TABLE OF CONTENTS The past three decades have seen a considerable reduction in the number of shipyard built and rigged derricks as shipboard lifting devices and their replacement with bought in cranes. The crane being less labour intensive, faster operating, more easily controlled and taking up less deck area. They do however require a higher degree of onboard maintenance.
When ordering a new ship the shipowner normally specifies the number, safe working load, position, and any special features of the cargo lifting devices to be fitted. Where derricks are specified the shipbuilder or an outside specialist consultant is then responsible for the detailed design of each derrick rig, together with the various fittings at the derricks and mast. Where patent derricks and masts are fitted the patentee may supply the drawings, etc., to the shipyard, who then build and erect these rigs. Masts, except some patent types, are the responsibility of the shipbuilders; blocks, wire, and usually derrick booms being supplied by an outside manufacturer to the shipyard's specification.
Masts on a general cargo ship may fulfil a number of functions but their prime use in modern ships is to carry and support the derricks used for cargo handling. Single masts are often fitted, but many ships now have various forms of bipod mast which are...
