Jumbo Derrick

A jumbo derrick is a heavy-lift derrick on a general-cargo or multipurpose ship, rigged to lift single units far heavier than the ship’s ordinary cargo gear, commonly 60 to several hundred tonnes. It is stepped at a strengthened mast or kingpost (a Stulcken or similar arrangement often serving two hatches) and worked with multi-sheave purchases, topping lifts, and guy tackles. Because rigging and topping a jumbo derrick is slow, deck cranes have largely replaced it, though it survives on project-cargo and older tonnage.