Essential Chart Work - Estimated Position - RYA Yachtmaster Theory Training
14 February 2024 · 3 min · 934 views
What this video covers
Dead reckoning extended with a tidal stream correction produces an estimated position (EP) — the core technique demonstrated here for RYA Yachtmaster theory.0:28 Starting from a known dead reckoning position, the method adds a tidal vector: in the worked example, a 1.5-knot tidal stream running 118° true over one hour displaces the boat 1.5 nautical miles along that bearing.Watch A plotter aligns the tidal vector to the chart's north lines, dividers set to 1.5 nm mark the endpoint along that line, and the resulting EP is marked with a triangle, a centre dot, the time (1710), and the log reading (16.5, up from 10.0 after 6.5 nm travelled).1:26 Chart notation conventions are explicit: three arrows on the tidal vector, one arrow on the water track.3:03 The technique applies specifically to tidal waters; non-tidal dead reckoning omits the vector step entirely.0:28 Accurate EP plotting requires keeping tidal course in true degrees throughout — no magnetic conversion needed before drawing it on the chart.1:23
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