About The Corryvreckan Whirlpool
The Gulf of Corryvreckand and its famous whirlpool/maelstrom lies off the west coast of Scotland, between Scarba and Jura - famous as the place where George Orwell wrote his big brother Novel, 1984.
The maelstrom of water that lies 300 yards off the shore of Scarba on the north west side of the gulf is caused by an underwater ridge of rock, which rises to a pinnacle whose top reaches to within 30 metres of the surface.
When water flowing through the Gulf of Corryvreckan, especially on a spring tide, meets this pinnacle it is forced up and around the flat east face producing in some rare cases one large whirlpool, although more frequently it will produce standing waves which can reach up to 15 feet in height.
On an ebb tide, as water flows back into the gulf from the Atlantic Ocean, hundreds of whirlpools of varying sizes can form as the water flows over the pinnacle. The most impressive effects can be seen when a particularly high spring tide forces water through the gulf, and the resulting waves at the pinnacle are met with strong winds directly from the west.
However, things can get even more complicated if strong winds from the east push and hold water out between Colonsay and the gulf over a period of perhaps two days. If the wind then changes direction or drops in strength this water is released to flow back into the gulf. If this coincides with a spring tide it will meet the water coming in from the Crinan Basin.
This is just one of many scenarios and the gulf is never the same twice.
Although George Orwell came close to drowning in the gulf when he miscalculated the tides, I can only find one recorded instance of a shipwreck which occured when a Norwegian Barque was blown by Gale force winds from anchor on Colonsay onto the southwest shore of Scarba, although this was not caused by the pinnacle or its effect but by storm force winds (See Argyll shipwrecks by Peter Moir and Ian Crawford published by Moir Crawford).
The crew were able to scramble ashore and were picked up later by a fishing boat. Sailing boats can go through as long as the tide strength and direction are in their favour. The problem is that the tidal flow in the gulf doesn't always match the tidal predictions. Kayakers, who have to rely on elbow power, will sometimes wait just round the northwest edge of Scarba until they actually see the tide direction change, and only then go through.
For a more detailed explanation on the tides and forces at work in and around the gulf, as well as the history of chart mapping and legends surrounding this area visit Mike Murray's website at whirlpool-scotland.co.uk
On Mike's website you can also purchase by credit or debit card a copy of the DVD produced by Mike and myself about the Corryvreckan which shows the gulf at its wildest and its quietest as well as explanations, diagrams and a slideshow of still images.
Small, naturally forming Whirlpool
On a spring tide water is pulled up the Sound of Jura, this also pulls some extra water out of the Clyde Basin. When this water reaches the North end of the Sound it is squeezed by the narrowing of the Sound just before it enters the Crinan Basin. The lochs of Crinan, Craignish and Melfort are already full and although some water escapes towards Fladda the bulk of the water has nowhere else to go but round into the Gulf of Corryvreckan.
As the water enters the gulf it has already been churned up by the rough contours of the seabed during its journey up the Sound and as it enters the gulf it pours into a 219 metre hole - which steadily rises to the base of the pinnacle at the west end of the gulf. This water then flows up the flat east face of the pinnacle and pours over and around the top creating either standing waves or in some cases one large whirlpool. The turbulence it produces can sometimes stretch across three quarters of the breadth of the gulf.
The water drawn up on the west side of Jura is lower as it encounters no opposition, when the water exits the gulf it 'falls' onto this lower water and mixes with it producing an overfall, or 'The Great Race' as it is better known. The affected area can stretch as far as five miles towards the Island of Colonsay to the west. Boats coming up from Islay heading north will swing well over to the west to avoid this area which can best be described as similar to an old style washing machine. Of course at other times it can be perfectly flat.
I watched this area from the Jura headland while filming the whirlpool for the video and some of the waves looked like they could be at least 30 feet high! Several waves appear to combine to produce a single large one.
You can sometimes see this area of turbulence in the distance if you go into the Bay of Pigs for tea.
What happens in the gulf doesn't always reflect the tide tables as there are so many other factors which can affect it, high pressure and low pressure areas, or wind swells which develop miles out in the Atlantic. All these plus the variable tidal movements conspire to dictate the final effect in the Gulf of Corryvreckan.
When the tide is on the ebb water flows back into the gulf from the Atlantic and this leads to a different effect. Sometimes numerous whirlpools will appear and dissipate around you as water flows over the top of the pinnacle.
Gulf Of Corryvreckan 3D Model Diagram - Acknowledgements
The 3D Model Below shows the seafloor of the Gulf Of Corryvreckan, based on Echosounding Data [See Credits Below].
This shows the gulf from the east with the deepest section of 219 metres marked, you can see just why there is so much turbulence even before the water reaces the pinnacle, which can be seen in the top right hand side corner of the image.
Many Thanks To Dr Jon Davies For Producing This Diagram.
Gulf Of Corryvreckan 3D Model Diagram - Credits
Data used to derive these images were collected by the Broadscale Mapping Project which was funded by the Crown Estate, Countryside Council for Wales, Natural England [formerly English Nature], Scottish Natural Heritage and the University of Newcastle [SeaMap Research Group], with further support from the European Commission under the Life Programme. Images were created by Dr Jon Davies [Joint Nature Conservation Committee] from data supplied by Dylan Todd [Scottish Natural Heritage]. [Copyright Jon Davies (JNCC].