You are on course 061° T, at a speed of 12.4 knots. At 0839 you see a rock bearing 059° T at a range of 4.4 miles. If you change course at 0845 to leave the rock abeam to starboard at 1.5 mile, at what time will the rock be abeam?
• Speed–distance–time relationship to find how far you travel between 0839 and 0845 • Using a bearing and range to plot the rock’s position relative to your track • Understanding that “abeam to starboard at 1.5 mile” describes the closest point of approach (CPA) and forms a right angle (beam) distance
• First, figure out where you are at 0845 by finding how many miles you moved from 0839 and advancing your position along course 061° T. How far is that, and where is the rock relative to your new position? • On your new course after 0845, the rock will be at its closest point when it is exactly 1.5 miles on your starboard beam. How does that relate to a right triangle between your track and the rock? • Once you know the along-track distance from your 0845 position to the abeam (CPA) point, how do you turn that distance into minutes using your speed of 12.4 knots?
• Compute the distance run from 0839 to 0845 using ( \text{Distance} = \text{Speed} \times \text{Time} ). Be careful with minutes-to-hours conversion. • When plotting or visualizing, ensure the beam distance (1.5 miles) is drawn perpendicular to your new course line, not your original course. • After finding the distance from the 0845 position to the abeam point, double-check that your time added to 0845 matches one of the multiple-choice answers.
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