A Salutary Experience 7 March 2011

Which is all jolly fine (see Swimming Off Exmouth) till something goes wrong. With hindsight I could have ticked all the boxes in ‘Pratical Considerations’ except nos. 1, 2 and 7. Failure to tick nos. 1 & 2 adequately nearly made 7 an irrelevance.

 

7th March 2011 was a great day; high pressure, nearly cloudless with an easterly breeze. Out of the wind it was warm. Back home, daffs and tulips were out. Water temperature 8.3° C. Quite a big spring tide, two weeks before the equinox. I swam in the middle of the ebb, about noon. [High water ca. 0800 hrs 3.8m; low water ca. 1400 hrs 0.4m] The Rule of Twelfths states that the rise or fall of tide will alter by approximately 1/12 of the total in the first hour, 2/12 in the second, 3/12 in each of the third and fourth hours, then reduce to 2/12 in the fifth and 1/12 in the final hour. So the least amount of water is shifting at the start and finish of ebb and flood and increases to a maximum in the middle.

 

It was choppy rather than rough, with two to three foot high waves coming ashore. The water was already quite far out. It seemed to take an age to get deep enough to swim so I ducked down well before I was even waist deep. For the first ten or twenty strokes I could still feel the bottom with my hands as I swam. “Right,” I thought, “let’s get cracking. Fifty strokes for France.” After about 30 strokes I decided to check for depth only to find I could no longer touch the bottom. I turned around and headed back to shore, taking a bead on a transit shore mark but found, to my alarm, that I was still going backwards. France was on!

 

orcombe point

 

 

The main channel from seawards into the Exe Estuary is marked by a line of buoys, indicated on the chart above starting with E. Exe, at bottom right of the image, and continuing with No.1, No.2, No.3 etc north-westerly. The local almanac states that the current in the main channel can run at up to 4½ knots. It was certainly hammering out on the day in question. An average swimmer – and I am a very average swimmer – can expect to swim at about 2 knots. A really good swimmer might manage 3 knots for a short distance. Clearly, expecting to make headway against a 4 knot, or even a 2 knot current, is optimistic bordering on plain stupid. But then I had not anticipated any of this.

 

I am not sure exactly what happened next, apart from slipping effortlessly into panic mode, but I noticed that each wave gave considerable assistance towards the shore while immediately behind it was a corresponding but slightly greater tug away. I tried to make best use of the former while resisting as much as possible the latter. Somehow I was soon able to touch bottom again. Fortuna favet fatuis – on this occasion anyway.

 

So technically I was back in my depth and everything was hunky-dory. Wrong! The undertow was so strong that I was unable to remain standing in the same place while shoulder deep. Waves either broke over my head or lifted me off my feet and I was then carried backwards, further out of my depth, by the undertow as the wave passed. Even when chest deep progress towards the shore was extremely hard. What seemed to work best was leaning as far forward as possible, which was not very far at the outset on account of the depth of water, and ‘running’ with the feet while flailing my arms like a madman. [Well, here I am aren’t I?] The result is a better definition of what it is to be “in one’s depth.” In adverse conditions I would say no more than waist deep. One inadvertent mouth- or lung-full of water when chest or shoulder deep would be seriously inconvenient!

 

Ironically, I had intended the swim to be an endurance trial for how long I could remain in the water before it got too cold for comfort and had planned to stay in for 10 minutes or so. As it was, I didn’t get around to that as I was too freaked out and just wanted to get ashore, but it did mean that I had taken note of the time as I entered the water. I was immersed for just under 6 minutes. As far as the temperature was concerned I could have stayed in longer, but the exertion required to return to safety was enervating and I was pleased to get ashore to put it mildly! The cold endurance will have to await another day.

 

The most important lesson learned is the absolute need for planning – not during, not after, but before! My rules [see above] gave me a false sense of security. I had no plan what to do if things went wrong. How could they? I’d got my check-list. In cold water there is very little time in which to stay effective. There is not only fatigue with which to contend but the cold renders the muscles less responsive and efficient. And it is the wrong place to start planning. I don’t know what I would have done had I not been extremely lucky, but having thought about it a lot since, I now have a plan of sorts should anything similar happen again. I should have had one before entering the water.

 

I was about where the is on the chart when I found myself out of depth. The deep water channel, indicated by the buoys, is presumably scoured from the leveller surrounding sandbanks and beach by the flow of water, but I am not aware exactly where it starts nor how steeply sloping its sides, but I assume I must have drifted into it. The exact spot I chose to swim is a narrow corridor of sand unimpeded by rocks ahead but bounded on each side by rocky promontories. These must somewhat reduce the current along the shoreline but once beyond their shelter the full force of the stream is encountered. Having failed to make a conscious note of this at the time, I think I must strayed unwittingly into a ‘danger’ zone.

 

Had I not been lucky what should I have done? What I actually did was instinctively swim as directly as I could for the shore. If I had not regained my depth this was probably the wrong strategy ‘long term’ i.e. for the next 5 or so minutes one could reasonably expect to swim effectively. Swimming westwards would have been an even worse choice as not only even more directly against the current but also towards a small ‘bay’ from whose shore the water may eddy at an accelerated speed seawards. By the same token, eastwards there might be a slackening of current, even, being really optimistic, an eddy ashore. (Straight Point, 200 ms or so off the chart, forms another large bay, Sandy Bay, which is comparatively sheltered and may eddy.) It would certainly be the best bet next time.

 

So, all in all I failed on “know your coast” as well with “take care with the tide.” Nautical charts are a good place to start. Another place is a nautical almanac. These are published every year and have a wealth of information about tides, currents, hazards etc but bear in mind they are prepared primarily for people in boats and concentrate on navigable waters. Apart from the fact that our poxy politicians seem hell-bent on closing them, your public library should have a current almanac. And make sure it is ‘current’. They are published annually and the data contained, especially for time and height of tide, alters yearly. If you plan to swim in un-navigable waters you will need to rely on your own interpretation of data from sea charts.

 

Me duce, tutus non eris.

Written on April 4th, 2011 , beini, Bird-seed Survey, Blogger Me, Sea Swimming, Exmouth

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