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Scholar Gypsy

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Scholar Gypsy last won the day on April 1 2014

Scholar Gypsy had the most liked content!


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    Retired Civil Servant
  • Boat Name
    Scholar Gypsy
  • Boat Location
    Ely, River Great Ouse

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  1. You should try the Bedford Ouse, where: 4 locks have mitre gates top and bottom (Roxton, Barford, Willington, Castle Mill - all built relatively recently) 8 locks have mitre gates at the bottom and a guillotine at the top (Hemingford, Houghton, Godmanchester, Brampton, Offord, Eaton Socon, Cardington, Bedford) 2 locks have a guillotine at the bottom and mitre gates at the top (St Ives, St Neots) 1 lock has a guillotine at each end (Brownshill) All the mitre gates have a slacker (paddle) each (except Castle Mill, below, which has a rather unusual slacker arrangement). It certainly keeps you on your toes....
  2. The kink in Braunston is 400m from the eastern end. I have this at the back, a bit Heath Robinsonish but it works well; and a low power light at the bows (just so an oncoming boat can see where the bows are).
  3. I had a fun conversation this year with the owner of this boat. The engine (air cooled, Lister I think) is in the bow locker (lid open for added cooling ...) and drives the prop via a hydraulic pump. The owner said it worked very well, and was quiet (at the stern!)
  4. The last wide beam I steered, the hydraulic steering was connected back to front. So in my mind I had to imagine the top of the wheel was like a tiller. We discovered this on entering the tidal Thames just downstream of Limehouse .... No harm done.
  5. Tangential point. I had a very slow leak on one of my engine hoses recently. It was fine when cold, I pumped the pressure tested up to 15 psi and it stayed there for hours. But when it heated up the hose leaked a little bit (15ml a day sort of amount, really annoying). I've now replaced it (and added some lagging to stop it rubbing against the exhaust manifold!).
  6. When I hired a boat on the Skegness canal a couple of years ago, they told me to drive on the left.
  7. Calculus is the obvious way of doing this. Using the notation of the video, the integral of y^2 (from 0 to h) is 2/3 x h x the integral of y on the same interval. But one can prove this result using pure geometry. For any triangle, join each vertex to the mid point of the opposite side. The three lines you get all intersect at a common point (called the centroid), which is the balancing point (centre of gravity) of the triangle. Also, the centroid is 2/3 of the way along the line from the vertex to the opposite mid point. From this one can deduce that the centre of action of the force on a lock gate is 2/3 of the depth of the gate - the two problems are related. (Imagine a right angle triangle with the 90 degrees at water level and the other two corners at the two bottom corners of the gate). For a proof of the centroid theorem see here: http://ceemrr.com/Geometry2/TriangleCenters/TriangleCenters_print.html https://en.wikipedia.org/wiki/Centroid Wikpiedia is rather unclear whether this result was found by Euclid or Archimedes, or three hundred years later by someone called Heron
  8. Cider is no good. You need to use canal water as it will have the correct surface tension. Another of way of thinking about how the force does not depend on the length of the pound is to imagine inserting a very light plastic gate G across the canal, at any arbitrary position. This divides the canal into two, a section one side of the gate (A) and a section the other side (B). In a static situation, the net force on the gate is zero, which means that the sideways pressure from the body A on the gate is exactly equal and opposite to the sideways pressure of the body of water B on the gate. Both are obviously independent of the shapes of A and B (as both A and B can be varied independently, and F(A) = -F(B) always). Now if you remove the water in A you have the sideways force on the gate (if the plastic is strong enough...) PS the centre of action of the force is 2/3 of the way down the gate.
  9. I've been on Swiss TV. Does that count? https://www.rts.ch/play/tv/19h30/video/jubile-de-diamant-de-la-reine-elisabeth-ii-le-point-dorgue-des-festivites-se-tiendra-dimanche-avec-une-parade-de-mille-navires-sur-la-tamise?urn=urn:rts:video:4036657
  10. The ML leaflet says 68' , so you should be fine, especially with a bit of diagonality. I have been through this lock three times now (well six really but you know what I mean). The first two the water was level: on the most recent occasion there was a 15cm difference in level. https://3rwzrk3imltm11ru71g1sxd1-wpengine.netdna-ssl.com/wp-content/uploads/2021/03/Navigation-Notes-2021-Web-Version.pdf
  11. I agree - the picnic tables were the clue.
  12. Francis Pryor's book is well worth a read. I quite enjoyed the film, it doesn't pretend to be a documentary about waterways. I agree Denver is very interesting, but every time I try to explain to someone how the system works their eyes seem to glaze over. The continuity errors were a bit annoying (eg the mooring "south of Ely" where they had the discussion about religion was actually near Brandon Creek, well north of Ely.
  13. A few photos. This is handy for tide planning https://nbsg.wordpress.com/2019/06/06/spring-cruise-4-trent-lock-to-cromwell-lock/
  14. This reminds me how I once drilled a hole in a bulkhead, and the drill bit just managed to unscrew one of these fittings that was hidden behind, on the main water circuit. Cue the water pump starting and a bit of water in the cabin bilges. The joint was completely inaccessible so I had to cut a section out and add a trombone shaped piece of plumbing to join it all up again....
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