MARCH 14, 2014 — A fleet of pusher tugs and barges is under construction in Brazilian shipyards for international agribusiness giant Louis Dreyfus Company. Designed by Robert Allan Ltd. of Vancouver, Canada, the shallow draft vessels are slated for delivery this year and will transport bulk grain products on the Amazon River system.
The vessels include three RApide 4000-Z3 class mainline pusher tugs (under construction at the INACE shipyard), one RApide 2600-Z3 class pusher tug and three RApide 2000-Z2 class port-assist pusher tugs. Sixty-four jumbo hopper barges, also of Robert Allan design are under construction at Estaleiro Rio Maguari in Belem, Brazil)
In the early phases of design, extensive Computational Fluid Dynamics (CFD) simulations were used to optimize the hull shapes to minimize total convoy resistance. In all cases, the Z-drives are fitted in customized tunnels designed to optimize flow and propulsion efficiency while reducing draft. In conjunction, logistics modeling of the transportation system optimized the selection of vessels for the desired route and analyzed operational drafts and cargo throughput at various river levels. These studies aim to reduce the overall cost of transportation, while the design of the vessels increases the standards of safety, maneuverability and comfort in the river system.
All vessels are designed to meet ABS and Brazilian Flag State (NORMAM-02/DPC) requirements and provide the highest standards for crew comfort and safety. In each tug, the wheelhouse provides maximum all-round visibility with a split forward control station providing unobstructed vision to the foredeck working area as well as to the convoy of barges ahead.
Common equipment throughout the fleet will limit the number of spares required and ease with maintenance.
The 39.6 m x 18 m RApide 4000-Z3 class mainline pusher tugs are designed to at a normal draft of 3.0 m and a minimum operating draft of 2.5 m. They will drive convoys of sixteen barges, transporting the equivalent of up to 1,400 double trailer trucks (“B-Train”) in a single convoy, at a significantly reduced overall cost and environmental impact.
The RApide 4000-Z3 is the first of several new generation, high power, Z-drive pusher tugs designed by Robert Allan Ltd. for operation in this area and joins a number of smaller, modern Z-drive push boats already in service with other Brazilian operators. The RApide 4000-Z3 accommodates up to 18 people with a large galley and mess on the main deck. The deckhouse extends aft over the main propulsion equipment, which comprises three Wärtsilä 8L20 engines capable of operation on heavy fuel oil, driving Schottel SRP 1215 Z-drive units. Two Caterpillar C18 diesel gen-sets are also fitted in the vessel’s main machinery space at the main deck level, with an additional emergency/harbour gen-set located in a separate space.
The 25.6 m x 10.5 m RApide 2600-Z3 is designed for a normal operating draft of 2.3 m and minimum operating draft of 2.1 m and will be used to propel smaller convoys and to provide assistance to larger convoys in shallow water. Accommodating up to 12 people, the deckhouse extends aft over the main propulsion equipment, which comprises three Caterpillar C18 diesel engines, each driving a Schottel SRP 330 Z-drive unit. The vessel’s auxiliary machinery space, located below the main deck, hosts two Caterpillar C4.4 diesel gen-sets.
The 19.5 m x 9.0 m RApide 2000-Z2 is designed for a normal operating draft of 2.5 m and minimum operating draft of 2.2 m and will provide assistance at loading and unloading ports and escort convoys through restricted regions.. The deckhouse extends aft over two Schottel SRP 330 Z-drive units, each driven by a Caterpillar C18 diesel engine located below the main deck. Electrical power is supplied by two Caterpillar C4.4 diesel gen-sets. The outfitting includes accommodation for 10 crew.
Robert Allan Ltd. designed the corresponding box and rake barges to ABS River Rule requirements. Extensive FEA analysis of the structure was used to optimize the design for minimum steel weight while ensuring long service life during river operations. Sliding aluminum hatch covers ensure the cargo stays dry at all times.
Barge dimensions are: length overall: 61.0 m, beam, molded, extreme: 13.75 m, maximum operating draft: 4.5 m.