Wikipedia at http://en.wikipedia.org/wiki/Canal_lock describes rotating-sector gates thus:
===begins===== Rotating-sector gates. These work very like traditional swinging gates, but each gate is in the form of a sector of a cylinder. They close by rotating out from the lock wall and meeting in the centre of the chamber. English examples are the sea lock on the Ribble Link and the lock at Limehouse Basin which gives access to the River Thames. A dramatically-large one can be seen at the Rotterdam flood defences (huge flood gates). ===ends===== Now, I have been to Limehouse, but I've never been to the Ribble Link. I've been looking at all the photos I could find of the sea lock on the Ribble Link. Most of them show the gate with the tide full, but there is no sign of a rotating gate. None of them show anything looking like "traditional swinging gates ... rotating out from the lock wall and meeting in the centre of the chamber." One photo shows the gate at low tide; from that, and from one boater's account of the gate being covered, it looks to me as if the gate rotates on a horizontal axis, pivoting upwards from the bottom. Can anyone clarify this for me and point to a photo that shows the nature of the gate? bjg
