Tidal Harbours

Make your way through French harbour gates and locks the easy way. Tidal Harbours lists every lock, gate, sill and drying harbour of the French Channel, the Atlantic coast, Belgium, Netherlands and the Channel Islands. For a lock or a gate harbour, it shows you the times for any day you like, easily. For a sill or a drying harbour, it shows when you can pass, from your boat's draught and from the heights of water computed from the local tide. WHAT IT DOES • Today's access windows, harbour by harbour, to the minute, for 187 harbours with a lock, gate or sill: read at a glance on your watch or on your phone's widget, without opening the app • The depth of water over the sill, worked out from YOUR draught and YOUR safety margin • The water under the keel, worked out from your draught, the tide, the day, the hour and the depth of the bottom • How long you stay aground, and when you float again • Tide tables with no limit in time for 186 reference points: high and low water, coefficients, ranges • How long you have left under the keel at anchor, and when the boat will touch. Set two draughts and let each anchorage remember which one applies • Every tidal harbour on the chart, with its openings at the hour you choose • The widget and the watch refresh on their own, so the next window is there when you look WHERE THE FIGURES COME FROM Every harbour was surveyed one by one. Sill levels come from the harbour authority or were checked against nautical charts. Lock times are copied from the calendars the harbours publish, and they are renewed every year. Where no times are published, the harbour's own rule is applied. The tide is worked out on the device, from a harmonic analysis over 145 constituents. Every tidal reference was computed from the official records of the French tide gauges and checked against the official tide tables of the naval hydrographic service over three full years. Our figures are verified by comparison with past predictions from the official tide tables. The small differences that remain are not hidden. EVERYTHING IS WORKED OUT ON BOARD No tide is ever downloaded. The app works with no signal at all, which is the only thing that matters at anchor. It creates no account, asks for no login, sets no tracker and carries no advertising library. It does know how to fetch and update lock calendars or harbour tides when they change. CAUTION Tidal Harbours is an aid to planning, not a nautical document. A calculation is not a guarantee: a lock can be shut, a rule can change mid-year, a gale can shift high water by half an hour. Always check with the official tide tables and the harbour office before you present yourself at a lock, a gate or a sill. Every harbour page carries its telephone number. Our tide calculations claim no certainty. Know how to check them. THE SUBSCRIPTION Three days' trial, then a yearly subscription. When it expires the app stays open: you keep the chart, the harbour pages, the levels and the numbers, but it no longer announces times or tides. Published times are updated harbour by harbour. Terms of Use: https://play.google.com/about/play-terms/ Privacy Policy: https://portsamaree.github.io/