Coa is a contract of carriage of goods by sea in essence , under which the carrier , during the agreed period , against payment of freight undertakes to carry the goods in agreed amount for divided shipments by the shipper from the agreed loading port to the discharging port . during implementation , the specific voyages should be governed by the agreed voyage chaterparty which is agreed upon between shipper and carrier after the conclusion of coa 通过比较分析，作者认为，包运合同是指，承运人在约定期间内分批将约定数量货物从约定装货港运至约定目的港的协议，在履行协议过程中，依航次租船合同对分批具体航次履行作进一步约定，最终实现承运人提供海上货物运输服务并收取运费的目的的海上货物运输合同。
With the development of shipping technology and containerization of marine transport , there are more and more instances when the bill of lading could not be availed of or secured at the time of entry of the goods at the discharge port , and so the delivery of goods without the bill of lading arises and disputes on such delivery are on the rise 随着国际航运技术的提高和海上货物运输向着集装箱运输的大型化、高速化、班轮化发展，提单晚于货物到达卸货港的现象频频出现，无单放货以及因无单放货引起的纠纷不断增加，无单放货索赔案件是实务部门处理的海商案件中较多的一种。
