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Navigating through the Skerries Islands

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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 Click to view haven, 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 Patrick’s Island whilst making an outer pass.

Tidal overview
Today's summary tidal overview for this route as of Tuesday, June 25th at 13:58. 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 ⅓ 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.

South by Southeast Stream

(HW Dover -0100 to +0500)


(Tidal flow )

Ends in 05:12:30

(Tue 13:11 to 19:11)

North by Northeast Stream

(HW Dover +0500 to -0100)

Starts in 05:12:30

(Tue 19:11 to 01:36)

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 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 Patrick’s, Colt, Shenick’s 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.

Shenick's Martello tower as seen from the shore
Photo: Public Domain

St Patrick’s, 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 Patrick’s Island and Colt Island, with a least depth of 3 metres, and it is this passage that is described here.
Please note

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 'Shenick’s 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)

Shenick’s Island, 53° 34.200' N, 006° 4.300' W
East of south tip of Shenick’s Island


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 Shenick’s Martello on the crest of the round Popeshall Hill, to the south, on 187°T to pass between Colt and St Patrick’s island.

The islands themselves are easily identified when those taking this cut. St Patrick’s 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 Patrick’s 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 Patrick’s Island, encroach almost midway upon the fairway that lies between St Patrick’s 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 Patrick’s 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' 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

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 island. Likewise, it has rocky shelves extending from the island most notably to the southeast. The northeast tip of Colt Island needs good clearance also.

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 Skerries Harbour Click to view haven waypoint 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.

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

With thanks to:
With thanks to Brian Lennon from the Skerries Sailing Club.

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Skerries Harbour Video Overview

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Please note eOceanic makes no guarantee of the validity of this information, we have not sailed this route and do not have first-hand experience to qualify the data. Although the contributors are vetted by peer review as practised authorities, they are in no way, whatsoever, responsible for the accuracy of their contributions. It is essential that you thoroughly check the accuracy and suitability for your vessel of any waypoints offered in any context plus the precision of your GPS. Any data provided on this page is entirely used at your own risk and you must read our legal page if you view data on this site.