Alderney sees few visits by sea kayakers due to the challenge of making the crossing from Guernsey. Tidal streams are exceptionally strong both in the Swinge to the west of Alderney and in the Alderney race to the east. The streams around the island are complex and reportedly somewhat unpredictable - the Admiralty tidal stream atlas is well worth studying, although the one in the RCC pilot book may have more detail close to the coastline.
Braye, Alderney: High water is 45 minutes after high water at St. Helier
Alderney Race: The north north-east going stream begins at 2 hours and 10 minutes before high water at St. Helier. The south south-west going stream begins at 4 hours and 5 minutes after high water at St. Helier. The flow reaches a speed of 7 knots at springs. Overfalls occur near Alderney, especially around the Brinchetais Ledge, Race Rock and Inner Race Rock. On the eastern side of the race, overfalls form over a 16 m bank 4 miles west-south-west of Cap de la Hague, as well as a 17 m bank further east. Between Race rocks and the 16 m bank are less disturbed flows. Between the 17 m bank and the La Foraine beacon is also a zone of flatter water.
Off The Noires Putes: Around 1 mile of the south-west of the south-west tip of Alderney: The east north-east going stream begins at 4 hours and 30 minutes before high water at St. Helier. The west south-west going stream begins at 2 hours and 30 minutes after high water at St. Helier. The east north-east going stream reaches a speed of 1.7 knots at springs. The west south-west going stream reaches a speed of 3.1 knots at springs. The stream here is likely affected by eddies off the south-east coast of Alderney.
Eddies on south-east coast of Alderney: An eddy forms here, with the following flows: The north-east going stream begins at 5 hours after high water at St. Helier. The south-west going stream begins at 2 hours and 55 minutes after high water at St. Helier. The north-east going stream reaches a speed of 3 knots at springs. The south-west going stream reaches a speed of 2.5 knots at springs. The north-east going flow is a narrow eddy running close inshore from from Coupé rock at the south-west tip of Alderney to Houmet Herbé Fort - the island at the north-east tip of Alderney. From 4 hours and 30 minutes before high water at St. Helier, the eddy may become rather large, extending between the coast and a perimeter defined by Orbouee (1km south-west of the island's south-west tip), a point 1 mile south-east of The Noires Putes and a point 1 km north east of Brinchetais Ledge (800 m off the eastern extremity of the island). The flows over Brinchetais Ledge can reach 6 knots.
East side of north-east corner of Alderney: The north-east going stream begins at 2 hours and 30 minutes before high water at St. Helier. The south-west going stream begins at 4 hours after high water at St. Helier. The north-east going stream reaches a speed of 4.7 knots at springs. The south-west going stream reaches a speed of 3.4 knots at springs. Overfalls forms over the Brinchetais Ledge (just east of the tidal island of Houmet Herbé) and near L'Étac de la Quoiré, as well as throughout the Alderney Race.
The Swinge: The north-east going stream begins at 2 hours and 50 minutes before high water at St. Helier. The south-west going stream begins at 4 hours after high water at St. Helier. The north-east going stream reaches a speed of 5.5 knots at springs. The south-west going stream reaches a speed of 6.8 knots at springs. Other sources give the time of the start of the south-west going stream as 3 hours and 15 minutes or 3 hours and 40 minutes after high water at St. Helier. Rates of 7-8 knots have been reported. The maximum south-westerly flow is reached by 4 hours and 40 minutes after high water at St. Helier. The north-east going flow is slack by 3 hours after high water at St. Helier. Heavy overfalls form. There are eddies on both sides of the channel. The flattest water may be near Corbet Rock and near the coast of Alderney.
Eddy on north coast of Alderney: From 25 minutes after high water at St. Helier, an narrow eddy from Sauquet Rock (just of the north east corner of the island) to the harbour entrance. The stream runs at over 3 knots.
North Coast of Alderney: The east going stream begins at 2 hours and 15 minutes before high water at St. Helier. The west going stream begins at 45 minutes after high water at St. Helier. The flow reaches a speed of 3 knots at springs. Prior to the tide turning in The Swinge, the west-going flow extends along the north coast, to 1 mile north of the breakwater tip and then south to Corbet rock. From 3 hours after high water St. Helier, the west-going stream extends across the north end of The Swinge towards Nannels.
Eddy off Alderney Harbour: An eddy here flows south-west starting 5 minutes before high water at St. Helier reaching a maximum speed of 4 knots at springs. The eddy is about 100m wide, and is separated from a similarly fast east-going flow by a narrow band of slack water.
Eddy between Alderney Harbour and Corbet Rock: An eddy here flows west south-west starting 45 minutes after high water at St. Helier.
Eddy around Ortac: During the main south-going flow, an eddy extends south-west from Renonquet and Burhou for several miles.
Eddies north-east of Renonquet: During the north-east going flow, eddies form behind Renonquet and Burhou.
Ortac Channel: Between Ortac and Casquets: The north north-east going stream begins at 2 hours and 15 minutes before high water at St. Helier. The south south-west going stream begins at 3 hours and 45 minutes after high water at St. Helier. The north north-east going stream reaches a speed of 5.5 knots at springs. The south south-west going stream reaches a speed of 5.1 knots at springs. Even in calm conditions, the channel is described as 'intimidating' due to confused water and large boils. The streams are reported to run at 7 knots in places.
Off Casqets: The north north-east going stream begins at 2 hours and 15 minutes before high water at St. Helier. The south south-west going stream begins at 3 hours and 45 minutes after high water at St. Helier. The north north-east going stream reaches a speed of 5.5 knots at springs. The south south-west going stream reaches a speed of 5 knots at springs. Eddies form behind Casquets during flow in both directions. Flows up to 7 knots have been reported west of Ortac.
Eddy north east of Casquets: On the north-east going flow, an eddy forms behind Casquets.
Eddy south west of Casquets: On the south-west going stream an eddy forms behind Casquets, which can extend for 2 miles.
Burhou Island: Burhou has the largest puffin colony in the Channel Islands. Landing is prohibited during the breeding season from March 15th to the end of July.