Published 2020-12-14 00:00:00
ATLAS C-Class new WTIV design from Knud E. Hansen
Versatility and Customization take centre stage in the new Wind Turbine Installation Vessel (WTIV) The ATLAS C-Class

KNUD E. HANSEN continues to build on its portfolio of innovative designs and extensive experience in the offshore wind farm sector with a new platform: The ATLAS C-Class. Named after the Greek Titan tasked with holding up the sky and heavens above, this platform boasts unparalleled strength and durability.

With a jacking deadweight of 18,000 tonnes, 6,800 square metres of cargo deck area and a 3,000 tonne @ 37 metre crane, it is currently the only WTIV capable of carrying six of the new-generation 14-16 megawatt wind turbines, and at least five of the next generation 20+ megawatts turbines.

The jacking deadweight and crane capacity also enable the vessel to carry at least four of the extra-large monopile/transition piece foundations, which are required for the 14–16 megawatts turbines.

The impressive size and scale of this groundbreaking design is matched by its versatility and customizable features. The ATLAS C-Class is intended as a platform which will form the basis for further customization according to our clients’ objectives. Cranes, thrusters, generators and jacking systems can all be modified and selected based on manufacturer availability such that the vessel can be tailored to suit the individual needs of each client. This represents a significant departure from competitors that offer off-the-shelf products with little flexibility.

PARTICULARS OF THIS PLATFORM ARE AS FOLLOWS:

Length Overall (excluding helideck) 170.00 metres
Breadth, moulded 60.20 metres
Depth to Main Deck 13.20 metres
Draught, moulded @ 18,000 t deadweight 6.70 metres
Speed @ 6.50 m draught incl. 10% s.m. 12.0 knots
130 cabins for contractors, crew and officers
Four 14 megawatt turbines and is equipped with a 1,600 tonne crane

In keeping with the objective of design versatility, the cargo deck incorporates uniform girder spacing in both longitudinal and transverse directions such that foundations for equipment and turbine parts can be standardized and installed in many different locations and orientations.

Energy savings and low emissions have been key drivers for the propulsion system. The vessel is powered by eight identical generators, each with 3,340 kilowatts of electrical power, which are arranged in two independent engine rooms. A DC grid system allows the engines to run at variable speed for maximum fuel efficiency. The DC grid system is coupled to a 4 megawatt battery pack for load leveling and peak shaving.

The batteries can supply “instant power”, which reduces the need for “spinning reserve power“ from generators running on standby (e.g. during DP operations), and they make it possible to recover approximately 60% of the energy that is used to jack the vessel to the operational height.

To further minimize power consumption, the vessel is equipped with some of the most efficient thruster units on the market. This includes four azimuthing stern thrusters, driven by highly efficient permanent- magnet motors and equipped with nozzles for maximum bollard pull. At the forward end, there are two tunnel thrusters and two retractable bow thrusters configured to maximize thrust. The platform is equipped with four 3-chorded trusswork legs which can support it in water depths up to 80 metres.

The spud cans are optimized for the lowest possible seabed penetration, and they are fitted with buoyancy boxes to reduce the draught in port, reduce the load on the seabed when the vessel is jacked up, and to help retract the legs out of muddy sea beds. The platform is elevated by a powerful high-speed electrical rack-andpinion jacking system designed for 5,000 load cycles.

This is significantly more than many of the competing designs and will ensure the leg racks will last the lifetime of the vessel. The optimal load balance of the vessel ensures the total jacking capacity of all four legs can by fully utilized in the fully loaded conditions.

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