Schnellboote

A Complete Operational History

Lawrence Paterson

• Publisher: Seaforth Publishing
• Year: 2015
• ISBN:
  9781848324091
• Topic: Geschichte
• Subtopic: Militär- & Seefahrtsgeschichte

"A detailed account of the fast patrol boats built and used by the Kriegsmarine during WWII... a book for every naval history enthusiast."— Firetrench The Kriegsmarine's Schnellboote—fast attack boats or S-boats to the Allies—were the primary German naval attack units in coastal waters throughout the Second World War. Operating close to their various bases they became a devastatingly effective weapon in nearly all the Kriegsmarine's theatres of war, from the Baltic to the Mediterranean and the Black Sea. It was in the English Channel, however, that they scored their most notable successes, destroying some forty warships and more than one hundred merchant ships. In addition to interception and attack, they were also used for minelaying, landing sabotage troops and general escort duties. There has been, to date, no comprehensive operational history of the S-boat in all the theatres in which it saw service, but due to the relatively small number of units it is possible to recount the duties and fates of each individual craft, and in this new book the author examines the career of each in detail. In addition, operations alongside the commando units of the Kleinkampfverbande are covered, and the smaller S-boats, designed primarily for their use, are described. As the War progressed, S-boats suffered from the increased Allied mastery of the seas and skies but they were a formidable foe right to the end; this new book is the first to do full justice to their record of success. "An important addition to the body of coastal forces literature, and should be essential reading for anyone interested in the wars of the 'Narrow Seas.'"—Battlefleet

1

Introduction

THE development of the torpedo during the nineteenth century opened fresh vistas for naval architects to explore. As well as the submarine, new surface craft evolved into the torpedo boat, destroyer (essentially an enlarged torpedo boat) and, finally, the motor torpedo boat. Small and agile motor torpedo boats (MTBs) found particular favour with the Italian and British navies. During the First World War, three Royal Navy junior officers suggested that such shallow-draught vessels operating at speed would be able to pass over defensive minefields in order to attack the German fleet at anchor. Although committed to action, their successes were few, not least of all because the craft’s design required the torpedo to be launched over the stern tail-first. Italian naval planners were also fielding such craft, sinking two Austro-Hungarian capital ships in the last two years of war. For their part, the German Navy also introduced such craft, though more defensive in nature.

At first they had developed pilotless wire-guided craft, armed with a remotely detonated explosive charge in the bow. These Fernlenkbooten (FL or remote-control boats) were used in action against British monitors shelling the German U-boat bases in Belgium, but with no real success. The Kaiserliche Marine then turned to the development of crewed boats, initially small, fast motor launches tasked with clearing anti-submarine nets laid by the Royal Navy outside Zeebrugge and Ostend. Three boatyards were approached to provide these craft, the most prominent being the Lürssen boatyard at Bremen, established by innovative boatbuilder Friedrich Lürssen in 1875 and run since 1916 by his son Otto. The following year LM1 was launched for the navy. The designation LM (Luftschiffmotorboote) reflected the fact that they were each powered by three powerful and lightweight Maybach Zeppelin engines.

An FL boat manhandled into its shelter for protection from enemy bombs in Flanders.

Lürssen was not the only boatyard engaged in producing the first six boats ordered in January 1917. Both the Naglo and Oertz shipyards had been contracted, though both yards had diversified – unsuccessfully it transpired – into aircraft design during the pre-war years.

LM1 and LM2 were built by Lürssen, LM3 and LM4 by Naglo, none of them possessing armament other than a 3.7cm cannon. Their primary use was dictated by bow-mounted net cutters. However, from Oertz’s LM5 onward the armament included a 45 cm bow torpedo and a single machine gun. Averaging a maximum speed of approximately 30 knots, fourteen LM boats were incorporated into the German Naval Corps Flanders, seven into the Baltic (LM7-13), and several skirmishes with Allied units are recorded, though without much success. In fact, only a single sinking has been attributed to these first small motor torpedo boats: the British transport steamer SS Penelope, torpedoed and sunk on 24 August 1917 by ObltzS Peytsch less than six hundred metres from Swalfer Ort Lighthouse in the Gulf of Riga.

LM boat undergoing sea tests outside Zeebrugge.

The firm Rolandwerft at Hemelingen also produced several LM boats; L18 and L20 commissioned in 1917, LM17 the following year and LM19 in 1919 after hostilities had ceased. Results had been relatively meagre for Germany’s first foray into small motor torpedo boats, but with the harsh terms of the Versailles treaty severely curtailing the size of any German fleet, interest remained high in continuing to develop such coastal defence vessels.

The post-war Weimar Republic was not allowed any U-boats on strength, their total surface strength, excluding minesweepers, limited to ‘six battleships of the “Deutschland” or “Lothringen” type, six light cruisers, 12 destroyers and 12 torpedo boats’. This final class, limited to not exceed 200-tons displacement, elicited further MTB development – a type of craft not explicitly covered by the treaty terms. The Reichsmarine immediately began experimenting with speedboat concepts once more, taking strong cues from the British and Italian navies. Several LM boats that had been built at the war’s end were transferred back into the navy and re-designated Unterseeboote Zerstörer, UZ for short. It was these that were first used to develop what would become future S-boat combat tactics, exercising against target hulks in small groups of two and three, using speed, low silhouettes and light grey camouflage that merged with the horizon.

An LM boat on anti-submarine patrol off Flanders. The tiny size is all too apparent.

Like much German military development, S-boats were hidden behind dummy civilian corporate fronts. The head of the Reichsmarine had entrusted Kapitän zur See Walter Lohmann, chief of the Reichsmarine’s transportation division, to administer an accumulated ‘black fund’ of unofficial money that enabled armament development to take place under the noses of the Allied Armistice Control Commission. In this he was assisted by the officer who would go on to head Germany’s minesweeping service, ObltzS Friedrich Ruge. Together they established, amongst other things, TRAYAG (Travemünder Yachthafen AG) in 1924 as a base and shipyard for the development and trial activities for fast MTBs. The following year they inaugurated the High Sea Sports Association (HANSA) for training of personnel in basic seamanship, small motor and sailing boat usage as well as radio communication. The Neustädter Slip GmbH was created as a repair and training plant for sport boats (and S-boats) in 1925 and the following year 60,000 Reichsmarks (RM) was given to the Motor Yacht Club of Germany for the testing of TRAYAG motorboats. The subterfuge proved successful – not only for MTB development, but also U-boat and aircraft projects.

During 1926 the Bremen firm Abeking & Rasmussen (designers of minesweepers, torpedo boats and submarine chasers in the last war, future designers of R-boats in the next) built the Experimental Boat K with a stepped planing hull; Travemünde’s Caspar Werft built the Narwhal, a large planing hull, and Lürssen built the Lür, a displacement-hulled boat. At first, attention was clearly placed on the planing hull concept that was successfully used for speedboats. In flat calm waters this hull shape enabled a boat to effortlessly skim across the water surface – ‘planing’, where the weight of the craft is supported by hydrodynamic lift rather than simple hydrostatic lift (displacement buoyancy). However, the future German MTBs were most likely to operate within the North Sea, which was frequently beset by heavy swells. Therefore it was Lürssen’s displacement hull that was chosen by the Reichsmarine as the starting point for MTB planning. Their attention was then drawn to a design Lürssen had created for a private customer – the Oheka II.

The customer, Otto Hermann Kahn, was an extremely wealthy investment banker, philanthropist and patron of the arts who had moved from Germany to the United States in 1893. During 1926 he placed an order with the Lürssen boatyard for a high-speed motor launch capable of both river cruising and use in the North Sea. One year after his order had been placed, Kahn’s speedboat was delivered, sporting radical new features that would see it become the fastest boat in its class worldwide. It carried the best features of a displacement hull – extreme seaworthiness even in heavy weather – and a planing hull towards the stern that would provide the requisite hydrodynamic lift when travelling at speed. Constructed of wooden planking over alloy frames, the boat was lightweight, increasing its overall speed and performance

The combination exactly suited the Reichsmarine’s needs. The craft’s sizeable displacement would also bear the weight of two forward-firing torpedo tubes mounted toward the bow. Lürssen was asked to build another of the same basic design in November 1929, with the addition of two detachable torpedo tubes and on 7 August 1930 this boat, named UZ(S)16 was commissioned into the Reichsmarine. The ‘S’ stood for ‘schnell’ and was added in order to differentiate this vessel from the former LM First World War boats. She was renamed twice more: to Wachboot W1 (guard boat) in March 1931, and finally to Schnellboot S1 on 16 March 1932. The term ‘Schnellboot’ had actually been used as a cover name for the development of MTBs; now it was a brand new class of warship.

S1 and S2 at sea shortly after commissioning.

S1 was constructed of mahogany and light metal composite, powered by three 900hp Daimler-Benz petrol engines as no marine diesels were available at that time. The Reichsmarine had commissioned both MAN and Daimler-Benz to develop lightweight high-speed diesels specifically for the S-boat, though S1 was ready well before the new diesels were. She was 26.5m (87ft) long with a beam of 4.2m (14ft) and a draught of 1.1m (3ft 6in) making S1 the largest high-speed coastal motorboat of the time, but still capable of 39.8 knots. As well as the two First World War vintage 50cm torpedo tubes there was a single 2cm flak weapon on the stern deck. Crewed by twelve men, the boat was capable of operating in a sea state up to 5 on the Beaufort Scale (equating to a wind speed of between 17 and 21 knots and waves up to six feet high).

Although S1 was the smallest of the designs that would follow, the interior layout remained similar throughout the war. Internally, seven bulkheads separated eight watertight compartments. From bow to stern, the first compartment contained a trimming cell, the anchor chain storage locker, the forward ‘head’ and then Feldwebel and Unteroffizier (NCO and junior officers) quarters, holding six bunks in total and having natural light provided by portholes in the hull. Next came the captain’s cabin (again with hull portholes) on the starboard side opposite the radio room to port, which also doubled as the radioman’s quarters. Fuel tanks (6,000 litres/1,300 gallons) lay directly under the bridge, followed by the first engine room, where the port and starboard engines were housed with a central walkway. The following compartment was engine room 1, holding the central engine, flanked by walkways either side, and two more fuel tanks (8,000 litres/1,750 gallons). Both engine rooms were provided with numerous skylights to provide as much natural light as possible into the relatively spacious working space. A built-in Ardex fire-extinguishing system helped reduce the risk of fire. Immediately astern of this lay the small galley, stern ‘head’ and the crew room, ultimately capable of housing up to fifteen men, atop the roof of which was the location of the 2cm Rheinmetall MG C/30 flak weapon. Here the cabin roof protruded above deck level, allowing portholes on either side. Finally, rudder gear and two more fuel tanks (4,000 litres/880 gallons) occupied the sternmost part of the boat.

Each bulkhead was designed to withstand flooding and light damage from shell splinters, and constructed of wood stiffened with aluminium. The engine beds were steel and each engine compartment ceiling was removable plating to enable the replacement of worn-out machinery. The boat had a double layer of hull planking, the inner hull nailed to the boat’s longitudinal frames, the outer layer riveted directly over the top. The deck itself was more planking, covered with canvas and then painted with a durable, waterproof, non-slip synthetic resin paint.

Although possessing excellent qualities and built to a high design specification, work began on an improved class almost as soon as testing began on S1. During 1931 construction of the S2 class (four boats numbered S2 to S5) started; these were commissioned into service between April and July 1932. The boat’s length had been increased to 27.9m (90ft) and the displacement also increased to 49 tons. This allowed an improved layout and added machinery, including a 100hp auxiliary Maybach engine which could operate the central propeller. Designe...