BetaNew calculation of the times
We are testing a new way of working out the crossing times. Try it in this browser and tell us whether it matches what you see on the spot.
What changes
Until now, the times have come from the predictions of WorldTides, a worldwide tide forecasting service.
The new calculation predicts the tide itself, from four years of readings from the tide gauges of the Shom, the French Navy's hydrographic service: the one in Roscoff, close by, for the water height at the crossing, and the one in Brest for the coefficients, worked out the Shom's way.
Its times can differ by a few minutes from the usual calculation's: that is exactly what we want to check with you.
Good to know
The new calculation only applies in this browser, and the people you send a link to stay on the usual calculation. In the Android app, it is turned on from the About screen.
A strip at the top of the pages reminds you it is on. You can go back to the usual calculation at any time, from that strip or from this page.
Either way, the times are a guide: leave a margin of about 30 minutes and don't set off if water reaches the road.
Data: Roscoff and Brest tide gauges, Shom (REFMAR), reused under the Licence Ouverte 2.0: refmar.shom.fr