 In 1915 the Admiralty was considering the next generation of warship to follow the Queen Elizabeth @-@ class battleships . The Director of Naval Construction ( DNC ) , Sir Eustace Tennyson @-@ d 'Eyncourt , was given instructions to prepare designs for a new battleship . The design should : " take the armament , armour and engine power of Queen Elizabeth as the standard and build around them a hull which should draw as little water as was considered practicable and safe , and which should embody all the latest protection and improvements against underwater attack . " The design ( ' A ' ) was submitted to the Admiralty on 30 November for consideration . The DNC had been able to reduce the draught in comparison to Queen Elizabeth by 22 % by widening the ship to 104 feet ( 31 @.@ 7 m ) and lengthening it to 810 feet ( 246 @.@ 9 m ) ; this had the consequence of restricting the ships to use only one dock in Rosyth and two in Portsmouth . Large anti @-@ torpedo bulges were fitted , and the secondary armament of twelve 5 @-@ inch ( 127 mm ) guns of a new design was mounted on the forecastle deck . The resulting high freeboard gave the design a greater ratio of reserve buoyancy to displacement than in any previous British dreadnought . The design 's stretched hull form also gave her an estimated speed of 26 @.@ 5 knots ( 49 @.@ 1 km / h ; 30 @.@ 5 mph ) , about 2 @.@ 5 knots ( 4 @.@ 6 km / h ; 2 @.@ 9 mph ) faster than Queen Elizabeth had been able to reach in service . The First Sea Lord , Admiral Sir Henry Jackson , responded on 6 December that one danger of such a large ship would be start a new arms race with the Americans that Britain could ill @-@ afford , and that better deck protection was necessary to defeat plunging shells during long @-@ range engagements . 
