Pacific Maritime Magazine - Marine Business for the Operations Sector

By Jim Shaw 

Building Better Bulkers

 

Photo courtesy of HKFS

The 56,824-dwt bulk carrier Trans Summer was less than a year old when it went down off Hong Kong in 2013 while carrying a cargo of nickel ore between Indonesia and China.

A large number of bulk carriers have been delivered over the past several years and more are on the way as iron ore, coal and grain shipments increase. In the first four months of last year 186 new bulkers were ordered, nearly double the number ordered in the same period of 2012, and these ships will shortly begin to enter service. Compared to a previous generation of bulkers, the new ships are safer and more technologically efficient, and in many cases they have been cheaper to build, the result of extremely low construction prices in Asia.

After a large number of bulk carrier losses in the early 1990s, including 20 ships in 1990 and 24 more in 1991, stricter safety and structural regulations have seen stronger hulls developed, particularly in the forward section, where reinforced corrugated transverse bulkheads are now installed between cargo holds No.1 and No.2. Cargo hold No.1 is also given a strengthened double bottom to ensure watertight integrity can be maintained at all times, even when the ship is damaged. Because of the possibility of green water coming in over the deck during heavy weather, the forward hatch covers have also been reinforced and the integrity of fore-deck fittings strengthened. To monitor potentially dangerous conditions, water ingress and non-secured hatch cover alarms have been installed, and breakwater bulwarks have been added to many ships depending upon their deck configuration.

Bulk carriers are also being built with double skin side shell framing to ensure extra safety in the event of structural damage. For crewmembers, free-fall type lifeboats are now mandatory on all new bulkers and anti-piracy citadels are becoming the norm.

New Nickel Ore Carriers

Because of the sudden loss of four ships carrying nickel ore in 2010/11, followed by two more in 2012/13, a new type of bulker has been developed for this specific trade, with INTERCARGO now considering nickel ore to be "the world's most dangerous cargo." Designed and built in accordance with the IMO's International Maritime Solid Bulk Code (IMSBC), the newbuildings incorporate longitudinal bulkheads in their cargo holds to ensure stability and structural strength throughout. In addition, the IMSBC code now requires that the moisture content of cargoes that might liquefy during transit, such as nickel ore, be tested before loading, and it forbids non-specialized vessels from loading cargoes with moisture content greater than the specified transportable limit.

Japan's classification society, ClassNK, developed the hull structure and stability requirements used in the design and construction of the first of the new nickel ore carriers, the 27,200-dwt Jules Garnier II. The society based its design on the physical properties of nickel ore and its tendency to liquefy while in transit if its moisture content is too high. Built by Japan's Naikai Zosen Corporation, and owned by the JX Shipping Company, this 161-meter by 26-meter ship is now used to transport nickel ore from the island of New Caledonia in the South Pacific to various destinations worldwide.

Fuel-Efficient Handy-Size

Photo courtesy of Naikai Zosen

Named after the French geologist who first discovered nickel in New Caledonia, the 27,200-dwt Jules Garnier II has been specifically designed to handle nickel ore cargoes that might liquefy during transit.

Beyond their new safety features, modern bulk carriers are also becoming more fuel efficient and their exhaust emissions less toxic. Representative of this new breed of bulker is a series of handy-size ships being built for the China Navigation Company (CNco), the first of which, Wuchang, was recently delivered. Designed by Finland's Deltamarin, the 39,500-dwt vessels have five double-skin cargo holds, the tanktops of which have been specifically strengthened to take heavy cargoes. In addition, all holds have double-skin hydraulic folding hatch covers and forced draft ventilation fans. On deck are four centerline-mounted electric cranes, each rated at 30 tons at a maximum outreach of 26 meters and all "twinnable" for a combined lift of 60 tons.

The electric cranes are said to use up to 70 percent less power than standard type hydraulic cranes. Other features which help minimize fuel consumption on the new CNco vessels are the use of variable speed cooling pumps, low wattage lighting and improved thermal insulation.

The main engine, an electronically-controlled slow-speed Wartsilä 5RTFlex 50–B diesel, is rated at 6,050kW at 99rpm and features low-load tuning with a high-efficiency turbocharger, thus allowing it to meet the latest environmental emission standards. Refined hull lines, in addition to the use of special rudder and propeller, along with low resistance anti-fouling paint, helps give the CNco ships a daily fuel consumption at designed draft of less than 18 tons, including 15 percent sea margin.

 
 

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