Mackensen Class Battlecruiser - Design

Design

The fourth and final Naval Law, passed in 1912, governed the building program of the German navy during World War I. The Navy Office decided the Navy should construct one battleship and one battlecruiser every year between 1913 and 1917, with an additional unit of both types in 1913 and 1916. By February 1915, the German High Command had realized that the war would not be won with a lightning campaign as in 1870. Therefore, the Navy department decided to replace the six armored and seven light cruisers that had been sunk by that point in the war. Kaiser Wilhelm II requested the new ships be armed with 38 cm (15 inch) guns; Admiral Friedrich von Ingenohl, the commander in chief of the High Seas Fleet, preferred the 30.5 cm gun of the preceding Derfflinger class ships. As a compromise, the new battlecruisers were to be armed with eight 35 cm (13.8 inch) guns.

The design staff was generally in agreement with the standard practice of using coal-fired boilers for two-thirds of the power plant, with the remainder being oil-fired boilers. Coal-fired boilers were preferred because the coal, stored in the sides of the ship, provided additional protection, particularly for the battlecruisers. There was a problem with any enlargement of the new ships over the preceding designs. The Imperial dry docks were only deep enough for ships with a draft of 9 m (30 ft). This meant that an increase in displacement would necessitate a longer and wider hull. This was compounded by restrictions on width imposed by the locks of the canal in Wilhelmshaven.