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Lee-Bow..... Windsurfers...etc (Dons tin hat)

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Post Options Post Options   Quote PeterG Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 8:04am
That sounds like a large figure, but the essence is correct. She would have had to effectively ferry glide across the current, and since her speed would not be that large compared to the current between Dover-Calais, there she would have to have swum at quite an angle to the direct course - so her distance swum (through the water - which is what counts) would have been significantly longer than 60 miles.
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Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 8:36am
No-ferry gliding is exactly what you wouldnít do unless you are a masochist. Just work out the bearing and swim at it. Allow the tide to take you west and east (3 or 4 cycles) -a lot less work! I am sure the swimmers have sussed that.
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 8:53am
The Channel Swimmers Assn. has this to say about distance :-

"Shortest distance in 21 statute miles, or 18.25 nautical miles (your pilot will use the latter and will want to estimate your speed in knots, i.e. nautical miles per hour); however, on either side of Cap Gris Nez, the French Coastline drops away, so, if you do not reach land at the Cap you have further to go to make landfall. This is particularly the case to the west and south of Cap Gris Nez, so your pilot should aim to avoid letting you get swept in that direction by a SW-going tide. Your pilot will plan a consistent compass heading for the most part of your swim, so that through the water your track will be a straight line, even though the tide will sweep you from side to side over the ground as it ebbs and flows. This will keep your total distance as close to 21 miles as possible, and avoid you wasting energy by swimming against the tide, especially as at times the tidal rate will exceed the speed you could swim at. However, in the last mile or so it may be necessary to swim somewhat against the tide to ensure you reach a suitable landing point: your pilot will need to adapt your course if your pace slows - the stronger the tide, the bigger the course alteration needed - but should aim to approach land uptide of your destination. For all these reasons, swimming during weaker neap tides is preferable."


Edited by Sam.Spoons - 05 Oct 19 at 8:53am
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Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 9:12am
Sam -thatís a pretty comprehensive explanation of how to do itó have you done it?. It is not 150 miles though despite what that journo said.
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 9:29am
No, not even close, as often happens a post piqued my curiosity and I did a quick Google.

Her track in the first crossing will have been as near to the 21 (statute) miles as possible, she will have swum at least 84 miles in total but, probably a fair bit more as she did the four crossings consecutively and they will have been out of sync with the tides by the final crossing.


Edited by Sam.Spoons - 05 Oct 19 at 9:30am
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 11:00am
She did in fact swim much further than the 21 miles, I saw the tracking illustration, it was a truly unbelievable achievement. As a kid I used to accompany my old chap on the Cross Channel swims and many a time the swimmer was effectively stationary over the ground, but swimming for hours on end just to maintain station, until the tide turned.

Finally because it's relevant, forty years ago this month just gone, a windsurfer called Mike Todd and I crossed the Channel on a Tandem windsurfer, 1979 same year as that earlier picture. We set off in slack water, but on the French side of the Varne bank, the tide engaged our, you've guessed it, lee bow and our speed over the water increased and we were able not to fully plane but to at least hook into our harnesses.


Edited by iGRF - 05 Oct 19 at 11:03am
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Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 11:06am
GRF yes thatís the problem her course over the ground may have been 150 miles or so but did she swim 150miles? Floating on your back in the middle for a few days you could really rack the miles up!
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 12:06pm
Apparently she was able to maintain a fairly constant speed through the water, something the CSA adjudicator (who had swum the channel several times himself) considered a remarkable achievement. That, inevitably, must have put her out of sync with the tides as to achieve minimum swimming distance though the water you'd ideally want the tide to turn at about your halfway point on a single crossing so that while it carries you several miles off track during the first half when it turns it carries you the same distance back before you land. They will have been able to time the first crossing to gain maximum benefit (or, at least minimum disruption) from the tides on the first crossing but subsequent crossings must begin no more than 10 minutes after landing from the previous crossing (and that time must be spent in the water having re-entered immediately after landing) so no opportunity to optimise the timing on subsequent crossings.

Edited by Sam.Spoons - 05 Oct 19 at 12:15pm
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 12:19pm
Well she was swimming for 40 hours wasn't it? So whereas her distance over the ground might be 4 x 21 miles which would have been the minimum, if she were making what, say 3 mph though the water, that would be the equivalence of 120 miles in a swimming pool.

Edited by iGRF - 05 Oct 19 at 12:20pm
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 19 at 12:35pm
The US 10k pool record is 2 hours 12 mins, or an average speed of 2.84 mph, (and pools are faster than open water 'cos of the kick off at every turn). I'd be surprised if she managed much over 2 mph.
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