楼上应该是与海运有一定相关(国航还是水经还是水管?)
Normally Chief Officer(大副)Sign the Mate's Receipt(大副收据).
Captain(船长)or Agent(on behalf of Captain or Owner) Sign the Bill Of Loading(提单). (可查阅信用证和提单的流通以及“远洋运输业务”等参考书)
However Captain as a command of the ship can sign the Mate's Receipt.
船长代表船东,船旗国。所有人在船上都应服从船长命令。法律也赋予船长在船上有半司法权和半警察权。(具体前查阅各国Maritime Law 和Navigation Act)