New Voith tractor from Sanmar

Sanmar Shipyard in Tuzla are now well established as builders of high quality towing vessels and also becoming well-known for exploring areas of innovation and breaking new ground. They built the world’s first LNG-fuelled tugs and are now exclusively offering a new Robert Allan design VectRA 3000 tug powered by Voith technology. A particular set of requirements were specified in the design brief including, a VSP tug under 500grt incorporating high-speed engines, electronic controls and fully MLC 2006 compliant for all crew accommodation. The challenges were focused therefore on machinery design and overall layout.

Robert Allan used their existing range of AVT tugs as a baseline reference but as each new design is tailored to the specific application, the hull form was developed to reflect latest experience from extensive CFD hull performance modelling. The VectRA 3000 is therefore being offered as one of Sanmar’s standard vessels with a length of 30.25m, moulded beam of 13m and a draught of 6m. Delivered bollard pull will be up to 70t and top speed not less than 12.5 knots.

The unique aspect of the design is the propulsion arrangement. Two Voith type 32-R5 250 cycloid propellers are situated forward, each powered by a Caterpillar 3516C high-speed diesel developing 5,050kW (total) at 1,800rpm. Rather than adopting the traditional Voith coupling, the engines are connected to the propulsion units through a pair of Reintjes WAF 843 clutch and reduction gearboxes. Transmission loss is reduced, increasing overall efficiency while also allowing the drives to be de-clutched at idle, significantly reducing fuel burn. Space, and in turn weight savings are gained by using high-speed engines allowing for a finer, more efficient hull form on the same deadweight.

The new electronic Voith Remote Control system is included, set up to work in combinator mode whereby both RPM and pitch increase together at a pre-defined ‘ramp up’. It is believed this is the first installation of high speed engines with VSP drives in conjunction with the Voith Electronic Control System.

The flush deck layout is relatively conventional for a Voith Tractor, but to comply with Maritime Labour Convention 2006 all accommodation is on the main deck providing two single and two double cabins all en-suite. A DMT Type TWE250kN frequency-controlled electric drive double drum towing winch is included carrying 700m of 54mm wire rope and 240m of 58mm synthetic rope. Electric power will be provided by two 86ekW Caterpillar C 4.4 generator sets.

The VectRA 3000 design will be classed by ABS with the notation *A1, *AMS, Towage Vessel, ABCU, Unrestricted Service, Fi-Fi1, HAB(W8), UWILD.

By Peter Barker