What is the route?
Why sail this route?There is an old saying that goes ‘the longest way round is the shortest way home’. If shortest could be exchanged for safest the saying aptly describes the primary benefit of this route.
The Bay of Biscay is noted worldwide among sailors as a notoriously dangerous sailing area with fearsome seas. This route ensures sufficient westing to avoid the danger of being set into the dangerous bay. Likewise selecting Bayona as the Spanish port of arrival, as opposed to the more convenient La Coruña, known locally in Galician as A Coruña, also keeps a vessel clear of the lesser known, but often very difficult local conditions that may be experienced off the Cape Finisterre area. Finally, southwest Ireland’s port of Kinsale is an excellent harbour by any measure to await the ideal weather window to come around for the jump.
All these elements combine to make this the safest and most comfortable route from Ireland across the notoriously challenging Bay of Biscay, if not for all northern Europe countries. The logic of the route works for southbound and northbound passages, although it is the former that is the more challenging due to the prevailing winds.
Tidal overviewToday's summary tidal overview for this route as of Monday, May 29th at 13:09. Between the Old Head of Kinsale and the entrance of Cork Harbour, the tidal streams follow the coast and are hardly noticeable. They only amount to ½ a kn attaining a maximum rate of 1kn in the centre of the Celtic Sea. Nevertheless, they could provide a useful lift to a departure if they may be availed of.
The east or northeast going stream commences at Dover +0045 (Cobh -0550), the west and southwest going commencing at Dover -0500 (Cobh +0050). At Dover +0400 an eddy will be encountered about 5 miles to the southeast of the Old Head of Kinsale.
West Going Stream
(HW Dover -0500 to +0045)
Starts in 01:29:11
(Mon 14:39 to 20:24)
East Going Stream
(HW Dover +0045 to -0500)
(Tidal flow )
Ends in 01:33:11
(Mon 08:03 to 14:43)
What are the navigational notes?
The Bay of Biscay is a notoriously dangerous sailing area and noted among sailors worldwide for its rough seas. Up until recent years, it was a regular occurrence for merchant vessels to founder in Biscay storms, particularly so in the winter. The primary reasons for its fearsome seas is the continental shelf that extends into the northwest section of the bay, and how it interacts with the Bay’s prevailing winds and storms. The below image, published in fall 1993 issue of Mariner's Weather Log, shows a Merchant ship with one of the huge waves that are common near the 100-fathom curve on the Bay of Biscay.
Photo: NOAA NWS (Public Domain)
The continental shelf is an underwater landmass in Biscay that creates a coastal shelf of relatively shallow water extending out into the sea. The shelf is up to about 100 miles (160 km) wide, off the coast of Brittany, narrowing to less than 40 miles (65 km) off the Spanish shore as shown in the bathymetric map below. The inner part of the shelf is shallow and fronted by a ragged leading edge that is dissected by numerous submarine sheer cliffs and canyons. The change from deep to shallow waters has the effect of steepening the Atlantic swell and because of this abrupt and irregular leading edge in Biscay, the seaway above can become confused and extremely rough even in a moderate storm. During early autumn the situation is sometimes exacerbated by a high Atlantic swell generated by a hurricane blowing thousands of miles away.
A quick example to illustrate this phenomenon can be seen on a route planning chart. If a direct route is drawn upon a chart from Kinsale to La Coruña a route of approximately 180° T, most viewers will be surprised to discover 240 miles due south from Kinsale Harbour there is a special purpose marker buoy. The isolated buoy, located in the centre of the bay, is called 1GB. It marks the positioned of Banco Perueno Sol where over a distance of 20 miles the depth changes from approximately 5,000 metres to 120 metres. Grimley, the surrounding area on the chart can be seen to be littered with consequential wreck marks.
The prevailing winds and currents are also a challenge as they have a tendency to set towards Ile d'Ouessant, in the north, and into the Bay of Biscay to the south of it. This places a southbound vessel on the starboard tack which has a tendency to set the vessel south by south-eastward or southeastward. These tacks only serve to embay a vessel and make it vulnerable to a southwest gale, which is the usual direction of the worst gales. All of this makes a southbound voyage across the bay the more difficult direction.
Photo: David McDonald via CC BY SA 2.0
Gales in the bay can be severe and winds may exceed 70 miles (113 km) per hour. Squalls are also a hazard to navigation and may occur at any time of the year. A large portion of this is due to local conditions in Biscay. The Bay of Biscay re-circulates a portion of the North Atlantic drift around in a clockwise circulation. This brings cold moist air into collision with hot Spanish mainland air currents that develops a series of cumulonimbus clouds. The result is turbulent weather systems and line squalls in the bay area and a high degree of instability along the north coast of Spain.
The indraft of the bay is at its strongest during gales where a yacht could easily find itself in survival conditions. If embayed in the Bay of Biscay, any change of the wind to the west would necessitate beating to windward against the current which could make it very difficult to weather Cabo Finisterre or even Cabo Ortegal. It should also be noted that the Atlantic swell can build up rapidly near the coast here and a number of ports can become dangerous to enter or even inaccessible.
Photo: Mark Murray via CC BY-SA 2.0
All of this can all be avoided by taking a route outside of the Bay of Biscay. The tack out to the west loses nothing in most events as the wind will generally be found to veer out west. That change of wind will be favourable and even permit a vessel to pursue a direct course with a free wind.
Finally, the overall passage will generally be found to be easier by passing over the obvious landfall of La Coruña. La Coruña is very tempting landing port as it shortens the trip but it has its own complications. 50 miles out from La Coruña the depths step up from 5,000 metres up to 120 metres over a distance of 10 miles. This steep shelving, when combined with rough local weather conditions, is best avoided.
Photo: Josef Grunig
Likewise, it is worth giving Cape Finisterre a wide berth. The Atlantic current usually sets right on-shore here and when combined with a pronounced local weather microenvironment at the cape, locally known as the Costa da Morte, which means Death Coast, causes it to be a foul corner as often as not. This is further complicated by the weight of commercial traffic within the Finisterre traffic separation scheme, reaching out to 10° west, that has to be negotiated close offshore.
Photo: Jose Luis Cernadas Iglesias
All of this can be avoided by keeping far enough out to sea and passing south to Bayona or beyond. Bayona does make an excellent landfall. Well protected in the Vigo estuary, the harbour allows boats to enter via the North Channel which offers the early protection of the Bayona Islands.
For those who do not want to go to go as far northwest as Ireland, the traditional trading route for old sailing vessels was to depart the Channel, going west of Ushant and out to or a little further than 10°W. That well-tested approach stands the test of time today. The ideal port to depart from the English Channel is the very serviceable port of Falmouth on England’s southwest corner. If the wind is from the west keep on a tack which enables most westing to be made to get a good offing, and keep clear of the Bay of Biscay, even standing northwest until well intersecting this route to pass outside Cape Finisterre on the starboard tack.
On the whole, this Atlantic route may be longer but it allows a vessel to stand well clear of all the rough water and disturbed seas upon the shelf in the Bay. It also avoids all the unpredictable weather upon Spain’s northern coast and the dense shipping traffic moving around Cape Finisterre.
The complete course is 611.90 miles from the waypoint 'Kinsale Harbour Initial Fix' to 'Bayona Initial Fix' tending in a southerly direction (reciprocal northerly).
Kinsale Harbour Initial Fix, 51° 40.000' N, 008° 30.000' W
This is just under a ¼ of a mile to the southwest of the Bullman South Cardinal Buoy Q + LF(W) Ev. 15 secs, bell and directly South of the harbour entrance.
► Next waypoint: 115.10 miles, course ⇓ 210.20°T (reciprocal ⇑ 30.20°T)
Continental Shelf Exit, 50° 0.000' N, 010° 0.000' W
Approaching the continental shelf.
► Next waypoint: 440.30 miles, course ⇓ 180.00°T (reciprocal ⇑ 360.00°T)
Western edge of the Traffic Separation Scheme, 42° 40.000' N, 010° 0.000' W
Close outside the western edge of the Finisterre TSS (traffic separation scheme)
► Next waypoint: 56.50 miles, course ⇓ 124.17°T (reciprocal ⇑ 304.17°T)
Bayona Initial Fix, 42° 8.000' N, 008° 57.000' W
1½ miles off the northwest end of Pt Lobo De Silleiro and 4½ miles outside the harbour.