 Two 21 @-@ inch ( 533 mm ) submerged torpedo tubes were fitted on the beam . Fourteen Mark II * * * torpedoes were carried which had a warhead of 515 pounds ( 234 kg ) of TNT . They had two speed settings which governed their range ; at 45 knots ( 83 @.@ 3 km / h ; 51 @.@ 8 mph ) they could reach 4 @,@ 500 yards ( 4 @,@ 115 m ) or 10 @,@ 750 yards ( 9 @,@ 830 m ) at 31 knots ( 57 @.@ 4 km / h ; 35 @.@ 7 mph ) . 
