Module 14 - Passage Planning
Navigational Records and Passage Logbook Entries
What you will learn
Keep a proportionate, risk-based navigation record that supports monitoring, communicates material changes and helps reconstruct progress if an electronic system fails.
A useful log records evidence and decisions at the moments they matter. It does not create accuracy by itself, and one fixed interval is not suitable for every leg.
Plan what will be recorded and how often before departure. For a small yacht, the method can be concise, but it should support the passage risks: time; position with source and quality; course or heading as relevant; speed or log reading; depth where useful; wind, pressure, weather and visibility; and significant changes in sail, engine, crew, communications, route, timing or destination.
Choose intervals from the consequences of losing track. Stable open water may justify a longer regular interval than pilotage, restricted visibility, nearby hazards or a tidal gate. Record at material events as well as the planned interval. There is no universal hourly rule in the reviewed IMO, RYA and MCA small-craft guidance; the plan should state the method and frequency needed for that risk.
A record supports dead reckoning and reconstruction if GNSS or a display fails, but it is not an independent fix unless the recorded evidence was independent. Write the source—such as GNSS, visual fix, transit, depth contour or radar range—and note unexplained disagreement rather than averaging it away. When the plan changes, record the decision and make sure the crew is following the revised version.
Worked example
Fictional log extract approaching a tidal decision point. The purpose is to show evidence, comparison and action rather than a decorative list of numbers.
- 11215: departed Bayhaven; GNSS position cross-checked with harbour transit; log 0.0; SW 4; 1014 hPa; gate plan 1600 with 45-minute contingency.
- 21315: visual fix agrees with DR; log 5.0; expected progress; forecast and crew state unchanged.
- 31440: GNSS and depth-supported DR disagree; reduced speed and preserved sea room while obtaining another independent fix.
- 41450: visibility worsening and revised gate ETA 1545; recorded diversion decision, revised route and crew brief before the alternative decision point closed.
Sense check: The extract records why the plan changed. A bare list of positions would not show the lost margin, conflicting evidence or accepted response.
| Record | Example detail | Decision value |
|---|---|---|
| Time and position | Source, quality and any disagreement | Reconstructs progress and uncertainty |
| Course, speed or log | Label heading, track or course correctly | Supports DR, ETA and change detection |
| Weather and depth | Wind, pressure, visibility, sea and relevant soundings | Tests forecast and safe-water assumptions |
| Significant event | Sail, engine, crew, communications or equipment change | Shows why workload or capability changed |
| Plan amendment | Decision, reason, revised route or limit and briefing | Keeps execution aligned with the accepted plan |
Choose a risk-based record
The passage moves from open water into a narrow, tide-constrained approach with background lights and a nearby shoal.
1. Open water
Use the planned regular interval and record material changes that affect route, ETA, weather or crew.
2. Before the approach
Record a reliable starting position, current ETA, depth expectation, weather and the agreed abort limit.
3. Inside pilotage
Increase the frequency and use the visual, depth and electronic checks named in the pilotage plan.
4. After a change
Record the revised decision and brief so the actual route, log and crew understanding remain aligned.
Sense check: The record becomes more frequent because the consequences and pace of change increase, not because a universal clock interval has elapsed.
Common mistake or limitation
- Writing positions without their source, making GNSS, DR and an independent fix look equally reliable.
- Using one fixed interval through open water and constrained pilotage regardless of how quickly danger or uncertainty can develop.
- Recording a diversion after the event but not updating the working plan or briefing the crew when the decision is made.
Recap
- Choose the log method and frequency for the risk of each passage leg.
- Record the source and quality of position evidence, not just a coordinate.
- Log and brief material plan changes so the record supports the current decision.
Optional quick check
Section 6 of 6
What is the best logging response on entering a constrained pilotage leg?
Common questions
What should be recorded in a navigation log?
Record time, source-labelled position evidence, course or heading, speed or log, relevant depth, weather and visibility, significant vessel or crew events, and material changes to route, timing or destination.
How often should a passage log be updated?
Choose a planned interval and method for the navigational risk, then also record material events. Constrained pilotage, restricted visibility, nearby hazards and tidal gates need more frequent evidence than stable open water.
Why keep a log if you have GNSS?
A log preserves progress, assumptions and decisions, supports DR and reconstruction after failure, and exposes disagreement—but only genuinely independent observations provide an independent position check.
Keep revising this topic
Sources and factual review
Reviewed 19 August 2026 - Day Skipper Revision.
Connect records to passage monitoring
Good records support the monitor stage of passage planning and make navigation decisions easier to review.