"Neil Arlidge" <[EMAIL PROTECTED]> wrote: >John wrote:
>> I know the rule is 'drop the paddles and shut the gate when you >> leave' but I was wondering why we shut the gate ? > ><Que Adrian> Shouldn't there be an accent on that? Anyway, for a discussion of this, look at Waterways World 2004 August, Page 77. The title of the article gives a clue to my opinion. It is "Leave 'em Open". John, I will email you a copy of it if you post your email address here. >Yes, it is a silly rule, but on the GU it does >have water saving properties, as a lock left empty with the bottom gates >shut and paddles down *should* eventualy fill if there is water going >through the top ground paddle (they can overspill and act as by-weirs) It is true that the design of the Grand Junction locks (but I think not those on the rest of the GU?) are such that the upper pound will overflow into the the top ground paddle culverts. However, I believe this was an alternative to building bywashes (which the GJ mostly does not have), as the top of the bottom gates is (or, should be) at the design water level of the upper pound. If the top pound is high and the bottom gates are left closed, the lock will eventually fill via the culverts, and then weir over the bottom gates. I think the "water saving" idea doesn't stand up, as if the upper pound is too high why bother to save a lockful from it? IIRC the Rochdale is the same (and the K&A used to be, but I think it has been much altered by BW's insisting on installing bywashes). Is it a Jessop thing (yes, Rennie did the K&A, but the GJ was done before that)? Adrian Adrian Stott 07956-299966
