You are underway on course 050? T and your maximum speed is 13 knots. The eye of a hurricane bears 100? T, 120 miles from your position. The hurricane is moving towards 275? T at 25 knots. If you maneuver at 13 knots to avoid the hurricane, what could be the maximum CPA?
• Relative motion between your vessel and the hurricane’s center • Using speed-time-distance relationships to find how far each will travel • Determining the closest point of approach (CPA) between two moving objects
• Sketch the situation on a plotting sheet: mark your course and maximum speed, then the hurricane’s track and speed from its starting position • Ask yourself: at what relative position along its track will the hurricane be when you are abeam (or nearest) to its path, given both speeds? • Think about whether heading directly away, across, or toward the hurricane’s track will increase the CPA and why
• Be sure to convert all speeds and distances consistently into nautical miles and knots with time in hours • Verify the relative velocity vector between your vessel and the hurricane before computing CPA • Check that the CPA distance you compute matches one of the choices and is greater than the initial lateral separation you can deduce from the geometry
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