Module 10 - Chartwork
What Is Chartwork?
What you will learn
Use a disciplined chartwork routine that turns current source information and observations into a labelled, checkable navigation decision.
Chartwork is not neat drawing for its own sake. It is a record of what the navigator knows, assumes and intends, kept clear enough that another person can check the decision.
Day Skipper chartwork combines a suitable current chart with bearings, positions, speed, time, tidal stream and depth information. The RYA course scope includes chartwork, position fixing and plotting a course to steer because these skills support decisions aboard a small vessel in familiar waters.
Begin with source control: confirm the chart or display covers the area at a useful scale, read its datum and notes, and check the edition or update status. Then define the question before drawing. Work in true directions on the chart unless the exercise explicitly asks for magnetic or compass, keep units visible, and label every position or vector with its time and meaning.
Finish by asking whether the answer is operationally safe. Check the route against hazards, depth, clearance, traffic and the assumptions behind the plot. A precise-looking line can still be wrong because the source, feature, time, unit or correction was wrong. Training-chart examples in this module are fictional and must never be used for navigation.
Make the working auditable
A crew member hands you a tidy route plot but cannot say which tidal hour, speed or chart edition was used.
1. Stop before trusting the line
A clean plot without traceable inputs is not a defensible navigation plan.
2. Recover the inputs
Record the chart source, start time, speed, tidal set and drift, bearing reference and any leeway assumption.
3. Rebuild and challenge
Repeat the construction, then compare it with hazards, depth and an independent position or route check.
Sense check: Someone who did not draw the plot should be able to explain what every line and number represents.
Common mistake or limitation
- Accuracy of drawing cannot compensate for a wrong chart, time, datum or tidal input.
- An unlabelled bearing such as 085 is ambiguous; write 085°T, 085°M or 085°C as appropriate.
Recap
- Chartwork records evidence, assumptions and a decision.
- Source checks and labels make the working reviewable.
- A safe answer includes a hazard and uncertainty check, not only a measured course.
Optional quick check
Section 1 of 7
Which feature makes a chartwork answer most useful to the skipper?
Continue studying Chartwork
This public lesson is part of Revision Module 10. Full revision access adds the guided Learn, Practise and Test flow, flashcards and revision progress.