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Post by TonyDunkley on Aug 19, 2019 7:36:23 GMT
The effects of the tide on a river changes drastically as you move further inland from the estuary, and by the time you're up as far as Cromwell on the Trent, and Naburn on the Ouse, local HW is as much as 4 or 5 hours later than it was for the same tide at Hull. Compared with the Flood and Ebb periods of each tide at or near the coast - approximately 6(+) hours of each - the period of Flood shortens as the tide runs inland, and the period of Ebb lengthens correspondingly. Where you are now, at Torksey, for instance it ''runs up'' (Flood) for up to around 2 hours and "runs down'' (Ebb) for around 10 and a bit hours. There are 'rule of thumb' correction figures you can apply to the predicted HW times at the usual reference port to estimate the tide time at various places upriver. Hull is the usual port for both the Ouse and the Trent, but many other factors also influence the time and height of the tide both at the reference port and as it moves further inland, . . such as atmospheric pressure, wind strength and direction, and the amount of rainfall in the river's catchment are over the previous few days, and they have to be applied to the approximate arbitrary correction times according to the prevailing weather and river conditions on the day. As for learning how to working out tide, departure, and arrival times for trips on tidal rivers, . . the best way by far is to keep coming back and spending as much time on them as you possibly can. There are some 'rule of thumb' correction times for various places on the Trent in those Boating Association Charts that Nick offered to e-mail to you the other day, but for more reliable and accurate figures there's nothing to beat on the spot observations of the times and heights of the immediately preceding tides (ie. local HW and Flood and levels), noting how much depth over such as side lock cills the tide "made", and making notes of by how they vary from the published predicted times for the reference port as the (roughly) 14 day tidal cycle goes from Neaps to Springs and back to Neaps again. Tidal rivers and the effects of the tides is a very complex subject, something of a black art even, and the Gods of the rivers have a wicked sense of humour that can catch out even the most experienced. I first started learning about it, as a 12 year old lad, from tug and bargemen in the Hull trade working up to Nottingham or Selby and York, . . but that was nearly 60 years ago, . . and I'm still learning ! Thanks again, interesting post. So...What’s a good time to leave Torksey this Wednesday to go up to Cromwell? There has been around 2' 6'' of fresh coming over Cromwell weir for nearly 2 days now, and this has coincided with Flood at Torksey being around only 50 minutes to an hour after HW at Hull (Albert Dock) on every tide since last Saturday morning. It's not easy to say just how long it'll be before all of that fresh runs off and the tide times upriver from Gainsborough get back to something like normal, and it's by no means certain it will happen by Wednesday morning ! With any significant amount of fresh still coming downriver and the tides 'taking off' - ie. reducing from Springs down to Neaps - it's essential to be underway and out of Torksey slightly ahead of the Flood starting to run up, or the last few miles to Cromwell can turn into a long tedious slog under Ebb, and wasting both time and fuel. ABP's source of tide info. is predicting a 7.0m HW at 1023 (BST) at Hull for Wed 21 August, so to be sure of getting as much help as possible from the Flood, I'd be out of Torksey Cut by 1125 at the latest. A few minutes 'working the slacks' * into the last of the Ebb from Torksey with a rising tide coming behind and catching you up can save an hour or more of slogging against the Ebb as you're approaching Cromwell. To make sure of getting away on time, I would pen down into Torksey Cut the night before. * The phrase 'working the slacks' means making use of the slower moving water in eddies and patches of turbulence, . . generally to be found close to the bank on straight 'racks' or on the 'nesses' on 'bights' - (the shallows on the inside of bends). It was a necessary everyday practice back in the days when the river was full of barges with loaded displacements of 150 tons or more and 30 bhp x 3 x cylinder Listers, . . but until you get to know the river very well, it's a practice best confined to rising tides only !
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Post by kris on Aug 19, 2019 7:57:07 GMT
I don't know if this fresh coming down will have gone by Wednesday.
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Post by Telemachus on Aug 19, 2019 8:05:19 GMT
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Post by kris on Aug 19, 2019 8:19:33 GMT
Yes I'm sat on the upper Trent waiting for it drop, but I don't think I'll be moving before weds-Thurs.
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Post by Telemachus on Aug 19, 2019 8:20:52 GMT
Yes I'm sat on the upper Trent waiting for it drop, but I don't think I'll be moving before weds-Thurs. Is the upper Trent on red boards?
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Post by Telemachus on Aug 19, 2019 14:07:24 GMT
Just pondering why a lot of fresh makes the flood arrive early. It seems a bit counter-intuitive - one might expect the fresh to push the flood away, slowing it down.
But then I remembered two things: firstly that obviously, with a lot of fresh the water level at low tide is higher.
And secondly, we should perhaps consider the flood up river to be in effect a wave. Certainly with a large tide, the wave is obvious (aegir /bore).
And wave propagation velocity is affected by water depth - waves propagate faster in deep water. Therefore with a higher low tide, the flood wave is going to propagate faster up river and thus reach places like Torksey earlier than would have happened with no fresh.
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Post by ianali on Aug 19, 2019 14:15:41 GMT
Thanks again, interesting post. So...What’s a good time to leave Torksey this Wednesday to go up to Cromwell? There has been around 2' 6'' of fresh coming over Cromwell weir for nearly 2 days now, and this has coincided with Flood at Torksey being around only 50 minutes to an hour after HW at Hull (Albert Dock) on every tide since last Saturday morning. It's not easy to say just how long it'll be before all of that fresh runs off and the tide times upriver from Gainsborough get back to something like normal, and it's by no means certain it will happen by Wednesday morning ! With any significant amount of fresh still coming downriver and the tides 'taking off' - ie. reducing from Springs down to Neaps - it's essential to be underway and out of Torksey slightly ahead of the Flood starting to run up, or the last few miles to Cromwell can turn into a long tedious slog under Ebb, and wasting both time and fuel. ABP's source of tide info. is predicting a 7.0m HW at 1023 (BST) at Hull for Wed 21 August, so to be sure of getting as much help as possible from the Flood, I'd be out of Torksey Cut by 1125 at the latest. A few minutes 'working the slacks' * into the last of the Ebb from Torksey with a rising tide coming behind and catching you up can save an hour or more of slogging against the Ebb as you're approaching Cromwell. To make sure of getting away on time, I would pen down into Torksey Cut the night before. * The phrase 'working the slacks' means making use of the slower moving water in eddies and patches of turbulence, . . generally to be found close to the bank on straight 'racks' or on the 'nesses' on 'bights' - (the shallows on the inside of bends). It was a necessary everyday practice back in the days when the river was full of barges with loaded displacements of 150 tons or more and 30 bhp x 3 x cylinder Listers, . . but until you get to know the river very well, it's a practice best confined to rising tides only ! Torksey lock keeper has said be ready to head out on Wednesday at 11.30. Also suggested that I’m ready a few minutes before as he might open the lock earlier. Il get out on the river and up the revs so as to get to Cromwell as early as possible then.
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Post by kris on Aug 19, 2019 16:37:57 GMT
Yes I'm sat on the upper Trent waiting for it drop, but I don't think I'll be moving before weds-Thurs. Is the upper Trent on red boards? It's off red boards now, the flood locks are off. But there is still more fresh coming down than normal so for me I'll wait until weds to go where I'm going.
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Post by TonyDunkley on Aug 19, 2019 17:30:52 GMT
There has been around 2' 6'' of fresh coming over Cromwell weir for nearly 2 days now, and this has coincided with Flood at Torksey being around only 50 minutes to an hour after HW at Hull (Albert Dock) on every tide since last Saturday morning. It's not easy to say just how long it'll be before all of that fresh runs off and the tide times upriver from Gainsborough get back to something like normal, and it's by no means certain it will happen by Wednesday morning ! With any significant amount of fresh still coming downriver and the tides 'taking off' - ie. reducing from Springs down to Neaps - it's essential to be underway and out of Torksey slightly ahead of the Flood starting to run up, or the last few miles to Cromwell can turn into a long tedious slog under Ebb, and wasting both time and fuel. ABP's source of tide info. is predicting a 7.0m HW at 1023 (BST) at Hull for Wed 21 August, so to be sure of getting as much help as possible from the Flood, I'd be out of Torksey Cut by 1125 at the latest. A few minutes 'working the slacks' * into the last of the Ebb from Torksey with a rising tide coming behind and catching you up can save an hour or more of slogging against the Ebb as you're approaching Cromwell. To make sure of getting away on time, I would pen down into Torksey Cut the night before. * The phrase 'working the slacks' means making use of the slower moving water in eddies and patches of turbulence, . . generally to be found close to the bank on straight 'racks' or on the 'nesses' on 'bights' - (the shallows on the inside of bends). It was a necessary everyday practice back in the days when the river was full of barges with loaded displacements of 150 tons or more and 30 bhp x 3 x cylinder Listers, . . but until you get to know the river very well, it's a practice best confined to rising tides only ! Torksey lock keeper has said be ready to head out on Wednesday at 11.30. Also suggested that I’m ready a few minutes before as he might open the lock earlier. Il get out on the river and up the revs so as to get to Cromwell as early as possible then. Reading off the EA's Torksey recorder/gauge on their website - it's at the pumping station between the Cut end and Jack's Ferry - this morning's Flood at Torksey was barely an hour after predicted HW at Hull. If you drop down the lock and tie-up in Torksey Cut on Tuesday night you'll be able to get away in good time on Wednesday morning, . . even if the tides are still early, and there are other boats penning at the same time and slowing the whole process down. The advantages of laying in Torksey Cut overnight are twofold, . . firstly there's no chance of being held up by other boats at the lock, and secondly you'll get to know the exact time of Tuesday night's Flood, from which you can work out a pretty accurate and reliable estimate for the time of Flood on Wednesday morning from the predicted time of Hull HW on Tuesday night and Wednesday morning. It's ultimately your decision, of course, and the Flood at Torksey might be coming a bit later in relation to Hull HW by then, but if that lock keeper is advising you to stay in the Fossdyke overnight Tuesday and pen out into the river the following morning, then he isn't doing you any favours with his advice, . . he's just reducing your options !
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Post by Telemachus on Aug 19, 2019 17:38:26 GMT
Torksey lock keeper has said be ready to head out on Wednesday at 11.30. Also suggested that I’m ready a few minutes before as he might open the lock earlier. Il get out on the river and up the revs so as to get to Cromwell as early as possible then. Reading off the EA's recorder/gauge at Torksey - it's at the pumping station between the Cut end and Jacks Ferry - this morning's Flood at Torksey was barely an hour after predicted HW at Hull. If you drop down the lock and tie-up in Torksey Cut on Tuesday night you'll be able to get away in good time on Wednesday morning, . . even if the tides are still early, and there are other boats penning at the same time and slowing the whole process down. The advantages of laying in Torksey Cut overnight are twofold, . . firstly there's no chance of being held up by other boats at the lock, and secondly you'll get to know the exact time of Tuesday night's Flood, from which you can work out a pretty accurate and reliable estimate for the time of Flood on Wednesday morning from the predicted time of Hull HW on Tuesday night and Wednesday morning. It's ultimately your decision, of course, and the Flood at Torksey might be coming a bit later in relation to Hull HW by then, but if that lock keeper is advising you to stay in the Fossdyke overnight Tuesday and pen out the following morning, then he isn't doing you any favours with his advice, . . he's just reducing your options ! I there can be an issue with insufficient water over the cill at low water. However with significant fresh and reasonably big tides would this be an issue at the moment? I have to agree with your earlier point about the quality of the lock keepers these days. Although all those I encountered at Selby and Naburn were pleasant and helpful, as soon as any slightly difficult questions were asked, they were unable to give an answer. It was all “done by numbers” eg you leave Naburn when the flood arrives, 2 hrs before high water. When I asked whether it would matter if we were a bit late / what were the consequences of going down a bit later, I didn’t get any sort of sensible answer other than “you go down 2 hrs before high water”. Seemed to me there would be no particular issue with going down later under the prevailing conditions, the river was still very full when we arrived at Selby, there would just an increased ebb flow to contend with. But apparently there is only one time to go!
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Post by JohnV on Aug 19, 2019 18:17:49 GMT
it was the desire to pick my own departure time from Naburn that made me drop down to the pontoon below the lock the tide before.
Incidentally the lock keeper at Naburn then was very good and seemed to know the river very well (on site man, lived in the lock house) I have forgotten his name which is annoying as he was very helpful .... probably have it written down somewhere in the log
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Post by ianali on Aug 21, 2019 11:15:13 GMT
Locked down to the river at Torksey 11.00 this morning. Out onto the river at 11.25 and was pushing the flow going towards Cromwell until about midday. Beautiful day!
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Post by Telemachus on Aug 21, 2019 12:26:44 GMT
Just missed you! (As expected). Left Keadby at 08:40 and arrived on the pontoons at Torksey at around 12:40. Cromwell tomorrow.
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Post by ianali on Aug 21, 2019 13:00:55 GMT
Just missed you! (As expected). Left Keadby at 08:40 and arrived on the pontoons at Torksey at around 12:40. Cromwell tomorrow. Hope you had good trip up. Steak pie was good in the swan last night!
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Post by Deleted on Aug 21, 2019 13:03:23 GMT
Just missed you! (As expected). Left Keadby at 08:40 and arrived on the pontoons at Torksey at around 12:40. Cromwell tomorrow. Not going for an excursion up to Lincoln??
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