Thursday, 22 June 2006 / Posted in Our Designs for Inspiration /
Lerwick Port Authority have taken delivery of their new 20m tug/pilot vessel Knab, which is MCA coded and classed with Det Norske Veritas (Class X1A1 R1 TUG) as a tug and pilot vessel, with capability to carry 12 passengers and a deck cargo capacity of 10 tonnes. The vessel was designed by McCaig and Napier Naval Architects & Marine Consultants (successors to The Napier Co. (Arbroath)) – to replace the existing Knab, a multi-role vessel designed by The Napier Co. over 20 years ago as a groundbreaking solution for the diverse activities and demanding conditions around the port of Lerwick in Shetland.
The new Knab, built by Vestvaerftet ApS in Hvide Sande, Denmark with steelwork by Riga Shipyard, Riga, Latvia, is designed to update and build upon the innovative concept of the original vessel. Versatility has been the watchword throughout the process of design, construction and fitout, and the final result is an exceptionally powerful and versatile vessel packaged into 20.50m length over fenders. The Knab’s propulsive power is by twin Kort-nozzle-assisted CP screw propellers, driven by Volvo D30A MT engines each rated at 530kW. Also contained within the space efficient engineroom are twin Volvo D5AT 77kW gensets and an additional Volvo TAMD74A 257kW auxiliary engine driving hydraulic equipment and pumps.
Deck gear is extensive and selected to meet the criterion of maximum versatility. Hydrakraft towing and tugger winches and a Mampaey towhook combine with a removable stern roller to provide a flexible workhorse with capabilities normally associated with a much larger tug. The Knab is also fitted with a Palfinger deck crane with a capacity in excess of 10 tonne-m, a fire monitor and fire hoses, salvage suction system and forward and aft capstans. The foredeck layout is fully optimised for pilotage operations again building on the experience of the port staff and vessel operators.
Sleeping accommodation is provided for 3 men with mess and galley space for 5, fitted out to an exceptionally high standard by Vestvaerftet ApS, including thermal and sound insulation fitted to exacting Danish standards.
The designers have eschewed the conventional heavy tug hullform for a fine round-bilge hull, designed in the Napier tradition and tailored to deliver exceptional speed, handling, seakeeping, and excellent stability. At sea trials the vessel has achieved an average speed of 11.4 knots on a waterline length of 19m. Class beating manoeuvrability, achieved by twin Becker high-performance rudders and a Hundested tunnel thruster, has exceeded all expectations, and a bollard pull of 19 tonnes ensures the Knab is superbly equipped for tug and towage duties in the dynamic and bustling port of Lerwick.
