Hatch covers are used to cover and protect the cargo in the cargo spaces. Hatch covers close off the hatch opening and makes it water tight. In the days of wooden ships, the hatch covers were made of wooden planks, beams and boards and were covered with tarpaulins.
Wooden hatch covers had many drawbacks. Mainly, they used to get spoilt due to continuous exposure to the moisture laden sea winds. Rain and sea water also used to produce detrimental effects on the wooden hatch covers. But with the advent of steel, the wooden hatch covers started disappearing.
Nowadays, mostly steel hatch covers are used.