A vented hatch cover for a container having an opening defining a hatch and a coaming on the container's exterior surrounding the hatch opening. The cover has an outer shell and an inner shell, each shell having a main body and a flanged portion. The bodies are sized to fit over and enclose the hatch...http://www.google.co.uk/patents/US6085664?utm_source=gb-gplus-sharePatent US6085664 - Vented hatch cover
