Sailing

Cruising between Brittany and Normandy: planning the tides and currents

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I rented a Dufour 335 with some friends last week to spend a few days cruising around Saint-Malo. By the way if you are planning such a trip, I really recommend Naviloc for their professionalism.

For those who do not know the area, West Normandy and East Brittany (especially Granville and Chausey) have some of the largest tides in the world: up to 12 meters.

So if you are sailing in this area, especially with a boat with more than 1.5 meters of draft, you definitely need to watch the tides carefully.

Planning the tides

The calculation for the heights and the time at each marina can be done manually with the usual documentation but the SHOM provides very handy tools such as the height hour by hour and the hours for a specific height.
The translation is currently incomplete but you can go to http://www.shom.fr/en/services/tidal-predictions/predictions-en-ligne/

SHOM Tides Forecast Screenshot

The default is Brest so you need to click on Choix (choice), then select the marina you are interested in:

  • choose Autre port de la même zone (other marinas in the same area) to select a marina around Brest or
  • choose Autre zone (other area) to first select another area in France first.

Once you have selected the marina, select either:

  • La hauteur d’eau heure par heure (3) to get a table of the tidal height hour per hour

SHOM Tides Forecast: Height per Hour

  • Heures pour une hauteur d’eau (4) to get the time of the day where the water is below a given height (specified in the field “hauteur”, in centimeters)

SHOM Tides Forecast: Hours for a Height

Planning the road and the currents

All the up to date maps and currents are freely available online on http://data.shom.fr/

Again the translation is not complete so you need to first select RasterMarine (or RasterENC for the vectorial) under Charts in the Catalog menu to make the charts appear.

To add the currents, select the time around high tide under Tidal Currents in the Catalog menu.

SHOM Charts and Currents

A quick help for the translation:

  • Pleine Mer = High Tide
  • Vive Eau = Spring Tide
  • Morte Eau = Neap Tide
  • Noeuds = Knots

One last tip: the Tools icon on the left allows you to:

  • display latitudes and longitudes by checking Afficher le graticule
  • compute a road length after a click on Démarrer le calcul, under Distance Computation

 

These tools saved me a few hours of planning so do not hesitate to contact me if you need any assistance to use them!

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