The initial design was based on a 13m harbour tug produced previously for Perth Harbour and fitted with a conventional Mampaey tow hook. After witnessing demonstrations in the Netherlands using Mampaey’s ‘manned’ working model ‘Mariette’ both Macduff and Peterhead Port Authority were convinced that the new tug would benefit greatly from fitting the DOT system.

The DOT system makes towing at low and higher speeds safe and controlled and when towing sideways the tug cannot capsize. Optimal balance is achieved by the oval shape and minimises the need of propulsion power to control the tug. Significant improvement is offered in ship assistance and improvements in crew and vessels safety. The system consists of an oval shaped rail integrated in the ships’ structure with free moving carriages on the rail supporting the towing hook.

The basic MacDuff tug design was entirely suitable and working in close cooperation with Mampaey subtle changes were made to the layout and hull form to optimise it for operation with the DOT system. The oval ring was positioned in the ideal longitudinal position, paying particular attention to the hull form aft to enhance handling whilst running astern. Peterhead’s new tug will be a truly multi-purpose vessel, equipped to tow, plough-dredge, carry out pilotage duties and general harbour services using its hydraulic crane.

MacDuff will complete the new vessel to meet the requirements of the UK MCA Workboat Code Category 3. With an overall length of 13.0m, beam of 5.4m, and draft (aft) of 2.3m, the twin screw vessel will have a bollard pull of 8.5 tons and service speed of 9 knots. Twin Scania DI12 main engines, rated at 350 bhp each will drive fixed pitch1,300mm diameter propellers via Twin Disc MGX 5114DC gearboxes with 4.59:1 reduction and equipped with quick shift transmission controls. Fixed nozzles and twin high performance aerofoil rudders will maximise thrust and manoeuvrability. A bow thruster will be installed to enhance handling even further.

The principle component of the DOT system, the oval ring, will be installed around the wheelhouse and carry a Mampaey quick release (disc type) towing hook with a safe working capacity of 15 tons. Other items of deck equipment will include a 5.7 tons/metre deck crane, and the ‘A’ frame and winch for plough dredging.

The vessel represents a significant investment for Peterhead Port Authority but it will give them a multi-functional ‘state of the art’ harbour tug capable of performing numerous tasks. Macduff Ship Design are currently working on a range of harbour tugs of to 25m in length incorporating the Mampaey DOT system and full details will be available at the forthcoming Seawork 2007 exhibition.