For lighter loads, Rolls-Royce supplies a range of dual-draglink deck-mounted cranes. The dual draglink crane has a geometry providing unique lifting performance. The parallelogram geometry provides a good working height and allows for short radius operations to make use of the deck area near the pedestal. Currently, two sizes are available – the DDC35 and DDC50 – and are designed to DNV LA2.22 for handling 35 and 50-tonne loads. State-of-the-art active heave compensation (AHC) uses hydraulics to control the position of the elbow derrick and so compensate for vessel movement, and not the winch, which is the case in alternative units. This feature minimises the amount of time the winch spends cycling and so reduces cable degradation.