Damen subsidiary Van der Velden Marine Systems (VDVMS) has notched up two order successes supplying rudder systems for push tugs operating in Paraguay and the US.

Krimpen aan de Lek-based VDVMS has been manufacturing manoeuvring systems for fifty years and its first order to report involves a retractable flanking rudder and a conventional rudder system to two push tugs for operation on the Paraná river in Paraguay.

The tugs, named Herkules XVII and Herkules XVIII were built by Werkendam-based shipbuilder Veka Group for Imperial Shipping Paraguay S.A. and will operate in conjunction with up to 12 barges transporting mainly iron ore and agricultural products, each convoy with a lifting capacity of 35,000 tons and 290m in length.

Flanking rudders are often specified for inland tow boats, located forward of the propellers and providing manoeuvrability when running astern. They are only required for a small percentage of the working time of the tug however and when operating normally create drag and turbulence to the inflow of water to the propellers. By making them retractable these inefficiencies are eliminated resulting in fuel savings.

The rudders mentioned above are just part of a larger steering package supplied to the two vessels. The flanking rudders comprise two high-lift rudders and asymmetric steering gears and VDVMS also provide the main rudder system comprising three high-lift fishtail rudders with stainless steel reinforced leading edges.

The vessels have five independently operated hydraulic power packs, three for the main rudders and two to retract and operate the flanking rudders. All main rudders are operated independently and controlled by a VDVMS Triple SP2700 control panel with the flanking rudders operated by two separate panels. There is also a proprietary follow-up steering system to operate each rudder independently.

Elsewhere, VDVMS in conjunction with US representative Ships Machinery International Inc is providing a BARKE high-lift flap rudder system for a new Jones Act Articulated Tug-barge for coastwise service in the US. Sea Power is under construction at BAE Systems’ Jacksonville, Florida shipyard for owner Sea-Vista ATB I LLC and due for delivery later this year. The vessel uses a pin connector system between tug and barge and the former complies with under 90m rules of classification society ABS.

Tank tests proved this rudder system the most effective for such a vessel allowing enhanced manoeuvrability and directional stability with significant fuel savings forecast over the life of the vessel through its efficiencies. The installation comprises two independently controlled and operated hydrodynamic rudders with Independent Proportional Steering allowing the rudders to be actuated either independently or synchronised.

The progressively operating flap linkage system is contained in a fully enclosed grease-lubricated housing resulting in minimum wear on linkage components and eliminating problems from contact with floating objects.

By Peter Barker