You are on a voyage from St. John, Canada to Galveston, TX. The distance is 2280 miles, and the speed of advance is 15.0 knots. You estimate 16.5 hours for bunkering enroute at Ft. Lauderdale, FL. If you sailed at 1642 hours (ZD +4), 27 February, what was your ETA (ZD +6) at Galveston?
• Time-Speed-Distance formula using nautical miles and knots • Converting total travel time (including bunkering delay) into days and hours • Carefully handling time zones (ZD +4 to ZD +6) and date changes over multiple days
• First, ignore bunkering and find how many hours it takes to travel 2280 nautical miles at 15.0 knots. What is the basic formula you should use? • After you find the steaming time, where do you add the 16.5 hours for bunkering—before or after converting to days? How many days and extra hours is the total? • When you add this total time to the departure time (1642 on 27 February, ZD +4), what date and time do you get in ZD +4—and then how do you correctly convert that to ZD +6?
• Make sure you use the correct formula: Time (hours) = Distance (NM) ÷ Speed (knots) • Double-check your conversion from hours to days + hours so you don’t lose or gain an hour by rounding • When converting from ZD +4 to ZD +6, remember that going to a higher zone description means local time becomes later, and then compare that carefully with the multiple-choice dates and times
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