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Thunder Child II Visits Famous Corryvreckan Whirlpools & Standing Waves

29th July 2020
Thunderchild II at the Corryvreckan whirlpool Thunderchild II at the Corryvreckan whirlpool Photo: Safehaven Marine

Cork Harbour Boat manufacturer Safehaven Marine undertook an 800nm four-day cruise in Thunder Child II to Scotland, living off the boat to visit a place called the Gulf of Corryvreckan. A pretty wild yet beautiful place writes Thunderchild's skipper, Frank Kowalski

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.

Thunderchild II heading into the standing waves at the Corryvreckan WhirlpoolThunderchild II heading into the standing waves at the Corryvreckan Whirlpool

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.

Sstationary at 6kts with the waves breaking behind Thunderchild IIStationary at 6kts with the waves breaking behind the boat

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.

Submarine topography of the Gulf of CorryvreckanSubmarine topography of the Gulf of Corryvreckan

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 North from Cork Harbour to Corryvreckan

Corryvreckan at Ardbeg Marina with a rainbow as a symbol of hope for a successful tripCorryvreckan at Ardbeg Marina with a rainbow as a symbol of hope for a successful trip

As Afloat previously reported, 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.

Thunderchild II alongside at Bangor Marina in County Down(Above and below) Thunderchild II alongside at Bangor Marina in County Down

Thunderchild II at Bangor Marina

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.

Thunderchild on her 800nm odyssey to Corryvreckan off the Scottish West CoastThunderchild on her 800nm odyssey to Corryvreckan off the Scottish West Coast

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 were buzzed overhead by Rescue 117 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.

Thunderchild II propellorsIn the amazingly clear waters of the North, Thunder Child II’s quad propellers quite clearly over the transom

Thunderchild II Leaves Bangor MarinaThunderchild II Leaves Bangor Marina, her golden colour glistening in the sun and below

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.

Thunderchild II crew: Skipper Frank Kowalski and crew: Carl Randalls (Drone pilot) Ciaran Monks, Mary Power and Kenny CarrollThunderchild II crew: Skipper Frank Kowalski and crew: Carl Randalls (Drone pilot) Ciaran Monks, Mary Power and Kenny Carrol

Thunder Child II Specification

  • L.O.A. 23m
  • Beam 5.4m
  • Displacment 25,000kg ( lightship)
  • Fuel capacity 8,000L
  • Range 750nm
  • Propulsion 4x Caterpillar C8.7 650hp engines, 4x France Helices SD23L Surface drives
  • Speed Max 54kts, Cruise 32-40kts
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About Safehaven Marine 

Safehaven Marine are designers and builders of FRP Pilot boats, Patrol boats, Crew transfer vessels, Hydrographic survey catamarans, Naval & Military craft and unique custom private motor yachts. All our vessels are built to the highest standards of strength & engineering and are renowned worldwide for their exceptional sea-keeping abilities, we set a new World long-range speed record in 2017 with our own vessel and crew. Established in 1996 we have built over 138 vessels supplied to 27 countries worldwide with over 40 pilot vessels in operation globally, and have become leaders in our field.

Based in Youghal, Co Cork Ireland, Safehaven manufacture our vessels from two modern factories, with all design work carried out in house, and built with our own experienced team of engineers, carpenters, electricians, shipwrights and laminators.

Always at the forefront of new technology and designs we continuously develop our range and push the frontiers of design: In 2020 we aim to set a UIM Transatlantic World record with our unique (patent applied for) new 22m high-speed vessel XSV20

Interceptor 42 pilot boat

The Pilot 42 model built by Safehaven Marine has been delivered to ports worldwide and has proved to be a superb sea boat performing admirably in pilotage operations with all owners extolling its virtues of seakeeping, strength and stability.

L.O.A. (Length overall) 13.2m

L.W.L. (Length along waterline) 11.5m

Length moulded (GRP hull only) 12.7

Beam Moulded (GRP only ex fender) 4.0m

Beam overall (Including fenders) 4.4m

Draft (Depth of hull below waterline) 1.35m

Displacement Lightship 14,500kg

Fully loaded 16,000kg

Fuel capacity 1600 litres

Water capacity 110 litres

Crew capacity 5 persons

Engines Volvo D9 425hp

Gearboxes ZF325

Subdivision 4 x separate watertight compartments

Crew capacity 1-2 crew plus 3- 4 pilots

Classification PRS

Speed 23.5kts fully loaded

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