Re: Fuel use

Tony Brooks wrote:
"Nick Atty" <1-nospam@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:mk6043hv5uf3h9apcg7k8sqpevs2cifijp@xxxxxxxxxx
On Mon, 07 May 2007 20:57:33 +0100, Gibbo <gibbo@xxxxxxxxxxxxxxxx>
wrote:

Nick Atty wrote:
We sometimes have discussions here about fuel use. Over the last few
weeks we've used Mintball a bit more than had become typical, and have
filled her up to completely full on two occasions.

So I can give some vaguely useful figures - a total of 213 miles and 148
locks (171 miles of this was narrow canal, the rest broad canal or
river) - consumed exactly 100 litres of gas oil.

So that suggests about 2 miles a litre, and given the speed and the
locks I'd say 1 litre an hour (CanalplanAC estimates 106 hours for the
travelling).

She's a 52 foot narrow boat with a 1.5l BMC.
Odd. That's about the same consumption I get on a 6 litre 4LW in a 70
footer.
But would you expect to use more because of the larger engine, more
because of the length, less because no doubt your engine runs more
leisurely (there was a chunk of high speed river work in there), or less
because you don't need to use the engine as much to keep station in
locks?
--

A canal boat probably spends its energy pushing water in front of it and making waves. This is all but independent of length/weight. For displacement craft it is wave making that usually limits their speed and hull resistance (friction) has a very much less influence.

As far as engine size is concerned, the engine has to produce the power to overcome the resistance to travel and as I said this will be very similar for different lengths of typical canal boat so the question is how efficiently the energy in the fuel is converted to thrust at the prop. A modern engine may burn its fuel better (and thus extract more power form it), but they are mostly indirect injected which suffer from losses caused by pumping air through small holes. The larger engines are probably direct injected that suffer no such losses so things even them selves out. If taken to extremes with (say) a large straight eight cylinder engine it may return a higher consumption because it is forced to operate at idle which is normally not very efficient.



Makes sense to me.

--
Gibbo

This email address isn't real.
.

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