[EMAIL PROTECTED] wrote:
>[EMAIL PROTECTED] wrote:
>> --- In [email protected], Martin <[EMAIL PROTECTED]> wrote:
>> >
>> > Daniel Hutchinson wrote...
>> > >Emilyanne can also push the gate open against 6/8inchs of water,
>> > >which as you say, greatly speeds up the slowest last few inches.
>> > No wonder so many lock gates are damaged and leaky and do not fit=20
>> > properly.
>> > Martin Clark
>> there is little damage to be done from gentaly pushing=20
>> open a gate against a small head of water. The boat pushes smoothly=20
>> and contiuasly against the middle of the gate, and the force exerted=20
>> on the gate is nateraly limited to that of the boats thrust=20
>> or 'static bollard force'.
>
>It's true that you're unlikely to damage a gate by pushing gently. But I'm
>surprised that you can push a gate open against a head as great as 6 to 8
>inches. A back-of-fag-packet (except that I don't smoke) calculation suggests
>that on a typical narrow lock this would take between a ton and a ton and a
>third of force.
AIUI, FMC steamers regularly used to push gates open. These boats
often worked fly, and the practice saved quite a lot of time. As
previously suggested, the big props and large torque of steamers makes
them particularly effective for this. But I think they put the bow
fenders against the gates relatively gently, and I also think this was
mainly done in locks with two top gates. I doubt it did/does much
harm to gates.
Other working narrow boats are reported to have rammed the mitre, with
someone on the bow with a wedge which was shoved into the gap created,
to hold it open. I would think this practice *would* shorten gate
life notably.
GU gates (top and bottom) used to have steel reinforcers on the
downstream edges of the mitres from the water line up for 1.5 m or so,
to protect the wood from wear from boats pushing gates open. I'm not
sure if these are fitted to new gates any more, but they should be
given the practice of narrow boaters of opening only one gate on broad
locks, as without such protection the wear created on the mitres
causes leaks.
Adrian
Adrian Stott
07956-299966
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