The passage plan

Passage planning is not paperwork for its own sake — it is the law, and it applies to pleasure craft:

Prior to proceeding to sea, the master shall ensure that the intended voyage has been planned using the appropriate nautical charts and nautical publications for the area concerned, taking into account the guidelines and recommendations developed by the Organization.

The standard shape is Appraisal, Planning, Execution, Monitoring. Appraisal gathers the ingredients: charts and pilot bookspilot bookA guide book of harbours and coastlines with local directions.full glossary → for the whole route, tides and tidal gatestidal gateA place or time the tide controls — a bar, a sill, a race — passable only in its window.full glossary →, forecast, daylight, crew strength and the boat’s state. Planning turns them into the route: courses and distances leg by leg, the tidal arithmetic from this course, danger clearances, ports of refuge you could duck into if the day sours, and a departure time chosen so the gates and the daylight fall right — usually the tide picks your start time, not your alarm clock.

Execution and monitoring are the underway halves: fixes or position checks on a regular drumbeat, an EP carried forward between them, actuals versus plan (if the SOG says you will miss the gate, the time to know is now), and a log kept well enough to navigate from if the electronics die.

Two human items belong in every plan. Tell a responsible person ashore where you are going and when to worry — and what to do when they do (the Coastguard, with your boat’s description). And plan for the crew you actually have: seasickness, cold and inexperience shrink a crew fast; the plan that needed everyone on deck at hour ten was never a good plan. Fuel for a motor passage follows the same honesty: a third out, a third back, a third in reserve.

This app’s planner walks exactly this method — appraisal data from the almanac, leg-by-leg tidal arithmetic with the workings shown — so practise the thinking there before you do it for a real coastline.