51. You make good 097°T from your 0830 fix. With a westerly current of 1.2 knots, what engine speed will you have to turn for from your 0830 position in order to arrive abeam of Six Mile Reef Buoy «8C» at 1030?

Choice D is correct: a speed through the water of 10.5 knots, combined with a 1.2-knot westerly current, achieves the required speed made good to arrive abeam of Six Mile Reef Buoy «8C» at 1030. The speed made good is determined by dividing the charted distance along the 097T track by the 2-hour time interval, and this value is then adjusted for the adverse effect of the current.