Scholar Gypsy
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Posts posted by Scholar Gypsy
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2 hours ago, Tractor said:
Mooring between St Johns Lock and Halfpenny Bridge, Lechlade.
Watch out for Heffers in this field, they go around in a juvenile 'mob', and will not only lick the boat, and lean on it, but try to eat the rubber window surrounds and the cratch cover
A guy will turn up to collect mooring fees, to explain all this but before this be on the look out for the Heffers.
The cows are not there this week (photo by Maria S on Facebook). I think this photo is taken from Halfpenny Bridge.
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Meanwhile near Denver on the Great Ouse the water level is below normal -- this is standard operating practice. There was a bit of a current yesterday, but it only really got noticeable when going under the main road bridge at Littleport and the railway bridge at the north end of Ely - where the river must be a lot shallower than elsewhere. Standing waves at Ely....
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I think you probably need a professional skipper, and to be careful about insurance. In theory this should be doable on a single tide, but that would require some travel in the dark. An overnight stop at Gravesend would be more relaxing.
You could ask on FB and you would get a recommendation. London Boaters or Thames Liveaboards.
Some info and photos of the most recent SPCC trip.
https://scholargypsy.org.uk/2016/05/16/medway-trip-day-1-limehouse-to-gravesend/
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19 minutes ago, ditchcrawler said:
Ther lock between Oulton Broad and Lake Lothing is similar known as Mutford Lock. I don't have any photos with me. I have found this video on line
It is of course not the only back-to-back double lock in the UK. For example
* Bow locks
* Torksey* Keadby
plus several that have either sector or guillotine gates and can operate in either direction, eg* Three Mills (I had the fun of working this myself recently! https://scholargypsy.org.uk/2023/11/16/after-the-protest-cruise-return-from-west-india-via-three-mills-to-st-pancras/ )
* Limehouse
* Denver
* Salters Lode
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On 18/12/2023 at 11:03, magnetman said:
I was intrigued by this device
Which is beside a disused lock on the river Darent near Dartford in Kent.
Maybe this was something to do with opening the gate as the sluice seems to be in the background.
(image stolen from the internet)
It is indeed a mechanism for opening the gate at the lock in Dartford. This is the best photo I can find (from a group visit in 2018). The rack and pinion engages on a quadrant attached to the gate, rotating it through (say) 75 degrees. It no longer works, sadly, though you can get through the lock around high tide. More photos here: https://scholargypsy.org.uk/2018/05/29/fc3-dartford/
On 17/12/2023 at 21:17, magpie patrick said:I found this picture on the Historic Erie Canal Facebook group altugh it's actually on the Black River canal, a feeder canal (feeding traffic rather than water)
I've seen balance beams, I've seen winches on the bank, I've seen rods fastened to the mitre post, but I ain't seen one of these before...
Text description
Delta Dam, July 18 1911
A great photograph from the new Black River Canal combine at Delta Dam in Rome. This is the middle of 3 locks that make up the one structure. The photo is showing the "hand operating machinery" which gives you a good idea of how the chamber gates were opened and closed. In a "lock combine", gates are shared between chambers. This is the lower gate for lock 9 and the upper gate lock 8.
There is a similar mechanism on a number of (non-navigable) tidal doors in the Fens. This one is at Boston Grand Sluice in Lincolnshire. When the non-tidal river (in the foreground) is higher than the tidal section, the water pressure forces the gates open. As the tide comes up to make a level the weight, steel cables and pulleys pull the doors shut to keep out the tide (as here). Just an enormous and very simple one-way valve!
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I have an identical unit to Magnetman (except it is installed with the taps above each other!).
However the hot tap is connected to a cheap TMV that is installed near to the Carlorifier, and which mixes the very hot water with cold water to produce warm water to feed the shower and the bathroom sink. (The galley sink is connected to the very hot water, not least so I can fill up the kettle). It's worked perfectly for nearly 20 years. As the schematic shows, I also added a bypass valve (W) so the pipework between the mixer and the taps could be drained.
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On 18/12/2023 at 09:17, magnetman said:
A cable tie of the right strength could work as the weak link.
Maybe a great big fan on the front of the Boat mounted athwartships would help.
Its a terrible thought but this little Sea Otter wants a bowprop.
Facebook (I think) sent me an item recently about one of the early US aircraft carriers. They had a load of planes lined up and tied down, facing to starboard (on the bows) and to port (on the stern), and then ran the engines and the boat span nicely. Of course I can't find it now, when it might be useful.
My only other tip - which worked for me a few years when pinned in Whitttlesea, was to push the bows over to the other bank, and get the bow stuck in the helpfully provided gloopy shallows. The boat stayed put for long enough for me to get to the other end and then motor off. An occasion where shallow water is helpful! A cable tie around a convenient tree might have worked.... -
2 minutes ago, manxmike said:
You'll need to be careful above Lechlade, some of the bridge holes are quite low. Check your air draft and remember the higher the river the less room under bridges!
I guess you mean "above Oxford".-
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4 hours ago, Tacet said:
Please sir, Pythagoras can't claim the credit for this phenomena. More to do with Galileo.
It's because at small angles there is little difference between the sine and tangent. And the longer the rope, the smaller the angle.
Galileo's observation that the period of a pendulum is (nearly) the same regardless of its amplitude also only works with smallish swings relies on the same thing.
I will ask my son, who is a maths teacher...
If you want a rough estimate, then the movement of the boat (forwards going up, astern when going downhill) isM = L - (L^2-h^2)^0.5 ~ 1/2 . h . h/L (to first order, as h/L <1)
So if h is 8, L = 32, then M is about 1.
(The pendulum result depends on the fact that sin (x) ~ x for small x.)
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For Sandford (which is tricky) I had a second bow line, going back from the bow, of similar length to the stern line, and tied to a bollard. That enabled to hold the boat against the wall, just. And it was hammering down with rain...
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I did the whole river from Teddington to Lechlade last summer. Going uphill I do this:
- get off the boat at the stern, with a stern line and a long light line that lies on the roof and is tied onto the bow line. Stop the boat completely before doing this & then stop the engine
- tie off the stern line, a reasonable distance astern of the boat
- tie off the bow line, a reasonable distance in front of the boat
- close the bottom gates
- start the automatic sequence for filling the lock
- take in the slack on the bow line as necessary
Going downhill
- Use as long a stern line as possible, and tie it off to a bollard (25 feet plus)
- Do NOT secure the bow line, but make sure it stays on the bank (eg wind the end very loosely around a bollard, or put a bowline in the end and drop it over a bollard alongside the boat)
- Close top gates, operate bottom sluices
- Tend the bow line, take up the slack and then letting it out as necessary
In both cases, Pythagoras is your helper. For example with a 25 foot stern line between the boat and the bollard, then as the boat goes down (or up) 8 feet (more than most locks) the boat will move forwards/backwards about 16 inches.
Here is Shifford, one of the deeper locks on the Upper Thames (and hand operated of course)
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And both locks appear to have ropes/chains for opening the gates?
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16 minutes ago, magnetman said:
Telegraph poles tell a story.
I think they are electricity poles, and I agree they don't look very French. https://en.wikipedia.org/wiki/Utility_pole -
1 hour ago, rusty69 said:
I'm never going on a boat ever again after watching that.
I did think, after watching the final episode, that the narrow boat must have had a rather powerful inverter; and probably a composting toilet. -
In the 5th episode of Boat Story (BBC iplayer https://www.bbc.co.uk/iplayer/episode/p0glcy88/boat-story-series-1-episode-5 at 56:30) there is a shot described as the Canal du Midi. (It's a rather complex plot). Looks more like the Leeds and Liverpool to me, with CRT bollards approaching the lift bridge. Any ideas >?!
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As well as the width issues -- as others have explained the Northampton Arm locks are 7' wide -- you should also check the draft (how much water you need) and probably more importantly the air draft of the boat (there are some quite low bridges around.,,)
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This would have been before the half tide lock was built at Richmond (1890s), and so would have dried out fairly comprehensively. It's the annual draw down at Richmond at the moment, until Monday 4th , and is well worth a visit around low tide.
https://www.pla.co.uk/assets/u19-23.pdf
Photos here: https://scholargypsy.org.uk/2017/11/18/what-happens-if-you-leave-the-paddles-open/-
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I went through this summer, in the middle of the festival. It was very fine. I spent about two hours filling my water tank, and having a nice long lunch stop. A procession of boaters kept arriving, and I let them fill their portable drinking water containers ....
... and I bought a nice belt as I went past this boat ...
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2 hours ago, magpie patrick said:
Which level has to reach 2.9m? The tidal or the non-tidal side?
The non-tidal side - strictly speaking the level at City Mill lock, a few hundred metres above Three Mills. If the water is above this level, then the headroom on the A11 road bridge is too low. Also the water level may be above the level in St Thomas's Creek - in which case the lock (which only has one pair of gates pointing that way) would not work either. It's quite a complex system, with not a lot of room for things to go wrong.
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Not very relevant, but this graph shows how Three Mills lock on the Olympic waterways was working on Wednesday this week (I was operating the lock after the FBW protest cruise!).
There was a strong tide, which mean that the weir lifted (the red line) at 1300 to keep out the tide. Then the impounded level (between Three Mills and City Mill) gradually rose, filled with fresh water from the Lea, which meant City Mill lock could not be operated (it locks out when the water is at 2.9m). At about 1530 the weir lowered automatically, and an hour later the boats were on the move - having spent three hours in the lock!
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1 minute ago, Tony Brooks said:
I don't think so, unless the boat is fully supported the hull will twist, hog, sag in any combination, so the shaft ends up slightly out of alignment. Once it is back in the water and supported along its length, it takes a while for the hull to go fully back to its normal floating shape. On the fleet, we never aligned the engine until at least 24 hours after it was refloated. While it is out of the water, many boaters will find doors and draws jambing.
Yes, I had one door bolt that was a bit sticky....
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On 13/11/2023 at 20:31, Stroudwater1 said:
Could the boat being out of the water dried things and caused this though ?
Ours seemed to be more prone to drops for some while after being out for 2 weeks pending hull work. All is good now and hardly get a drip a week. Just kept tightening the greaser twice a day till tight, didn’t do anything else.
Took a year to subside though it never dropped as badly as the OPs boat.
My stern tube now drips much less after a week out of the water in September (for blacking). Very strange! -
This is the one I had in mind at Alwalton - a new stretch of river was built to take out the kink!
https://maps.nls.uk/geo/explore/side-by-side-old/#zoom=15.8&lat=52.55889&lon=-0.32293&layers=168&right=193
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I think that's a flash lock, ie just one guillotine gate. When a boat wants to transit it is lifted and the boat either zooms downstream or is winched upstream as the levels equalise. I have seen photos of a very similar structure on the Brandon Ouse, near Hockwold. The remains of that are just about visible. I think one can also see the old lock structure downstream of Awalton, though I may be imagining that. One certainly can just below Lower Wellingborough lock (which looks like a 1970 structure rather than a 1930s one).
Down to Thames this year licence required?
in Cruise Diaries & Reports
Posted · Edited by Scholar Gypsy
Incompetence
I agree. Here are Scholar Gypsy's logs for the last fifty years. There is also a separate engine log.
One of my son's regular crew has produced this (click the link) from a careful analysis of the log for the trips he (the son) has done. (I am Papa, JJ is the son, Tom B is the mathematician friend). Hover your mouse over the chart. May not work on all mobile phones (it does on mine: Chrome on Android)
https://scholar-gypsy.vercel.app/