Lesson previewElectronics as Support1 section shown
Preview lesson
Electronics as Support
What you will learn
Use an electronic navigation display as one part of a checked navigation picture rather than as an unquestioned position or route authority.
Electronic navigation is valuable because it can combine position, route and movement information quickly. The skipper still has to understand the display, compare it with independent evidence and act when the screen and the outside world do not agree.
RYA guidance describes electronic systems as powerful tools for planning, executing and monitoring a passage, while requiring the navigator to confirm the plan, monitor the system and identify inaccurate information. A crisp boat symbol is a calculated position on selected chart data; screen precision does not prove that the position source, chart, settings or route is correct.
Build confidence from agreement between different kinds of evidence. Compare the displayed position and movement with the lookout, charted and observed marks, depth trend, expected time and track, compass information and traffic picture as appropriate. Two apps using the same device, GNSS source or chart data may share one failure and are not automatically independent checks.
Keep the lookout and control of the boat primary. Choose moments, roles and display settings that limit heads-down time. If important evidence conflicts, protect sea room and time first—slow, hold, stop or move to safer water where appropriate—then identify which assumption, input or observation is wrong.
Electronic-navigation confidence loop
- 1UnderstandKnown inputs
Confirm chart, route, source, units, offsets, alarms and power.
- 2ReadScreen claim
Interpret position, heading, COG/SOG, vector and depth correctly.
- 3Cross-checkOutside reality
Compare lookout, marks, depth, time, compass and traffic evidence.
- 4DecideSafe action
Continue only with agreement; create margin when evidence conflicts.
Evidence agrees
Continue the checked plan while lookout and monitoring remain active.
Evidence conflicts
Slow, hold or move to safer water as appropriate, then verify the plan, source, settings and observations.
Confidence comes from understood inputs and agreeing evidence, not from the apparent precision of a boat symbol. A disagreement is a decision cue, not an invitation to keep following the line.
| Display claim | Independent evidence | Decision question |
|---|---|---|
| The boat is in the channel | Leading line, buoy sequence, visual bearings and depth trend | Do position, surroundings and water depth form one credible picture? |
| The route is clear | Current chart detail, local information, hazards, restrictions and safe margins | Was every leg inspected rather than merely accepted? |
| Progress is on plan | Expected time, cross-track tendency, heading, COG/SOG and observed movement | Is the boat moving where the plan requires, with margin ahead? |
| The system is healthy | Power, source status, accuracy indication, update status and another usable method | Can the navigator recognise and manage degraded or lost information? |
When the screen and the channel disagree
A small boat's plotter symbol appears on the planned side of a narrow channel, but the leading marks are opening the wrong way and the depth is reducing earlier than expected.
1. Protect the boat
Reduce speed or move to the pre-planned safe state while maintaining lookout and control; do not wait for the display to admit an error.
2. Compare evidence
Check the visual alignment, buoy sequence, depth trend, expected time and an appropriate independent position method against the plan.
3. Check the system
Confirm the position source, chart coverage, scale, layers, datum or offsets and whether the active route is the intended one.
4. Decide from the safe picture
Continue only after the mismatch is explained and the route retains margin; otherwise hold, divert, return or seek help as the real situation requires.
Sense check: If the response is simply to zoom in and trust the more precise-looking symbol, the navigation picture has not been independently checked.
Common mistake or limitation
- Treating a high-resolution display or small position circle as proof of exact real-world position.
- Calling a second app on the same phone and power source an independent backup.
- Looking down to resolve a display problem while lookout, traffic and boat control deteriorate.
Recap
- Electronics enhance planning and monitoring; they do not remove the navigator's decision role.
- Agreement between independent evidence builds confidence, while common-source agreement can be misleading.
- When important cues conflict, protect the boat before diagnosing the display.
Optional quick check
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