General Subjects

ta taximan · Aug 26, 2014 8:55am

Your ship has steamed 2014 miles at 22 knots using 680 tons of fuel oil. The distance remaining to your next your port is 1766 miles. If you decrease speed to 18 knots, how much fuel will be used to reach that port?
A. 327 tons
B. 488 tons
C. 399 tons
D. 1220 tons

jd jdiesel · Aug 26, 2014 6:23pm

399 is the uscg answer, but I got 487.85?? sorry not sure about that one...

cD cDEa0rvQKsKWcU4Rg · Aug 31, 2014 11:37pm

For diesel fuel consumption is proportional to speed cubed. For steam, fuel consumption is proportional to speed squared. I presume "steamed" (instead of "motored") indicates it's a steam boat. The original rate of consumption is 680/2014 = .3376 tons per mile. Multiply this by 18**2/22**2 = .6694 for an new rate of consumption = .2260 (Note that the units for speed cancel each other out.) Multiply this by the distance to obtain answer "C"