Damen reach a milestone in ASD tug development

The tugs are the last to be built to the highly successful ASD Tug 3111 design, which is now to be replaced by the new ASD Tug 3212. Damen considers the new tug as an important milestone in ASD design. It recognises the high level of sophistication reached by the ASD Tug 3111 and the need to introduce a new design, incorporating all the best features of that vessel in a new powerful tug with even greater potential for the future.

Karloo and Kalarka were constructed at the Damen Changde shipyard in China and were described by the yard’s production manager Wim de Rooy as, “A superb example of tugboat design. The tugs are compact, broad, extremely low and offer great stability. A carefully designed superstructure and inward sloping exhaust uptakes enable the tugs to work safely, close alongside modern container ships with flared bows. It is an extremely clean design with clear deck spaces and no superfluous equipment or fittings likely to cause fouling or represent a hazard.”

The highly developed ASD Tug 3111 hull form, incorporating a long deep central skeg, is the result of many years of experience, testing and research into the needs of Damen’s customers. Karloo and Kalarka are harbour tugs with excellent performance. A bollard pull of 69.3 tons ahead and 64.6 tons astern is combined with excellent manoeuvrability, enabling the tug to reposition quickly and apply force exactly where it is required, whether pushing or pulling. When towing in the ‘indirect mode’, considerable additional force can be applied thanks to precise manoeuvrability and excellent inherent stability.

The wheelhouse design was developed to give good all round visibility and standardised controls are aimed at ease of operation, with a user friendly layout for operation by a small crew. Noise and vibration levels aboard the ASD Tug 3111 are extremely low thanks to flexibly mounted main engines and flexible drive couplings.

On deck, efficient Ridderinkhof hydraulically powered single drum winches are positioned fore and aft. The forward winch incorporates the anchor windlass and has a maximum brake holding load of 185 tons. A line pull of 27.2 tons at 22.5 m/minute is specified and a maximum rope retrieval speed of 65 m/min. The drum carries a 160m synthetic fibre towline of 104mm diameter with a14m stretcher (pennant) of 60mm rope. The aft winch has a brake load of 175 tons and the same line pull. Spooling gear is fitted and the drum accommodates a synthetic towline of 220m in length and 96 mm in diameter.

In order to meet the demands of ‘push-pull’ operation, the bow is wide and heavily fendered with tubular rubber and moulded block fenders. Tubular rubber is also used to protect the aft quarters and heavy ‘D’ section moulding is fitted along the sides.

A Heila HLM 10-2S deck crane is installed to handle stores and equipment and has a maximum lifting capacity of 2 tons at a maximum reach of 4.5m.

Fully air conditioned accommodation is provided for a crew of up to six persons. Single berth cabins are fitted out for the Captain and Chief Engineer and two double berth cabins for the remainder of the crew. The entire accommodation is insulated and finished with durable modern linings and the wheelhouse has a floating floor and ‘Dampa’ acoustic insulation on the ceiling. Noise levels throughout the accommodation are extremely low.

The Damen ASD Tug 3111 will be a hard act to follow. Of the twenty tugs of that type now in service, ten were built in the last five years by the Damen Changde shipyard, where great care and attention to detail resulted in vessels finished to a very high standard for discerning clients such as SMIT, Spezzini, Hamersley Iron and Half Tide Marine.

When the first new ASD Tug 3212 is introduced in the Spring of next year it will become obvious that an already successful ASD concept can still be improved. Although the design is new, all of the many highly successful features found in the ASD Tug 3111 will be retained. During the design process Damen worked closely with their clients to ensure that the performance and production quality will satisfy the needs of the market for shiphandling tugs well into in the future.

Among the foremost objectives of an ambitious ASD 3212 design team was to improve the towing characteristics in exposed locations with waves of up to 2.5m high. Assisting large tankers and container ships in those conditions proved difficult for the ASD 3111. The new vessel will have a higher bow with a more flared and slender shape and a completely revised hull form with bilge keels that has undergone tank testing at MARIN.

A new type of heavier two stage ‘super-absorbent’ bow fender has been developed to deal with the enormous forces generated by waves when pushing at sea. Also completely new are the cast stainless steel towing bitts and 200 tons offshore rendering/recovery winches developed by Damen Marine Components/Maaskant and designed to withstand a constant tractive force of up to 80 tons while working in a swell.

More powerful Caterpillar 3516C TA/D engines and new Rolls-Royce propulsion units of extremely rugged construction and larger controllable pitch propellers will increase what is already an impressive performance even further, to achieve a bollard pull of 75 tons and free running speed of 14 knots.

The future owners of the new ASD Tug 3212, will purchase not only a powerful, affordable tug but also one built to a ‘state of the art’ design. A completely new Praxis MEGA operating and control system will utilise a series of multifunctional touch screens located on a newly designed control console in the wheelhouse and in the engine control room. The LCD screens, intended for use in any lighting conditions, will enable the engine, propulsion, and auxiliary systems to be monitored and controlled with ease. Additional touch screens will be used to display and control the winch and hydraulic systems.

Accommodation aboard the new ASD Tug 3212 will be fully adapted to meet the new Maritime Labour Convention 2006 (MLC 200) requirements, with all cabins above the waterline. The result is a more spacious and comfortable interior in the new Damen standard colour scheme.