Canal Boat — November 2017

(Darren Dugan) #1
canalboat.co.uk Canal Boat November 2017 17

LETTER OF THE MONTH


LETTERS


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I read Kevin Blick’s article (CB, October) with great
interest, and hope that I might be allowed to offer
some thoughts of my own. My own perspective for
this is a little unusual – my wife and I have been
clocking up four weeks a year aboard hire boats for
over 30 years now, and for most of that time I have
deployed a GPS which accurately displays speeds
accurate to 0.1 mph, so my views are based on sound
facts rather than guesswork.
So let’s get down to the fundamentals. A boat’s
prop works by drawing water through itself. This water
usually has to come either from the sides or beneath,
as the prop is generally too close to the hull for much
water to be drawn from above. If the prop is unable
to pull water through itself freely, as is the case, for
instance, when the cut is either narrow or shallow,
then no amount of extra throttle will change that fact.
Think, for instance, how all narrowboats labour when
leaving locks, as well as when negotiating narrow
bridge holes or aqueducts. Thus the maximum speed
attainable by any boat is usually determined by the
profile of the cut itself. Incidentally, everyone who has
ever taken a boat onto a navigable river will know that,
wind and current aside, any boat feels far more lively
on a river than on a canal.
In a few places – Duke’s Cut springs to mind here


  • you can actually feel the change as the boat makes
    the transition from ‘wide and deep’ to ‘narrower and
    shallower’, or indeed vice versa. Conversely, I suspect
    that no one has ever achieved a true 4mph anywhere
    on the Macclesfield!
    All this means that for the vast majority of the
    canals, the existing 4mph limit is in fact no more than
    an aspiration. Even attaining this speed is usually
    impossible, and any thoughts of maintaining an
    average of 4mph over an hour or more remain mere
    fantasy, especially as you will invariably be slowing
    down frequently for moored boats.
    I use my own bespoke software for planning my trips,
    and I never plan for more than 3mph for UK canals,
    and for our forthcoming trip on the Southern Oxford,
    I have assumed an average of no more than 2.5mph.
    Some stretches of, for instance, the Grand Union or
    the Trent & Mersey do permit slightly higher speeds, as
    would the Caledonian Canal, though sadly I


have no personal experience of boating on the latter.
Now let us consider the matter of passing moored
boats. There are actually two separate issues at
play here, as both speed and throttle-setting are
relevant. Happily, most narrowboats these days
have efficient bows which produce relatively little
wash and very few boats have the square sterns that
produce noticeable stern wash – indeed the stern
wash produced by most boats is pretty negligible
these days.
My experience is that the thing that peeves most
boaters, myself included, is that of having the boat
pulled away from the bank by passing traffic.
The important thing to understand here is that the
pull is not being produced by bow or stern wash, it’s
that pesky prop trying to suck loads of water through,

as the steerer is using too much throttle. It doesn’t
matter how slowly that boat is moving, it’s the use of
excessive throttle that will do the damage. In France
we had the interesting experience of trying to moor a
boat with a heavily loaded peniche passing us in the
opposite direction.
This boat was only doing, maybe 1.5mph, but
because the skipper hadn’t throttled back, the pull on
the ropes was so severe that it was all that we could
do to succeed in holding on to just one of the ropes,
such was the pull on them as the peniche passed.
I would conclude by wholeheartedly agreeing with
KB’s assertion that the blame for excessive speeding
is equally shared by both owners and hirers. I believe
it’s about 50/50, and has been for many years.
CHRIS DODGE, via email

Using too much throttle is actually pointless – and here’s why


My dad has recently become disabled and needs
a wheelchair. So wherever we want to take him by
car, needs to have wheelchair access.
Do you know of anywhere within driving distance
of say one hour from Newcastle upon Tyne where
he can see the canal, preferably with a pub nearby
and/or disabled toilet facilities? He loves the

open water and now he’s become disabled it’s
something he and my mam can no longer do as
he can’t drive now and everything needs to revolve
around wheelchair access and a toilet.
ANN, via email
There aren’t many canals that far north but how
about Ripon, with a pub and accessible tripboat?

Where can my disabled dad see a canal?


It doesn’t take much to upset things
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