Crossing the Bay of Biscay is a rite of passage. Rachael Sprot has expert advice on how to handle the ‘Golfe de Gascogne’

It’s that time of year when yachts and crews from northern Europe flock south, migrating to warmer climes. But like all good migration routes there’s an obstacle in the way: the Bay of Biscay.

Biscay gained its notorious reputation because in the prevailing westerlies a square-rigged vessel could be ‘embayed’ for days. Failing to make sufficient ground to windward they’d drift inexorably closer to the French coast and potential disaster. However with 21st century forecasting techniques and a modern yacht it no longer needs to be the feat of endurance it once was – but it does still need preparation, strategy and a healthy dose of respect.

In my dealings with Biscay over the years I’ve motored across in light airs with pilot whales for company, beaten across in a howling gale (using every pair of socks I owned) and on one occasion I sat west of it with the drogue out until it calmed down, determined to keep the sock inventory dry.

A Biscay crossing is as variable as the weather itself and there’s no one-size-fits-all rule that can be applied to the passage.

However, if we identify the various challenges and plan for them in advance then we can tailor make a crossing strategy that works for each boat, crew and weather forecast.

6 elements to consider crossing the Bay of Biscay

There are six main factors to consider: the distance, prevailing conditionS, heavy weather, the continental shelf, the lee shore element, and shipping


The shortest distance across Biscay without going into the Bay itself is 360 miles from Brest to A Coruña. A vessel heading directly from Falmouth around Finisterre to the Rias can expect to add another 150 miles onto that.

For many crew Biscay will be their first taste of long distance sailing and it needs to be treated as a mini ocean passage. It brings with it all the associated challenges of ocean sailing: fatigue, seasickness and the distance from help when things go wrong.

Much of this can be mitigated by planning the crossing well in advance, keeping on top of routine maintenance and familiarising your crew in the preceding weeks and months.


  • Make sure the crew are well-briefed on safety issues: what to do in the case of fire, flooding and how to abandon ship
  • Check that all safety kit is functional and within its service date
  • Conduct an MOB drill prior to departure
  • Carry plenty of fuel, fresh water, food and gas
  • Inspect the sails and rig
  • Service the engine and ensure that you’re well supplied with spares
  • Run a robust watch system so that everyone gets enough rest
  • Encourage everyone to take seasickness tablets prior to departure

The weather in the Bay of Biscay becomes much less predictable in the autumn and winter. Photo: Kila Zamana/

Prevailing Conditions

Meteorologically speaking the Bay of Biscay sits squarely in the mid-latitudes – that zone of low pressure between the Azores high and the Arctic high.

The ideal time to cross is May-August when the weather’s more settled, but many yachts aren’t ready to leave at that point and an autumn or spring crossing often fits better with cruising plans. Furthermore, the course is south-west, straight into the prevailing wind direction.

Despite the improvements in upwind sailing performance of the last two centuries, a 400 mile beat is still a daunting prospect and likely to turn a two-to-three day passage into a four day slog.


  • An up to date weather forecast is essential prior to departure
  • If possible time your passage for settled weather even if this means a bit of motoring or leaving earlier
  • If you decide to go with unsettled weather, use the wind shifts to your advantage (see page 36)

Heavy weather is a regular feature. Photo: Amory Ross/Team Alvimedica/Getty

Heavy weather

The average crossing time for Biscay is three days – that’s a long time in the life of the North Atlantic. Having a flexible schedule is the best defence against heavy weather – if you’re on a tight deadline there’s always a temptation to leave with a less than favourable forecast.

However, unless you’re transiting in the summer months you’re likely to encounter strong winds at some point along the route so it’s important to be prepared. As ever small boats need to be more mindful of heavy weather in the forecast. Not only are they more vulnerable to breaking seas, but the slower your boat the longer the passage duration and the more likely you are to be caught out at the end of the passage.


  • Know how to rig storm sails and set them early if you think you might need them
  • Prepare meals in advance
  • Stow the boat well below decks
  • Establish good routines from the outset when it comes to clipping on and moving around the deck
  • Have time on your side when looking to cross

Continental Shelf

Somewhere between 60 and 100 miles offshore the continental shelf ends and the ocean begins. Here the depth plunges from a mere 100m to over 3,000m.

Atlantic swells rolling in from weather systems hundreds of miles react to the depth change by heaping up, creating a short, steep sea. In strong onshore winds the shelf will be very unpleasant, and even in moderate weather it is noticeably uncomfortable to cross. You’ll breathe a sigh of relief once you’re past it and the wavelength increases.

The shelf is also a favourite spot for French fishing boats. In my experience these are magnetically attracted to sailing yachts, and the more challenging the conditions the stronger the pull…

You’ll need to keep a particularly good watch and be prepared to take early avoiding action.


  • Time your departure from Falmouth or Brest to ensure that the conditions when you reach the shelf are as favourable as possible. Watch out for any cross swell which will exacerbate the sea state.It may be tempting to cross Biscay on the north-westerlies straight after the passage of a depression, but the combination of a lingering south-west swell with a fresh north-west breeze could create hazardous cross seas
  • If you think the shelf might be tricky, try to cross in daylight when you can see the waves (and fishing boats) approaching
  • Put your best crew on watch for this section of the voyage
  • In rough weather, better conditions have been reported by staying west of 7°

Lee shore

As the square riggers of the 19th century knew only too well, the Bay of Biscay is one big lee shore. Once past Brest there are few all-weather ports of refuge and if the weather sets in there really is no option but to put as much distance between you and the coast as possible.


  • In onshore weather, avoid tacking into the Bay: keep your sea room and stay west of the rhumb line
  • If in doubt stand out, and don’t attempt landfall until the conditions have improved

You can never rely on a ship’s crew seeing you. Photo: Zoonar GmbH/Alamy

Shipping in the Bay of Biscay

If the geography of Biscay wasn’t enough to contend with there’s a constant stream of merchant vessels heading along the Traffic Separation Schemes off Ushant and Finisterre. A course from Brest to A Coruña will keep you out of the shipping lanes and relatively clear of traffic. But a course from Falmouth to Finisterre will see you slowly converge with the shipping route and you’ll spend a long time dodging ships.

Early in my sailing career I was on one of these slow, converging courses coming home from Galicia. We were sailing downwind on a 70ft, 40-tonne steel boat with a large following sea and a tanker approaching from astern on a near collision course.

Due to the sea state I didn’t want to round up to cut across them, and a gybe would have been a lot of work. I decided as the stand-on vessel to hold course and let them take the avoiding action. After an hour they were a mile or so astern of us with a CPA that was too close for comfort. I radioed to ask their intentions and to my horror they hadn’t seen us either visually or on radar and they were in ballast condition so couldn’t manoeuvre easily. We had no option but to get out of their way. It was a sobering lesson in how you need to take matters into your own hands when avoiding ships.


  • Away from the TSSs sailing yachts are the stand-on vessel in encounters with merchant shipping. However, you can never rely on a ship’s crew seeing you and I always prefer to take decisive avoiding action if in any doubt
  • If you find yourself plagued by endless shipping encounters change course and cut directly across the line of traffic, it is usually confined to a 4-5 mile stretch and easy to avoid

Photo: Tor Johnson

Routes to cross the Bay of Biscay

Departure points

There are two main departure points for vessels heading south across Biscay: Falmouth and Brest. They are both major ports with all-weather access, good facilities and plenty of cruising options nearby if you need to wait for a weather window.

Arrival points

Making landfall after a long passage is always the most challenging part, and the more preparation you can do for it the better. Depending on your choice of route there are three options:

  • 1. North Spanish ports of Gijón and Viveiro
  • 2. A Coruña
  • 3. Rias south of Finisterre

Gijón and Viveiro

If persistent south-westerlies are a problem and you’re not in a major rush to get around Finisterre, then landfall further into the Bay may be preferable: Viveiro and Gijón have decent marinas with good facilities, though Gijón is a long way east. Both would be difficult to approach in winds from the north but are well sheltered from the prevailing west and south-westerlies. The problem will be continuing the voyage westwards, but if you simply can’t make enough ground to windward to get to A Coruña they’re safe and attractive alternatives.

A Coruña

A Coruña is a favourite staging post for many yachts crossing Biscay in either direction and for good reason: it’s a lovely city with good marinas and shelter from the prevailing westerlies. The only drawback on a voyage southwards is that it leaves Cape Finisterre to be dealt with. The notorious coastline between A Coruña and Finisterre is aptly named the Costa da Morte and needs to be avoided in onshore swell.

The Rias

If the going’s good, it’s worth rounding Finisterre and making for one of the Rias. The first big Ria south of Finisterre is Muros. It has a decent marina and a lovely little town for that well-earned cerveza. Further on you’ll find wonderful cruising options in the Ria de Arousa, the Ria de Pontevedra and the Ria de Vigo. Yachts on a tight schedule may skip the Rias entirely and just do a quick stop in Bayona (at the mouth of the Ria de Vigo) before continuing south.


Forecasts are all important for a Biscay crossing: both how you get them, and how you interpret them. Many yachts making this passage don’t have the luxury of sat-comms and rely heavily on their final GRIB file before leaving. But there are also the UK, French and Spanish shipping forecasts broadcast over VHF when in range.

If you’ve got Navtex that should carry signal most of the way across. The shipping forecast is only for 24 hours from the point of issue and the sea areas are huge, so they probably won’t help you avoid a gale entirely, but they will warn you that it’s coming. Don’t forget it’s also broadcasts on 198LW and, if nothing else, the dulcet tones of Radio 4 are very soothing in a blow!

Shipping forecast areas for the passage are huge and will give more of a broad brush indication of weather patterns than precise details for your location. The boundary line between Biscay and Fitzroy sea areas crosses right through the rhumb line so some reading between the lines is required to interpret the forecasts for the two different areas.

These days the departure forecast for a three-day passage should give a relatively accurate picture of the type of weather you’ll experience. It will tell you whether to expect light airs, westerly airflow, unsettled weather or more of a blow. The details such as wind direction and strength or the timing of fronts will change but you should have enough information to know if there’s likely to be any heavy weather and that’ll help you decide on a crossing strategy.

Forecast models

I always like to consult two forecast models as well as the shipping forecast prior to an offshore passage. The ECMWF and GFS models are well-established and easy to access online through sites such as Windy and Predict Wind – both allow you to toggle between the models to compare and contrast the predictions.

Left: Scenario A: PredictWind shows a wave height of 5m, with a wave direction of 274.6° True, wave period 10 seconds. Right: Scenario B: wind strengths in the south of Biscay are similar but wave height reduces to 2.2m, direction 291.9°


It is sea state, not wind strength, that makes conditions challenging. With any long-distance passage it always pays to keep an eye on the weather charts well in advance of the trip to build up an idea of what kind of weather patterns are established, but it is particularly true for a crossing of the Bay of Biscay where swell is a key player in the passage.

Swell catches people out because it isn’t directly linked to the conditions around you – it’s a reflection of what’s been going on further afield. Waves grow with time and distance so to understand the swell conditions you need to be looking further out into the Atlantic and further back in time.

The charts (above right) show two very different swell forecasts despite the fact the wind forecast for the southern half of Biscay is a westerly Force 6 in both instances. Force 6 (22 knots) is on the limit of what most of us would like to be out in, but these two examples highlight that there are Force 6s, and then there are Force 6s…

The first chart (Scenario A) shows a 5m sea state created by an enormous low pressure system that had been pushing swell down from the Denmark Strait for two days. The second chart (Scenario B) shows the swell created by a smaller system which moved through more rapidly. The first is a complete no-go in my opinion: 22 knots close-hauled isn’t fun though it could be doable for a short while with the right boat and crew; but a 5m wave height could be dangerous, especially if it’s breaking.

The second scenario indicates a possible weather window for a fast boat making the short hop from Brest to A Coruña though – aiming to be about halfway across at the time of this forecast period so that you avoid the worst of any residual swell from the system to the north.

Read the weather conditions en-route and be informed about what’s likely to happen next. Photo: B.A.E. Inc/Alamy

Under way

In the absence of forecast information en-route, it’s important to be your own meteorologist. Be alert to the conditions by logging the wind, visibility, sea state and barometer on the hour.

Remember that a 6mb rise or fall in three hours indicates the imminent arrival of strong winds and you’ll want to adjust your sail plan. Cirrus cloud coupled with the steady drop of the barometer is your advance warning of a low pressure system: expect the wind to back slightly, then veer as the warm front arrives, and veer again when the cold front goes through.

What if…

With all the preparation in the world, things still go wrong. It always pays to think through the ‘what if’ scenarios – medical emergency, steering failure, dismasting, water ingress – and consider your options. Make sure you’ve got chart coverage for your ports of refuge, lodge your passage details and crew list with a shore contact and brief your crew on what to do if you, the skipper, are incapacitated.

Thrill of the crossing

Crossing Biscay is always a thrill, its awesome reputation is etched into the sailor’s psyche from early on. And it should be daunting, there are few other places where the Atlantic reigns with such indifference to our sailing ambitions. You don’t have to spend long in the yacht club bar in Bayona before someone testifies to Biscay’s enduring potency: vertiginous waves, disastrous break-downs, human triumph over adversity. They are the exception rather than the rule though. Plenty of people will be sitting in a corner wearing dry socks and wondering what all the fuss was about.

Gijón/ Photo: Espelt Gorgozo/Alamy


Deciding on a crossing strategy will depend on the six factors already explained, plus the limitations of your boat, your crew and your time frame. You can reduce the impact of any of these factors by trying not to encounter too many at once: shipping + the shelf + heavy weather = high stress!

Try to break them down by tackling them in stages: stay away from the shipping route in heavy weather, for example.

Short-handed/ slow boat

If you’re double-handed or on a smaller yacht with an average speed of less than 6 knots then a Brest-A Coruña/Viveiro crossing makes more sense, staying clear of the shipping route to keep things simple (if wind angles allow). The shorter distance increases your chances of getting across in a limited weather window.

Fully crewed/ fast boat

My preferred route on a larger yacht is to go Falmouth-Muros, staying west of the rhumb line and outside the shipping route until the second half of the passage (and until you’re well past the shelf), then cutting across the traffic and making for the inshore traffic zone off Finisterre. If the conditions deteriorate in the second half of the passage you can always bear away to A Coruña or Viveiro but having stayed west to start with, you’ve got options.

Using the wind shifts

If you have to make the passage during unsettled weather with low pressure systems lurking around, then you’ll need to use the wind shifts to your advantage. During the passage of a typical low pressure system the wind backs slightly to the south or south-east initially before veering south-west as the warm front passes over, and veering again to west-northwest on the cold front.

If you start off on port tack (shown red) while the wind is in the south it will help you make ground to seaward, and then tack over when the wind veers south-west, crossing the lines of shipping at steeper angle (green), and follow the wind around as it continues to veer (blue) to bring you back up to the rhumb line.

It won’t look this neat in reality, and depending on the size of the system this whole pattern may be compressed into 24 hours, but the point remains the same: in predominantly westerly weather any shift can be a gift if you play it well.

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