These are boom cranes mounted on see-going vessels and used to transfer cargo from larger cargo ships to lighter port-going vessels.
这些是登上在看见去的船和使用的景气起重机从更大的货船转移货物到更轻的口岸去的船。
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The boom can be changed to the smallest form when not in use and is widely arranged for fishing boats, probe vessels, engineering ships, military vessels and special ships.