Innovative designs from CMHI get DNV GL approval

Written by Nick Blenkey
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Arctic single column drilling unit

Two new designs from China Merchants Heavy Industry (CMHI) — an arctic single column drilling unit and a wind turbine shuttle — have just received Approval in Principle (AiP) from classification society DNV GL.

They may say as much about Chinese offshore drilling and offshore wind ambitions as they do about its development of advanced marine technology.


The arctic single column drilling unit (SCDU) consists of a round floater with an upper and a lower hull, an enclosed deckhouse, and a round footing. It is designed for well work-over, exploration, and development drilling operations in water depths up to 700 m in moderate environments, including Arctic and sub-Arctic areas (open water and up to 1.5 m ice thickness), moored by a 16-point mooring system.

The round conical shape of the strengthened hull structure is designed to deflect and break the ice, protecting the drilling riser and other equipment in the moonpool against level ice.

DNV GL assessed the design according to a high-spec class notation string: 1A Cylindrical Drilling Unit(N) Crane-offshore(N) DRILL(N) E0 POSMOOR Non-self-propelled HELDK (S, H, N) DAT (-40) Ice(L) PC(5) Winterized(Polar, -45°C) BIS BWM(T) Clean(Design).


Unlike other installation vessels, the CMHI wind turbine shuttle has a small waterplane area twin hull (SWATH) design. This results in very low resistance at the design draught (16 m) and excellent seakeeping performance, good motion behavior characteristics, and high transit speed of 14 knots.

Capable of transporting and installing two fully assembled wind turbines or two wind turbine foundations, the vessel has a highly redundant dynamic positioning system installed and the wind turbine hoist tackles are equipped with an active system to compensate for the heave motion of the vessel. The WTS can provide a “one-piece” installation service for offshore wind turbines, as well as jacket foundations, piles, and other components.

The design was assessed according to the class notations: 1A Column-stabilized Wind turbine installation unit Crane-offshore DYNPOS(AUTRO) E0.

Wind turbine transporter features SWATH hull design
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