The two ribs at the Royal Quays are on floating docks. The video shows how to get them off, and back on again.
Ribs are secured with a clip at the front to stop them drifting off. Remove the clip before reversing off the dock and clip it back again when you have returned.
Don’t forget to flush the engines after use – see videos here – and put the cover on the blue rib. see also the very useful pictoral note below from Francesco