Module 10 - Chartwork
Dead Reckoning (DR) and Estimated Position (EP)
Active recall
Section 2 of 7
Explain the main idea from dead Reckoning (DR) and Estimated Position (EP) in your own words.
Dead Reckoning (DR) is the process of estimating your position based solely on your course steered and distance run through the water — without accounting for tidal stream or leeway. It gives a basic 'where we should be' position.
An Estimated Position (EP) builds on DR by adding estimated tidal stream and leeway. It is a fuller estimate, not a guarantee of accuracy: poor inputs can make it wrong. On the chart, mark a DR with a cross and 'DR', and an EP with a triangle and time.
Key points
- DR = course + distance only (no tide, no leeway)
- EP = DR plus estimated tidal stream and leeway; keep an uncertainty allowance
- DR marked: + with 'DR' and time
- EP marked: △ with time
- Always work from a known fix when possible
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