Passage Planning Fundamentals
A passage plan is not a piece of bureaucracy; it is the difference between arriving at an unfamiliar harbour entrance with the tide under you and daylight on the leading marks, or arriving in the dark against a four-knot ebb. The International Maritime Organization formalised the process in Resolution A.893(21) as four stages — appraisal, planning, execution and monitoring — and the beauty of that framework is that it scales. The skipper of a 9-metre cruiser planning a 25-mile hop across Lyme Bay uses exactly the same logic as the navigator of a container ship routing from Rotterdam to Singapore. What changes is the depth of detail, never the structure.
Stage one: appraisal, or gathering everything that matters
Appraisal means assembling all relevant information before a single line goes on the chart. For a coastal passage that includes corrected charts at usable scales, the relevant pilot book or cruising guide, tide tables and tidal stream atlases, and at least two independent weather forecasts. Check the Notices to Mariners for your area — buoyage gets moved, lights go unlit, and firing ranges open without much fanfare. Note your vessel's limitations honestly: draught, air draught for bridges, fuel range under power, and the crew's real experience level. A passage that is trivial for three watch-keepers can be punishing for a couple with a toddler aboard. Write down the constraints now, because every later decision flows from them.
Stage two: laying off the route
Now plot the route, working from small-scale planning charts down to large-scale approach charts. Identify waypoints at every alteration of course and give each one a name and number that the whole crew can use. For each leg, note the course to steer, the distance, and the expected speed over ground once tidal stream is applied. Mark no-go areas: drying banks, traffic separation schemes you may not enter, restricted zones. Draw clearing bearings off prominent features — a lighthouse, a headland, a conspicuous tower — so that you can verify at a glance that you are outside danger even if the chartplotter dies. The finished route should answer one question instantly: where must the boat be, and when?
Tides and tidal gates: the timetable of the sea
In tidal waters the stream often matters more than the wind. A six-hour passage through the Alderney Race or the Sound of Islay is comfortable with the stream and nearly impossible against it, with spring rates exceeding 8 knots in the Race. Work out your tidal gates first — the windows during which key points must be passed — and then build the departure time backwards from them. Use the tidal stream atlas to compute the net set and drift for each hour of the passage, and apply it as a course correction rather than chasing the track later. For estuary departures, check the height of tide over any bar or sill: many harbours, from Salcombe to Arbroath, are simply closed to a 1.8-metre draught at low water springs.
Weather strategy and the go/no-go decision
A forecast is a planning tool, not a promise. Compare at least two sources — a national met service synopsis and a model-driven product such as GRIB data — and pay attention to where they disagree, because disagreement signals uncertainty. Decide on limits before departure, when judgement is calm: for many cruising crews that might be a forecast maximum of force 5 on the nose, force 6 free, and no passage if visibility is expected below a mile near rocky coasts. Identify the stable weather window you need, add a margin of several hours, and resist the schedule pressure that has driven more boats onto rocks than any storm. The most useful sentence in passage planning is the one that says: we will review the decision at 0600.
Pilotage plans: the last mile is the hardest
Most groundings happen within sight of the destination, so prepare a separate pilotage plan for the approach and entry. Sketch the harbour entrance from the chart and pilot book, noting the sequence of buoys, the characteristics of each light, leading lines and their bearings, and the point at which you will call the marina or harbour office on VHF. Write the plan so it can be read aloud: after the green buoy QG, turn to 047 degrees on the leading marks, depth should not fall below 3 metres. Note tidal stream across the entrance — places like IJmuiden or La Rochelle can set you sideways fast — and decide in advance where you will abort to if the entrance is untenable.
Contingencies, boltholes and plan B
Every leg needs an answer to the question: what if? List the boltholes along the route — harbours, anchorages and bays that are accessible at your draught, at any state of tide, in the forecast wind direction. Note their distance and bearing from the track so the decision to divert takes seconds, not half an hour of frantic chartwork. Think through the specific failures that matter: engine failure in a tidal gate, a crew injury, fog closing in near a traffic scheme. For longer passages, plan fuel with a one-third reserve and identify the point of no return after which diverting back becomes harder than carrying on.
Execution and monitoring: making the plan live
Once underway, the plan becomes a checklist against reality. Log position, course, speed, wind and barometer every hour on coastal passages; the written record is your fallback if electronics fail and your evidence of trends — a barometer dropping 4 hPa in three hours is a louder warning than any app. Cross-check the chartplotter with independent methods: a depth contour, a visual bearing, a radar range. Brief the crew before departure on the route, the watch system, the boltholes and the abort criteria, so that any competent person aboard could take over the navigation. Update the plan as facts change, and record the decision when you deviate from it.
Scaling the framework from day sail to ocean leg
The four stages stretch effortlessly. For an afternoon sail, appraisal may take ten minutes and the pilotage plan is three lines on a notepad — but it exists. For an ocean leg, appraisal grows to include pilot charts of monthly wind roses, tropical cyclone seasons, and routing decisions like the timing of a trade-wind crossing from the Canaries to the Caribbean, roughly 2,700 nautical miles for which December departures remain the classic choice. Monitoring grows from hourly log entries to daily position reports, weather-routing downloads and rig checks. The constant is the habit of mind: gather facts, commit to a plan, then test it against the world every single watch.
Explore on the map
A plan begins with knowing what lies along your route, and that is exactly what our interactive map is for. Browse marinas, anchorages and cruising destinations along your intended track, check what facilities await you at the other end, and shortlist the boltholes in between. Open the map, trace your next passage, and start the appraisal stage today.