BNR 200 - Duke ii

At Shipyard Gebr. Kooiman, the design of the Mustang has evolved through construction and development into a stronger and larger anchor handling tug supply (AHTS) vessel, which was reflected in full in the Norne, delivered in 2011. Highly satisfied with the performance of the Mustang, the owners of Probus Mare decided to contract the same builder for a new vessel, which would be called Duke II.

Compared with the already high status of the Norne, the shipyard established an improved ice class to 1A Super, according to the Finnish-Swedish ice class ratings. This is the highest ice class valuation which can be obtained for an AHTS, and the last step before it would have icebreaker status. The rating means the vessel can work in difficult ice conditions without the assistance of an icebreaker. Although the hull shape and powertrain of the Norne did not need to be changed, a significant number of adjustments were required to obtain this high rating.

Both the Mustang and the Duke II operate in the oil and gas industry sector, where they work as versatile support vessels by anchor handling, towing pontoons and delivering small quantities of fuel or containers. It is expected that the Duke II, with her higher ice class rating, can extend the work season in the spring and autumn.

One important aspect of the ice class rating is the requirement that the propulsion system is capable of dealing with the considerable effects of blocks of ice which come against the propellers. This resulted in an increased propeller shaft diameter (260 to 335 mm) and considerably larger gearboxes, which made them almost larger than the main engines. The rudder shafts are also thicker and the steering system is more powerful, which makes manoeuvring faster. An ice knife at the back edge of each rudder prevents blocks of ice coming between the rudder and the hull when moving astern.

The hull of Duke II was built in the Czech Republic for reasons of cost efficiency, after which the vessel was fitted out on the covered slipway at Shipyard Gebr. Kooiman in Zwijndrecht. As a result of the full-service approach of the shipyard, which means that almost all aspects of the shipbuilding are supplied in-house, the communication lines remain short, and that contributes to efficiency, customer satisfaction and reduced building time.