Abstract: A hatch installation comprises a hatch surround defining a hatch opening and a hatch door. The hatch door has a mounting end and a free end, and is pivotal between a closed position in which it abuts against the hatch surround and an open position spaced away from the hatch surround. The installation includes a cover member shaped to form a ventilation passage together with the hatch surround having one ventilation opening at the free end of the door and the other ventilation opening towards the end. The ventilation cover includes a water screen having three baffles and a sheet mesh for screening out moisture entrained with air. The ventilation cover includes a further sheet mesh water screen across the other opening. The sheet mesh acts with the hatch door to remove moisture entering through the opening.