IanD

Because simple analogies and relativity don't mix... 😉 If you think that's bad, try quantum physics...

The reason steel canal boats have to be heavy and low in the water -- if we ignore air draft -- is stability, because they have a heavy steel cabin. Boats built out of aluminium drew less and were still stable because of having a much lighter superstructure, but cost would be a problem nowadays. Maybe HDPE can provide a lower cost solution that's still robust enough?

The one I posted earlier (60l twin coil) is specified as having two 5kW coils with 0.6m2 surface area each -- which means quite a lot of (copper) fins, which is presumably one reason for the high cost. Too big for a 5kW Webasto though... They did originally suggest something even more ridiculous when I asked "What's the biggest yield coil you've got?", more than 20kW per coil IIRC -- meaning a cold tank to an 85C hot one in about 15 minutes, if you've got anything that can generate that much heat. A bit like bragging about how your car can do 0-60 in 3 seconds though, impressive but pretty pointless... 😉

If you think casting or CNC machining a prop like the Scarrow is expensive, try 3D printing it in one of the large-scale sintered metal 3D printers... 😉

Yes. IIRC a normal prop is about 50% efficient at converting shaft power into thrust , the Sharrow is about 60% efficient -- the reason is that less energy is wasted in tip vortices.

Maybe less likely to catch stuff around the root than a normal prop, but if it gets caught through the loops then the usual remedy of going ahead/astern a few times to throw the rubbish off is unlikely to work... Buit for traction on land you need a decent towpath instead of a mudbath... 😞 A jet engine mounted on the roof would avoid all these problems, and would *certainly* discourage too-close followers... 🙂

So go and look up the other articles and actual tests -- not by Sharrow -- directly comparing the Sharrow and normal props. Google is your friend... 😉

They're all tweaked designs based on conventional turbine propellers, and still waste energy in tip vortices which the Sharrow doesn't. Having dug into the details it does look like a genuine advance in prop design, unlike the Axiom. But would certainly be a lot more prone to fouling on canals, the loops will catch stuff that is thrown off with a normal prop. And they're expensive because they're more difficult to make, and proprietary... 😞

If you go and read the articles there are actual test results; IIRC at the same engine power, they deliver something like 20% more thrust. This shouldn't be a problem for any driveline. Alternatively for the same speed they lower fuel consumption by the same amount, with no more thrust on the driveline at the same speed.

I've been through exactly this discussion with my boat. Going by Dave Jesse's measurements the standard Surecal coils only deliver just over 1kW, he measured a temperature rise of 16C/hour for a 55l Surecal: https://www.perseverancenb.com/post/how-to-measure-the-calorifier To speed up water heating from both generator and diesel boiler (both can put out more than 10kW) I'm having a custom calorifier made by coppercylinder.co.uk which has two large-area finned coils rated at 5kW each (and extra-thick 60mm lagging to keep it hot overnight). These are probably too big for a Thermotop C, but they'll do any size you want. The only problem is -- of course! -- the cost, over £1000 for mine... 😞

You taking lessons in advanced Chinese cookery then?

Yes, a sad loss to the canal, there are few good pubs on that stretch... 😞

Should have stayed at the Jack Mytton, excellent beer and food when we were there... 😉

There should be lockies there at Easter, when we went through last summer they seemed to know what they were doing and controlling the flow of boats properly. A couple of boaters got narked at having to wait instead of just piling in, but that's their problem -- IIRC they were doing five up/five down (or maybe three, or four...) and going up we were unlucky to arrive just after the last boat in the string, but we just accepted it and had a beer while we waited for an hour or so.

They also need to be taught what they are and aren't allowed to do, and that sometimes they aren't going to get instant attention. I imagine that without this -- basically, good training and discipline by an owner who understands how they think -- they could be a total nightmare...

If you've got enough electrical power/battery capacity to run an induction hob, you've probably got enough to run an electric oven -- though maybe not both at the same time. Whether you have a suitable means of replacing the power used (solar, generator...) is another matter entirely... 😉 Going entirely gas-free is *very* expensive if you do it purely to replace gas cooking, it doesn't really make sense. If you already have the electric/battery/charger capability for other reasons (e.g. hybrid drive) then it's a no-brainer... 🙂

I guess that this is another example of risk vs. reward -- undoubtedly there are a few tragic cases with dog injuries due to stick or ball throwing, this has to be balanced against the millions of dogs who do it all their lives, get great pleasure from it, and suffer no injury at all... 😉

My daughter has a year-old sprocker called Moose who is lovely, clever and well trained, but impossible to tire out -- if you're happy to play fetch and throw a stick or a ball for several hours, she's happy. When they spent a week on a boat with us she had her very own "special" stick which started off several feet long and ended up just long enough to throw. Oh yes, rather keen on water too, only went in the cut a few times... Combine that with the collie herding instinct and flightiness and you're in for a whole *heap* of fun -- or trouble, as some may call it, he may end up mad as a box of frogs... 😉

Which days you're at Llangollen probably matters more than the date. A lot of week hire boats are there midweek, so it's quieter at the weekend. A walk up to the Aqueduct Inn at Froncysyllte is highly recommended. Best pub for food and drink (but not cheap) in Llangollen is probably the Corn Mill, but booking is advisable. If timing works, the Willeymoor Lock Tavern is a good overnight stop, very friendly and decent pub grub and beer.