Scholar Gypsy

From Meridian chartware in Norwich (I had a chat with them at the Boat Show in London in January - very friendly and helpful company). I bought (for £100 + VAT): the Imrays chart (here), to match my paper chart; and the Norcom navistick here - this includes 4GB storage (like a normal memory stick), there is a cheaper one without. It all runs on Windows 7 on my three year old not particularly massive laptop. As with many things, it works most reliably after a reboot and with no other software running. The slightly tricky bit is installing the driver (to create a virtual COM port). It's also worth noting that although I can get the GPS to work with the chart software, with Google earth [i may need this for Denver to Kings Lynn, as decent charts are not really available - Naughty Cal has been very helpful in letting me have what is available], with the satellite viewer and position logger supplied, it will only talk to one at a time. I have also adapted a plastic Ketchup bottle so that (with a 3m USB extension - the longest recommended) the laptop can stay inside the engine room in the dry, while the dongle is outside. I have found the Easychart software much easier to use and more stable - the Seatrak that is also supplied has also sorts of added gadgets that I don't think I want or need (or really understand yet!), and tends to crash more often. As you can see from the example posted above, I have so far worked out how to create a number of waypoints, a route to join them up, and an exclusion zone (around Pope's Corner). Then you just turn the log on, and you get all the data on the pages at the back - it records when you travel a distance, or alter course, by more than preset amounts. Happy to answer any further questions.

Very nice video/slideshow. Looks quite breezy. Reminded me that when I last did Cromwell lock, the lockie lowered a hook on a long line, to which we attached our mooring lines which he then pulled in and tied us off!

Another option is GPS, which I have invested in for my trip on the Wash. Our guide thought it might be useful in fog, given the buoys are clearly marked on the chart. The output from last Sunday's test voyage is here. About £100 for a dongle and some software, in my standard laptop ...

Interestingly, some more trigonometry shows that angle CBD = angle ABC. This rather surprised me. As a special case, when the mitre angle (ABC) is 45 degrees, then the force RB is parallel to the lock side (and is equal to the force (well half of it, of course) that would be exerted on a single gate stretching right across the lock.

Thanks, my Dutch is not that good, but the forces diagram is the same as in my posting above, I think. He has resolved the quoin force along and perpendicular to the gate; I resolved it parallel to and across the lock. The answer should be the same. (2s/d = tan theta etc).

I think you are underplaying the risks here. See the article in today's Indepdendent...... Please don't fry your phone. Simon

Please see this stylised model of a mitred lock gate. The only assumption made is that the bottom cill does not exert much force on the lock gate - that would be easy to achieve if one used rubber seals to make it watertight, not the pressure of the gate on the cill. Interestingly, the force at the hinge along the lock's length is a constant, not affected by the angle of the gates; if the angle of the mitre is 45 degrees (so the gates meet at a right angle) then there is no transverse force on the lock walls at all. I wonder if what the paper about strains etc is trying to say?

On the VHF question, I do think the one-day course was a bit OTT, and the two day one a bit of a racket. I have been lobbying the PLA gently for something a bit simpler and shorter for inland users. This was prompted by the surprising fact (learnt at a recent PLA open meeting) that many rowing coaches on the Tidal Thames do not have VHF on board their boats - a mix of equipment cost, training courses and set licences (which are free, contrary to what some thought!) were all mentioned. In the meantime, the RYA's book tells you all you need to know - with a bit of practice with a friend sitting in a different room (or on the other end of a cheap walkie talkie).

Yes - the trailer of them cruising in the dark looking for a mooring may give a clue!

Thanks for replies - also helpful for my trip on the Tidal Trent, which I have not done since 1990.... I bought charts from the very friendly Boating Association here - and also a natty burgee. You don't even have to pay subs to join - my type of club.

I would recommend buying a large plastic container of QS, as it will then make an excellent device to go underneath an oil filter to catch any drips when you change it.

ABP require two people on board, & VHF, downstream of Gainsborough, I believe.

Yes, that must be right. A simplified example is worked out in this thread from 2013 ... Well the instructions on the locks certainly call them gates. And a gate valve goes up and down, rather than swinging. On the other hand, the things at the other end are, of course, called V-Doors not gates ....

Thanks all - I think I probably was exaggerating a bit with 45 seconds, it just feels that long. Although I don't feel brave enough to take the injectors out, I think I might have a go with the heaters, even though that was not covered in my one day RYA course. I am sure I can find a video on youtube somewhere.... (Neither was changing the thermostat, but that went fine....).

Not particularly, I would say. It's a K series (K4D).

Not too bad. The boys went for a swim and then we noticed the outlet from the (very small) sewage works. The bank was surprisingly firm under all the foliage, the plank did its job.

Thanks for the replies (and to Ditchcrawler for a PM): very helpful as always .. The oil consumption is minimal. I think I will investigate (or get someone to investigate) the heaters.

Most of the locks on the Nene; and some on the Bedford Ouse (eg St Neots, St Ives)?

I'd be grateful for any comments on the following diagnosis. The last few times I have started the Mitsubishi 4 cyl engine (after 2 weeks in the Fenland icy blasts) it has started first time, after 45 seconds of the heaters. But it runs a little rough for about 30 seconds, sounding as though one of the cylinders is missing, with white smoke coming out of the exhaust. Then suddenly after about 30 seconds I guess something gets hot & it starts running smoothly and the white smoke disappears. All is fine for the rest of the day (including when the engine was restarted after lunch etc). I reckon I need to get the injectors serviced / reconditioned. This was last done 10 years ago. The engine is 20 years old. I'd be grateful for any thoughts. I am somewhat risk averse at present, as I do not want it to conk out in the middle of the Wash, where I hope to go in May.

I don't think that is correct. The plane of the seal at the heel post is parallel to the gate: the pin at the foot of the gate and the collar etc at the top of the gate are what transmit the horizontal thrust from the lock sides on the gate (in the plane of the gate). There's another thread about the forces on lock gates that I will try to find sometime .. S

I am not sure I would buy the point about sealing. A well installed & maintained single gate can be completely watertight, while mitre gates always seem to leak a bit (and sometimes a lot!)

And the Denham Yacht Centre is not far away (but I agree, go to UBC first!). Map here. Denham is a bit further north by the lock, here.

I would also recommend a lifebuoy, or a heaving line. Both for chucking to someone who has fallen in.

I was making the numbers up of course. But since then I have found again this website which tells me the mean daily flow at Isleham was 1.8 cumecs in 1986, and 95% of the time it is more than 0.5 cumecs. Jesus lock in Cambridge is 2 cumecs (or was in 1983), and Denver is about 15 (but NB the site says: "Complexity of the structure and its management is reflected in the homogeneity of the flow series - which has extensive periods with no data or zero flows. Data should be used with great caution"). So my numbers looked OK within a factor of 2, or 4, or so - not bad ?

0.5m along the whole of the Ely level is let us say 60 km x 30m average width x 0.5 m, so 900,000 cubic metres. So that's a flow rate of say 5 cumecs (cubic metres a second) for 48 hours. I am guessing a bit here - need to look for some flow gauges data now! - but that feels a sensible number. The Middle level main drain pumps at full blast can do 100 cumecs, Teddington weir in January 2014 was about 250 I seem to recall.