Compass Work, Chartwork and Position Fixing
Variation, deviation, true and compass courses, chart maintenance, plotting, bearings, ranges, transits, DR and EP.
How to prepare for a Boatmasters' Licence
Use the actual area, vessel and operation to select the route, build Annex 8 or 9 underpinning knowledge, complete the required records and training, and rehearse practical handling on the relevant vessel.
Core concepts
Concept 1
Magnetic and gyro systems have different sources of error, checks and failure indications.
Exam cue: Label every direction as true, magnetic, compass or gyro.
Concept 2
Level 2 chartwork includes current publications, chart corrections, scale, symbols, plotting and the effect of set, drift and leeway.
Exam cue: Check edition, correction status, scale and symbols before using a chart.
Concept 3
A reliable fix uses sound geometry and timely observations; DR and EP retain uncertainty that grows with time.
Exam cue: Choose position lines that intersect at a useful angle and record their time.
Risk pitfalls and guardrails
Applying variation or deviation with the wrong sign.
Guardrail: Do not treat the aggregate 601-item study allocation as an official MCA paper or assume knowledge study replaces service, records, medical fitness, safety training or practical handling.
Plotting a bearing from an unverified compass or old observation.
Guardrail: Do not treat the aggregate 601-item study allocation as an official MCA paper or assume knowledge study replaces service, records, medical fitness, safety training or practical handling.
Treating a DR or GPS symbol as a guaranteed safe position.
Guardrail: Do not treat the aggregate 601-item study allocation as an official MCA paper or assume knowledge study replaces service, records, medical fitness, safety training or practical handling.
Memory anchors
True-Magnetic-Compass
Variation links true and magnetic; deviation links magnetic and compass.
Correct Chart
Edition and corrections matter before any precise plot.
Two Lines
Independent position lines with good geometry make a stronger fix.
Set and Drift
Current changes the track and distance made good.
Leeway
Wind can move the vessel sideways from the heading.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
A charted true course must be converted to a magnetic course for the vessel. Which angle accounts for the difference between true and magnetic north?
A vessel compass develops an error because of magnetic equipment fitted nearby. What is this vessel-specific error called?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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