Free chartwork workbench

Plot an estimated position, one vector at a time

A dead-reckoning position advances course and distance through the water. An estimated position then applies estimated effects such as leeway and tidal set and drift. Change each input, inspect the fictional plot and keep the assumptions visible.

Study position work

Fictional plotting inputs

Build the estimate

Positive leeway is plotted to starboard of the course; negative leeway is plotted to port. Decide the correct side from the fictional wind effect before entering it.

Worked result

DR, tide and EP

DR
045°T · 5.00 M
Tide vector
120°T · 1.50 M
EP from start
064°T · 5.69 M
Made good
5.69 kn
Estimated position vector plotA fictional chartwork plot showing the dead reckoning vector, leeway-adjusted movement, tidal vector and resulting estimated position.NEP
  • DR
  • Through water + leeway
  • Tidal set and drift

Tidal vector distance 1.50 nautical miles.

  1. 1. Plot DR5.0 kn × 1.00 h = 5.00 M on 045°T.
  2. 2. Allow leewayMove the through-water track to 050°T for this teaching scenario.
  3. 3. Add tide1.5 kn × 1.00 h = 1.50 M towards 120°T.

How to use the result

  1. 1. Start from evidence. Use a known position and a recorded time.
  2. 2. Plot the DR. Advance the course steered by distance through the water.
  3. 3. Apply estimated effects. Plot leeway on the correct side and tidal movement in the direction of set.
  4. 4. Label and challenge it. Mark the EP and time, then compare it with independent position evidence when available.

Free printable

Course to steer and leeway worksheet

A structured plotting sheet for desired ground track, tidal vector, water track, leeway, variation, deviation, and the final compass course.

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Sources and factual review

Reviewed 12 August 2026. The teaching model follows the published RYA Day Skipper position-fixing and course-to-steer scope and the IMO principle that voyage plans must be monitored against reliable position evidence.