Hidrovias project taking shape: Unique Canadian designs for push boats and barges for the Rio Parana/Rio Paraguay waterway
February 28, 2014
The last two months of 2013 saw the first vessels for the massive Hidrovias do Brasil project taking shape. This project will ultimately see a large fleet of push boats and barges in service, moving iron ore from Vale’s Corumba mine, in SW Brasil, 2,500 km to tidewater near Buenos Aires. The Hidrovias contract calls for the construction and operation of 8 powerful river push boats and 144 hopper barges. The barges will be operated in 4 x 4 convoys of 16 (Figure 1) to transport the iron ore in lots of approximately 40,000 tonnes per shipment down the waterway, as illustrated in Figure 2. The operation will be a 24 hours per day, 11 months per year operation with minimum downtime.
This fleet of highly specialized push boats and barges have all been designed by Robert Allan Ltd. of Vancouver, Canada, building on that company’s extensive experience designing extreme shallow draft vessels for the Canadian northland.
The barges, each measuring 61 m x 15 m x 4.27 m, are conventional hopper Mississippi style barges, designed to maximum allowable convoy dimensions, and must carry the required 2500 t deadweight with limited draft due to restricted under keel clearance.
There is a combination of “box” shaped barges for mid-convoy and rake-ended barges for the ends. A rigorous design exercise was required in order to minimize the steel weight in the barge structure without sacrificing the strength required for this demanding service. Finding a shipyard with the capacity to build and deliver 128 barges in the required time frame was also a challenge, but investigations soon led to the extensive facilities of ZPMC in China. One of the major attractions of this facility, most noted for their extensive production of large container cranes, was the availability of their own semi-submersible ocean transporter fleet which could be used to deliver the barges. Figure 3 shows the first shipment of 32 barges arriving near Buenos Aires, ready for offloading. Robert Allan Ltd. provided construction overseeing services for the barge fleet on behalf of the Owners.
The last batch of barges will also deliver a 54 m x 25.2 m 1,600 MT floating dry dock, also built at ZPMC and designed by Robert Allan Ltd., for use by Hidrovias do Brasil in servicing their new fleet of push boats and barges.
An additional 16 barges are currently under local fabrication at CIE S.A. in Asuncion, Paraguay.
The push boats, designated as the RApide 4500 Class, are limited to 2.1 m draft in the dry season and 2.4 m in the wet season. The contract for construction of the eight push boats was awarded to Uzmar of Turkey, and the first two vessel of class are currently completing Owner acceptance trials (Figure 4).
The biggest challenge in the design of these vessels was the necessity to be able to stop the entire convoy in less than 2.5 flotilla lengths when operating fully laden and at full speed running downstream. Extensive analysis and testing was performed to ensure this capability, as well as developing a suitable hull form to meet the pushing, braking and manoeuvring requirements, while achieving the fuel capacity, draft restrictions and endurance required for the entire operation. Hull form optimization studies and fuel consumption analyses were performed, and Robert Allan Ltd. worked closely with major equipment vendors to ensure the optimum propulsion system. CFD analysis was performed to verify the fuel consumption model, optimize hull form and efficiency, and to verify the crash stop requirements (Figure 5). Further scale model testing at the Vienna Model Basin was conducted to verify the results of the CFD analysis.
These high-performance push boats, measuring 46.5 m x 16.5 m x 4 m, are propelled by a state of the art diesel-electric propulsion system, with three main diesel generator sets providing 3 x 1,710 ekW of power to 3 x 1,600 kW motors, each driving a Schottel SRP 1215 Z-drive with nozzle modified for shallow draft operation. The major electric components (AFE drives, propulsion motors, generators, etc.) are ABB components, supplied by Elkon, while the generator engines are three Wärtsilä 9L20, medium speed engines, each producing 1,800 bkW at 1,000 rpm.
These push boats will run on HFO, with the ability to operate on MDO if needed. Each push boat has a total fuel capacity of 500 m³ of HFO and 30 m³ of MDO, and a ballast capacity of 400 m³. The potable water capacity of 34 m³ is supplemented by two onboard flash evaporator units.
The vessel is outfitted for a maximum complement of 18 persons, with six single cabins and 6 double cabins spread over two deckhouse levels. Above a large wheelhouse with unobstructed 360° views allows operators excellent visibility of the barge convoy ahead as well as supervising barge connection work taking place on the raised forecastle deck.
On trials the push boat achieved bollard pull and free running speed values exceeded contract requirements and as might be expected, the manoeuvrability, with triple Z-drives was exceptional. It is expected, in the Q1/2014, the first two push boats will be loaded onto a heavy lift ship for the trans-Atlantic voyage to Uruguay. The other six push boats will follow, with all delivered to Uruguay by Q3/2015.
Ore movements will start in October 2014 to keep up with the global demand for iron ore.
For more information on this project or on any of the design and consulting services offered by Robert Allan Ltd., please contact us at email@example.com.