Calculating slack water in the Corryvreckan

I am currently writing a sea kayaking guidebook book for Pesda Press "Argyll and the South West, Ardnamuchan to the Solway Firth by Sea Kayak. (ISBN 978-1-906095). This is one of the most complex areas of the UK coastline and I am determined that it will be a piece of work which is thoroughly researched, both in terms of previously published information and also of first hand experience.

I think I am pushing the good will of Franco, the publisher, but I do not want to rush a guide based on my experience of a piece of coastline on one trip, one way, in one set of weather conditions. The Corryvreckan is an example of a serious bit of coast, a key point in the planning of any voyage in these parts. If you click the Corryvreckan tag link on the right, you will discover that we have passed through this Gulf E/W both ways, along both coasts, crossed it N/S both ways, at a variety of states of tide and in a variety of wind and swell conditions. We have camped on both its north and south shores and climbed into the hills of Scarba and Jura to photograph the various eddies and over falls.

For those of you who are interested in such a sea kayaking guide, I appreciate your patience, thank you.

According to published data, in the Corryvreckan, the west going flood starts at -0100 Dover springs and -0015 at neaps. The east going ebb starts at +0515 Dover springs and +0600 at neaps, a time difference of about 6.5 minutes per day between springs and neaps.

On the 16th October 2009 it was 2 days after springs, HW Dover occurred at 1025 and 2256, so the slack between the east going ebb and the west going flood should occur at -0047 HW Dover ie 0938 and the slack between the west going flood and east going ebb should occur at +0528 HW Dover ie 1553.

We entered the west end of the Corryvreckan at 1446 and landed at Camas nam Bairneach at 1500. We enjoyed a view of the flood in action and a short luncheon but were keen to be on the water, in mid channel, to observe the exact moment of slack water. We launched again at 1525.


Phil powering into the last of the flood at 1530. The current was still flowing west at 2.5kn.


At 1539 several yachts entered the Corryvreckan. At 1544, in mid channel, the current was still flowing west at 2kn (see map below).


Then at 1549, with the soaring ridges of Ben Cruachan in the distance,...


...the water turned oily calm and slack water had arrived. It lasted a whole 5 minutes until the ebb started with a bang and boils and eddy lines disturbed the surface again. In the distance, you can just see the small lighthouse on Reisa an t-Sruith in front of Tony's bow.


So the published start of the flood was calculated at 1553 and we observed slack water between 1549 and 1554. Pretty good Eh?

Well, err, actually no. There was no wind and we were in a high pressure system with preceding light winds and little swell. There are very many factors that can alter the change of tide in these parts and you need to go prepared to observe what you find on the day (and of course to have checked your calculations).

Thank you for your patience while I get the book right... :o)

Showdown with a goat in the Corryvreckan!

We entered the Corryvreckan in somewhat calmer circumstances than our last visit. Even in windless conditions the flood was bubbling and boiling like a witch's cauldron. The sight and sound of such a huge volume of water rushing by at 18km/hour was quite moving, in fact Phil later described it as a buttock clenching experience.


We took the counter eddy (that runs east along the south shore of Scarba) right into the heart of the Corryvreckan until we came to the headland before Camus nam Bairneach. The eddy ended at a small headland and swung out into the main flow where it joined the rotating mass of water which forms the whirlpool. I said “Phil you need to get round this headland so paddle quite hard and don’t look back.”


The best chart for discovering the various eddies is the 1856 Admiralty chart.


The headland is in the bottom middle of this photo taken from high on the slopes of Scarba. Here the eddy (calmer water in lower right in the photo) swings out into the main flood (which is flowing to the right) where it joins in a great swirl that creates the whirlpools of the Corryvreckan. To get round this headland into the shelter of the bay you do need to paddle quite hard for 150 metres. If you can't PLF and get round the headland, you are in for a very special treat. The eddy will carry you right into the whirlpool and the Great Race beyond, so you can get a really close look at this natural wonder. Make the most of this experience but just don't expect to be able to share it with others afterwards.


We got round the headland and landed in a little bay to wait for the flood to ease off. We took this territorial goat by surprise, it clearly was not used to having its privacy invaded during the flood! The smelly brute squared up to us and stood his ground but his harem of females all ran off up the hill. Ultimately he found them more attractive than a confrontation with us and he made a measured retreat.


We had to drag the boats well up the beach...


...as seething surges of tidal water threatened to whisk them away into the jaws of the ‘vreckan.


Tony took some photos from the headland, which we had recently fought our way round.


This is the Corryvrekan on a windless day. In a westerly gale the standing waves reach 5m in height and can be heard in Crinan 13km away. Fortunately for Phil, this is just about as calm as it gets.


While Tony was taking photos, Phil was content to sit and gaze in wonder. I think he was still a bit shaken after our confrontation with a goat!

P.S. Please remember that the Corryvreckan is a very large and serious tide race. It is in a remote location and, if you do get into trouble, it will carry you straight out into the open Atlantic for 5 miles before the Great Race subsides. Mike Murray knows a great deal of the Corryvreckan and how unpredictable it can be. A visit to his website should leave you under no illusions about the seriousness of this paddle. Another website well worth a visit is David Philip's Hebridean Wild. His gallery contains many photos of the Corryvreckan such as this one, which is enough to send a chill through any kayaker's heart.

John F asks: "Okay, so how bad would it be if one were swept through the whirlpool? If you had to hang on to your boat, do you think you could keep your head above water? Don't know if I want to find out, first hand."

Well John, a recent TV documentary about the Corryvreckan called Lethal Seas featured an interesting experiment. A weighted dummy wearing a life jacket was dumped into the sea just before the Corryvreckan whirlpool. It disappeared within moments. It was recovered several miles out to sea half an hour later. A dive meter showed that it had been down to at least 200m and the dummy's life jacket had gravel in its pockets and straps.

Menace hung in the windless air, even for the most daring and venturesome.

Common sense would suggest that we should have relaxed on the beach on Scarba's NW coast until near slack water in the Corryvreckan.


We were not having any of that, we wanted to see the whirlpool in action!


As we paddled down the west coast of Scarba, with Colonsay on the horizon, it gradually dawned on Phil that the only way back, was through the Corryvreckan!


As we worked our way down the coast...


...Jura began to appear...


...above the raised beaches of Scarba's wild SW corner.


The rule of thirds does not apply to the Corryvreckan. The spring tidal flow remains at a full 18km/hr almost until slack water, which at springs only last a few minutes. This was the situation as we rounded the SW tip of Scarba with an hour and 10 minutes before slack water.

We were going to use a counter eddy along the south Scarba shore, which the Clyde Cruising Club describes thus: "There is a ribbon of comparatively smooth water within 10m of the whole of the S Scarba shore, but this passage is not recommended, even for the most daring and venturesome."


As we approached the entrance to the Corryvreckan, a fine mist hung in the windless air, which betrayed the menace of the seething currents below.

Free fall on Scarba

Tony and Phil carried the boats well above the tide line as we know that there is the possibility of tidal surges here. A tourist RIB roared round the bay en route from the Corryvreckan to the Grey Dogs. These trips bring much needed visitors and money to the local economy.


This was a marvellous spot to relax and have lunch.


We had a terrific view over the Firth of Lorn to Ben More on Mull.


The cliffs that surrounded our little beach formed a natural amphitheatre with walls over 100m high.


This waterfall cascades over the full height of the cliffs. In wet weather it forms an impressive spout.

We enjoyed our view of the mountains and the waterfall for free!

Friends to watch over you

Looking back at the Grey Dogs, from a distance of over 2km, it all seemed so calm and innocent.


To the north the mountains of Mull dominated the distant horizon. The long necklace of islands that make up the Garvellachs and the Black Islands lay in the middle distance and little Guirasdeal and Lunga were in the foreground. What a magnificent playground.


We paddled below the dark cliffs of the north shore of Scarba.


We were watched from upon high.


Rounding the NW corner of Scarba, distant Islay and Jura came into sight. We were now paddling on the open Atlantic and the swell increased.


We found a little scrap of beach with some shelter from a reef. Tony and Phil went in first. I made a very awkward landing. Then Tony got a good hold of my boat and Phil lifted me right out and up onto my feet. They then carried my boat well above the surge line. I had been fine when paddling, with my injured knee in its brace under my dry trousers, but I now realised how dependent I was on the others for landings.

Thanks guys, I could not have managed this trip without you!

:o)

Sleeping Grey Dogs

Leaving the Pool of the Song, we felt another pull. This time it was the pull of the Grey Dogs tidal race. It was spring tides maximum flow and there was not a breath of wind so we could hear the Dogs growling from some way off. Phil said "We are not going through there are we?"

"Oh no!" said Tony, quite truthfully, as we carefully vetted the Dogs' condition through the south channel before...


...turning in to the straighter north channel. Just as we passed the point of no return, Tony quietly said "Phil, see when we turn the corner, just after this wee island? Just keep paddling".


Tony led the way down the inverted "V" between the worst of the eddylines as the water sloped downhill between the gap. Phil stuck to his stern. I brought up the rear, ready to pick up any pieces.


There was ony about 4 or 5 standing waves and then we were through onto flat, boily water at 18km/hour.


The stirred up water extends...


...well to the west of the Dogs.


But at last we hit calm water again. Phil was noticably moved by his recent experience. "Was that like a grade 4 river?" he asked. We hadn't the heart to tell him it was only grade 2!


By now Phil had regained his composure: "What an experience !.. Only one thing guys... Where is my badge ?"

"Now, now, Phil, if it's wee bajes yer efter, ye'll jus' need tae jine a club!"

We were very lucky to hit the Grey Dogs when they were sleeping. If there is any westerly wind or swell then they can be rather different.


We would not have taken Phil through the Grey Dogs...


...if we had found conditions to be like these two recent trips.

Pool of the Song in the Sound of Luing

We broke out of the tide towards the Corryvreckan and entered the Sound of Luing between Scarba and Luing. Kilmory Lodge, which is one of the few houses on Scarba, stood high on the hill side above us.


On the other side of the Sound, low lying Luing presents a gentler contrast to the steep hills of Scarba. In the distance, we were preceeded up the Sound by a pod of about 30 bottlenose dolphins, which were thrashing the surface of the water in a long line and some were leaping clean into the air.


We had seen them here before, in February 2004, but at much closer range.


We stopped for second breakfast below the Lodge on the wooded shores of Scarba, at the delightfully named Poll n h-Ealaid, "pool of the song" . Phil noticed the strength of the tide, which nearly swept him past this little harbour...