Module 14 - Passage Planning
Weather strategy for a coastal passage
What you will learn
Define a route-specific weather window, compare independent and time-bounded evidence, and tie forecast or observed change to early passage decisions.
A weather window is not a low wind number. It is the period when expected conditions fit the route, tide, vessel, crew, arrival and fallback with enough uncertainty margin.
Define the acceptable weather before choosing a favourable forecast. Consider wind against tide, exposed headlands, fetch, sea state, visibility, rain, temperature, harbour entry, darkness, seasickness and crew capacity. A condition inside the yacht's nominal limit can still be unsuitable at a lee shore or after an exhausting night leg.
Use current relevant official marine forecasts and warnings with their issue time, valid period and area. Compare the Shipping Forecast, Inshore Waters Forecast, coastal observations, pressure and cloud trend, NAVTEX or other maritime safety information available for the route. Several apps may use the same model, so agreement is not automatically independent confirmation.
During the passage, compare observations and updates with the expected sequence. Set review points and observable triggers before departure: reef before exposure, hold before the headland, choose the refuge by its latest decision time, or delay the arrival. Waiting, shortening and diverting are normal outcomes when the combined evidence leaves too little margin.
| Evidence | Route question | Decision it can change |
|---|---|---|
| Issue and validity | Is it current for the headland and arrival times? | Depart, delay or obtain a newer issue |
| Wind, tide and sea | Where will direction, stream, fetch and exposure combine? | Timing, reef, route or sea-room margin |
| Visibility and rain | Which navigation and lookout stage gains workload? | Watch support, speed, pilotage or refuge |
| Observed trend | Is reality following the expected sequence? | Continue, hold, shorten or divert |
Tie forecast language to the route
The latest inshore forecast is southwest 4 or 5, increasing 6 soon, rain and moderate or poor visibility. The headland stream will oppose the wind and the destination is exposed to southwest seas.
1. Anchor time and area
Confirm issue, validity, warnings and when 'soon' reaches the headland and arrival legs.
2. Map exposure
Relate direction and force to the opposing stream, sea room, visibility and harbour approach.
3. Set triggers
Name an earlier reef, headland hold, refuge deadline and no-go condition before departure.
4. Compare reality
Use updated forecasts, pressure, cloud, visibility, wind and sea to test the expected sequence.
Sense check: Three apps showing the same model do not provide three independent forecasts, and Force 6 does not create one universal yacht response.
Common mistake or limitation
- Choosing a forecast because its headline number is favourable without checking issue, validity, area or warnings.
- Counting forecast apps instead of identifying common data and genuinely different evidence.
- Waiting until conditions exceed a limit before deciding where to reef, hold, shorten or divert.
Recap
- Define a weather window from the route, vessel, crew and alternatives before selecting a forecast.
- Use current official evidence and understand whether apparently different sources are independent.
- Tie review points and observable changes to early action while the fallback remains open.
Optional quick check
Section 9 of 10
What makes the forecast a usable weather window for this passage?
Sources and factual review
Reviewed 2 September 2026 - Compass Revision editorial review.
Build a weather-aware passage plan
The passage-planning module joins weather, tidal gates, pilotage, watchkeeping, contingencies and monitoring.