Ordinary seaman

From WikiPOBia

The Ordinary seaman was the lowest rating for a capable sailor. An Ordinary seaman was a step up from the complete novice, the "landsman" and could be expected to know his station and task, i.e., where he was supposed to be at a given command and what he should do. The term survives in the US Merchant fleet as the lowest level of Merchant Mariner Documentation (MMD).