opes or wires attached to derricks to prevent them from swinging during cargo handling operations are().
Masts and derricks of cargo ships are made of().
Sailors should know the ()(安全工作负荷量)of derricks.
The SWL of the derricks are different from 5 tons to 10 tons.()
Please swing the derricks ()wharf side.
Most general cargo ships have two derricks and two winches at each hatch.()
Before ()the harbour, all derricks must be secured properly.
Topping wires fix the height of the derricks and () to the deck may be used to prevent fore and aft movement.
Before leaving the harbour, all derricks must be ()properly.
Lifting capacities of derricks vary from three to ten tons. ()