Every boat heading between the English Channel and the Bay of Biscay has to get past the Pointe du Raz, the wild western tip of Brittany, and there are exactly two ways to do it. You can squeeze through the Raz de Sein, the narrow tidal gate between the mainland and the Ile de Sein, or you can stand well out to sea and go right round the Chaussee de Sein, the long reef that runs offshore from the island. One is short, fast and demands precise timing. The other is long, simple and demands patience. I have done both, and the choice is worth thinking through before you leave.
The inshore route: the Raz de Sein
The Raz is the classic Breton tidal gate. It is the strait between the La Vieille lighthouse on its mainland tower and the Ile de Sein, and it runs streams that reach up to 6 or 7 knots on a big spring. Through that gap the tide builds steep, dangerous overfalls when wind opposes the stream, and the whole area is littered with the kind of folklore that grows up around water that has drowned people. Coming down from the north you pass roughly midway between the Pointe du Van and the small rocky hump of the Ile Tevennec with its stubby lighthouse, then line up for the gap.
The Raz is only really safe at slack water, and the slack windows are short. The useful one is around HW Brest plus 4 hours, when the stream pauses for roughly half an hour before the flood sets in, and there is a briefer slack near HW Brest minus 2 hours. Miss them and you are either fighting a foul stream that may run faster than your boat, or riding a fair one through overfalls you would rather not be in. The piece on the Chenal du Four and Raz de Sein passage sets out the timing alongside the Four, because most boats take the two gates on the same tide as a pair.
The reward for getting it right is speed. The Raz is the direct line. Take the slack with a fair tide behind you and you are round the corner in minutes, carried through on the first of the new stream, with the whole of Audierne or the Baie de Douarnenez open ahead.
The offshore route: round the Chaussee de Sein
The alternative is to forget the gate entirely and stand out to sea, leaving the Ile de Sein and the long Chaussee de Sein reef to seaward of you, then bending back in once you are well south or north of the obstruction. The Chaussee is a real hazard, a chain of drying rocks and shoals stretching some miles west of the island, so the offshore route is not a casual short cut close to the danger. It is a deliberate decision to give the whole lot a wide berth.
The cost is distance. Going right round the Chaussee de Sein adds somewhere in the order of 20 to 30 nautical miles to the passage, which on most cruising boats is four to six extra hours at sea. That is the price of not having to hit a half-hour slack window with precision.
What you buy with those miles is freedom from the tidal clock. Offshore the streams are weak and the water is open, so you are no longer married to HW Brest plus 4. You can leave when it suits you, sail through the night, and arrive when you arrive. In strong winds, or with wind against the inshore stream, the offshore route is also simply safer, because you avoid the overfalls altogether.
How to choose
The decision usually comes down to three things: the weather, your timing, and your nerve.
- Settled weather, a fair slack within reach, and daylight: take the Raz. It is quicker and there is no sense adding 25 miles for the fun of it.
- Wind against the inshore stream, a big coefficient, or a slack that falls in darkness or fog: go offshore. The overfalls in the Raz with wind over tide are genuinely dangerous, and no schedule is worth them.
- Your timing is hours adrift of the slack: rather than punching a foul stream or hanging around for the next window, the offshore route lets you keep moving without waiting.
There is also a hybrid worth knowing about. If you are early or late for the Raz, you can anchor or wait in the lee of the coast, at Audierne or in the Baie de Douarnenez depending on direction, and take the next clean slack rather than committing to the offshore detour. Patience is usually cheaper than miles.
A note on the boat and the crew
A well-found yacht with a reliable engine, a skipper comfortable with tidal timing, and a settled forecast can treat the Raz as a routine passage. A short-handed crew, a doubtful engine, or any sea running against the stream tilts the balance hard towards the offshore route. The Raz has a fearsome name partly earned and partly inherited, and the right answer is not to prove anything: it is to pick the route that matches your boat, your crew and the conditions on the day.
What the Raz actually looks like on the day
It helps to know what you are steering into so the name does not spook you more than the water does. On a calm slack with no swell, the Raz is an anticlimax: a stretch of slightly disturbed water between a lighthouse and an island, and you motor through wondering what the fuss was about. That is the version you are aiming for. The fearsome version arrives when the stream is running hard, especially against the wind or against a residual swell, and the surface breaks into short, steep, overfalling seas that can come aboard and knock a small boat about badly.
The reason the Raz earns its reputation is that the transition between those two states is fast. The stream goes from slack to several knots in not much more than an hour, so a passage that was benign when you committed can turn unpleasant before you are through if your timing is sloppy. That is the whole argument for hitting the slack squarely: not because the water is always dangerous, but because the window in which it is easy is short and closes quickly.
Planning the slack down to the minute
Because the slack windows are so brief, the Raz rewards precise planning more than almost any other passage in France. Work out HW Brest for your day, apply the slack offsets, and back-calculate your departure so that you arrive at the gap at the turn rather than chasing it. Allow honestly for your boat speed and for any foul tide on the approach, because the commonest mistake is to set off too late, arrive on the building stream, and find the easy window already gone. If in doubt, be early and wait in the lee rather than late and committed. The same tidal discipline runs through the whole region, and the Chenal du Four and Raz de Sein passage guide pairs the two western gates so you can plan them on a single tide.
Where it fits the wider coast
The Raz is the hinge between the two halves of a France cruise. North of it lies the Channel coast and the granite rivers, and crews working down from there often stage at the rivers of the Pink Granite Coast, such as the Ile de Brehat and the Trieux, before committing to the western corner. South of it the water warms and softens, and the first real reward is Quiberon Bay through the Teignouse passage and the islands of the Gulf of Morbihan beyond. The Raz is the gate between those two worlds.
The honest verdict
Most of the time, on a fair forecast with the slack in daylight, the Raz is the right call: it is the direct route and the timing, once you have done it once, is not hard. But the offshore route is not a failure or a cop-out. It is the seamanlike choice whenever the weather, the tide or the crew make the gate doubtful, and the 20 to 30 extra miles it costs are a small premium for going round trouble rather than through it. Know both, and decide on the morning, not in advance.
