Course modules
Start with the free revision module, then unlock all practice and revision features.
Getting started
Work through the revision path in order, then use each module's Practise and Test steps and flashcard pass to turn reading into recall.
2 modules are open now. Start with the teaching-first lesson beside this introduction; placement remains optional.
2 modules
Open another available module when you are ready.
Module 1
Not startedSource-reviewed pathway from prerequisite knowledge through recognised study, qualifying passage, on-board evidence, examination and exact award route.
4 topics · Learn, Practise and Test
Module 2
Not startedSource-reviewed coordinate and time chain from body GP, GHA and declination through LHA, Aries and SHA, chronometer correction, UTC date and reconstructable sight records.
4 topics · Learn, Practise and Test
8 modules
Preview a representative lesson, then unlock full revision access when you are ready to continue.
Module 3
Premium lockedA teaching-first correction chain from timed sextant altitude Hs through index correction, dip and body-specific tables to observed altitude Ho, with practical evidence limits.
8 topics · Learn, Practise and Test
Module 4
Premium lockedA source-reviewed Ho–Hc intercept chain, assumed-position discipline, towards/away plotting, one-line evidence limits, and Sun-run-Sun transfer with uncertainty.
7 topics · Learn, Practise and Test
Module 5
Premium lockedPlan and bracket Sun upper transit, reduce corrected altitude to signed latitude, and audit a Sun-run-meridian position.
6 topics · Learn, Practise and Test
Module 6
Premium lockedBuild a traceable same-time celestial bearing check, calculate signed compass error and separate current variation from heading-specific deviation.
6 topics · Learn, Practise and Test
Module 7
Premium lockedEvidence-led route and season choice, fatigue-resilient watches, resource runway, vessel repair readiness, communications, landfall, and recorded plan changes.
4 topics · Learn, Practise and Test
Module 8
Premium lockedGlobal circulation, moving wind regimes, pressure tendency, ITCZ and monsoon evidence, climatology, forecasts, warnings and onboard weather review.
4 topics · Learn, Practise and Test
Module 9
Premium lockedTropical-cyclone formation limits, basin warning sources, centre-track and wind-extent evidence, hemisphere and motion reasoning, early avoidance, option expiry, and auditable handover.
6 topics · Learn, Practise and Test
Module 10
Premium lockedDegraded-navigation recovery from the last trusted state through dependency tracing, bad-data isolation, DR uncertainty, independent position evidence, power and watch continuity, and auditable handover.
7 topics · Learn, Practise and Test
Audio Challenge
Five spoken decisions with authored answers, reviewed explanations, and no microphone.
Audio revision is available. Listen to 10 short recaps alongside the modules.