Rostock-class Cruiser

SMS Rostock - As built

The *Rostock*-class was a class of two heavy cruisers built for Imperial Germany in the early 1920s, in the Kaiserschlacht timeline. They were the first cruisers in service to carry guns larger than 8 inches in calibre in proper turrets. Combined with a good balance of speed and protection, these vessels were highly advanced for their time, which delayed their completion. The two ships *Rostock* and *Schwerin* were in service from 1925 to \_\_\_\_.

## Design

In 1916, the Royal Navy laid down cruisers of the *Hawkins-*class. Armed with 7.5" guns and with a high speed of 31 knots these vessels threatened to outclass all cruisers in the Kaiserliche Marine*.* The *#history* Central Admiralty was consulted for a design in response in 1919. *Rostock*'s role would be that of a fleet action cruiser, designed to screen larger ships, in particular the battlecruiser forces, with her predecessor *Cöln.*

*Rostock*, the name given to one of two selected designs, was to be of 10000 tons displacement. The ship was fairly slender, with a length of 193.45m at the waterline and a beam of 18m. At normal load the *Rostock* drafted 6.65m. She had a flush-deck hullform inspired by that of the *Derfflinger*-class battlecruisers.

Protection was to be significantly better than the rival *Hawkins,* with a uniform 90mm main belt and 55mm extended belt over the steering gear. Deck armor was 60mm thick over the machinery and magazines, equalling that of the *Cöln-*class, and 25mm thick over the steering gear. The conning tower was protected by 100mm of armor. A 50mm bulkhead was integrated into the ship's structure to form a single shallow layer of underwater protection, and an additional 20mm centerline longitudinal bulkhead provided subdivision for the machinery spaces.

The *Rostock-*class also marked a transition to full oil-burning machinery, with 10 oil-fired boilers and a three-shaft geared turbine setup providing 71000 shaft horsepower for a design speed of 31 knots. The vessels had a range of 5500 nautical miles at 15 knots.

*Rostock* had powerful artillery, carrying 6 newly-developed 21cm SK L/45 C/19 guns in 3 two-gun turrets, the first cruiser to do so. Problems with the complex turret that was capable of a respectable 6 rounds per minute per gun significantly delayed *Rostock*'s completion, but the weapon proved to be more than satisfactory in service. She also carried 8 8.8cm SK L/45 guns, capable of engaging both surface and air targets.

## Service History

Initially scheduled for construction as soon as possible, in 1919, delays in the design process of the main battery turrets first pushed the date of lay-down to late 1920. In practice, meaningful construction of *Rostock* only began in 1921, and for *Schwerin* 1922. By 1924 both ships were fitting out and underwent speed trials, and the *Rostock*-class was accepted into service in 1925.

## Ships in Class

### SMS *Rostock*

The lead ship of the class, named after the city of Rostock in the north German state Mecklenburg-Vorpommern, achieved a speed of 31.15 knots on speed trials and was commisioned in August 1925.

### SMS Schwerin

The second ship of the class, named after the city of Schwerin in the north German state Mecklenburg-Vorpommern. Achieved a speed of 31.40 knots on trials and was commissioned in December 1925.