page_title: S138-class torpedo boat
section_title: General characteristics and machinery
hierarchical_section_title: S138-class torpedo boat / Design / General characteristics and machinery
caption_attribution_description: Deutsch: Blick über eine Torpedoflottille an der Zollbrücke im Travemünde.
context_page_description: The S138 class was a group of sixty-five torpedo boats built for the German Kaiserliche Marine and the Ottoman Navy in the early 1900s. Almost all of the boats served with the German fleet, with only four being sold to the Ottoman Empire in 1910.
context_section_description: The boats of the S138 class varied in dimensions, and they gradually increased in size as more vessels were built. The boats were 70.2 to 74 meters (230 ft 4 in to 242 ft 9 in) long at the waterline and 70.7 to 74.2 m (231 ft 11 in to 243 ft 5 in) long overall. They had beam (nautical) of 7.8 to 7.9 m (25 ft 7 in to 25 ft 11 in) and a draft of 2.75 to 3.06 m (9 ft 0 in to 10 ft 0 in) forward. The hull for each boat was divided into thirteen watertight compartments, though after V150, they were reduced to twelve compartments. They had a crew of three officers and seventy-seven enlisted men, though from V150 onward, they had larger crews, with eighty-one enlisted men aboard. When serving as half-flotilla flagships, the boats would have a flotilla leader's staff of four officers and nine enlisted men in addition to the standard crew. The vessels carried a yawl and a dinghy apiece, though later in their careers they carried up to three yawls and the dinghy.
  The S138-class boats had a variety of different propulsion systems. The first group of boats, from S138 to V160, were propelled by a pair of vertical, 3-cylinder triple expansion steam engines that drove a pair of three-bladed screw propellers. Steam was provided by three coal-fired water-tube boilers. The rest of the members of the class received direct steam turbines of various manufacturers, including AEG, Schichau-Werke, Zoelly, Germaniawerft, and Parsons. All of the boats used the same two-shaft arrangement as the other members of the class, with the exception of the boats G169 through G172, which were equipped with six Parsons turbines driving three shafts. Steam for both the reciprocating and turbine engines was provided by four Scotch marine boilers; the boats from S138 through V161 had four coal-fired models, while the remainder of the class had three such boilers and one oil-fired version.
  The reciprocating engine-powered boats were rated at 30 knots (56 km/h; 35 mph) from 10,800 to 10,800 indicated horsepower (10,900 to 11,000 PS). The two-shaft turbine boats were rated at 14,600 to 17,300 shaft horsepower (14,800 to 17,500 PS) and 32 knots (59 km/h; 37 mph), while the three-shaft vessels were designed to reach 15,000 shp (15,000 PS) and 32 knots, respectively. The boats had storage capacity for 116 to 194 t (114 to 191 long tons; 128 to 214 short tons) of coal and, for those boats with oil-fired boilers, 60 to 181 t (59 to 178 long tons; 66 to 200 short tons) of fuel oil. As a result, cruising radius varied significantly, from 920 to 3,500 nautical miles (1,700 to 6,480 km; 1,060 to 4,030 mi) at 17 knots (31 km/h; 20 mph). Each vessel was equipped with two 17 kilowatts (23 hp) 110-Volt generators for electrical power. Steering was controlled with a pair of rudders, one at the stern and the other in the bow, the latter being retractable.
caption: Sailors loading bags of coal aboard one of the S138-class boats
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