Navigation lock

A navigation lock is a lock built to pass vessels between water levels on a navigable waterway, as distinct from a flood-control or water-management structure. It works by impounding the ship in a chamber and filling or emptying it through culverts or wall ports until the level matches the next reach, then opening the gates. Filling and emptying systems are end-port (gates and ports at the ends) for small lifts or distributed-manifold culverts in the floor for large chambers, sized to fill fast without generating hawser-snapping currents on the moored ship. Chamber length, width, and sill depth set the largest vessel the waterway carries. CEMT classes European inland waterways partly by their lock dimensions.