Ephemera 9: the flash lock at Killaloe

As part of its new mooring scheme at Killaloe, Waterways Ireland has commissioned contractors (L&M Keating Ltd) to carry out various works including the installation of a lock at the upper end of the canal, beside the Phoenix boathouse and just downstream from the Pierhead. The lock is to control access to the canal; presumably the stop planks in the existing lock chamber will be removed, allowing boats to pass down under the bridge.

The lock under construction

As I understand it, this lock is to have a single pair of gates. Boats wishing to pass through will tie up temporarily and use a squawk-box (or similar technological marvel) to communicate with the bridge-keeper at Portumna, who will cause the gates to be opened and then, presumably, closed after the boat has passed through. This system will prevent the use of the canal by cads and bounders using jetskis, speedboats and other excrescences.

Stanked off and pumped out

However, the water through Killaloe Bridge has a gradient or slope, especially in flood and when Ardnacrusha power station is running. The canal above the lock will be at the higher level; the canal below the lock will be fed from the bottom end, where it rejoins the river. So is there not likely to be a difference in height at the lock? Is this the equivalent of a flash lock?

I’m sure there is an engineering answer to this; I would welcome enlightenment.