What is the "crane curve" on a DP capability plot, and what does it represent for operations planning?

A. The crane curve is only relevant on crane barges, not on vessels with deck cranes

B. The crane curve is a maintenance schedule showing when crane services are due

C. The crane curve shows how the vessel's DP position-keeping capability (the weather conditions it can handle) is reduced when the crane is deployed at a specific load and radius — it defines the maximum environmental condition in which a lift can safely proceed in DP, and is used when setting ASOG limits for crane operations

D. The crane curve shows the maximum lift capacity of the crane at different radii — it is a structural limit, not a DP limit

A. Crane lifts only matter for DP if the load exceeds the vessel's Safe Working Load

B. Lifting a heavy load shifts the vessel's centre of gravity upward and athwartships (depending on crane position), altering the vessel's roll and pitch characteristics and therefore the environmental force response — a DP system not updated with the correct crane position and load may miscalculate the forces needed to maintain position, reducing accuracy

C. Crane lifts have no effect on the DP model — only weather forces are modelled

D. The DP system automatically compensates for crane loads through the load cell feedback

A. Pendulation is the rotation of the crane jib, not the load

B. Pendulation has no effect on DP — it is a rigging safety concern only

C. Load pendulation is the swinging of a suspended load in an arc below the crane hook, which creates a dynamic, oscillating side force transmitted through the crane structure to the vessel hull — the DP system must counter this cyclic force, and the constant changing direction of the force can cause oscillating thruster demands that stress both the DP system and the power management system

D. Pendulation only occurs when the load is in the water, not when suspended in air