The Netherland-based agricultural merchant and processor Louis Dreyfus Company has embarked on a major tug and barge building programme involving seven pusher tugs and 64 jumbo hopper barges.
The customised Robert Allan Ltd (RAL) designed fleet of craft will transport bulk grain products on the Amazon river system and while this column has reported on similar pusher tug and barge projects for the region before, this particular order is notable for its scale.
The package involves: three RApide 4000-Z3 class pusher tugs (currently under construction at INACE shipyard in Fortaleza, Brazil), one RApide 2600-Z3 class pusher tug, three RApide 2000-Z2 class port-assist pusher tugs and no fewer than 64 hopper barges (currently in build at Estaleiro Rio Maguari in Belem, Brazil).
Transportation of bulk materials on the Amazon involves a complex set of considerations required to optimise the various routes with testing tidal and shallow-water conditions. For this order CFD simulations were used to optimise the hull shapes to minimise total hull resistance.
The Z-drives are fitted in customised tunnels designed to maximise flow and propulsion efficiency while remaining within draught limitations. The make-up of the possible combinations was designed around logistics modelling of the transport system for the desired routes influenced by operational draughts and cargo throughput at various river levels.
The vessels meet ABS and Brazilian flag requirements and highest standards of comfort and safety for crews. Following the standard configuration of positioning the tug behind the barges, maximum visibility is provided all-round from the wheelhouse, a split forward console providing unobstructed views of the foredeck working area and barge convoy ahead.
IN DETAIL
With the number of potential permutations possible from the combination of vessels, it is worth looking at the details as presented by RAL. The largest of the three tugs, the ‘mainline’ RApide 4000-Z3 will push convoys of sixteen barges transporting the equivalent of up to 1,400 double-trailer trucks.
Accommodation including large mess and galley for up to 18 people is contained in the deck house which extends aft over the main propulsion equipment. Power is provided by three Wärtsilä 8L20 engines capable of operating on heavy fuel oil, in turn driving Schottel SRP 1215 Z-drives. Two Caterpillar C18 diesel gensets are also provided in the vessel’s machinery space at main deck level.
Principle dimensions of the RApide 4000-Z3 class are: length overall 39.6m, beam moulded 18m, minimum operating draught 2.5m and maximum draught 3m.
Working downwards in size, the RApide 2600-Z3 is intended for pushing smaller convoys and providing assistance to larger convoys in shallow waters. Propulsion for these examples is provided by three Caterpillar C18 main engines, each driving Schottel SRP 330 Z-drive units. Auxiliary machinery is again from Caterpillar in the form of two C4.4 diesel gensets.
Principle dimensions include a length overall of 25.6m and a moulded beam of 10.5m. Minimum and maximum operating draughts are 2.1m and 2.3m respectively and accommodation is provided for 12 persons.
The smallest of the trio of pushers, of which three will be built, is the RApide 2000-Z2. Described as being ‘nimble’ they will provide assistance at the loading and unloading ports and escort convoys through restricted regions. Where the larger versions have three propulsion units, these are each propelled by two Schottel SRP 330 Z-drive units, powered by Caterpillar C18 diesel engines. Two Caterpillar C4.4 gensets complete the machinery installation.
These final three being considered come in at 19.5m length overall on a moulded beam of 9m with a minimum operating draught of 2.2m and 2.5m maximum. Accommodation is provided for 10 persons.
Completing the order, the 64 box and rake barges will be built to ABS River Rule requirements. FEA analysis was used to optimise the design for minimum steel weight while ensuring long service life. Sliding aluminium hatch covers on the 61m long barges ensure the cargo remains dry at all times.
By Peter Barker
