Knud E. Hansen presents new wind turbine installation vessel design

Ship design agency Knud E. Hansen presents a new platform, the Atlas C-Class. The wind turbine installation vessel is currently the only one capable of carrying six of the new-generation 14-16 MW wind turbines, and at least five of the next generation 20+ MW turbines.

The design features a jacking deadweight of 18,000 tonnes, 6800 square metres of cargo deck area and a 3000 tonne @ 37 metre crane. In addition to being able to carry te latest generations of wind 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 MW turbines.

The Atlas C-Class is intended as a platform that will form the basis for further customisation according to 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 individual needs.

Principal particulars

  • 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

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 standardised and installed in many different locations and orientations.

4 MW battery pack

Energy savings and low emissions have been key drivers for the propulsion system. The vessel is powered by eight identical generators, each with 3340 kW 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 MW 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). According to the ship design agency, they also make it possible to recover approximately sixty per cent of the energy that is used to jack the vessel to the operational height.

To further minimise 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 maximise thrust. The platform is equipped with four three-chorded trusswork legs which can support it in water depths up to 80 metres.

5000 load cycles

The spud cans are optimised 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-and-pinion jacking system designed for 5000 load cycles.

According to Knud E. Hansen 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 be fully utilised in the fully loaded conditions.

Accommodation

The main deck of the accommodation block includes an operations centre consisting of offices and meeting rooms as well as a hospital, day room, TV room, change room, and workshop. Above this is a large galley with spacious mess as well as ample provision rooms.

The three decks above include a total of 130 cabins for contractors, crew and officers. The top deck consists of a bridge with centerline and wing consoles and a large helicopter deck. Below the main deck is a gymnasium, cinema, TV room, games room, and sauna as well as a laundry room and store rooms.

Further development

Negotiations are currently ongoing with companies in the offshore wind sector to further develop the Atlas C-Class platform based on their individual requirements. It is the first in a series of planned WTIV platforms of varying sizes. One of those already under development is a smaller A-Class platform that can carry four 14 MW turbines and is equipped with a 1600 tonne crane for clients who require a smaller variant to install wind turbines on pre-installed foundations.

Author: Mariska Buitendijk

Mariska Buitendijk is one of SWZ|Maritime's journalists as well as the magazine's copy editor.