 Earlier in 1917 , however , construction of Hood 's three sisters had been suspended as the amount of labour and material they required would be better employed in the construction and repair of merchant ships and escorts needed to keep open Britain 's lines of communication in the face of the U @-@ boat blockade . Design work continued however , although Hood was too far advanced to incorporate these changes , and ultimately would have been extensive enough for the other three ships to constitute their own class . At the end of 1917 the suspended ships ' design was modified to increase the thickness of the turret roofs to six inches ( 152 mm ) , and ( unspecified ) alterations were made to the armoured bulkheads . These cost a total of 267 long tons ( 271 t ) in displacement . Other changes were a redesigned bridge structure and moving the funnels closer together and the exchange in position between the fifteen @-@ inch shellrooms and magazines . This latter change would have caused the hull 's form to be filled out somewhat to accommodate the handling room of the rearmost turret at the cost of a slight loss in speed and ammunition storage . 
