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Lough Swilly

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What is the route?
This is a safe run down Lough Swilly and includes waypoints used the Lough Swilly Yacht Club to lead into Fahan Marina. The first part of run up Lough Swilly is in the well-marked deepwater shipping channel that may be used at any stage of the tide. But shortly after Buncrana, the route leads into the Fahan Channel which has a bar across its entrance with only 1-metre MLWS. Most medium draft vessels intending on continuing to the marina will require an arrival at this point of the route to be timed to high water ± 2 hours to cross the bar.

Why sail this route?
This provides a useful set of waypoints to approach and pass down the north end of Lough Swilly as far as Fahan and/or enter the marina.

Tidal overview
Today's summary tidal overview for this route as of Wednesday, April 17th at 13:54. Lough Swilly's tidal streams are scarcely perceptible at the entrance. They build progressively southward and can attain a spring rate of 1½ to 1¾ kn off Rathmullan Pier. High water for Lough Swilly is HW –0500 Dover, +0110 Galway, mean level 2.3 metres with a duration 0605. Allowing it is about 12 miles with a favourable stream to the 'Inch Spit' buoy the ideal time to enter for a boat capable of 5 knots and intending on visiting Fahan Marina would be two hours after the in-going stream commences or earlier with a tide wait.

Lough Swilly Out-Going Tidal Stream

(HW Londonderry -0210 to +0415)

Starts in 01:26:14

(Wed 15:21 to 21:46)

Lough Swilly In-Going Tidal Stream

(HW Londonderry +0415 to -0210)


(Tidal flow )

Ends in 00:55:14

(Wed 08:50 to 14:50)

What are the navigational notes?
Please use our integrated Navionics chart to appraise the route. Navionics charts feature in premier plotters from B&G, Raymarine, Magellan and are also available on tablets. Clicking the 'Expand to Fullscreen' icon opens a larger viewing area in a new tab.

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Please zoom out (-) if all of the waypoints are not displayed.
The above plots are not precise and are indicative only.


The entrance to Lough Swilly between Fanad Head and Dunaff Head
Image: Tourism Ireland

Lough Swilly is a deep and sheltered north facing glacial fjord lying between the western side of the Inishowen Peninsula and the Fanad Peninsula, in County Donegal. The spacious inlet penetrates southward into the land for twenty-six miles to its tidal head, near the town of Letterkenny, and it varies from one to three miles wide. The entrance is well defined by Fanad lighthouse on the western point, and by the bold and lofty headland of Dunaff Head on the eastern side 3½ miles apart. Mid-channel depths at the entrance are in excess of 35 metres and 18 metres to within a short distance of either shore. The general depth of the lough is from 18 to 12 metres, on a bottom of sand, or sand and mud. Both sides of the lough are bordered by hills, 90 to 305 metres high, which are mostly bare at the entrance, but more fertile and cultivated farther to the south.

Lough Swilly
Image: Greg Clarke via CC BY-SA 2.00

Entry is simple, day or night in all reasonable weather conditions and at all stages of the tide which makes it the principal harbour of refuge for vessels passing north of Ireland. Once safely inside the lough provides numerous well sheltered anchorage with excellent holding, a marina at Fahan with plenty of space for visitors and a pontoon, usually May to September, at Rathmullan. To name but a few of the berthing oppertunities, eOceanic covers: Pincher Bay Click to view haven, Ballymastocker Bay Click to view haven, Scraggy Bay Click to view haven, Macamish Bay Click to view haven, Rathmullan Click to view haven, Ramelton Click to view haven, Buncrana Click to view haven, Dunree Bay Click to view haven, Crummie’s Bay Click to view haven and Lenan Bay Click to view haven and Lough Swilly Marina Click to view haven at Fahan which the list of waypoints leads directly to and has ample visitor berths and basic toilet / shower facilites available. All of this makes Lough Swilly, argaubly, the principal yachting area on the north coast of Ireland.


The complete course is 13.93 miles from the waypoint 'Lough Swilly' to 'Fahan Channel 8' tending in a south south easterly direction (reciprocal north north westerly).

Lough Swilly, 55° 17.840' N, 007° 35.030' W
This is an offshore waypoint from which to start a passage clear of the entrance heads where rough water may be experienced during heavy weather.

       Next waypoint: 6.22 miles, course 176.47°T (reciprocal 356.47°T)

Dunree Head, 55° 11.640' N, 007° 34.360' W
Dunree Head, situated 5 miles within the Lough and marked by a lighthouse, is where the lough narrows gradually to a width of about 1 mile.

       Next waypoint: 4.52 miles, course 140.12°T (reciprocal 320.12°T)

Buncrana, 55° 8.170' N, 007° 29.290' W
At Buncrana the course of the lough bends southwestward.

       Next waypoint: 1.36 miles, course 187.72°T (reciprocal 7.72°T)

'Inch Spit' buoy, 55° 6.820' N, 007° 29.610' W
This is in the vicinity of the ''Inch Spit' port buoy, Fl.R3s, situated 1¼ miles southwest of the pierhead at Buncrana. This marks the Inch Spit that dries.

       Next waypoint: 0.54 miles, course 168.41°T (reciprocal 348.41°T)

Fahan Channel 1, 55° 6.290' N, 007° 29.420' W
Fahan Bar – least depths occur between Fahan Channel 1 & 2.

       Next waypoint: 0.14 miles, course 199.40°T (reciprocal 19.40°T)

Fahan Channel 2, 55° 6.160' N, 007° 29.500' W
Fahan Bar.

       Next waypoint: 0.10 miles, course 186.54°T (reciprocal 6.54°T)

Fahan Channel 3, 55° 6.060' N, 007° 29.520' W
This helps vessels proceed along the Fahan Channel following the port-hand buoys to the marina ideally staying as close to the marks as possible.

       Next waypoint: 0.10 miles, course 167.11°T (reciprocal 347.11°T)

Fahan Channel 4, 55° 5.960' N, 007° 29.480' W
Fahan Channel, follow the port-hand buoys staying as close to the marks as possible.

       Next waypoint: 0.21 miles, course 169.21°T (reciprocal 349.21°T)

Fahan Channel 5, 55° 5.750' N, 007° 29.410' W
Fahan Channel, follow the port-hand buoys staying as close to the marks as possible.

       Next waypoint: 0.31 miles, course 155.78°T (reciprocal 335.78°T)

Fahan Channel 6, 55° 5.470' N, 007° 29.190' W
Fahan channel narrows.

       Next waypoint: 0.24 miles, course 163.38°T (reciprocal 343.38°T)

Fahan Channel 7, 55° 5.240' N, 007° 29.070' W
Northwest corner of marina breakwater.

       Next waypoint: 0.18 miles, course 140.75°T (reciprocal 320.75°T)

Fahan Channel 8, 55° 5.100' N, 007° 28.870' W
This is the position of the Marina entrance. Parts of the marina are not fully dredged. Follow the Red / Green markings on the columns for the deepest water but beware of silting in the fairways.


Fanad lighthouse
Image: Tourism Ireland

The entrance is well defined by Fanad lighthouse on the western point, FI (5) WR 205 38m 18/14M, and by the bold and lofty headland of Dunaff Head on the east 3½ miles apart. The 151 metres high Crockdonelly and Murren Hill, surmounted by a conspicuous radio mast, rise 1.2 miles to the south by southwest and 3 miles south by southwest, respectively, of Fanad Head. A spit with less than 8 metres of water extends nearly half a mile northeastward from the lighthouse. In heavy gales the sea breaks on this and the uneven ground adjacent; and even after the gale has subsided the rollers are dangerous, rendering it necessary to give the point a wide berth in passing.

Dunaff Head as seen from the south
Image: Andreas F. Borchert via CC BY-SA 2.0

Dunaff Head, at the east side of the entrance, is bordered by 180-metre high sheer cliffs which are on the north side and 45 to 120 metres high on the west and south sides. The summit of the head, which is 219 metres high, is somewhat rounded and falls in a very abrupt slope to the bordering cliffs. The 501 metres high Raghtin More stands 2.5 miles southeast of Dunaff Head, its prominent summit appears from the north to have a flat top. Dundaff head also tends to have confused seas in its vicinity caused by waves reflecting off its sheer cliffs so it is best to stick to the central waypoint to proceed into the lough.

Dunree Head lighthouse five miles within Lough Swilly
Image: Jakub Michankow

The entire length of Lough Swilly is marked with various easily identified lit navigation marks along the main deepwater shipping channel that makes it a trivial route to follow as far as the 'Inch Spit', Fl.R3s, port buoy.

Inch Spit Buoy
Image: Brian Deeney of Donegal Cottage Holidays
After that, the route leads into the Fahan Channel where it becomes much more challenging as it has a bar with only 1-metre MLWS at its entrance. Therefore the full length of the route, for most medium draft vessels, will require an arrival at the 'Inch Spit' buoy at high water ± 2 hours to continue to Fahen Marina. More details surrounding this part of the route can be found in the Lough Swilly Marina Click to view haven pilotage.


The central entrance is easy and dangers up the lock are largely fringe its sides and are to the most part well marked. Once in the lough follow the waypoints southward where the land rises above to high hills and increases in height as we proceed up the lough, the mountains on either side presenting a bold and majestic appearance. The principal dangers flanking this route are as follows:

  • • Swilly Rocks. Two drying ledges situated 1¾ South by southwest of Fanad Head. Comprising Swilly More, that dries 1.5 metres, and Swilly Beg, that dries 0.9 metres, these are the principal dangers that flank the west side of the inner entrance.

  • • Marine farms and shellfish beds south from Scraggy Bay.

  • • Colpagh Rocks, situates 2 miles southeast of Dunree Head and drying to 4.1 and 2.9 metres.

  • • Carrickacullin group of rocks that dry 3.2 metres a mile southwest of Buncrana Pier. These are very much in the way of a vessel moving from Buncrana Click to view haven to the Fahan Channel to proceed on to Lough Swilly Marina Click to view haven.

  • • The Kinnegar Spit, drying to 0.5 metres and extending from the west shore north of Kinnegar Head.

  • • Inch Flats, a sandbank drying to 0.9 metres, that extend a mile northward of Inch Island.

Lough Swilly Marina
Image: Greg Clarke via CC BY-SA 2.00

What is the best sailing time?
May to September is the traditional Irish Sailing season with June July offering the best weather. June and July’s statistical incidence of strong winds are however two days of winds up to force seven. As such, depending on personal sailing preferences, a vessel may expect to be held-up or enjoy robust sailing conditions. Ireland is not subject to persistent fog. Statistically complete days of persistent fog occur less than once in a decade.

With thanks to:
Graham Wilkinson and the Lough Swilly Yacht Club.

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