As the English Channel is entered, and the
fairway narrows, the rotatory currents of the approach become gradually
more and more rectilinear. The rates of the currents in the fairway
vary with the width, and are greatest in the narrowest parts.
In the middle of the fairway, between Bill of Portland and Saint Catherine’s Point, on the English coast, and Cap de la Hague and Pointe de Barfleur, on the French coast, currents attain rates up to about 3.5 knots at springs. In the widest parts, currents seldom attain rates exceeding 2.5 knots at springs.
Although the surface current has a dominant NE and E directional set, it is influenced significantly by the wind, which is variable in direction during all seasons, although W winds predominate.
The prevailing direction of the North Atlantic current is therefore likely to be most in evidence after strong and long continued SW or W winds.
The time of HW changes rapidly along the French coast, and is about 6 hours later at Le Havre than at lle d’Ouessant. The time at which the tide turns usually differs considerably from the time of local HW. The flows, therefore, cannot be described as “flood” and “ebb”, and are usually termed E and W. However, it must be understood that the E current is that which runs up the Channel, from the Atlantic towards Dover Strait, and the W current that which runs down the Channel, from Dover
Strait towards the Atlantic.
The actual directions of the currents are reported to differ considerably from E or W. In the estuaries and rivers, currents are usually called the “incoming” and “outgoing” but may be referred to as flood and ebb. Among the Channel Islands, the times and directions of the flow differ greatly from those in the fairway of the English Channel. Therefore, care is required when approaching the above localities. The tidal flows at locations to the W and NW of Ile d’Ouessant are significantly affected by current due to the prevailing wind.
Extract from NGA / UKHO sailing directions documents
Manche - English Channel