At the southwestern end of the Cotentin, the Blanchard Raz is located between La Hague Point and the Channel Island of Alderney at the northern entrance to the Rout Passage.
The sailing instructions are clear about the Blanchard Raz, it is a very delicate passage in periods of heavy water. Thus, sailors must be particularly careful about the tide times to use this passage.
A violent current to be negotiated with caution
In the middle of the passage of the Blanchard Raz, the flow current flows to the northeast. Its maximum strength is reached around the Cherbourg MP. The maximum power of the ebb and flow - which carries to the south-west corresponds to the BM of Cherbourg.
In the raz the reversal takes place approximately at the mid-tide Cherbourg hours. The strongest current is at the "La Foraine" buoy located about 1 mn SW from the La Hague lighthouse. The maximum speed of the flow varies from 6 to nearly 12 knots depending on the coefficient and time of the tide. The maximum speed of the ebb varies from 4 to 9 knots.
As we have seen in the article on raz the wind against the current will raise a very bad sea. So we'll calculate an arrival time at the raz that corresponds to the slack.
If the passage is relatively long like the Blanchard Raz, the slack is not always enough.
So we have to choose another strategy. As far as possible, the tidal wave should be entered at the slack water preceding the current in the same direction as the wind. So when the current recovers, it will be weak and will not lift a breaking sea.
Some recommendations for the passage of the Blanchard Raz:
- It is essential to consult and scrupulously respect the sailing instructions (mandatory on board). The reference work is that of the shom: C2A-INA "France (north and west coasts): from the Belgian border to the tip of Penmarch". It is available from most ships or directly on the Shom website.
- We advise you to arrive during the day, as the area around Raz Blanchard is dotted with lockers.
- As far as possible, it is preferable to choose a small tidal coefficient and a moderate wind (unless you are experienced, avoid the passage with a wind above 25 knots)
- Pass to the slacker.
- If this is not possible, always choose wind and current in the same direction.
Good times to spend the Blanchard Raz
For a boat coming from the North and heading south:
By wind from NW to NE: Present in the raz 3 hours after the high sea of Cherbourg: slightly favourable current.
By wind from S to SW : To arrive in the raz 2 hours after the high sea of Cherbourg: slackens, therefore almost no current.
For a boat coming from the South and heading north:
By wind from NW to NE: Present in the raz 4 hours after the high seas of Cherbourg: slightly unfavourable current not raising a breaking sea, but slowing down the progress a little.
By wind from S to SW : Arrive in the raz 3 hours before the open sea of Cherbourg: it is time for the slack water.
Waiting areas in case of need
It is sometimes necessary to "delay" the passage of the Blanchard Raz, either because we are too early or simply late
Waiting area to reach the south: Anse Saint-Martin, beware of the Parmentiere rocks located at the entrance. In the bottom of the cove there is a sandy bottom between 3m and 4m.
Waiting area to reach the north: The approach to the port of Goury allows a waiting anchorage on a rocky bottom from 3 m to 5 m, consider using a rope.