England Ireland Find Havens
England Ireland Find Routes


Bangor to Dublin, either way, with 12 hours of favourable tide

Tides and tools

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What is the route?
This 90-mile route takes a vessel down the north part of the Irish Sea hugging the Irish coastline from Belfast Bay to Dublin Bay. It passes from Bangor, Belfast Lough to Howth Dublin passing:

  • • Inside Copland Island via Donaghadee Sound

  • • Inside the South Rock Light Vessel

  • • Outside Rockabill

  • • Outside Lambay

  • • Outside Ireland's Eye

Or the reverse.

Why sail this route?
This route is primarily a tidal timing optimisation that utilises the converging and diverging tides at St. John’s Point to create a passage making efficiency. It provides a vessel that is capable of maintaining six knots with 12 hours of continuously favourable tides for the length of the passage.

Tidal overview
Today's summary tidal overview for this route as of Thursday, December 9th at 10:58. This efficiency is all about tidal timing. There is only one opportunity per tidal cycle to avail of the tidal aberration and, as it is centred on arriving at St. John’s Point at high water, the departure time is the same for northbound as it is for southbound passages.


(HW Dover +0500 to +0600)

Starts in 08:41:51

(Thu 19:40 to 20:40)


(HW Dover +0500 to +0600)

Starts in 08:41:51

(Thu 19:40 to 20:40)

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 great tidal wave from the Atlantic Ocean splits a little to the south of the southwest coast’s Skellig Islands, and sets in two separate paths around the island of Ireland. One part goes to the north, sweeping round the northwest coasts and enters the Irish Sea by the North Channel. The other part goes to the east, rounding Cape Clear to enter the Irish Sea by the South Channel. Seven hours after the separation occurred the two streams flow together again in the vicinity of St. John’s Point, to the south of Strangford Lough.

This presents a unique Irish Sea tidal efficiency for a cruising vessel passing along this section of the coast. Utilising this tidal opportunity a vessel may avail of more than a dozen hours of continuously favourable tidal streams to speed a passage. Or, conversely, potentially endure almost continuous adverse streams by not optimising a departure time.

All that is required is to have St. John's Point central to the passage and take the benefit of the flood tide converging to the point. Then, having taken advantage of the six hours of tide to arrive at the point at high water and half an hour of slack, continue with the benefit of the diverging ebb as it turns to retreat away from St. John's Point. This then provides six hours of a favourable tide for the onward journey.

The tidal oddity can be used for both north and southbound passages. Vessels that can maintain around six knots should be able to make a passage from Belfast Bay to Dublin Bay with a favourable tide all the way.
Please note

This is largely an inshore route where vessels are a ¼ of a mile off the coast for the majority of the passage. So be vigilant not to drift inshore of the direct route described.


The complete course is 87.28 miles from the waypoint 'Bangor Bay' to 'East of Howth' tending in a southerly direction (reciprocal northerly).

Bangor Bay, 54° 40.200' N, 005° 40.300' W
Outside the harbour

       Next waypoint: 1.61 miles, course 55.89°T (reciprocal 235.89°T)

Ballymacormick Point , 54° 41.100' N, 005° 38.000' W
500 metres north off the shore

       Next waypoint: 1.32 miles, course 84.33°T (reciprocal 264.33°T)

South Briggs Red Bouy, 54° 41.230' N, 005° 35.730' W
North of South Briggs Red Bouy

       Next waypoint: 2.56 miles, course 127.92°T (reciprocal 307.92°T)

Donaghadee Sound, North, 54° 39.658' N, 005° 32.243' W
Just north of Foreland Spit Red Bouy

       Next waypoint: 0.34 miles, course 141.90°T (reciprocal 321.90°T)

Donaghadee Sound, South, 54° 39.390' N, 005° 31.880' W
100 metres Northwest of Governor Rocks red buoy marker

       Next waypoint: 8.55 miles, course 151.58°T (reciprocal 331.58°T)

Skullmartin Maker, 54° 31.875' N, 005° 24.875' W
50 metres east of Skullmartin maker L Fl.10s

       Next waypoint: 7.49 miles, course 171.07°T (reciprocal 351.07°T)

South Rock Light Vessel, 54° 24.485' N, 005° 22.880' W
1000 metres inshore of the South Rock Light Vessel

       Next waypoint: 21.53 miles, course 201.81°T (reciprocal 21.81°T)

St. John’s slack water point, 54° 4.500' N, 005° 36.500' W
Approximately 9 miles south of St John’s Point

       Next waypoint: 43.89 miles, course 201.37°T (reciprocal 21.37°T)

East of Howth, 53° 23.600' N, 006° 3.300' W
Half a mile east of the harbour, south Rowan is 500 metres away


Vessels approaching from the north, making a southbound passage, should be outside the entrance to Bangor Harbour five hours after high water Dover (Bangor is Dover +0007) to pick up a small shore-hugging back eddy out to Donaghadee Sound. Then use the waypoints as presented.

This tide optimisation works both ways and at the same departure time. Northbound boats should be outside Howth Harbour at the same time, (0430 after high water Dublin) and depart north. A slight variation going north would be to pass inside Ireland’s Eye and inside Lambay Island to avail of the extra speed caused by tide funnelling between landmasses.
What is the best sailing time?
Sailing season for Ireland is May to September, with June and July offering some of the best weather. Nevertheless the incidence of winds up to force seven and above in June and July are on average two days each month. So you may be either held up or having a blast depending on your sailing preferences. Ireland is not subject to persistent fog – statistically complete days of persistent fog occur less than once in a decade.

Are there any security concerns?
Never an issue known to have occurred to a pleasure vessel sailing off the Irish coast.

With thanks to:
Burke Corbett, Gusserane, New Ross, Co. Wexford.

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