At 1845 zone time on 24 October, you depart Bimini Island, LAT 25°50.0'N, LONG 77°00.0'W (ZD +5). You are bound for Bishop Rock, LAT 49°40.0'N, LONG 6°34.0'W, and you estimate your speed of advance at 13.6 knots. The distance is 3,491 miles. What is your estimated zone time of arrival at Bishop Rock?
• Time-Speed-Distance: Use the basic formula to find total travel time based on distance and speed. • Converting travel time: Break total hours into days and hours, then add to departure date/time. • Zone Descriptions (ZD): Consider departure and arrival longitudes to determine if/when the zone time changes along the route.
• First, compute how many hours it takes to travel 3,491 miles at 13.6 knots. Is it more or less than 10 days? • After finding total hours, convert that to days and remaining hours, then add to 1845 on 24 October. What calendar date and time do you get in the same time zone? • Next, think about how many time zones (15° bands of longitude) you cross between 77°W and 6°W. Do you move to earlier or later zone times as you go east?
• Be sure you use the correct formula: Time = Distance ÷ Speed, with distance in nautical miles and speed in knots. • Double-check your conversion of total hours to days and hours (no dropped or rounded hours). • Verify the sign and number of ZD changes between the departure longitude (ZD +5) and the arrival longitude (near ZD 0); adjust the arrival clock time accordingly.
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