Page 28: of Marine News Magazine (April 2014)

months of the year. ?These boats are among the  rst to be speci cally de- signed for the challenges of this particular river system,? said Mike Fitzpatrick, vice president at Robert Allan. ?There are 40 or so push boats [currently] operating on the Paraguay Paraná, and up until last year, they were all pretty much hand-me-downs from the Mississippi River. They?re 30 or 40-year-old push boats purchased in the States and transported down to the river, typically too deep for the Paraguay Paraná. They work, but only during certain por- tions of the year and in certain portions of the river. A Mississippi boat is too deep; it doesn?t have enough fuel capacity, and generally doesn?t have enough crew accom- modation. They?re not ideal for the river system.? Looking to forgo the limitations of existing Paraná  eet, RA generated a design geared for the river on which they?d operate. ?The goal was to design vessels that were opti- mized for the required service on the Paraguay Paraná,? Fitzpatrick said, ?which means fuel capacity for a range of 5,000 kilometers, accommodation for upwards of 16 people, and relatively shallow draft.? Fitzpatrick said the concept for the vessels was in the works as far back as 2005 when the Corumba mine was owned by the U.K.-headquartered mining company Rio Tinto, who would own and operate the vessels themselves. Contracts were in place to build the push boats at ship- yards in Brazil, Chile and China, with barge construction contracts in Paraguay, Argentina and China, when the  -nancial crisis of 2008 caused the project to be scrapped, and the mine was then sold to Brazilian mining corpora- tion Vale. Vale sat on the project for a few years until it eventually decided the time was right to award operational contracts. That?s when Hidrovias do Brasil entered the pic- ture, working with RA to present a design for Vale. The highly specialized  eet is to be built entirely in Tur- key?s Uzmar Shipyard, known as the ?workboat and tug factory.? The  rst two vessels for Hidrovias do Brasil were transported from Turkey to Uraguay via semi-submergible heavylift vessels were delivered in early March 2014 and are currently undergoing owner acceptance trials, with the remaining six vessels expected for delivery by the third quarter of 2015. Special Features The vessels are propelled by a diesel-electric propulsion system, which is helpful to improving operational ef cien-cy in a few important areas. An electric azimuth drive will provide a better option than a conventional six-shaft pro- peller boat in terms of maneuverability and speed and also allows for a shallower draft (2.1 meters). But according to Fitzpatrick, ?The primary technical, operational reason for going diesel-electric was to ensure a safe crash stop.? ?The biggest reason for azimuthing drives,? Fitzpatrick explained, ?is the requirement on the river that the vessel be able to stop in 2.5 convoy lengths, which is about 700 meters. Up until some point probably about two years ago, that regulation was somewhat loosely de ned as just being able to stop in 2.5 convoy lengths, but it didn?t stipulate under what conditions, so people were doing that slightly loaded,  at water, going up river. About two years ago, the Brazilian authorities clari ed the requirement to say that the crash stop has to happen from a fully loaded condition going down river at full speed, and they have to be able to stop not just relative to the water, but over ground.? Fitzpatrick continued, ?This is a very challenging re- quirement, and ultimately it has driven the installed power and the propulsion equipment. With azimithic drives, 100 percent of our ahead thrust we can also get astern, where with conventional propellers you?re only going to get 50 percent astern thrust.? INLAND DESIGNSFirst of class HB Hydra on trials in Turkey. CFD image of crash stop simulationApril 201428 MNMN April14 Layout 18-31.indd 28MN April14 Layout 18-31.indd 283/20/2014 11:50:14 AM3/20/2014 11:50:14 AM