 The Delawares carried a battery of ten 12 @-@ inch ( 305 mm ) guns in five turrets , an increase of two guns over the South Carolinas . With these ships , the US Navy re @-@ adopted a full @-@ fledged medium @-@ caliber weapon for anti @-@ torpedo boat defense . While the 5 @-@ inch ( 127 mm ) gun was smaller than that used by other major navies , this would , with few exceptions , become the standard medium @-@ gun caliber for the US Navy for the better part of the 20th century . As for speed , the Delawares were capable of 21 kn ( 24 mph ; 39 km / h ) , a significant improvement over the earlier class 's 18 @.@ 5 kn ( 21 mph ; 34 km / h ) . This would become the speed for all American standard @-@ type battleships . Propulsion systems were mixed ; while North Dakota was fitted with steam turbines , Delaware retained triple @-@ expansion engines . US turbines at this point did not give great advantages in output or speed over triple @-@ expansion systems , as the engineering difficulties faced by turbine manufacturers there were still extremely great , and were much less fuel @-@ efficient , a significant concern for a Navy with Pacific responsibilities but lacking Britain 's extensive network of coaling stations . 
