 Displacement was limited to in the new designs so that the length of construction would be shortened from the normal four or more years that a battleship required, to an estimated three to three and a half years.Required characteristics for the battlecruisers was a displacement of , a main battery of six guns, a secondary battery of dual purpose guns, a top speed of , a range of at , and enough armor to counter the guns of heavy cruisers.Like the P class, there were problems with fitting an all-diesel drive into the hull of the ships.