From your 0820 position you change course to your rendezvous position, one mile due south of buoy "NH", speed 14.5 knots. You estimate the current to be 260°T at 0.5 knot. The wind is northwesterly at 20 knots and you estimate 2° leeway. What is your course per gyrocompass (pgc) to the rendezvous position, if you correct your heading for current and leeway?
• Applying set and drift of current to a planned track line • Adjusting a true course for leeway caused by wind • Converting between true course and gyro course (pgc) when gyro error is involved (or confirming if any correction is needed)
• First, sketch the track from your 0820 position to the rendezvous point relative to buoy 'NH'. What is the true course from your present position to the rendezvous point with no current or wind? • How does a current from 260°T at 0.5 knot move your vessel relative to the water when you are making 14.5 knots through the water? In which direction must you aim to compensate? • Leeway is caused by a northwesterly wind. Which way will the leeway push the bow, and do you correct by adding leeway to the windward or leeward side of your intended course?
• Be clear whether your 14.5 knots is speed through the water, not speed made good over ground. • Draw the current vector and the ship’s through-the-water vector head-to-tail to get the course and speed made good, then adjust the heading so the resultant over ground goes straight to the rendezvous point. • Confirm whether any gyro error or variation/deviation information is given in the problem; if none is stated, think carefully about whether any additional correction from true to pgc is required.
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