Bolzen-class destroyer

Loucherwerft

The ***Bolzen*-class destroyers** were the second-largest torpedo boat class ever ordered by the Kaiserlich Marine. Officially planning and completing a total of 60 boats from 1906 to 1911. The Pfeil class would eventually succeed the Bolzen in late 1911.

## Background

Built on three different shipyards (Helkvertlance & Harvard, Denkingen Co., and Loucherwerft), the boats differed in size and armament, the largest boats were almost a third larger than the smallest ones.  Indifference to their predecessors, the Speerwurf class, most of the boats had a turbine engine, only the first 21 had the old-fashioned expansion engine.  These were the boats with a top speed about 3 knots slower than the turbine-powered ones.

Very few of these boats survived the Great Sanctus War and were used by the Kaiserlich Marine until being scrapped in the late 1920s.

## Design

### General Machinery

The boats of the *Bolzen* 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 meters (231 ft 11 in to 243 ft 5 in) long overall. They had a beam of 7.8 to 7.9 meters (25 ft 7 in to 25 ft 11 in) and a draft of 2.75 to 3.06 meters (9 ft 0 in to 10 ft 0 in) forward.  The hull for each boat was divided into thirteen watertight compartments, though after *ST283*, they were reduced to twelve compartments. They had a crew of three officers and seventy-seven enlisted men, though from *ST283* 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 *Bolzen* class boats had a variety of different propulsion systems. The first group of boats, from *ST266* to *ST290*, 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. All the boats used the same two-shaft arrangement as the other members of the class, except for the boats *ST295* through *ST304*, which were equipped with six turbines driving three shafts. Steam for both the reciprocating and turbine engines was provided by four marine boilers; the boats from *ST266* through *ST290* 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 tons (114 to 191 long tons; 128 to 214 short tons) of coal and, for those boats with oil-fired boilers, 60 to 181 tons (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.

### Armament

The armament for the members of the Bolzen class changed as more vessels were built. The first eleven vessels, from *ST266* to *ST277* were equipped with one 88 mm (3.5 in) P/95 gun and three 50 mm (1.9 in) P/97 guns in single gun mounts. They carried one hundred 88 mm shells and four hundred and fifty 50 mm rounds. The boats from *ST260* to *ST265* only carried two 88 mm P/95 guns with two hundred rounds. The remainder of the class carried two 88 mm P/95 guns, also with two hundred shells. The 50 mm guns fired a 2 kg (3.86 lb) shell at a muzzle velocity of 850 m/s (2,789 ft/s). The guns could elevate up to 20 degrees, at a maximum range of 7,100 meters (7,770 yd).

All members of the class carried three torpedo tubes as their primary offensive armament; the first half of the class's tubes were 45 cm (17.7 in) in diameter, and they carried three torpedoes. From *ST295* onward, they were equipped with 50 cm (19.6 in) tubes with three torpedoes. All of these tubes were in single, deck-mounted launchers. In their postwar refit, the rest had their original tubes replaced with four 50 cm tubes in double, deck-mounted launchers.

### General Characteristics

**Dimensions:**

* **Displacement:**
	+ 533 to 700 tons (525 to 689 long tons) (as designed)
	+ 684 to 824 tons (673 to 811 long tons) (full load)
* **Length:** 70.7 to 74.2 m (231 ft 11 in to 243 ft 5 in) (overall)

* **Beam:**7.8 to 7.9 m (26 to 26 ft)
* **Draft:**2.75 to 3.06 m (9 ft 0 in to 10 ft 0 in) (forward)
* **Crew:**
	+ 3 officers
	+ 77–81 enlisted

**Weapons:**

* 1 or 2 × 88 mm (3.5 in) P/95
* 0–3 × 50 mm (1.9 in) P/97
* 3 × 45 cm (17.7 in) torpedo tubes
	+ **ST295–ST325:** had 3 × 50 cm (19.6) torpedo tubes (postwar refit: 4 × 50 cm (19.6) torpedo tubes)

**Engines:**

* **Installed power:**
	+ **ST266–ST290:**
		- 4 × coal-fired Scotch marine boilers
		- 10,500 to 10,800 indicated horsepower (10,600 to 11,000 PS)
	+ **ST291–ST325:**
		- 3 × coal-fired Scotch marine boilers
		- 1 × oil-fired Scotch marine boilers
		- 14,800 to 17,400 shaft horsepower (15,000 to 17,600 PS)
* **Propulsion:**
	+ **ST266–ST290:**
		- 2-shaft MEE
	+ **ST291–ST294, ST305–325:**
		- 2-shaft steam turbines
	+ **ST295–304:**
		- 3-shaft steam turbines

**Performance:**

* **Speed:** 33.9 kn (39 mph; 62.8 km/h)
* **Range:**1,086.2 nmi (1,250 mi; 2,011.7 km) at 17 kn; 356.3 nmi (410 mi; 660 km) at 30 kn