@Captain Ted: I preferred the newer style using galvanized flat bar of approx. 100 x 10 mm.
We had problems with the rubber wrapped wires that they snapped as the rubber hose was not water tight enough. Wires corroded inside the rubber hose.

We had them in mid 70,s with rubber-wrapped wires instead of these. It was good, as with those wires you could pulled them from fwd/aft towards their positions and would thereby push the remaining air out from under the cover which made the job overall easier

Those old style securing bars over the hatches were later considered too thick and had to be replaced for thinner ones

Built by Schiffswerft Holst Hamburg-Neuenfelde,Germany.