We lived through the full evolution of hatch covers from the manually handled boards seen in the picture, which had been used for centuries. The next stage, on the early post-war ships, were slab hatches - two covering the beam of the hatch. These had to lifted by derricks, although it was possible for a couple of strong lads to slide one over another to give access to a ladder. Next came pontoons which extended right across the hatch and could only be lifted using derricks. Then came the noisy rolling, folding hatches. And finally, in the containerships, came the single, strong cover, weighty enough to have been classed as a Heavy Lift in the conventional ships.