Author 'Crabecanoe' (Id 118047 ) : Saturday, April 10, 2010. Roubaix Canal. Lock the Plomeux. In Progress in the pool between the locks of the Black Hat and the lock Plomeux. From the bottom of my canoe where I am taking the photo, the sluice gates seem impressive, and the sky high. It is a window towards the light, toward what is blue, towards freedom.