The Corryvreckan Whirlpool
New Download Available!!
Following a visit to the Corryvreckan Whirlpool a number of years ago, Dan Tipp was inspired to write a seven-page thesis about the Corry. This fascinating document is available in two different formats:
|Word Document File [340 K]||Basic Text File [20 K]|
The Corryvreckan - Some Useful Facts, By Mike Murray
I was prompted to set up this site because of the apparently never-ending stream of misleading or slightly factually incorrect information floating around [no pun intended] about the Corryvreckan. If anyone sees a statement on this website that appears to be misleading, or incorrect - please get in touch and have it corrected!!
I was researching some material in a bookshop recently and saw an Encyclopaedia on Scotland. Naturally I took it down and thumbed through to 'Corryvreckan' and found information suggesting
that the pinnacle rose to within 15 feet of the surface...
... I think this is probably just a typo or denominational error... the charted depth of the top of the pinnacle is 29 metres, or around 100 feet! In the old measure of Fathoms it would have been correct - a fathom is 6 feet.
The latest and most obvious example of incorrect information being given was the BBC Coast Television Series, which stated that the tidal flow in the Corryvreckan was up to 16 knots. I didn't think the tide flowed anywhere in the world as fast as that... the programme should have said 16 kph, or eight and a half knots, a very subtle difference!!
However - I am indebted to Peter Wright who states that the fastest tidal current in the world is at the Saltstraumen maelstrom (67 14'N, 14 36.5'E) where the tide rips through a narrow channel to fill an inland fjord, 60 miles ESE of the 'Moskstraumen' maelstrom (67 48'N, 12 50'E). It is officially 23kts (37kmph) but locals have recorded 25 kts.
Also to Iain Crosbie, who pointed out that the Lofoton Maelstrom in Norway is reputed to run at up to 25 Knots [see Maelstrom website for more information]. Iain also pointed out that tides in the Pentland Firth run faster than those at the Corryvreckan. In Japan, at Naruto there is a narrow channel between Shikoku Island and the mainland.
The highest tides in the world occur at the Bay of Fundy in Canada, and nearby another whirlpool is created - called The Old Sow, this whirlpool is the largest in the Western Hemisphere. See the Old Sow Whirlpool website for more details.
More Whirlpool Facts
A brief outline of how the 'whirlpool' works follows. 'Maelstrom' would be a better description.
The geographical relationship between the islands and mainland of the Argyll coast create an area of sea which has a very complex tidal system.
As the main flood flows north passing the Mull of Kintyre it sucks the water out of the Clyde Estuary, resulting in an extraordinary anomaly between Crinan and Lochgilphead.
Only six miles apart and the tide is high at one and low at the other... diametrically opposed!
As the flood proceeds up the Sound of Jura it is squeezed by the narrowing of the Sound and this increases the flow to a point where it passes through the Gulf of Corryvreckan at eight and a half knots on a full spring tide.
The maelstrom in the Corryvreckan works differently when the tide is ebbing from when it is flooding.
On the ebb, water is flowing in relatively undisturbed from the open sea.
On the flood, water has flowed up the Sound of Jura and has been agitated by the geography of the seabed.
There are innumerable humps and holes and reefs in the Sound and these create terrific tidal flows, up-thrusts and eddies all over the place until finally in the Gulf there is a huge hole down to 219 metres before being confronted by a pinnacle of rock off the Scarba shore which rises to 29 metres from the surface.
The steep east face of the pinnacle forces a massive upthrust of water to surface in pulses which are then swept away westward by the tidal flow and these dissipate into vortices or whirlpools moving west.
This is all clearly visible when there is no wind and the turbulent patterns are fascinating to see in mirror calm conditions.
However when there is any serious wind strength, particularly from the west, the up-thrusts at the pinnacle fold into the oncoming waves and accentuate them. Thus building, in gale force conditions, standing waves that can be 8, 10 or 15 feet high. A truly awesome sight!
When the wind is from the South East or from N or E of North, then the Gulf is in the lee and it tends to be less rough - one can see the pure tidal turbulence. The relative state of Springs to Neap tides also affects the strength of the flows and hence turbulence. So as you can imagine there are many, many factors which affect the performance and so one can never be entirely sure how it will be behaving before one gets there.