At times these can be akin to watching the bath water run out of a bath! The tidal Morbihan (an enclosed sea with a multitude of small islands) is roughly 10Nm long and an average of about 3Nm wide with the river Auray and other small tributaries draining into it. Twice a day all of the tidal flow has to pass through the ½ Nm wide narrow entrance near Port Navalo and at mid springs the flood or ebb can reach up to 8 knots! Additionally, because of variable seabed contours and the islands, considerable (and potentially dangerous) whirlpools can develop where different currents meet each other.
To illustrate the tidal complexity of this wonderful cruising area, HW at Vannes is around 2 hours different to HW at the Port Navalo entrance. On the chart navigation may look like a nightmare at first glance, but with careful tidal planning it becomes a beautiful and rewarding cruising area.
Nick Fletcher kindly provided the above report
Make sure you have some power on tap because this place is crazy when a spring tide is underway. No one is going in the direction they are pointing but almost cartoon-like sliding massively this way or that. The water gently boils up underneath you, you fly through rapid-like small overalls and a few metres from this some local will be quietly fishing in his small boat held entirely still by the various eddies.
Away from the mouth, things quieten down and further away again, you can find almost pond-like serenity. Don’t think Poole; this place is vast, the islands more numerous and larger. It is all on a very different scale. No shortage of rocks and oyster beds, so don’t wander off course too nonchalantly. Apparently, a 5 kt speed limit, but by dusk, this seems to vaguely increase, out of season and by locals, to about 40knts!
There are 3 “pontoon” arrangements, numerous anchorages, rivers, a lock to the medieval town of Vannes (superb, why bother going all the way to La Rochelle?).
In short, too much to put in short notes. Suffice to say, you could spend a lot of enjoyable days in this inland sea.
Gavin May kindly provided the above report – 2021