Port Authority chief executive Allan Wishart said, 'The new vessel is very much a sign of the times, with the increased power required to help handle the range of larger vessels which now call at Lerwick and are making a growing contribution to port activity. She represents another important investment in the future of the port.'

The new Knab was built by the Vestvaerftet shipyard of Hvide Sande in Denmark at a cost of £1.8m. Naval architects McCaig and Napier of Glasgow, were responsible for the design, working in close cooperation with staff from the Port Authority. The same company was responsible for designing the first Knab, built in Norway in 1980 and the later Kerbister.

Deputy Harbourmaster, Captain Calum Grains, and Engineer Chris King participated in the new vessel's successful trials in Denmark and are delighted with its performance.

Knab is a twin screw vessel of 20.3m in length overall, with breadth of 7.4m and service draft of 3.3m. The vessel is heavily built, with a raised forecastle, to deal with the extreme weather conditions prevalent in the area during the winter months and complies with the requirements of DNV 1A1 TUG R1.

Power for the twin screw propulsion system is supplied by two Volvo Penta D30 diesels, each developing 720bhp at 1,400rpm. The twin three blade propellers rotate within fixed Kort nozzles and are driven via Heimdal reverse-reduction gearboxes. High performance 'Becker' rudders are installed and controlled by Tenfjord steering gear and independent Rolls-Royce controls. A Hundested fixed pitch bow thruster is powered by a dedicated, variable speed Volvo Penta TAMD 74Q diesel engine of 350bhp. On trials Knab produced a bollard pull of 22 tons and maximum free running speed of 11.4 knots.

The towing gear fitted aboard Knab leaves no one in doubt as to its viability as a tug.

A Hydracraft T16176B100 twin drum hydraulic towing winch has a line pull of 25 tons and maximum brake holding load of 80 tons. Each drum is equipped with a 110m towline of 32mm diameter Dextron 12 plus (12 strand Dyneema within a protective cover). Hydracraft also supplied the T10438A100 hydraulic 'tugger'winch located on the port side of the after deck. Mampaey supplied a quick release towing hook for secondary, or emergency use, and Karmoy Winch the capstan, aft, and the combined capstan and anchor windlass on the foredeck.

The new Knab was officially christened on the 1st of July and it is expected that its predecessor will be renamed and advertised for sale.