Yachtmaster-level use of GNSS, chart plotters, electronic charts, radar, AIS, alarms, and backup navigation.
GNSS integrity, WGS84 datum, DOP, multipath, jamming, and spoofingChart plotter route checks, waypoint placement, and cross-track limitsENC, raster charts, update status, and display-scale risksRadar tuning, radar fixing, VRM/EBL, and parallel indexing
18 guided lessons · 24 practice questions · 25 flashcards
3 outcomes · self-guided revision
Explain yachtmaster-level use of GNSS, chart plotters, electronic charts, radar, AIS, alarms, and backup navigation.
Apply GNSS integrity, WGS84 datum, DOP, multipath, jamming, and spoofing to a realistic onboard situation.
Recall the core check: electronic systems support, not replace, navigation.
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Lesson summaries
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Electronic Navigation Mindset
Electronic navigation is an aid to navigation, not a separate standard of seamanship. A Yachtmaster-level navigator uses GNSS, chart plotters, radar, AIS, depth, log, compass, and visual...
Electronic systems support, not replace, navigation
GNSS positions are usually referenced to WGS84, but charts may have a different or imperfect datum. Modern UKHO charts are normally compatible, yet older charts, harbour plans, and some f...
A route plotted electronically must still be appraised like a paper route. Check the entire track at the largest practical scale, especially around waypoints, headlands, drying banks, ove...
Electronic charts are not all the same. Official Electronic Navigational Charts (ENCs) are vector charts designed for ECDIS and approved systems. Raster charts are scanned or image-based...
Electronic alarms are useful only if they are configured sensibly and understood by the crew. Cross-track error, depth, anchor, AIS CPA/TCPA, arrival, and guard-zone alarms can all reduce...
Radar performance depends on the set-up. Range scale, gain, sea clutter, rain clutter, tuning, heading alignment, and display mode all affect what you see. A poorly tuned radar may miss s...
Radar range is usually more accurate than radar bearing on a yacht set. A radar fix from two or more ranges to identifiable charted objects can be very reliable. Use variable range marker...
Radar range is often more accurate than radar bearing
Radar can show whether a contact is closing and whether the bearing is steady. A constant bearing with decreasing range indicates collision risk. MARPA or ARPA may calculate CPA and TCPA,...
Constant bearing and decreasing range means collision risk
AIS broadcasts a vessel's identity, position, course, speed, and other data. Plotters can calculate CPA and TCPA from AIS targets, making AIS extremely useful for identifying ships and pl...
A Yachtmaster passage plan should include what happens if the plotter, GNSS, radar, AIS, depth sounder, log, or charging system fails. The answer may be paper chartwork, backup handheld G...
Two displays are not necessarily two independent sources. A chart plotter, AIS overlay, DSC radio, tablet, and autopilot may all receive position from the same GNSS antenna or network. If...
Several screens may repeat one sensor and one error
Identify the source, power, network, and failure mode behind each value
A vector-chart display is a filtered view of a database. Safety depth, safety contour, shallow contour, deep contour, category layers, and scale determine which dangers are emphasised. Sm...
Derive display settings from draught, UKC, tide, squat, and uncertainty
Know how the fitted plotter selects and displays contours
A contact bears 045° relative at 6.0 NM. Three minutes later it still bears 045° relative but is at 5.0 NM. The near-constant relative bearing and decreasing range indicate collision risk...
One nautical mile closed in three minutes equals 20 kn relative closing speed
Five nautical miles at 20 kn gives a nominal 15-minute zero-range time
Restricted Visibility: Evidence, Rule 19 and Command
In or near restricted visibility, safe speed and a proper lookout are the starting conditions, not optional responses after a target appears. Have engines ready for immediate manoeuvre, d...
Rule 19 governs vessels not in sight in or near restricted visibility
Use safe speed, lookout, lights, signals, engines, radar, and position evidence together
Warning signs include an unexplained position jump, impossible course or speed, several vessels appearing displaced from radar echoes, a charted buoy shown on land, loss of time agreement...
A plausible display can still contain a false GNSS position
Protect sea room and disengage position-dependent automation first
Electronic Watch Handover and Configuration Control
A watchkeeper needs more than the active waypoint. Handover should cover the current fix and its evidence, course and speed, cross-track trend, next alteration, traffic and CPA concerns,...
Handover the evidence, limits, alarms, defects, and call-the-skipper triggers
Log route and sensor changes that alter the navigation picture
Electronic Navigation at Yachtmaster level is not just recall. The answer has to show command judgement, evidence quality, margin, and a fallback if the first plan stops being safe.
State the evidence you trust and the evidence you distrust.
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