Module 14 - Passage Planning
Extended Coastal and Offshore Passage Planning
What you will learn
Integrate fuel, water, stores, communications, shore contact, crew endurance and diversion strategy into a longer passage without relying on fixed percentage or reporting rules.
Longer passages compound uncertainty. Resources, people, communications and alternatives need calculated margins and explicit triggers, not folklore.
Break the passage into operational legs with expected time, exposure, gates, position checks, watch changes and refuge decisions. Test whether a delay on one leg defeats the next tidal gate, darkness assumption, crew-rest plan or alternative. A destination and refuge that fail under the same weather or timing constraint do not provide useful resilience.
Estimate usable fuel, water, food and energy from known consumption and realistic duration, then add a documented margin for credible delay, diversion, adverse current, extra engine use and unusable capacity. A rule of thirds may be a conservative operator heuristic, but it is not a universal substitute for the passage-specific calculation.
Leave a current plan with a trusted person ashore: vessel and crew details, route, destination, ETA, check-in method and an agreed escalation plan. RYA SafeTrx closed in 2026; RYA guidance still recommends telling someone where you are going and says a late-return concern can be raised by calling 999 and asking for the Coastguard. Agree when concern becomes overdue rather than teaching one arbitrary daily call rule.
Choose and test communications suited to route and coverage. Mobile service, maritime radio and satellite systems have different reach and purpose; no one method is guaranteed. A material delay, diversion, communications failure or crew problem should update the on-board plan and the person ashore while communication remains available.
Worked example
Fictional fuel model only: expected engine use is 5.5 hours at a measured 2.4 litres per hour. The skipper adds 6.8 litres for the route's adverse-current, manoeuvring and diversion scenarios. The 30-litre tank has 4 litres known to be unusable.
- 1Expected consumption: 5.5 h × 2.4 L/h = 13.2 L.
- 2Add the documented route contingency: 13.2 L + 6.8 L = 20.0 L required usable fuel.
- 3Available usable fuel: 30 L nominal − 4 L unusable = 26 L.
- 4Remaining buffer after the model: 26 L − 20 L = 6 L. Confirm that this satisfies the yacht's operating policy and latest route evidence.
Sense check: The multiplication, addition and usable-capacity subtraction agree. The figures are fictional and do not establish a reserve policy for another yacht.
| Longer-passage element | Plan before departure | Trigger for review |
|---|---|---|
| Fuel and energy | Known use, usable capacity, contingency and backup | Consumption, delay or system load exceeds model |
| Water and food | People, duration, weather, reserve and access underway | Delay, loss, sickness or higher use |
| Crew endurance | Competence, protected rest and arrival reserve | Repeated errors, seasickness or failed rest |
| Communications | Coverage, power, schedule and alternative method | Missed contact or route leaves coverage |
| Shore contact | Current route, ETA, check-ins and escalation | Delay, diversion, crew or communications change |
Make shore support actionable
The yacht diverts at 0230, the original mobile check-in area will be missed and the new ETA is four hours later.
1. Update aboard
Record the revised route, destination, ETA, resource model and monitoring triggers.
2. Update the crew
Re-brief watches, arrival roles, communications and rest plan for the new passage.
3. Update ashore
Send the new destination, ETA and next check-in while a suitable link is available.
4. Reset escalation
Confirm what the trusted person should do if the revised check-in is missed.
Sense check: A successful diversion can still create a false overdue alarm if the shore plan remains on the original route and ETA.
Common mistake or limitation
- Using nominal tank capacity or a thirds mnemonic without measured consumption, unusable fuel and route-specific contingency.
- Treating a shore contact as a data recipient without agreeing check-in tolerances and escalation actions.
- Assuming a communications device will cover the whole route without testing power, reach, set-up and backup.
Recap
- Calculate resources from known use and usable capacity, then document route-specific contingency.
- Agree a current shore plan, check-in tolerance and escalation rather than one universal schedule.
- Update resources, crew, communications and shore contact whenever the passage changes materially.
Optional quick check
Section 10 of 10
What is the sound use of a rule-of-thirds fuel policy?
Sources and factual review
Reviewed 2 September 2026 - Compass Revision editorial review.
Continue studying Passage Planning
This public lesson is part of Revision Module 14. Full revision access adds the guided Learn, Practise and Test flow, flashcards and revision progress.