Preparing "exploration"
For river exploration, motorboats are largely to their advantage thanks to their very reduced draught. In sailing boats, it's a different story, as the keel adds a challenge. You will have to be able to guess the path of the river bed and avoid going up the bottom to avoid leaving a furrow in the mud.
However, many rivers are suitable for sailing. Some allow it only at high tide, while others are accessible at all times. So in preparing to "explore" the chosen river, one will first consider the navigability of the river and the distance over which one can enter at any time, and then compare this with low tide. This small study will help organize the navigation.
Before entering a river, it will be necessary to study the available documents, paper maps and nautical guides. A comparison with the possible cartography of the river bank may reveal a certain imprecision, or even a lack of information beyond the first stretches of the river.
Do not hesitate to consult the web which is full of cartographic resources, we think of Google Earth, but also the Shom site which allows a consultation of its most precise maps.
Depending on the scale of the map, the river L'Aven may seem impassable, so study the maps and sailing instructions carefully. On the nautical charts, the yellow areas represent the land, the green portions emerge at low tide by coefficient 120 and the blue portions are in water even at low tide.
If the river dries up completely at low tide, then a round trip will be necessary around the time of the MP. To estimate the travel time it is necessary to integrate the current and not to overestimate the surface speed. One goes up a river to stroll, then there is no reason to exceed 3 knots.
We can also choose to beached during the tide. For example, the Aven river dries up completely at low tide. Even with a keelboat, arriving at Pont-Aven at high tide, one can spend a very pleasant night stranding along the quays of the painters' city before leaving the next day.
