P Class Cruiser - Design

Design

In the early 1930s, Adolf Hitler began a rearmament program in Germany. He signed the Anglo-German Naval Agreement, which allowed Germany to build up its navy to 35 percent of the strength of the British Royal Navy and effectively repudiated the restrictions of the Treaty of Versailles on the German fleet. This led to a decision in 1937 to build ships to an improved Deutschland-class cruiser design. Design work on the new class of armored ships began that year. After more than twenty designs were considered to meet the navy's specifications, one was chosen; it was designated as cruiser "P". It called for a 20,000-metric-ton (20,000-long-ton) with a maximum speed of 34 to 35 kn (63 to 65 km/h; 39 to 40 mph), armed with six 28 cm (11 in) guns in two triple turrets.

By 1938, it became clear to Admiral Erich Raeder that Hitler's aggressive foreign policy would bring conflict with Britain. He therefore decided that a significantly larger force of armored ships would be necessary to execute an effective commerce raiding campaign against the British. Raeder's intention to fight a commerce war against Britain was the basis for Plan Z, which included twelve ships of the P-class design. The design work on the new ships proceeded in parallel with work on the O-class battlecruiser design. Experiments were conducted on at least nine different design proposals between March 1938 and December 1939. The designs varied somewhat in terms of dimensions as well as armament; some of the designs featured three 28 cm triple turrets.

Many problems were encountered with designing the ships, the most prevalent being armor. The required maximum speed of 34 kn (63 km/h; 39 mph) meant that the minimum length had to grow from the original 217 m (712 ft) to 229.5 m (753 ft). It also meant that the beam could be a minimum of 25 m (82 ft)—unless diesel engines, like those used in the Deutschland's, were desired; they would increase the beam by 2 m (6.6 ft). Unfortunately for the designers, the widened beam meant that an even longer hull was needed to maintain hydrodynamic efficiency. All of this complicated the armor arrangements, as more armor was needed to cover the longer length and widened beam. Eventually it was deemed that it was impossible to include diesel power on a 20,000-metric-ton (20,000-long-ton) displacement.

Initially, twelve ships were ordered based on the P-class design. The ships were ordered under the provisional names P1 through P12; the contracts were awarded to a number of German shipyards, including Deutsche Werke in Kiel, Blohm & Voss in Hamburg, and the KM Dockyard in Wilhelmshaven. However, Plan Z was reduced in size, and the number of armored ships was pared down to only eight vessels. This caused several of the contracts to be shifted around amongst the various shipbuilding companies. The first keel was set to be laid on 1 Feb 1940. The revised version of Plan Z, approved on 27 July 1939, removed the P-class ships from the construction queue. Instead, the decision was made to build the O-class battlecruisers only.