[geeks] lawn mowing efficiency

[Greg A. Woods]

[ On Sunday, April 21, 2002 at 23:26:55 (+0100), David Cantrell wrote: ]
> Subject: Re: [geeks] lawn mowing efficiency
>
> Well, count the characters in each of those.  Same distance covered in each
> one.  However, you should really be concerned not with the least walking
> distance but with expending the least amount of energy.  Doing it in rows
> requires several 180 degree turns, whereas the spiral requires a larger
> number of 90 degree turns.  I imagine that a 90 degree turn requires less
> energy than a 180 degree turn, but that that will at some point be cancelled
> out by the increased number of turns required.  I suggest that you experiment
> by mowing several lawns of different sizes.  Not only will you be advancing
> the boundaries of science, but your neighbours will love you for it too.

I bought myself an electric mower when I became a home owner in the
city, figuring it's safer and cheaper to store a hundred foot extension
cord than it is to store gasoline in the garage, plus the only
maintenance required on an electric mower is blade sharpening, which
though I really love small engine work when I have the time, not having
to do it on a regular basis is a real benefit when I don't really have
the time or space to work on engines.  It's also a LOT less polluting
considering that quite a bit of our local power comes from nuclear
plants.

Now with an electric mower you've pretty much got to do the back & forth
rows pattern to avoid cutting your cord.  However an electric mower
usually has a flip-over handle, thus almost elminating the need to do
anything but a slight steering motion to move the mower over to the next
row.  You just have to walk around to the other end and try not to trip
on the cord -- quite low energy requirements, or if you're really lazy
you just push one way and pull the other (which you can do with a gas
side-eject mower but it doesn't work quite so well).  :-)

As for clippings, well I don't know what most electric mowers without
bags do, but mine is a "mulching" mower and it creates a little
hurricane under the cover that circulates the clippings a few times and
then blasts them down.  Unfortunately this makes it very inefficient at
cutting because it also blows down the long blades of grass and so I
generally only take a half a swath and thus double-cut the whole lawn.

Now if you really want to pollute less and expend lots of energy, they
still make push mowers.....  :-)

(a really sharp blade and good rubber tires on a well lubricated push
mower can cut quite nicely and without all that much effort -- modern
models are quite a joy to run, and there's nothing quite so clean a cut
as a proper cylindrical mower blade that pulls the grass against the
cutter and then follows up with a little roller!  I've got a 60'x140'
lot though (with another about 10' frontage), and only a tiny 32'x24'
house and a small one-car garage with a narrow driveway and most of the
rest is grass (except the back deck and the garden plot I've been
working on) -- a push mower would take easily two hours and would have
to be done twice as often as even with my inefficient mulching electric
mower)

-- 
								Greg A. Woods

+1 416 218-0098;  <gwoods at acm.org>;  <g.a.woods at ieee.org>;  <woods at robohack.ca>
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