CONTENTSChapter 1 BULK CARRIERS PAST, PRESENT & FUTURE Evolution. Bulk Carrier Practice. Download as PDF, TXT or read online from Scribd.
BULKERS
Number of ships in %35 30 25 20 15 10 517%
6,263 ships Bulk Carrier Fleet May 2004 (Bulk carriers larger than 5,000 dwt)32% 24%
17%
9%
1%
0 Small Handysize Handymax Panamax Capesize VLBC Classes
MAN B&W Diesel A/S, Copenhagen, Propulsion Trends Denmark in Bulk Carriers
Propulsion Trends in Bulk Carriers
Page Introduction ............................................................................................... Market Development ................................................................................. Definition of a bulk carrier ........................................................................... Hull design of a bulk carrier ......................................................................... Bulk carrier sizes and classes ..................................................................... Bulk carrier market .................................................................................... Average Ship Particulars as a Function of Ship Size .............................. Average hull design factor, Fdes ................................................................... Average design ship speed, Vdes ................................................................. Ship speed V as a function of actual draught D ........................................... Propulsion Power Demand as a Function of Ship Size .......................... Average bulk carriers ................................................................................. Average bulk carriers with ice class notation ............................................... Propulsion Power Demand of Average Bulk Carriers as a Function of Ship Speed .................................................................... Small and Handysize bulk carriers ............................................................... Handymax and Panamax bulk carriers ........................................................ Capesize and VLBC bulk carriers ............................................................... Summary ................................................................................................... References ................................................................................................. 3 3 3 3 4 5 7 7 7 9 10 10 12
13 13 13 14 15 15
Propulsion Trends in Bulk Carriers
IntroductionBulk carriers, container vessels and tankers are the three largest groups of vessels within the merchant fleet and, with our papers on container vessels and tankers already published, this is the third in the series, Ref. [1] and Ref. [2]. The demand for raw materials like coal, steel, copper, etc., has increased considerably since the turn of the millennium, especially in consequence of globalisation and the great demand for raw materials in China, owing to the economic growth in this large country. This means that the Chinese industry, among others, is absorbing large quantities of iron ore and other bulk cargoes. This consequential higher demand for bulk transports, compared to the bulk supply, has caused a dramatic increase in freight rates. The bulk carrier market, therefore, is very attractive, which has caused a boost in newbuildings. The optimum propeller speed is changing as well, steadily becoming lower, because the larger the propeller diameter that can be used for a ship, the actual propeller speed and pertaining power requirement will be correspondingly lower, and the lower the propulsion power demand per ton bulk transported. These factors have an influence on which main engine type should be selected/installed as the prime mover, and also on the size of the bulk carrier to be built. The purpose of this paper dealing with bulk carrier sizes above 5,000 dwt, and based on an analysis of bulk carriers built/ ordered over the last seven years is to illustrate the latest ship particulars used for modern bulk carriers, and determine their impact on the propulsion power demand and main engine choice, using MAN B&W Diesels latest two-stroke engine programme as the basis. 4
Market DevelopmentDefinition of a bulk carrierIn dictionaries, a bulk cargo is defined as loose cargo that is loaded directly into a ships hold. Bulk cargo is thus a shipment such as oil, grain, ores, coal, cement, etc., or one which is not bundled, bottled, or otherwise packed, and which is loaded without counting or marking. A bulk carrier is therefore a ship in which the cargo is carried in bulk, rather than in barrels, bags, containers, etc., and is usually homogeneous and capable of being loaded by gravity. On the basis of the above definitions, there are two types of bulk carriers, the dry-bulk carrier and the wet-bulk carrier, the latter better known as tanker. This paper describes the dry-bulk carrier type, normally just known as bulk carrier or bulker. Bulk carriers were developed in the 1950s to carry large quantities of nonpacked commodities such as grain, coal, etc., in order to reduce transportation costs. As mentioned, bulk carriers are one of the three dominating merchant ship types together with tankers and container vessels. Today, bulk carriers comprise about one third of the world fleet in tonnage terms. The worlds, so far, largest bulk carrier is the M/V Berge Stahl with 365,000 dwt, built in 1986. This huge iron ore bulk carrier measures 343 m in overall length and has a breadth of 63.5 m, and scantling draught of 23.0 m. This ship is propelled by an 18,300 kW MAN B&W two-stroke main engine, type 7L90MCE, and has a service ship speed of 13.5 knots.
Hull design of a bulk carrierThe double hull design has for several years, for safety and environmental reasons, been required for new tankers of 5,000 dwt and above. However, for bulk carriers the standard design, since the 1960s, has been a single hull ship with a double bottom, i.e. a hull with single side shells. Therefore, when talking about single or double hull, the words side, skin or side shell are often used instead of hull. Studies have shown that the main cause of recorded bulk carrier losses is side shell damage, Ref. [3]. In principle, the application of double hull (skin) on bulk carriers, therefore, will increase the safety and reduce the number of bulk carrier losses. Today, only about 2% (2004) of the existing bulk carriers are born double sided. Besides the increased safety and the ability to better withstand collisions, the use of double skinned bulk carriers will give a more efficient cargo handling caused by the absence of hull frames and brackets protruding into the cargo holds, replaced by the smooth side of the inner hull. For safety reasons, IMO (International Maritime Organisation) and IACS (International Association of Classification Societies) are bringing in new regulations for implementation of water ingress alarms in cargo holds and forward spaces. They are also discussing the necessity of introducing regulations requiring double side shells for bulk carrier newbuildings longer than 150 m. Today, there may be operational or commercial reasons for some owners to choose a double skin design, but there is no present legislation requiring a mandatory double hull bulk carrier design. At the 78th session held in May
2004 in the Marine Safety Committee of IMO, the double hull proposal was actually rejected by the majority of the members. However, a number of shipyards and designers are already now offering double hull bulk carriers in order to meet the possible future demand, but also in order to obtain a more efficient cargo handling as required by some shipowners, especially when transporting e.g. the sticky coal or coke. Furthermore, it seems that the light weight of the double hull ship will be only slightly increased, if at all, because of the use of thinner steelBulk carrier type Small Overall ship length up to Handysize Scantling draught up to Handymax Overall ship length (re port facilities in Japan) Panamax Ship breadth equal to Overall ship length up to (re port facilities) Overall ship length up to (re canal lock chamber) Passing ship draught up to Capesize Breadth VLBC Very Large Bulk Carrier Overall ship length
plates. Of course, more welding needed for the double sides will increase the man-hours and, thereby, the price of the ship. Only a minor increase in propulsion power may be expected.
weight tonnage, which corresponds to the fully loaded deadweight at full summer saltwater draught (normally a density of 1.025 t/m3), also called the scantling draught of the ship. However, sometimes the deadweight tonnage used refers to the design draught, which is normally less than the scantling draught and equals the average loaded ship in service. Therefore, the deadweight tonnage that refers to the design draught which is used for design of the propulsion system is normally lower than the scantling draught based deadweight tonnage. The sizes of the bulk carriers described in this paper are based on the scantling draught and a seawater density of 1.025 t/m3 and mainly on the single hull design normally used as only 2% are of the double hull design. Depending on the deadweight tonnage and hull dimensions, bulk carriers can be divided into the following main groups or classes; however, there will be some overlapping into adjacent groups, see Fig. 1: Small Handysize Handymax Panamax Capesize VLBC < 10,000 dwt 10,000 35,000 dwt 35,000 55,000 dwt 60,000 80,000 dwt 80,000 200,000 dwt > 200,000 dwt
Bulk carrier sizes and classesThe deadweight of a ship is the carrying capacity in metric tons (1000 kg) including the weight of bunkers and other supplies necessary for the ships propulsion. The size of a bulk carrier will normally be stated as the maximum possible deadShip size (scantling) Up to 10,000 dwt
Dimensions approx 115 m
10,000 35,000 dwt ap
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