Grandes Marées: France Tides
Tide times, and why they are
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
The next king tide is in the app, free, along with the reason it is one. The sky on screen is the real sky above your port, this minute.
A tide app that explains the tide.
Any app will give you the time of the next low tide. This one also gives you something to say about it: why that coefficient, why the tides run so high in September, why the sea comes back faster than anyone expects. Enough to carry a whole dinner, and to hold forth over Monday's coffee. Sixty entries, thirty-six diagrams, three levels of reading, from a text you read aloud with a child to the astronomical calculation. All of it free.
THE SKY ABOVE YOUR PORT, THIS MINUTE
The screen is not decoration: it is the real sky above the port you are looking at, at the time it is. The sun rises and sets at its own hour, the moon climbs at tonight's phase, and the water reflects both. At night the screen is brightest when the moon is full — which is to say when the tides are strongest.
THE COEFFICIENT, AND WHY IT IS WHAT IT IS
France measures the strength of a tide with a number from 20 to 120, the coefficient. You will not find it in British or American tide tables, and no other app explains it. This one says why it is what it is: full moon two days ago, Moon at perigee, close to the equinox. It is never the moon phase alone. Next time someone asks what a coefficient of 95 means, you will not have to say "er, a big one". You will say why.
YOU WILL BECOME INSUFFERABLE AT THE PUB
Touch the sky, the time of the next tide or the coefficient, and they explain themselves. Three chapters — rhythm, strength, light — and three registers side by side: "To read with a child", "To understand", "To go further". Each entry names what it simplified, and links to the one that corrects it.
The whole explanatory space is free, in all three registers. We do not sell understanding.
FREE
• Tide times and heights, every day, in every port
• Today's coefficient and its cause
• The sky, the curve, the next king tide
• The entire explanatory space, diagrams included
• English and French
WHAT THE ONE-OFF PURCHASE UNLOCKS
• Every king tide of the next six months, as a diary
• Monthly coefficients, month after month
• Low-tide windows on YOUR terms — you set the minimum coefficient and the window that suits you; the app does not decide for you
• The lunar calendar
• Notifications, before a tide and before a king tide
• Home screen and lock screen widgets, with the real sky and the real curve
Bought once, yours for good. Never a subscription.
IT ASKS NOTHING OF YOU
No account. No advertising. No data collection. No network request while it runs: everything is computed on your phone, including the position of the sun and the moon. Only the purchase talks to the store. The app works entirely in airplane mode, at the end of a pier with no signal.
THE PORTS
86 ports: the whole of France's Atlantic coast, the Channel and the North Sea. If you allow it, the app suggests the nearest port — computed locally, your position never leaves the device.
HOW ACCURATE, HONESTLY
Predictions are computed from official harmonic constants and have been checked against published predictions. The order of magnitude is about ten minutes, and the app itself explains where and why it can be wrong — the Seine estuary, wind, pressure. One whole entry is devoted to what the screen makes beautiful and what it never fakes.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Grandes Marées now has its App Store page in English.
Nothing changes in the app itself: it has been fully bilingual from the start, French and English.
The developer, LBA Conseil, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- LBA Conseil
- Size
- 23 MB
- Category
- Weather
- Compatibility
Requires iOS 16.0 or later.
- iPhone
Requires iOS 16.0 or later. - Mac
Requires macOS 13.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English and French
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Grandes Marées: France Tides $3.99
- Copyright
- © 2026 - LBA Conseil