Subsea 7 gets 250 tonne knuckle boom

Huisman will deliver a 250 tonne capacity knuckle boom crane for a new Subsea 7 multi purpose offshore construction vessel.

Netherlands-based lifting, drilling and subsea solutions specialist Huisman's new crane was load tested at the Huisman facility in Schiedam, the Netherlands. The crane will be installed onboard Subsea 7's new vessel Seven Pacific.

Work for the crane will be in offshore construction and subsea installation to a water depth of 2,500 metres. It is the fifth crane of this type to be delivered by Huisman. other recently delivered knuckle boom cranes include three 120 tonners for Hornbeck Offshore, Subsea 7 and EZRA and one 150 tonner for Technip. Another 150 tonner, suitable for a water depth of 3,000 m, was under construction in mid September for Otto Candies.

A unique in-house developed secondary controlled hydraulic drive system allows real-time active compensation of the heave movement of the tip of the crane boom to minimise load movement. During heave compensation energy can be stored in an accumulator to reduce power consumption. Huisman introduced secondary controlled hydraulics as a drive system for the main crane of the Smit Semi 1 in 1986.

In addition, the new crane will have three independent electro-hydraulic power units. This level of reduncay allows the crane to remain operational with only one or two pump sets running.

Other features include constant tensioning, manual overload protection system and automatic overload protection on the auxiliary hoist.