Essential Chart Work - Dead Reckoning - RYA Yachtmaster Theory Training
5 February 2024 · 4 min · 2K views
What this video covers
Dead reckoning position-plotting is demonstrated step by step for RYA Yachtmaster theory, using a scenario where GPS fails and fog closes in at 1610.Watch Starting from a known GPS fix, the technique requires two inputs: compass heading and distance traveled. The worked example uses a magnetic heading of 146 degrees and a distance of 6.5 nautical miles covered in one hour. Variation of 7 degrees west, read from the compass rose, is subtracted from the magnetic heading to produce a true bearing of 139 degrees — true north being required because the chart is referenced to true north. A plotter is set to 139 degrees, aligned with the chart's north lines, and the direction of travel is drawn from the starting position. Dividers measure 6.5 nautical miles along that line, and the DR position is marked where they land. Deviation correction is acknowledged but skipped in this example. Dead reckoning is identified as the least accurate position-finding method but the essential foundation for more advanced chartwork.0:36
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