--- In [email protected], Adrian Stott <[EMAIL PROTECTED]> wrote:
>
>.
> >
>
> Steve, a Frenchman beat you to this idea by about 150 years.
>
> Exactly this system was used in the Pouilly-en-Auxois tunnel on the
> summit of the Burgundy canal. This tunnel was too low for unladen
> peniches to pass through, so such peniches were navigated into a
> floating caisson, which was then sealed behind them. Flotation
tanks
> in the caisson were then flooded , making the caisson float lower.
The
> caisson was then towed through the tunnel by an electric tug. The
> flotation tanks were pumped out, and the peniche released, at the
> other end.
>
> When I went through the tunnel about a decade ago, the caisson, and
> the tug, were still moored there, but I think they hadn't been used
> for many years and that the power cable along the tunnel roof
(power
> was picked up by the tug via a trolley-bus type arrangement, using
a
> rather worrying and low-hanging bare wire) probably was no longer
safe
> or workable.
>
> There's (almost) no commercial traffic over this summit any more.
>
> However, the system worked well, and may well be worth considering
for
> Froghall..
>
> But is Froghall tunnel sufficiently deep enough to allow a caisson
to
> float low enough to make this work? And is it wide enough to
accept a
> caisson at all.
>
> Worth investigating, IMHO.
>
> Adrian
>
> Adrian Stott
> 07956-299966
Ah - yes - the concept develops .
Pump water IN not
Quoting Steve -
Suppose your boat floated into a tank which was quite
deep, say 5ft draught or so. The door is closed and the water pumped
out. The whole lot will stay afloat as some of the water has been
replaced by air, but the roof of your boat will be maybe 18 inches
lower, depending on draught as it sits on the bottom of the tank.
Would this work...?
not OUT !
The French method obviously worked and obeys Archemedes.
In the Froghall situation it would be expedient to sort out a
solution that requires negligible maintenance and no operatives
involved.
Doityourself caisson opetation not on !!
Only a change of tunnel height or tunnel water level seems to solve
the problem.
Pete
www.thecanalshop.com
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