The Alderney Race is the gate that catches out more cross-Channel sailors than any other, and it does so because the figures are simply outside most people's experience. The French call it the Raz Blanchard, and it runs between the island of Alderney and Cap de la Hague at the northwestern tip of the Cotentin peninsula. The whole flow of water funnelling between the cape and the island accelerates into a strait that, on the biggest tides, runs faster than almost anywhere in the British Isles. Get the timing right and you are flushed through at speed with the kettle on. Get it wrong and you can find yourself stationary over breaking overfalls with the boat going sideways.
I have crossed it both north and south, on neaps and near springs, and the lesson is always the same: the Race rewards arithmetic and punishes optimism.
The streams that make it famous
The Race can run up to about 9 or 10 knots on a big spring, and during equinoctial tides figures approaching 12 knots have been recorded. Those are not numbers you push against. Even on an average tide a yacht making 6 knots through the water can be carried backwards if it arrives at the wrong hour, which is exactly how boats end up trapped in the overfalls.
This puts the Alderney Race in the same category of seriousness as the western Brittany gates, and the planning discipline is identical to the raz de sein timing approach: reference everything to a known high water, find slack, and refuse the gate when wind and tide oppose.
Timing on HW Dover
The Race is timed off High Water Dover, not Brest, because most boats crossing here come from the Solent, Poole or the eastern Channel. Slack water at the Race falls roughly around HW Dover and again about five hours later, with the streams turning hard either side. Going south, the practical aim is to arrive at the Race about 40 minutes before HW Dover, which sets you up to be carried through on the start of the south-going stream rather than fighting the last of the north-going.
Pilot books quote the slack differently depending on which reference port they use, with some citing HW St Helier plus 4 hours, so the sensible habit is to work it from the tidal stream atlas for your exact date rather than a remembered rule of thumb. If you have planned the raz blanchard alderney race tides before, the method will feel familiar, and the worked timings there are a useful cross-reference.
The two routes through
There is more than one way to take the Race, and the choice depends on your boat speed and your nerve.
The deep-water route runs through the middle of the strait, where the stream is strongest and so is the help when the tide is fair. This is the fast option and the one most yachts use, lining up to be in the strongest water exactly when it sets the way you want to go.
The inshore route hugs the Cotentin coast inside the worst of the stream, passing close to Goury and the Cap de la Hague lighthouse, where there is a small drying harbour you can duck into in trouble. The inshore eddies can give you a foul stream when the main race is fair, so it is a tactical option rather than an easier one, and it demands close attention to the rocks off the cape. The anchorage at Goury under the cape is a recognised waiting spot, and the realities of holding there are covered in the cap de la hague cotentin tides notes.
Why wind against tide is the killer
As at every tidal race, the danger is not the stream alone but wind opposing it. A fresh northerly or northeasterly over a strong north-going Race builds steep, breaking, dangerous seas, and the overfalls off the cape stand up into a genuine hazard for a small boat. The combination of a high coefficient and wind against the tide is the textbook trap, and the textbook answer is to wait.
My rule for the Race is the same as for the Brittany gates: a settled forecast, an honest look at the strength of tide for the day, and no crossing if wind and stream are set to fight. Cherbourg to the east and the Channel Islands to the west both give you comfortable places to sit out a poor window, and a day's delay is nothing against the alternative.
Linking it into a passage
For boats heading south from England into Normandy and Brittany, the Race is the first serious tidal gate of the trip. A common plan is to leave the Solent or Poole, cross overnight, and time the arrival at the Race for the slack before the south-going stream, carrying it on toward Cherbourg, Saint-Vaast or the Channel Islands. From there the route opens into the wider north brittany cruising guide grounds, with Saint-Malo and the Rance within a comfortable hop.
The Race is also the natural stepping stone for a Channel Islands cruise, and the timing logic ties directly into the cherbourg to channel islands passage plan if you are working that route.
A worked example, southbound
To make the timing concrete, here is the shape of a southbound crossing the way I run it. Say HW Dover falls at 1400 on the day. I want to be at the Race about 40 minutes before, so around 1320, to catch the turn to the south-going stream. Working back from there, a yacht making 6 knots over the ground needs to leave the Solent or Poole the previous evening for an overnight passage, arriving off the Casquets in the small hours and timing the last few miles to hit the Race at 1320.
The trick is that the stream does the heavy lifting once you are in it. Arrive on time and the south-going flood, building from slack, can add several knots to your speed over the ground, flushing you down toward Cherbourg or the Channel Islands in a fraction of the time it would otherwise take. Arrive an hour late and the same water is now running hard against you, and a 6-knot boat simply stops, or worse, goes backwards over the overfalls. There is no middle ground here, which is exactly why the 40-minutes-before-HW-Dover figure is worth committing to memory.
I always build slack into the plan for the unexpected: a calm patch that slows the boat overnight, a foul tide on the approach, a course made good that is not quite what the plot promised. If I am going to be more than half an hour late at the Race, I would rather heave to or stand off and wait for the next favourable window than push on into a foul stream.
Reading the water as you arrive
For all the arithmetic, the final check is your own eyes. As you close the Race, look at the state of the overfalls. On a fair, settled day with the stream just turning, the water is lumpy but orderly. If you can see ranks of breaking, standing seas where the chart shows the worst of the race, that is the sign that wind and tide are fighting, and it is the moment to reconsider regardless of what the printed slack time says.
The overfalls off the Cap de la Hague are notorious for building faster than the open Channel forecast suggests, because the cape funnels both wind and tide. I treat a deteriorating sea state as the deciding vote. The plot gets me to the right place at the right time, but the water in front of the bow has the final say.
The crossing in five checks
Before I commit to the Alderney Race I run the same short list, and it has kept me out of the overfalls every time.
- The HW Dover time and the slack windows worked off it.
- The strength of tide for the day, with the worst springs treated as a hard test.
- The wind direction against the stream I will carry, with opposition a reason to wait.
- The choice of deep-water or inshore route for my boat speed and conditions.
- A bolthole identified in advance, whether Goury, Cherbourg or the islands.
Do that and the Alderney Race becomes a fast, exhilarating, well-judged passage rather than the trap that fills the forum threads. It is one of the most powerful pieces of water in the Channel, and it answers entirely to the boat that arrives on time.
