 The ships carried approximately 3 @,@ 200 long tons ( 3 @,@ 251 t ) of coal , and an additional 850 long tons ( 864 t ) of fuel oil that was to be sprayed on the coal to increase its burn rate . At full capacity , the ships could steam for 3 @,@ 330 nautical miles ( 6 @,@ 170 km ; 3 @,@ 830 mi ) at a speed of 10 knots ( 19 km / h ; 12 mph ) . 
