GMCB bulks up
Grontmij Carl Bro’s (GMCB) series of Diamond bulk carriers continues to prove its popularity.
T
he task of creating a vessel that offers owners and charterers major operational cost savings
in maintenance and harbour turnaround time, while significantly enhancing safety and environmental protection, was initiated by GMCB with operational and regulatory input from Graig Group and Det Norske Veritas (DNV). The process resulted in the much-publicised Diamond 53 bulk carrier design. Te geared, wide hatched, 53,000dwt
Handymax bulk carrier has a high specification to address the concerns raised by IMO/IACS at the time it was designed regarding bulk carrier safety. Feedback from the first five vessels delivered from Chinese yards indicated efficient cargo operation and easy hold cleaning and manoeuvrability. In China, a total of 53 vessels have been ordered to date and 25 have been delivered. Last year GMCB, with Chengxi Shipyard and DNV, upgraded the design of the steel structure to meet the requirements of the new Common Structural Rules (CSR) for bulk carriers. Te first two Diamond 53 bulk carriers
were delivered from Vietnam last summer; one vessel by Vietnam’s Ha Long Shipyard and another by Nam Trieu Shipbuilding Industry Co. Vinashin is to build a further 27 Diamond 53s at Nam Trieu and Ha Long. Te deliveries of the two first vessels were somewhat delayed, but the delivery schedules are expected to improve. Based on the success of the Diamond
53 design, GMCB also designed a smaller 34,000dwt version, the Diamond 34. Te main dimensions of this Handysize shallow draught geared double-hull bulk carrier is a length overall of 180.00m, length bp 176.75m, max moulded breadth 30.00m, moulded depth 14.70m, scantling draught 9.75m, and design draught 9.00m. Te deadweight at design draught is 30,300tonnes. Te five cargo holds have a total capacity of 45,500m3 (grain) and are equipped with end-
The Naval Architect April 2008
CFD calculations of wave pattern for original hull lines (upper) and optimised hull lines (lower) for the Diamond 34.
folding hydraulically-operated hatch covers and four 30tonne deck cranes. Service speed is 14.0knots. In 2006 Graig Group contracted
four such vessels, with four options, at Vinashin’s Pha Rung shipyard with delivery dates beginning in mid 2008. Towards the end of the same year, GMCB signed a contract for delivery of design documentation for two plus two vessels for Shandong Baibuting Shipbuilding Co Ltd in China. Te delivery of the first ship is expected before the end of 2008. The hull shape of the Diamond 34
was developed together with FORCE Technology, and a number of different hull shapes were examined. Te tests and
simulations showed that a practically vertical stem without a bulb resulted in the smallest resistance and best propulsion efficiency and fuel economy. With the help of potential flow Shipflow CFD calculations prior to model testing, total resistance was reduced by some 2% from the original. Flowtech’s Chapman viscous flow programme was used to optimise the aftship. According to Tomas Eefsen at FORCE Technology, the Chapman soſtware is very efficient for evaluating the ship’s wake field, and is now commonly used in single-propeller projects. The calculations were later documented by model tests and by 3D wake measurements. NA
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Diamond 34, the latest bulk carrier design by GMCB and Graig Group.
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