Brian from sunny Suffolk <[EMAIL PROTECTED]> wrote: >So do lots of boat using the narrow locks use more water than the same >amount of boats using the broad locks. And this is not the same as big >or small boat using more or less water. I mean that you fill the large >locks with boats, not one at a time.
In general, the most efficient use of a lock is when all of the water surface area inside it is covered with boat. A narrow lock completely filled by a full-length narrow boat (or a number of shorter narrow boats the lengths of which total that of a full-length narrow boat) is thus maximally efficient. You could equal, but not improve on, that efficiency by packing a larger lock just as full. However, the rise of the locks makes a difference too. A lock with a smaller rise uses less water than one with a larger rise. So because in a flight the water in effect gets re-used from lock to lock, the more locks used to total in sequence to a given rise, the less water is taken from the top pound in general by the flight. The configuration matters as well. A staircase has different water usage from that of a single lock or a separate-locks flight <omits dicussion of staircase water usage to save space and avoid tedium>. The narrow locks at Stourport are two successive two-rise staircases, while the wide locks are two successive singles. So wrt rise, the narrow locks are twice as efficient. However, because they are staircases, it is possible for them to be used quite inefficiently, but not overall to be less efficient than if they were a slight of two singles (like the broad flight) instead of two staircases. So, it appears BW is correct to insist that boats that can use the narrow flight should do so, rather than use the broad one, even if they can pack the latter full. Adrian PS The only time I have taken my barge into the top basins at Stourport, I was surprised how difficult it is to steer around the bend between the two locks on the way down. It is a very awkward layout. I guess it was designed assuming the craft would be handled using ropes. Adrian Stott 07956-299966
