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Home / Racing & Cruising / Cruising / Navigating through the Skerries Islands
Home / Racing & Cruising / Cruising / Navigating through the Skerries Islands

Navigating through the Skerries Islands

Note: The following information is complements of Mr. Brian Lennon (SSC Member) and eOceanic

Chartlet overview for illustration purposes only, not to be used for navigation. - Photo: eOceanic 2017

The Skerries island group are located off the east coast of Ireland four miles to the southeast of Balbriggan and about 12 miles north of Howth Harbour. The group is made up three small islands of St Patricks, Colt, Shenicks Islands, with a further Red Island that is joined to the shore and more of a headland. They vary from 15 to 18 metres in height and all have extensive rocky foreshores.

What is the route?

This is a Skerries Sailing Club set of waypoints and directions to assist a vessel cut through the Skerries Islands and enter Skerries Harbour, or indeed continue a coastal passage.

Why sail this route?

This is a useful cut through the islands shortening the passage for coastal hugging boats and makes for some more interesting sailing. It also avoids turbulence that can be encountered at the northeast corner of St Patricks Island whilst making an outer pass.

Tidal overview

Tidal streams in the vicinity of the Skerries Islands are irregular and subject to back eddies. The northward going tide turns in the north entrance between St Patrick's Island and Colt Island at Dover +0500 (Dublin +0430), but a of a mile to the east of St Patrick's Island at Dover -0500 (Dublin -0530). The southward going tide turns between St Patrick's Island and Colt Island at Dover -0100 (Dublin -0130) and at Dover HW Dublin (-0030) to the east of St Patrick's Island. Rates vary from 1 to 1½ knots. Close north, in Skerries Bay, the streams run continuously eastward.

Shenick's Martello tower as seen from the shore.

St Patricks, the outermost island, is distinguished by the ruins of a church on its southwest end, Shenick's and Red islands by Martello towers. The two latter are connected with the mainland, Shenick's at low water only, and Red Island by a causeway, which provides shelter to the drying Skerries Bay and Harbour on its north-west side. There is a passage between St Patricks Island and Colt Island, with a least depth of 3 metres, and it is this passage that is described here.

A vigilant watch should be maintained for lobster pots, sometimes with floating ropes, all along this coast and between the islands.


The complete course is 2.64 miles from the waypoint 'Skerries Harbour' to 'Shenicks Island' tending in a east south easterly direction (reciprocal west north westerly).

Skerries Harbour, 53° 35.080' N, 006° 6.600' W
West of Skerries pierhead

       Next waypoint: 0.36 miles, course  354.35°T (reciprocal  174.35°T)

Perch, 53° 35.440' N, 006° 6.660' W
Northwest of perch buoy

       Next waypoint: 1.04 miles, course  97.76°T (reciprocal  277.76°T)

Colt, 53° 35.300' N, 006° 4.930' W
Northeast of Colt Island

       Next waypoint: 0.50 miles, course  186.10°T (reciprocal  6.10°T)

Bay, 53° 34.800' N, 006° 5.020' W
Transit urning point amid islands

       Next waypoint: 0.74 miles, course  144.53°T (reciprocal  324.53°T)

Shenicks Island, 53° 34.200' N, 006° 4.300' W
East of south tip of Shenicks Island

Passage Notes

Skerries Harbour area and the islands. - Image: Xhemajl Abdullahu (jimmy)

This description is sequenced from south to north but may be used either way. The below chartlet outlines the positions of the above-listed waypoints but the sightlines and charted lines of transits may best be seen on Admiralty Chart No. 633 'Plans on the East Coast of Ireland' that is recommended.

Chartlet overview for illustration purposes only, not to be used for navigation. - Photo: eOceanic 2017

Admiralty Chart 633 illustrates the primary transits for the cut, the crown of Colt Island on 325° T, as a lead-in, and the alignment of Shenicks Martello on the crest of the round Popeshall Hill, to the south, on 187°T to pass between Colt and St Patricks island. The islands themselves are easily identified when those taking this cut. St Patricks is readily distinguished by the conspicuous church ruins on its southwest end and the principal dangers to be avoided are around this end of St Patricks Island.

Colt Island and St Patrick's Island as seen from the southwest Image. - Kent Wang via CC ASA 4.0

Key amongst these is the covered Dthaun Spit that is a sandy spit extending almost 400 metres to the southwest of St Patricks Island, encroach almost midway upon the fairway that lies between St Patricks and Colt islands. It has a least depth of 0.6 metres about 250 metres out from the shoreline. Another drying reef extends 500 metres to the south of St Patricks Island that encloses Plough Rocks drying to 2.5 metres, and Roaring Rocks on its southern extremity.

Safely Passing eastward of Shenik's Island. -  Photo: Brian Lennon

The 'SHENIK' waypoint sets the route up to leave Shenick Island about ¼ mile to port. Shenick, like Red Island, may be readily identified by its Martello tower, and Shenick again like Red Island, connects to the mainland but only at low water.

Colt and Church Islands as seen from the SHENIK Waypoint.  - Photo: Brian Lennon

Steering towards the central 'BAY' waypoint is achieved by aligning on the centre of Colt Island on a bearing 325° T as seen on the chart. 

Martello Tower on Shenick lining up with Popeshall Hill astern on a bearing of 187° - Photo: Brian Lennon

Break off this at the 'BAY' waypoint to steer to 007° T towards 'COLT' waypoint where an astern bearing, as seen on the chart, the Martello Tower on Shenick lines up with Popeshall Hill behind it on a bearing of 187 T°. 

Passing westward of St Patrick's with the water seen just breaking over Plough Rock - Photo: Brian Lennon

This line of bearing then leads between St Patrick's Island and Colt favouring the latter to keep clear of Dthaun Spit extending from St Patrick's Island. This said, all boats are well-advised to stay at least 200 metres off Colt. Its southeast shoreline is particularly deceptive with an outlying rock that drys to 1.5 metres 300 metres south of the sland. Likewise, it has rocky shelves extending from the island most notably to the southeast. 

Colt Island as seen on the inside or western side - Photo: Brian Lennon

North of the islands at the 'COLT' waypoint, situated about a ¼ mile past Colt Island, a boat may either continue northward, if northbound, or turn due west to the 'PERCH' waypoint to approach Skerries Bay and Harbour. The end of the harbour and anchorage areas should be visible at this point.  

Approaching PERCH From COLT - Photo: Brian Lennon

The waypoint is located close northwest of the Perch buoy which should be should be left to port, passed on its northern side, to avoid the Cross Rock. This is located on the outer end of a ledge extending to the northward of Red Island and dries at low water.

Skerries Bay and Harbour at high water - Photo: Brian Lennon

The final waypoint is Skerries Harbour waypoint, this is set west of the pier in the middle of the anchoring area in the harbour supporting drafts of about 2 metres.
The listed waypoints are offered as a guide and should not be used for navigation. Before using waypoints it is essential that you check their accuracy, their suitability for your vessel and the precision of your GPS.

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 gales in June and July are on average two days of winds each month of winds up to force seven. 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.

Last updated 6:08pm on 5 July 2024

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