Showing posts with label tidal races. Show all posts
Showing posts with label tidal races. Show all posts

Tuesday, 10 November 2020

Autumn on Etive

Of all the seasons, autumn in Scotland is my favourite.  the colours are at their best and there's a tangible sense of change in the air - I've never thought it to be a season of decline or dwelled on the shortening day length.  Allan, Raymond and I were looking for a sea kayak trip during a period of settled weather in mid-October; we decided on paddling on Loch Etive which we hoped would give us a good trip and allow us to experience the autumn colours from the water too.



Loch Etive is a 30km long, fjiord-like sea loch with its entrance into the Firth of Lorn at Connel, just north of Oban.  When the glaciers carved out the loch and then retreated, a sill of rock was left near the entrance.  This sill limits the flow of water leaving the loch on an ebb tide, with the effect that the level of the water outside the loch drops faster than that in the loch.  From quite early in the ebb a tidal fall forms at Connel where the loch is spanned by a road bridge.  On a spring tide, which it was when we did this trip, the Falls of Lora were in full and spectacular flow.  We stopped to admire the spectacle, and to watch the river kayakers who use the Fall as a play spot.  We, however, had no intention of taking 5 metre fully laden sea kayaks anywhere near this spot on a spring tide and planned to stat our trip some way up the loch!



We gathered at Taynuilt where the loch again narrows but without the excitement of a tidal fall to contend with.  We'd need to paddle against the last of the ebb tide for a short while but were confident of finding eddies along the shore to help us past this short section.  It was a bright morning but with a chilly breeze which was forecast to drop during the afternoon.  Loaded and ready, we got on the water for our short adventure.



Approaching the narrows there are tantalising glimpses of the mountains which line both sides of Loch Etive and give it such character.  I've climbed the hills and walked one side of the loch but hadn't previously paddled here, so was looking forward to exploring as much as we could.




We got through the narrows with little difficulty, though against a bit of a breeze as well as the ebb stream.  The play of light on the hillsides, alternately lighting the rich autumn colours, was lovely - though we noticed a cloud sheet was beginning to form over the area.




As shafts of sunlight became less frequent their effect seemed more pronounced, pefhaps also due to the lowering angle of the sun at mid afternoon.






 All too soon the cloud sheet drew right across the sky, and though the scenery ahead was getting more spectacular the absence of vivid colour took something away.  We certainly weren't complaining too much though, this is a great place to explore by sea kayak - and we had an unexpected treat ahead of us.

Tuesday, 26 April 2016

Corryvreckan - "a depe horlepoole quhairin if schippis do enter thair is no refuge but death onlie".....

At 1525 we launched from Port nam Furm to make our transit of the Gulf of Corryvreckan, intending to take advantage of the slack water period as the flood tide subsided.

This narrow channel running between the islands of Scarba to the north and Jura to the south has a fearsome reputation - the quote in the title of this post is from a 16th century "rutter" or pilot book compiled by Alexander Lyndsay, the pilot on James Vth's voyage around his kingdom.  In the days of sailing ships the Admiralty Pilot warned against attempting the passage and even today in the age of powerful vessels and GPS, the current Admiralty West Coast of Scotland Pilot states that it is "very violent and dangerous" and that "no vessel should attempt the passage without local knowledge".

The Corryvreckan (speckled cauldron), third largest tidal whirlpool in the world, is only part of the problem.  Huge volumes of water pass through the channel on both flood and ebb tides, on the north-going flood the water pours up the Sound of Jura and is forced through narrow passages to the north and west, the Corryvreckan taking a significant part of the stream.  On the south-going ebb the process is reversed and water is forced through the channel from west to east.

The seabed in the channel approaches and the channel itself is very complex and accelerates the flow of water, producing tidal streams of up to 8 knots (16  kph).  A complicating factor is a pinnacle on the north side of the channel which rises from a 219m deep "hole" to within 29m of the surface, with a very steep face on its eastern side.  On the flood tide particularly, this topography combined with the speed of the flow causes a massive upthrust of water which surges past the pinnacle and sets up an enormous whirlpool with vortices spinning off downstream to the west.  If you then combine this dynamic water with a wind and swell from the western entrance to the channel, the resulting conditions can be truly elemental with standing waves of up to 9 metres and a roar which can be heard up to 20 kilometres away.

As we set out, we met the tour boat "Sea Leopard II" coming eastward from the channel.  As soon as he saw us, the captain throttled right back to minimise his wash - a courtesy we were grateful for; a wash in confused water can produce quite difficult waves.  The video embedded on Craignish Cruises website is an excellent explanation and film of the Corryvreckan - and if you don't fancy kayaking the strait then the Sea Leopard II would be by far the best way to experience the whirlpool and the wildlife of the area.  To get an idea of the power of the tidal stream at Spring tides, this video shows the RNLI lifeboat in the main flow.....

We were very cautious because from Port nam Furm it isn't possible to see what conditions are like in the Gulf itself.  We expected some swell from the west due to strong winds in the preceding days, so it would have been unseamanlike and foolish to have attempted the passage when the flood tide (3 days before Springs) was running strongly.





As we entered the channel and gained a clear view to seaward we were relieved to see quiet conditions and no breaking swell - it appeared that our prospects would be somewhat brighter than "death onlie" !  As if stage-managed, the sunny conditions were replaced with a grey cloud sheet as we entered...





In the narrowest part of the channel the water was swirling and forming gentle hydraulic cushions, but our timing had been good and we passed through easily on slack water.  One factor in our planning of time and tide for this passage was that if we encountered nasty conditions at the west side of the Corryvreckan we could wait a short time for the ebb to build and push us back through the channel to safer water in the Sound of Jura.






However, the timing needed to be calculated accurately - slack water lasts just minutes and the flow picks up very quickly.  By the time we reached the west entrance the east-going flow could already be felt and paddling became a bit more strenuous.




On the Jura side of the western entrance are a couple of small islands and skerries.  We passed inside Eilean Beag (little island) as the ebb began to really get started and had to PLF for a good 15 minutes to escape being drawn back through the Corryvreckan.  For a good five minutes we were paddling at maximum output but making good just over 1kph against the strengthening tide.  To see how strongly this section can run at full flow, the same bit of water is featured from the 9 minute mark in the HebrideanWild video.





After a strenuous pull we won safely clear of the Corryvreckan.......the wild west coast of Jura was now ours to explore.

Monday, 4 May 2015

Breaking in and breaking out at Morar

Mike, Douglas and I had planned to stay two nights at the Glenuig Inn in addition to a wild camp during our Glenfinnan - Inverailort journey.  This gave us the opportunity to do a day trip from Morar to Arisaig, returning the same way.  You can follow this day's paddle in "Sea Kayak Stereovision" by reading Douglas' blog starting here



We drove from Glenuig to Morar and parked in a layby just to the east of Toigal (a hundred metres or so downhill from the car park marked on the OS map) where there's good access to launch onto the tidal part of the River Morar.  Beyond the bridge which carries the A830  road to Mallaig we could see the waterfall where the the fresh water from Loch Morar pours down to meet the salt water.





Using eddies and small channels we were able to make our way up against the flow, passing under the new road bridge to where a smaller road bridge and the railway viaduct squeeze together over the rocky channel down which the water was roaring.  As we were launching near low water a day after Springs, the drop was at its most pronounced.  Like the final waterfall from the River Shiel to the sea, this drop is the result of the continuing rise of the land here following the release of glacial ice (isostatic rebound).

The power of the water passing down the 5.5 metre difference in height between the freshwater Loch Morar and the sea has been utilised just above the Falls of Morar by a 750KW hydroelectric power station which was installed in 1948.  The fresh water section of the River Morar is a contender for the shortest river in Scotland, and it drains the deepest freshwater loch in the country, so the potential is for a hydro-scheme is very clear.

We wondered whether it would be possible to inspect the fall a little more closely......





Breaking into the flow required a fair bit of energetic paddling, but as is sometimes the case we found that once at the base of the fall itself we could maintain station quite easily.  On the bank we noticed two drystone footings; these may have either caried an earlier bridge or possibly the footings of a mill.





At this range the noise of the fall is quite impressive! After having some fun in all this aerated and moving water we let the flow take us back down into the quietly moving water in the Morar estuary.





At first we could hear mostly man-made noises; cars on the A830 road and a train crossing the viaduct, but as Mike pointed out, the further we travelled downstream the more the man-made sounds faded to be replaced by more natural sounds.......





...until the calls of birds - Curlews, Oystercatchers, Redshanks and the rest - became the only sounds.  It felt that we had broken out from "civilisation" and slipped firmly into the natural world.





However, we had one more break-out to achieve.  At the mouth of the Morar estuary is a sand bar over which the ebbing tide runs strongly.  When the wind is from a westerly direction impressive standing waves can be formed here as the wind opposes the strengthened flow.  We arrived at the end of the ebb and with a light southwesterly breeze and so........





...our break-out was fun rather than difficult.....





.....lots of fun!......





Having broken out from the Morar estuary we turned south to head along a coast famed for the quality of its beaches.

Wednesday, 29 April 2015

A push to the finish on Loch Ailort


When we left the beach at Ardnish we started on the last leg of our journey from Glenfinnan to Lochailort.  A fresh breeze from the southwest was welcome as we could utilise our sails to help push against the ebb tide pouring from Loch Ailort.






Our route took us past the bothy at Peanmeanach.....





...and on towards the narrow middle section of the loch.  The scenery is rugged and complex here, and dominated by the Corbett of Rois-Bheinn (sometimes Anglicized as "Roshven").






As the loch narrows there's a shallow section which forces the tide up and increases the rate of the stream and was kicking up into standing waves by the wind-against tide.





We managed to keep just clear of the main tidal stream while a few metres away the race charged past us. On the day of a solar eclipse, there was one of the biggest tides of the year and it seemed that the whole loch was emptying!  Even with the assistance of our sails it was a real push on this section.



 


We won clear of the race and passed through a group of small skerries.  According to the Tide Tables we'd reached low water but actually the ebb was still running, although with less force.






As a squally shower passed overhead there was a sudden increase in the wind which hurled us forward under sail, a couple of minutes of exhilarating speed......






.....before the wind died completely and the sun lit the slopes at the head of the loch.   A final couple of skerries and we reached the public slipway at Inverailort.

Our arrival point is just 17 kilometres from Glenfinnan by road, but we'd taken the long way round,  paddling down Loch Shiel and the River Shiel, out to the sea on Loch Moidart and then via the Sound of Arisaig to paddle the length of Loch Ailort.  Our route had been 65 kilometres and had taken in a wild camp on Loch Shiel and a night at the Glenuig Inn - and of course a solar eclipse!

The trip had one last surprise in store for us though.....





The extremely low Spring tide which coincide with the eclipse had left the end of the slipway over a metre above the water when we arrived!  There was nothing for it but to land the boats and between the three of us manhandle and lift each boat up onto the slipway.  We were grateful that our camping gear wasn't in them!

As we ran the shuttle to retrieve the second car we reflected on what had been a superb trip - and one we know that we'll repeat some day.