The Corryvreckan whirlpool, or ‘Maelstrom’, as would be a more appropriate description, is formed as the tide enters the narrow stretch of water between the Islands of Jura and Scarba that is the Gulf of Corryvreckan. Here the tidal flow speeds up to 8.5kts as it is squeezed between the islands, and there it encounters a variety of underwater seabed features. On the western entrance a basalt pinnacle rises up from depths of 70m to 29m, and lying to East, directly in front of the pinnacle is a deep hole in the seabed, with a depth of 219m.
As the water flows through the gulf it falls into this hole, and then encounters the steep face of the pinnacle, causing a massive upwelling surge of water to rise to the surface. On a flood tide this surge meets swells entering the Gulf from the West, and creates standing waves that can reach heights of 9m. These ‘standing waves’ are not like normal waves as they form directly over the pinnacle, standing still and breaking heavily on the spot. Whirlpools are also formed over the pinnacle as well as throughout the Gulf, as opposing water columns sheer, and these can be up to 50m wide.
During a storm on spring tides it is said that the angry roar from the seething waters of the maelstrom, with its standing waves and whirlpools can be heard up to 10 miles away, and local mythology refers to this as the voice of ‘Cailleach’ (The Hag) of the Whirlpool.
In a well found boat the gulf can be safely navigated in fair conditions, or at slack water, but I can imagine that in a Westerly gale on a flood tide, you wouldn’t want to be anywhere near the place, as it would truly be described as ‘Unnavigable’. Indeed it was once classified as such by the Royal Navy. On the day we visited with Thunder Child we had Westerly winds of Force 5 gusting 6, and a 3.9m tide which enabled us to experience the standing waves on the flood and the whirlpools on the ebb.
The word Corryvreckan translates to ‘Cauldron’ and that perfectly describes the seething sea state around the whirlpools, and it was quite an experience to have the throttles set for 6kts, holding station just ahead of the standing waves that were breaking behind the boat, and not be moving at all!
There is an Old Irish text known as Cormac’s Glossary written by the King and Bishop of Cashel, Cormac mac Cuilennáin who died in the year 908: “There is a great whirlpool which is between Ireland and Scotland to the north, in the meeting of various seas, its thunderous eructation and its bursting and its roaring are heard among the clouds, like the steam boiling of a cauldron of fire.” I felt that was a pretty cool description of the place as how the place might have appeared of old during a storm.
Coryvreckan is reputed to produce the third largest whirlpools after the Saltstraumen and Moskstraumen Maelstroms in Norway, however the unique submarine topography of the gulf of Corryvreckan and its capability to produce dangerous standing waves means that in storm conditions, it is potentially one of the most violent stretches of water in the world.
The Voyage: Casting off at Cobh in the afternoon on Saturday 18th July 2020 Thunder Child II arrived at Bangor marina at 9.30pm for refuelling after averaging 32kts over the 275nm run. Overnighting on aboard we set sail early Sunday morning heading up the Northern Ireland coast to Rathlin Island, itself a place notorious for producing challenging seas with its tidal strong race and overfalls, before a lumpy crossing to Scotland to enjoying two days taking Thunder Child II through the standing waves and whirlpools in the Gulf of Corryvreckan, and capturing some cool Ariel drone video. Whilst we were there It was also nice to see one of our old Interceptor 42 passenger boats ‘Venturer’ for the first time since we built her 15 years ago, and still looking good. Operated by Craignish Cruises running boat tours in the Gulf, they guided us on a tour around the islands visiting the notorious ‘Grey Dogs’ tidal race and seeing the Sea Eagles nesting nearby.
Spending Sunday night isolated on the breakwater at Ardfern marina we headed to Belfast late afternoon on Monday. Next day we were onwards to Dun Laoghaire for lunch and down the East coast of Ireland where we we’re buzzed overhead by Rescue 116 of the Irish Coastguard, which was great to experience and gave us the excuse to give Thunder Child the beans, and although heavy with fuel we still managed to hit over 50kts.
We arrived home to East Ferry Marina, Cobh late Tuesday evening after an enjoyable voyage for her crew comprising: Skipper Frank Kowalski and crew: Carl Randalls (Drone pilot) Ciaran Monks, Mary Power and Kenny Carrol. During the voyage Thunder Child II ran faultlessly and proved her capabilities of averaging high speeds for long distances.