enlarging the hull were compounded by restrictions on width imposed by the locks of the canal in Wilhelmshaven. As a result, (Grand Admiral) Alfred von Tirpitz, the head of the RMA, prohibited a design displacement greater than . The initial design was approved on 30 September 1912, though the heads of the General Navy Department— (Vice Admiral) Günther von Krosigk and (Rear Admiral) Reinhard Scheer—and the Weapons Department head, Gerhard Gerdes, had to submit any revisions they deemed were necessary. The design staff suggested using triple or even quadruple gun turrets to keep the displacement under the 30,000-ton limit. Another suggested alternative was to use six 38 cm (15 in) guns in twin turrets, one forward and two aft; Wilhelm II accepted that design on 2 May 1913, though Friedrich von Ingenohl, the commander in chief of the High Seas Fleet, preferred the 30.5 cm gun of the -class ships. As a compromise, the new battlecruisers were to be armed with eight 35 cm (13.8 inch) guns. The question of whether the new ships should be powered entirely by oil-fired boilers was less controversial. 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, which carried less armor than their battleship counterparts. The finalized design was approved on 23 May 1914. General characteristics The -class ships were long and had a beam of and a draft of forward and aft. The ships were designed to displace on a standard load, and up to fully laden. The s hulls were composed of longitudinal steel frames, over which the outer hull plates were riveted. This was the same type of construction as in the preceding -class battlecruisers, and was intended to save weight compared to the traditional method of construction, which incorporated both longitudinal and transverse frames. The ships' hulls contained 18 watertight compartments and a double bottom that ran for 92 percent of the length of the hull. This was significantly greater than the older -class ships, which had a double bottom for only 65 percent of the length of the hull. Experience with previous battlecruiser designs led to the adoption of a continuous upper deck, which raised the level of the deck