You are on a voyage from Limoy, Costa Rica to Los Angeles, CA. The distance from departure to arrival is 3150 miles. The speed of advance is 14.0 knots. You estimate 24.0 hours for bunkering at Colon, and 12.0 hours for the Panama Canal transit. If you take departure at 1836 hours (ZD +6), 28 January, what is your ETA (ZD +8) at Los Angeles?
• Speed–Distance–Time relationship for speed of advance (SOA) in knots and distance in nautical miles • How to add bunkering and canal delay times to the sea passage time to get total voyage time • Conversion between Zone Time (ZT) and Greenwich Mean Time (GMT) using Zone Descriptions (ZD +6 to ZD +8)
• First, how do you compute the total time underway in hours from a distance of 3150 miles at 14.0 knots? What is the formula and unit check? • After you find the steaming time, how do you correctly add the 24 hours for bunkering and 12 hours for the canal transit, and then apply that total to the departure date and time? • Once you have the arrival time in GMT or in ZT for ZD +6, how does changing from ZD +6 to ZD +8 affect the local clock time in Los Angeles—do you move the clock ahead or back, and by how many hours?
• Verify that you are using Speed = Distance / Time rearranged correctly to solve for Time in hours with knots (nm/hr). • Be sure you convert total hours of voyage time into days and hours, and carefully carry over extra days when adding to the calendar date (watch the month change). • Double-check how Zone Description signs work: confirm whether moving from ZD +6 to ZD +8 makes the local time earlier or later relative to GMT before picking your answer.
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