipyard was awarded first six boats. From 1916, the shipyard during World War II total of 66 CMB, where in 1917 an enhanced version of55 ft(≈16.76 m) in length with two torpedoes was used. At that time, the plan had the boats carry a dinghy of cruisers already proved impractical.

After the war, initially single larger boats procured for experimental purposes, then followed the British Admiralty, the concept further and sold the remaining boats to other countries or put them out of service.

The manufacturer Thornycroft continued producing for foreign navies boats based on the55 ftmodel, so that at the beginning of World War II finished several CMB were available or were in production and could be taken over by the Royal Navy. These turned out but quickly become obsolete and the production ran in favor of more modern types to 1942.

MTB

Only in 1932 the British Admiralty took the speedboat idea again in 1935 and issued an order for a so-called first flotilla of six boats to the British Power Boat Company, now under the name of MTB. At the outbreak of World War II, the British Navy had three flotillas, each with six of these boats.

These first boats were two 18 inch torpedoes, and two 0.303 inch (7.7 mm) machine guns, armed from the First World War.
By the end of World War II about 450 boats were built, who came on all theaters of war used. However, this figure also 12 experimental boats are included that have never in combat and some boats the other uses were fed, as the eight underpowered75 ft (≈22.86 m) boats of Thornycroft, as after a short time target tugs were used. About 60 boats from the British gave to other navies. In exchange, the Royal Navy’s 21 boats fromU.S. production in service that was provided as part of the Lend-Lease program from theUnited States.

After wrangling the chief designer of BPB with the Admiralty rose Vosper on the main supplier of fast patrol boats for the Royal Navy. The most common type was finally the72 ft(≈22 m) Vosper boat. The designer of BPB Hubert Scott-Payne leftEnglandand participated in the development of the U.S. PT boats especially in collaboration with Elco.

MGB / MTB

Especially facing up to the threat posed by German E-boats, they developed a boat type that eluded the usual classification and listed in the inventories is therefore inconsistent. These boats have a special position among the MTB and are therefore shown separately at this point, with its technical details.

From 1942, under the leadership of the Fairmile Marine Company more than 200 so-called Fairmile D boats with 115 ft produced (≈ 35 m) long and about 100 tons displacement, which represented an evolution of the of Fairmile built in large numbers coast guard boats (motor launch). You should meet the requirements of MGB and MTB simultaneously. Two thirds of the boats were expected to MGB, some boats were also assigned to do any more of the classes and run as MGB / MTB. In addition, boats are listed twice because they reclassified according conversions. Unofficially, they were called “Dog Boats”. The boats carried identifiers from P600 to P800 and some P5000er numbers.

The boats were round bilge boats and relatively insensitive to rough seas. The drive was carried out with four Packard engines 4,800 hp, which acted on four shafts. In the heavier MTB equipment so the boats reached only about 27 knots and had a range of about 500 nm kn at full speed, and up to 2000 nm at 11. Some of the boats put the RAF because of the great range and Indifference to weather a very occasionally, as long distance lifeboats for downed pilots.

In 1940 Camper & Nicholson was commissioned by the Turkish Navy 8 boats of 117 ft length and 95 tons displacement, which were adopted at the completion of the Royal Navy. At this time though, no need was defined by such boats, but they corresponded largely to what was developed two years later by Fairmile. Five of these boats were converted to blockade runners with 45 tons load capacity that brought especially ball bearings and machine tools from Sweden. 1944, then an order for a further 10 boats, but before the end of the war no longer were used.
These boats differed significantly in their design from the smaller MTB and MGB. They were carried out not only as Rundspantboote but also in a composite with steel frames. They were driven by three Packard engines Paxman or the speeds of 28 or 31 knots allowed.

The MGB / MTB were armed and in the use of different MTB than two 21 inches (≈53.3 cm) and more rarely with four 18 inch torpedo tubes, and various machine guns and cannons. The artillery armament consisted mostly of two 6-pounder guns (5.7 cm) or a 6-pounder and a 2-pounder (4 cm), Pom-Pom, and additional 20-mm Oerlikon machine gun s and several machine guns. Also were included up to eight water bomb n. To operate the weapons was the crew up to 30 men.

Postwar boats

After the war, the Royal Navy, most speedboats quickly decommissioned. Only the end of the war has come into use 73 ftVosper Type II remained active.
The British Navy experimented until the mid-1960s with other drive concepts such as delta-s diesel engine or gas turbine gave the MTB concept but eventually.
There are given two larger series of new boats in order.
The last petrol-driven MTB represented the 12 boats of gay class that ran from 1952 to 1954 from the stack. The boats stayed until mid-1960 in service, then ordered them to be part of the reserve and sold them mostly to the early 1970s.
The 18 boats of the Dark class constituted the last real class of MTB use boats. They ran from 1954 to 1958 from the pile and were the only class of the Royal Navy speedboat driving a diesel. Her two exceptional Napier Deltic engines kn awarded them a top speed of 47. There were also several small series and individual boats.
With the two boats of the Brave-class (also in Germany as Vosper-class tested) 1958 the last boats were procured with torpedo armament. Your driving was done with two gas turbines and a diesel engine for maneuvering at low speeds. These boats were but no longer than MTB, but given the classification as Fast Patrol Boats and served only as a test bed. Lastly, the “HMS Brave Borderers” sold for use as a target ship 1982nd.

Shift

The CMB of World War I took a variety of tasks, such as education or the laying of artificial fogs and also in some of mine, but remained relatively unsuccessful in terms of sinkings. Only after the war in the conflict in the wake of the Russian Revolution they did with the sinking of the Russian cruiser Oleg, the battleship’sPetropavlovsk and a depot ship, as well as the severe damage to the old battleship Andrei Perwozwanni in attacks on theport ofKronstadt attention to themselves. These successes bestowed Thornycroft foreign customers in theUK, however, the boats were decommissioned.

At the beginning of World War II, the Royal Navy had then 18 new boats by BPB, but in contrast to the German and Italian speedboats MAS no concept of operations.
The MTB were grouped into so-called flotilla of six to eight boats. One of the flotilla was in Hong Kong and was scuttled after its capture by the Japanese, so that in theFar East, the MTB have recorded no more bets.

The first deployments of MTB on the European theater in 1940 ran lossy and inefficient. Boats attacked from a distance at full speed, what the enemy warned early on by the loud engine noise, the boats also fired their torpedoes at long range and often missed the mark.

From these experiences, they developed a use doctrine, which had the stalking and infiltration into enemy convoys to the destination. These are the boats ideally placed in the dark in the way of a convoy or attempted from behind with a low drive to penetrate the organization, since the observation of backward experience, was the worst. Only shortly before the torpedo shot should be taken at high speed stage the attack position and then expired with maximum speed. The optimal attack position was obliquely ahead of the targeted vehicle.
The behavior after the torpedo was shot individually different. Many boatmen were hiding in the running behind a veil artificial fog, while others preferred the free view to make any further torpedo attacks possible, or at the expiration donate by continued bombardment with automatic weapons confusion.

It turned out that the division into MTB and MGB who attack with their artillery armament safety vehicles and cover the retreat of mountain bike should not often correspond to real operating conditions. MTB also had to repeatedly deliver with enemy units intense fire. Particularly in the channel use were frequent confrontations with security forces and hostile German speedboats on shortest distance, therefore took the secondary armament of the MTB in the course of the war all the time. Some boatmen equipped their boats on their own initiative from even with small arms fire and hand grenades.

The bike was in contrast to the capital ship that often had long wait times, almost constantly in use and had frequent enemy contacts. These were but mostly unspectacular, though lossy night operations against merchant shipping or to prevent German speedboats.
In the public perception of the stakes of MTB occurred in connection with the breakthrough German capital ships through the English Channel, in the attack on the docks ofSaint-Nazaire and in safeguarding the Allied invasion fleet.

A total of 83 MTB lost during the war. From the causes of the losses, the main threats to the speedboats are identified. The fight with surface units was 18 cases (about one fifth) the most common cause, followed by 14 air raids and 10 hits mine. It is noteworthy that as many as 9 (a tenth) of the losses caused by collisions with other, mostly their own vessels. An indication of the demands and dangers was in close association ride. Many boats (+ several Canadian) were lost in a fire at theportofOstend.

Crew

The manning of boats also depended on the number of weapons carried.
The small CMB of World War were served only 2 to 3 man, the larger, as they were similarly used in the Second World War had 5 man crew.
The MTB were driven 10 to 15 men. A boat was usually led by a First Lieutenant.

The crew stood in the bow two lounges with some fold-out beds is available. These were not designed for continuous occupancy. Although there was kerosene stove with cooking facilities, however. Complete no sanitation and little storage space for personal gear or supplies, under war conditions, crews still lived for weeks on end on the boats

The high exposure to noise and vibration of these boats and their sensitivity to sea state were described as a significant impediment to the work of crews, especially on the mental constitution. Direct consequence was Fehleinscheidungen and use of time.

Technik

Core

The boats were often disparagingly referred to as plywood boats. In fact, there were only a few of the bridge superstructure and interior finishing of plywood. The hull was constructed as a dense framework of high-grade solid wood on which the cladding was carried out in several layers.
This made it easy for the boats, and resistant. A welcome side effect was certainly the saving precious metal. However lacked up to steel apron to the helm any armor and the boats fell slightly due to the gasoline fuel by bombarding them on fire.

The chine hulls lifted at highway level of the water and fell so in slides over the water resistance significantly.
So we could be reaching speeds of around 50 knots with individual types.
However, this was only in calm seas. In waves they had recovery time after strong.

The Vosper and BPB independently developed boats were relatively flat and wide, and with a few exceptions in the inner structure similar to the structure varied according to the size of the boats and manufacturer details.

Here is an example of a 70-foot Vosper boat:

The Vosper70 ftboats had an oak keel placed on the 67 frames of birch or mahogany and were associated with aspiration. The bend region was a peripheral Eichenholzverstäkung. Four reinforced ribs pulled a watertight bulkhead s plywood boats and divided them into five sections. The front two were used as crew quarters, then followed the departments for the main fuel tank, the engine compartment in the rear for more and more tanks and the rudder system. Only between the two front compartments below deck there was a connection. The underwater hull is provided with three layers of mahogany Karweel, wherein the two inner layers ran diagonally offset by 90°. Between the layers of wood impregnated cotton fabric was glued. Above the waterline fell off one of the bias ply. The engines were resting on galvanized steel girders, which distributed the weight over a larger number of frames.

The postwar boats deviated so far from the construction method, known as the Gay-class were essential parts of plywood, the Dark-class and some of the experimental boats built with aluminum frames, individual boats and all-alloy.

Drive

When at the beginning of the Second World War, production was ramped up, put her in theUKonly Thornycroft engines suitable for use on boats. However, with only 650 hp, so that larger boats including four engines had to be installed, each of which drives a shaft two.

The competitors had to look for alternatives, there were initially engines from Napier and Isotta-Fraschini used. The British engines were only available in small numbers and are relatively inefficient. While on a boat came Rolls-Royce Merlin engines to test, by the huge demand of the RAF but this engine was designed for use on MTB no longer available. The excellent Italian engines were after Italyentered the war in 1940, of course, no longer available, so soon engines were procured from U.S.production. First Admiral of Sterling engines and Hall-Scott, the latter with only 650 hp (later also 900 hp), but did not provide at the relatively high weight is not the power needed to achieve the desired performance of knots by 40.
First of BPB were then adapted for maritime use aircraft engine US-based Packard used. These provided initially at 1 200 hp successor models up to 1500 hp. These engines were big and heavy and required an increase of the boats, the more power the engine was like this out, however, and especially Packard could supply the necessary quantities. These engines put so later in the increasingly standard engine also represents other yards.

The 4M-2500-Packard engines were twelve – cylinder V-engine with 60° bank angle and had 40.8 liters of displacement, centrifugal compressor with intercooler, four valves per cylinder and twin ignition. The engines had a huge consumption of aviation fuel with 100 octane, so that the boats, despite the often over 10,000 liters of tank capacity even at 20 knots and a range of only around 400 nm (≈740 km) had. (By comparison, the German speedboats that time were about 700 nm at 30 knots (≈ 1300 km) go far.)

In the standard model with three engines and three waves of average motor and the additional slow speed engine was behind the two outer engines installed rear-facing position and deflected through a transmission to the central screw shaft. The slow speed motor gave the boats a speed of 6 to 8 knots. This was often a Ford V8 engine. The change of engines, from the ambush position when out of the slow speed motor was engaged in and the central main engine to the transmission and was a not unproblematic process.

The steering was over on the number of waves of two or three spade rudder hanging in the power of the propeller.

In the two post-war classes on the one hand the proven Packard engines were used, on the other hand, in the Dark class, two Napier Deltic diesel engines, each with en 2500 hp. This gave the boats kn speeds up to 47th.

Arming

The main weapon of MTB was torpedoes. Given the small size of the boats were equipped from the CMB and first MTB BPB with light 18 inch torpedoes Mark VIII, which were originally intended for dropping by aircraft. Later 18 inch torpedoes were still partly due to shortages in the supply of torpedoes and 21 inches for use on MTB, which resulted from conversion of MGB. In the MGB was true to the cannon armament reduced, it nevertheless remained less room for the payload of torpedoes. Some Fair Miles received 18 inch torpedo tubes in order to provide them with four of them can.
The vast majority of MTB led but with the much more efficient 21 inch torpedoes. Besides the mentioned Fairmile “D” MGB / MTB, all British MTB World War II had invited two torpedoes.

For the CMB, the 18 inch torpedoes were centered behind the helm in the direction of travel on rails in a tray from which they were selected by a cordite propellant charge repelled by a push rod with the tail first to the back and started by a rip cord after falling overboard. This meant that the boats when launched immediately at full speed had sharp move out of the path of the torpedoes herliefen now behind them. The bike, however, had torpedo tubes mounted sideways on the deck next to or shortly after the bridge assemblies. This threw some of the torpedoes from parallel to the direction of travel, or at angles of 7.5° -10° to the direction of travel. Especially early Vosper-boats had to ensure indentations in the hull before the torpedo tubes to get a trouble free of torpedoes. The torpedo tubes threw torpedoes using a pyrotechnic charge.
The secondary armament consisted of boats and 1942 only from machine gun s (MG). These were also in the Second World War, to remnants from the First World War. First came two to four 0.303 inch (7.7 mm) Lewis MG Mark I used that was replaced in 1940 by 0.303 inch Vickers machine gun. That later came 0.5 inch (12.7 mm) Vickers machine gun. For the latter, as only sheltered stalls simple weapons turrets were installed, which consisted of an open-topped steel cylinder with an attached swivel head, which turned around the shooter with muscle power with the MG. This also equipped with double guns towers were usually amidships behind the helm. Other common locations for gun were on the foredeck and in the very back of the boat and were partly surrounded by textile splinterguard mattresses. Additional MG came often in stands on the torpedo tubes or laterally attached to the bridge stands used.
From 1942 it was for the Navy’s20 mm Oerlikon anti-aircraft guns available. The MOUNTINGS the weapon has been changed again and again, about to improve the Höhenrichtbarkeit. From 1943 the20 mm Oerlikon gun mount with a double shield of12 mm thickness in use. In this form, the weapon was the usual features on MTB. The high theoretical rate of fire of 470 rounds per minute was, however, due to the low supply of ammunition carried only 480 rounds per barrel (in 60-shot magazines) are limited in their effectiveness.

Depending on availability, some boats Vosper was a retrofit with single 2-pounder (4 cm) pom-poms Mark VIII, were also a number of MGB, which were equipped with this weapon, converted during the war to MTB. Some of the acquired from the U.S. Navy boats, and under license in Canada had 1944, 40-mm Bofors gun on board e Shortly before the end of the war came a few boats with 6-pounder (5.7 cm) guns in motorized towers on the foredeck for use.

The boats usually led by two, sometimes four400 lb(≈181 kg) bombs in water dropping frames, and one or two 2 inch rockets launchers. On the back cover edge a chemical mist generator (CSA Apparatus) was installed.

After the war, armed with four torpedoes and also predominantly single Boforsgeschütze40 mmand20 mmOerlikon twin guns were used.

Communication and sensor

The boats were equipped devices with touch and voice.

From 1940, the first boats were simple radar device type 286PU, a simplified type 286 (ex Mk.I ASV). First, the devices had a fixed antenna with a search angle of 140 degrees to the front, and later also a rotatable antenna. The observation range was – partly because of the low overall height – low (1.25 to 4.5 nautical miles for ships depending on size, just over 10 nautical miles for aircraft). The device has been increasingly criticized because of its limited range and inaccuracy from 1941. It was succeeded in 1942 Type 291U, with slightly better performance, especially for the air surveillance. Basic Data: P-band (214 mc / s), 100 kW output with 1.1 ms pulses, resolution) 3-5 degrees, detection range of aircraft to 30 nautical miles, for vessels up to 5.5 miles. The internals on MTB had to evaluate only one A-Scope for mapping without frequency modulation sweep, not an actual radar screen that is associated typically with a PPI (Plan Position Indicator).

About the same time began the installation of ASDIC devices.

Technical specifications

The specifications vary depending on the manufacturer and type.
Here in selecting each type of boat the three main producers is given, which was produced in the largest quantities. Even within these classes there were, depending on the time of production changes, especially in the arms and engines that are not playing, the boats were also retrofitted so that the secondary armament generally towards the end of the war has been significantly strengthened. The BPB boats are here exceptionally in their secondary armament because it is reclassified MGB.

References

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