A bulk carrier or bulker is a
merchant ship
A merchant ship, merchant vessel, trading vessel, or merchantman is a watercraft that transports cargo or carries passengers for hire. This is in contrast to pleasure craft, which are used for personal recreation, and naval ships, which are u ...
specially
designed
A design is a plan or specification for the construction of an object or system or for the implementation of an activity or process or the result of that plan or specification in the form of a prototype, product, or process. The verb ''to design'' ...
to transport unpackaged
bulk cargo
Bulk cargo is commodity cargo that is transported unpackaged in large quantities.
Description
Bulk cargo refers to material in either liquid or granular, particulate form, as a mass of relatively small solids, such as petroleum/ crude oi ...
— such as
grains
A grain is a small, hard, dry fruit (caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legume ...
, coal,
ore
Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 April 2 ...
, steel coils, and cement — in its
cargo hold
120px, View of the hold of a container ship
A ship's hold or cargo hold is a space for carrying cargo in the ship's compartment.
Description
Cargo in holds may be either packaged in crates, bales, etc., or unpackaged (bulk cargo). Access to ho ...
s. Since the first specialized bulk carrier was built in 1852, economic forces have led to continued development of these ships, resulting in increased size and sophistication. Today's bulk carriers are specially designed to maximize capacity, safety, efficiency, and durability.
Today, bulk carriers make up 21 percent of the world's merchant fleets, and they range in size from single-hold mini-bulk carriers to mammoth ore ships able to carry 400,000
metric tons of deadweight (DWT). A number of specialized designs exist: some can unload their own cargo, some depend on port facilities for unloading, and some even package the cargo as it is loaded. Over half of all bulk carriers have Greek, Japanese, or Chinese owners, and more than a quarter are registered in
Panama
Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...
.
South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
is the largest single builder of bulk carriers, and 82 percent of these ships were built in Asia.
On bulk carriers, crews are involved in operation, management, and maintenance of the vessel, taking care of safety, navigation, maintenance, and cargo care, in accordance with international maritime legislation. Crews can range in size from three people on the smallest ships to over 30 on the largest.
Cargo loading operations vary in complexity, and loading and discharging of cargo can take several days. Bulk carriers can be gearless (dependent upon terminal equipment) or geared (having cranes integral to the vessel).
Bulk cargo can be very dense, corrosive, or abrasive. This can present safety problems that can threaten a ship: problems such as
cargo shifting
Cargo consists of bulk goods conveyed by water, air, or land. In economics, freight is cargo that is transported at a freight rate for commercial gain. ''Cargo'' was originally a shipload but now covers all types of freight, including transp ...
,
spontaneous combustion
Spontaneous combustion or spontaneous ignition is a type of combustion which occurs by self-heating (increase in temperature due to exothermic internal reactions), followed by thermal runaway (self heating which rapidly accelerates to high tem ...
, and cargo saturation. The use of old ships that have corrosion problems — as well as the bulk carriers' large hatchways — has been linked to a spate of bulk carrier sinkings in the 1990s. These large hatchways, important for efficient cargo handling, can allow the entry of large volumes of water in storms or if the ship is endangered by sinking. New international regulations have since been introduced to improve ship design and inspection and to streamline the process of a crew's abandoning ship.
Definition
![Bulk_carrier_midship_section-i18](https://upload.wikimedia.org/wikipedia/commons/f/f4/Bulk_carrier_midship_section-i18.svg)
The term bulk carrier has been defined in varying ways. As of 1999, the
International Convention for the Safety of Life at Sea
The International Convention for the Safety of Life at Sea (SOLAS) is an international maritime treaty that sets minimum safety standards in the construction, equipment and operation of merchant ships. The International Maritime Organization ...
defines a bulk carrier as "a ship constructed with a single deck, top side tanks and hopper side tanks in cargo spaces and intended to primarily carry dry cargo in bulk; an ore carrier; or a combination carrier."
Most
classification societies
A ship classification society or ship classification organisation is a non-governmental organization that establishes and maintains technical standards for the construction and operation of ships and offshore structures. Classification societies ...
use a broader definition, by which a bulk carrier is any ship that carries dry unpackaged goods.
Multipurpose cargo ships can carry bulk cargo, but can also carry other cargoes and are not specifically designed for bulk carriage. The term "dry bulk carrier" is used to distinguish bulk carriers from bulk liquid carriers such as
oil
An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...
,
chemical
A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wi ...
, or
liquefied petroleum gas carriers. Very small bulk carriers are almost indistinguishable from general cargo ships, and they are often classified based more on the ship's use than its design.
A number of abbreviations are used to describe bulk carriers. "
OBO
Obo is the capital of Haut-Mbomou, one of the 14 Prefectures of the Central African Republic, prefectures of the Central African Republic. It is close to the Pole of inaccessibility#Africa, African Pole of Inaccessibility.
Poste Airport is loca ...
" describes a bulk carrier that carries a combination of ore, bulk, and oil, and "O/O" is used for combination oil and ore carriers. The terms "VLOC", "VLBC", "ULOC", and "ULBC" for very large and ultra-large ore and bulk carriers were adapted from the
supertanker
An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk cargo, bulk transport of petroleum, oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quant ...
designations very large crude carrier and ultra-large crude carrier.
History
Before specialized bulk carriers were developed, shippers had two methods to move bulk goods by ship. In the first method,
longshoremen
A stevedore (), also called a longshoreman, a docker or a dockworker, is a waterfront manual laborer who is involved in loading and unloading ships, trucks, trains or airplanes.
After the shipping container revolution of the 1960s, the number o ...
loaded the cargo into sacks, stacked the sacks onto
pallet
A pallet (also called a skid) is a flat transport structure, which supports goods in a stable fashion while being lifted by a forklift, a pallet jack, a front loader, a jacking device, or an erect crane. A pallet is the structural foundat ...
s, and put the pallets into the cargo hold with a
crane.
The second method required the shipper to charter an entire ship and spend time and money to build plywood bins into the holds.
Then, to guide the cargo through the small hatches, wooden feeders and shifting boards had to be constructed.
[Hayler, 2003:5–13.] These methods were slow and
labor-intensive
Labor intensity is the relative proportion of labor (compared to capital) used in any given process. Its inverse is capital intensity.
Labor intensity has been declining since the onset of the Industrial Revolution in the late 1700s, while its inv ...
. As with the
container ship
A container ship (also called boxship or spelled containership) is a cargo ship that carries all of its load in truck-size intermodal containers, in a technique called containerization. Container ships are a common means of commercial intermodal ...
, the problem of efficient loading and unloading has driven the evolution of the bulk carrier.
![Bulk carrier ship view from top](https://upload.wikimedia.org/wikipedia/commons/3/3a/Bulk_carrier_ship_view_from_top.jpg)
Specialized bulk carriers began to appear as
steam-powered ships became more popular.
The first steam ship recognized as a bulk carrier was the British
collier ''
John Bowes John Bowes may refer to:
*John George Bowes (c. 1812–1864), Canadian politician
*John Bowes (art collector) (1811–1885), English art collector and thoroughbred racehorse owner
**John Bowes (steamship), ''John Bowes'' (steamship), 1852 steam coll ...
'', built in 1852.
[Bruno-Stéphane Duron, , mémoire de DESS, 1999.] She featured a metal
hull, a
steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be trans ...
, and a
ballasting system which used seawater instead of sandbags.
These features helped her succeed in the competitive British coal market.
The first
self-unloader
file:Bradley Unloading in Hopper 1958.jpg, SS Carl D. Bradley unloading hopper in 1958
A self-discharger (or self-unloader) is a ship that is able to discharge its cargo using its own gear. The most common discharge method for bulk cargo is to us ...
was the
lake freighter
Lake freighters, or lakers, are bulk carrier vessels that operate on the Great Lakes of North America. These vessels are traditionally called boats, although classified as ships.
Since the late 19th century, lakers have carried bulk cargoes of m ...
''Hennepin'' in 1902 on the
Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...
. This greatly decreased the unloading time of bulk carriers by using conveyor belt to move the cargo. The first bulk carriers with
diesel propulsion began to appear in 1911.
Before
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, the international shipping demand for bulk products was low—about 25 million tons for metal ores
[International Maritime Organization, 1999:1.]—and most of this trade was
coastal
The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in n ...
.
However, on the Great Lakes, bulk carriers hauled vast amounts of iron ore from Minnesota and Michigan's northern mines to the steel mills. In 1929, 73 million tons of iron ore was transported on the Lakes, and an almost equal amount of coal, limestone, and other products were also moved. Two defining characteristics of bulk carriers were already emerging: the
double bottom
A double hull is a ship Hull (watercraft), hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull ...
, which was adopted in 1890,
and the triangular structure of the ballast tanks, which was introduced in 1905.
After World War II, an international bulk trade began to develop among
industrialized nation
A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...
s, particularly between the European countries, the United States and Japan.
Due to the economics of this trade, ocean bulk carriers became larger and more specialized.
[International Maritime Organization, 1999: 1, 2.] In this period, Great Lakes freighters increased in size, to maximize economies of scale, and self-unloaders became more common to cut
turnaround time
Turnaround time (TAT) is the amount of time taken to complete a process or fulfill a request. The concept thus overlaps with lead time and can be contrasted with cycle time.
Meaning in computing
In computing, turnaround time is the total time t ...
. The thousand-footers of the Great Lakes fleets, built in the 1970s, were among the longest ships afloat, and, in 1979, a record 214 million tons of bulk cargo were moved on the Great Lakes.
Categories
Size categories
![Capesize bulk carrier at Suez Canal Bridge](https://upload.wikimedia.org/wikipedia/commons/f/fb/Capesize_bulk_carrier_at_Suez_Canal_Bridge.JPG)
Bulk carriers are segregated into six major size categories: small,
handysize
Handysize is a naval architecture term for smaller bulk carriers or oil tanker with deadweight of up to 50,000 tonnes, although there is no official definition in terms of exact tonnages. Handysize is also sometimes used to refer to the span of ...
,
handymax
Handymax and Supramax are naval architecture terms for the larger bulk carriers in the Handysize class. Handysize class consists of Supramax (50,000 to 60,000 DWT), Handymax (40,000 to 50,000 DWT), and Handy (<40,000 DWT). The ships are used for ...
,
panamax
Panamax and New Panamax (or Neopanamax) are terms for the size limits for ships travelling through the Panama Canal. The limits and requirements are published by the Panama Canal Authority (ACP) in a publication titled "Vessel Requirements". ...
,
capesize
Capesize ships are the largest dry cargo ships with ball mark dimension: about 170,000 DWT (deadweight tonnage) capacity, 290 m long, 45 m beam (wide), 18m draught (under water depth). They are too large to transit the Suez Canal ( Suezmax limi ...
, and very large.
[MAN Diesel Group, 2005, p. 3-4.] Very large bulk and ore carriers fall into the capesize category but are often considered separately.
Categories as per regions
Categories occur in
regional trade
Regional Integration is a process in which neighboring countries enter into an agreement in order to upgrade cooperation through common institutions and rules. The objectives of the agreement could range from economic to political to enviro ...
, such as Kamsarmax,
Seawaymax
The term Seawaymax refers to vessels which are the maximum size that can fit through the canal locks of the St. Lawrence Seaway, linking the inland Great Lakes of North America with the Atlantic Ocean.
Seawaymax vessels are in length, wide ...
, Setouchmax, Dunkirkmax, and Newcastlemax also appear in regional trade.
* "Kamsarmax" : Maximum
length overall
__NOTOC__
Length overall (LOA, o/a, o.a. or oa) is the maximum length of a vessel's hull measured parallel to the waterline. This length is important while docking the ship. It is the most commonly used way of expressing the size of a ship, an ...
229 meters refers to a new type of ships, larger than
panamax
Panamax and New Panamax (or Neopanamax) are terms for the size limits for ships travelling through the Panama Canal. The limits and requirements are published by the Panama Canal Authority (ACP) in a publication titled "Vessel Requirements". ...
, that are suitable for berthing at the
Port of Kamsar (
Republic of Guinea
Guinea ( ),, fuf, 𞤘𞤭𞤲𞤫, italic=no, Gine, wo, Gine, nqo, ߖߌ߬ߣߍ߫, bm, Gine officially the Republic of Guinea (french: République de Guinée), is a coastal country in West Africa
West Africa or Western Africa is t ...
), where the major loading terminal of
bauxite
Bauxite is a sedimentary rock with a relatively high aluminium content. It is the world's main source of aluminium and gallium. Bauxite consists mostly of the aluminium minerals gibbsite (Al(OH)3), boehmite (γ-AlO(OH)) and diaspore (α-AlO(O ...
is restricted to vessels not more than 229 meters.
* "Newcastlemax" : Maximum beam 50 meters, and maximum length overall of 300 meters Refers to the largest vessel able to enter the
port of Newcastle
The Port of Newcastle is a major seaport in the city of Newcastle, New South Wales, Australia. It is the world's largest coal port.
It is made up of facilities located at Port Hunter - Yohaaba in the Hunter River estuary. The port was the fir ...
, Australia at about 185,000 DWT
* "Setouchmax" : About 203,000
DWT, being the largest vessels able to navigate the
Setouchi Sea
The , sometimes shortened to the Inland Sea, is the body of water separating Honshū, Shikoku, and Kyūshū, three of the four main islands of Japan. It serves as a waterway connecting the Pacific Ocean to the Sea of Japan. It connects to Osaka ...
, Japan
* "Seawaymax" :
LOA
( ), also called loa or loi, are spirits in the African diasporic religion of Haitian Vodou. They have also been incorporated into some revivalist forms of Louisiana Voodoo. Many of the lwa derive their identities in part from deities venerate ...
226 m max / 7.92 m draft. Refers to the largest vessel that can pass through the canal locks of the
St. Lawrence Seaway (Great Lakes, Canada)
* "Malaccamax" : LOA 330 m / 20 m draft / 300,000 DWT, Refers to the largest vessel that can pass through the
Straits of Malacca
The Strait of Malacca is a narrow stretch of water, 500 mi (800 km) long and from 40 to 155 mi (65–250 km) wide, between the Malay Peninsula (Peninsular Malaysia) to the northeast and the Indonesian island of Sumatra to the southwest, connec ...
.
* "Dunkirkmax" : Maximum allowable
beam
Beam may refer to:
Streams of particles or energy
*Light beam, or beam of light, a directional projection of light energy
**Laser beam
*Particle beam, a stream of charged or neutral particles
**Charged particle beam, a spatially localized grou ...
= 45 m / LOA 289 m. max (175,000 DWT approx) for the eastern harbour
lock
Lock(s) may refer to:
Common meanings
*Lock and key, a mechanical device used to secure items of importance
*Lock (water navigation), a device for boats to transit between different levels of water, as in a canal
Arts and entertainment
* ''Lock ...
in the Port of
Dunkirk
Dunkirk (french: Dunkerque ; vls, label=French Flemish, Duunkerke; nl, Duinkerke(n) ; , ;) is a commune in the department of Nord in northern France.[river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...]
transport. They are often built to be able to pass under
bridge
A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...
s and have small crews of three to eight people.
Handysize and Handymax ships are general purpose in nature.
[Lamb, 2003.] These two segments represent 71% of all bulk carriers over and also have the highest rate of growth.
This is partly due to new regulations coming into effect which put greater constraints on the building of larger vessels.
Handymax ships are typically 150–200 m in length and 52,000 with five cargo holds and four cranes.
These ships are also general purpose in nature.
The size of a Panamax vessel is limited by the
Panama canal's lock chambers, which can accommodate ships with a beam of up to 32.31 m, a length overall of up to 294.13 m, and a draft of up to 12.04 m.
Capesize ships are too large to traverse the Panama canal and must round
Cape Horn
Cape Horn ( es, Cabo de Hornos, ) is the southernmost headland of the Tierra del Fuego archipelago of southern Chile, and is located on the small Hornos Island. Although not the most southerly point of South America (which are the Diego Ramírez ...
to travel between the Pacific and Atlantic oceans. Earlier, capesize ships could not traverse the
Suez
Suez ( ar, السويس '; ) is a seaport city (population of about 750,000 ) in north-eastern Egypt, located on the north coast of the Gulf of Suez (a branch of the Red Sea), near the southern terminus of the Suez Canal, having the same boun ...
and needed to go around the
Cape of Good Hope
The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa.
A common misconception is that the Cape of Good Hope is t ...
. Recent deepening of the Suez canal to 66 ft (20 m) permits most capesize ships to pass through it.
Capesize bulk carriers are specialized: 93% of their cargo is iron ore and coal.
Some ships on the
Great Lakes Waterway
The Great Lakes Waterway (GLW) is a system of natural channels and artificial canals which enable navigation between the North American Great Lakes. Though all of the lakes are naturally connected as a chain, water travel between the lakes was i ...
exceed Panamax dimensions but they are limited to use on the Great Lakes as they cannot pass through the smaller
St. Lawrence Seaway to the ocean. Very large ore carriers and very large bulk carriers are a subset of the capesize category reserved for vessels over .
Carriers of this size are almost always designed to carry iron ore.
In October 2022, Mitsui O.S.K. Lines (MOL)'s bulk carrier ''Shofu Maru'' arrived in
Newcastle Newcastle usually refers to:
*Newcastle upon Tyne, a city and metropolitan borough in Tyne and Wear, England
*Newcastle-under-Lyme, a town in Staffordshire, England
*Newcastle, New South Wales, a metropolitan area in Australia, named after Newcastle ...
on its maiden voyage, becoming the first bulk carrier to be partially powered by hard sail wind power propulsion technology. A five percent fuel savings was anticipated.
General types
Fleet characteristics
The world's bulk transport has reached immense proportions: in 2005, 1.7 billion metric tons of coal, iron ore, grain, bauxite, and phosphate was transported by ship.
[UNCTAD 2006, p.11.] Today, the world's bulk carrier fleet includes 6,225 ships of over 10,000 DWT, and represent 40% of all ships in terms of tonnage and 39.4% in terms of vessels.
[Office of Data and Economic Analysis, 2006:1.] Including smaller ships, bulk carriers have a total combined capacity of almost 346 million DWT.
[UNCTAD 2006, p. 21.] Combined carriers are a very small portion of the fleet, representing less than 3% of this capacity.
The
lake freighter
Lake freighters, or lakers, are bulk carrier vessels that operate on the Great Lakes of North America. These vessels are traditionally called boats, although classified as ships.
Since the late 19th century, lakers have carried bulk cargoes of m ...
s of the
Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...
, with 98 ships of 3.2 million total DWT, despite forming a small fraction of the total fleet by tonnage and only operating 10 months a year, carried a tenth of the world's bulk cargo because of the short trip distance and fast turnarounds.
As of 2005, the average bulk carrier was just over 13 years old.
About 41% of all bulk carriers were less than ten years old, 33% were over twenty years old, and the remaining 26% were between ten and twenty years of age.
[UNCTAD 2006, p. 23.] All of the 98 bulk carriers registered in the Great Lakes trade are over 20 years old and the oldest still sailing in 2009 was 106 years old.
[Office of Data and Economic Analysis, 2006:2.]
Flag states
As of 2005, the
United States Maritime Administration
The United States Maritime Administration (MARAD) is an agency of the United States Department of Transportation. MARAD administers financial programs to develop, promote, and operate the U.S. Maritime Service and the U.S. Merchant Marine. Det ...
counted 6,225 bulk carriers of or greater worldwide.
[Office of Data and Economic Analysis, 2006:6.] More bulk carriers are registered in
Panama
Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...
, with 1,703 ships, more than any four other
flag state
The flag state of a merchant vessel is the jurisdiction under whose laws the vessel is registered or licensed, and is deemed the nationality of the vessel. A merchant vessel must be registered and can only be registered in one jurisdiction, but ma ...
s combined.
In terms of the number of bulk carriers registered, the top five flag states also include
Hong Kong
Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China ( abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delt ...
with 492 ships, Malta (435), Cyprus (373), and China (371).
Panama also dominates bulk carrier registration in terms of
deadweight tonnage
Deadweight tonnage (also known as deadweight; abbreviated to DWT, D.W.T., d.w.t., or dwt) or tons deadweight (DWT) is a measure of how much weight a ship can carry. It is the sum of the weights of cargo, fuel, fresh water, ballast water, provi ...
. Positions two through five are held by Hong Kong, Greece, Malta, and Cyprus.
Largest fleets
Greece, Japan, and China are the top three owners of bulk carriers, with 1,326, 1,041, and 979 vessels respectively.
[Office of Data and Economic Analysis, 2006:4.] These three nations account for over 53% of the world's fleet.
Several companies have large private bulk carrier fleets. The multinational company
Gearbulk Holding Ltd. has over 70 bulk carriers.
The Fednav Group in Canada operates a fleet of over 80 bulk carriers, including two designed to work in Arctic ice.
Croatia
, image_flag = Flag of Croatia.svg
, image_coat = Coat of arms of Croatia.svg
, anthem = "Lijepa naša domovino"("Our Beautiful Homeland")
, image_map =
, map_caption =
, capit ...
's
Atlantska Plovidba d.d.
Atlantska plovidba d.d. is a Croatian shipping company.Atlantska Plovidba 2007, ''Welcome''. Founded in 1955 in Dubrovnik, the company works mostly in the dry bulk and heavy lift markets, serving both domestic and international clients
History ...
has a fleet of 14 bulk carriers. The
H. Vogemann Group
The H. Vogemann Group is a German shipping company. Founded in 1886, the company is privately owned by its managing partners and its fleet of bulk carriers has a capacity of more than .
The group consists of two companies: Bereederungsgesellscha ...
in
Hamburg, Germany
(male), (female) en, Hamburger(s),
Hamburgian(s)
, timezone1 = Central (CET)
, utc_offset1 = +1
, timezone1_DST = Central (CEST)
, utc_offset1_DST = +2
, postal ...
operates a fleet of 19 bulk carriers.
Portline
Portline Transportes Marítimos Internacionais, SA., often simply called Portline is a Portugal, Portuguese Ship transport, shipping company. The company has diverse business activities, including bulk cargo, dry bulk, containerization, containeri ...
in Portugal, owns 10 bulk carriers.
Dampskibsselskabet Torm
TORM based in Copenhagen, Denmark, is a shipping company that owns and operates product tankers. The Company's product tankers carry refined oil products such as gasoline, jet fuel, naphtha and diesel oil.
History
Torm was founded by Ditlev ...
in Denmark and Elcano in
Spain
, image_flag = Bandera de España.svg
, image_coat = Escudo de España (mazonado).svg
, national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond")
, national_anthem = (English: "Royal March")
, i ...
also own notable bulk carrier fleets. Other companies specialize in mini-bulk carrier operations: England's
Stephenson Clarke Shipping Limited
Stephenson Clarke Shipping Limited, established in 1730 is Great Britain's oldest shipping company. The company specializes in short sea bulk cargo such as aggregates, alumina, grain, coal, fertilizers and steel.
History
Reverend Ralph Clarke, ...
owns a fleet of eight mini-bulk carriers and five small Handysize bulk carriers, and
Cornships Management and Agency Inc.
Cornships Management and Agency Inc. was a Turkish shipping company.Cornships 2007, ''Home''. The company managed and provided agency services for the fleet owned and controlled by Corn Marine Ltd. of Malta. The company specialized in dry bulk c ...
in
Turkey
Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...
owns a fleet of seven mini-bulk carriers.
Builders
Asian companies dominate the construction of bulk carriers. Of the world's 6,225 bulk carriers, almost 62% were built in Japan
[Office of Data and Economic Analysis, 2006:5.] by shipyards such as
Oshima Shipbuilding
Oshima Shipbuilding Co., Ltd. is a privately held Japanese shipbuilding company. The company was founded on February 7, 1973, and began operations in June 1974. It is a joint venture between Sumitomo Corporation, Sumitomo Heavy Industries, a ...
and
Sanoyas Hishino Meisho
Sanoyas Hishino Meisho Corporation is a Japanese company that consists of four principal business groups and twelve affiliated companies.Sanoyas Hishino Meisho 2007, ''Groups''. The business groups are: the Ship and Steel Structure Group, the Park ...
.
South Korea, with notable shipyards
Daewoo
Daewoo ( ; Hangul: , Hanja: , ; literally "great universe" and a portmanteau of "dae" meaning great, and the given name of founder and chairman Kim Woo-choong) also known as the Daewoo Group, was a major South Korean chaebol (type of conglomerat ...
and
Hyundai Heavy Industries
Hyundai Heavy Industries Co., Ltd. (HHI; ) is the world's largest shipbuilding company and a major heavy equipment manufacturer. Its headquarters are in Ulsan, South Korea.
History
HHI was founded in 1972 by Chung Ju-yung as a division of the ...
,
ranked second among builders, with 643 ships. The People's Republic of China, with large shipyards such as Dalian, Chengxi, and Shanghai Waigaoqiao, ranked third, with 509 ships.
Taiwan
Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...
, with shipyards such as
China Shipbuilding Corporation
CSBC Corporation, Taiwan (, literally "Taiwan International Shipbuilding Corporation") is a company that produces ships for civilian and military use in Taiwan. It is headquartered in Kaohsiung, with shipyards in Kaohsiung and Keelung. It was ...
,
ranked fourth, accounting for 129 ships.
Shipyards in these top four countries built over 82% of the bulk carriers afloat.
Freight charges
![Baltic Shipping Rates](https://upload.wikimedia.org/wikipedia/commons/0/04/Baltic_Shipping_Rates.png)
Several factors affect the cost to move a bulk cargo by ship. The bulk freight market is very volatile, and it fluctuates, along with the type of cargo, the ship's size, and the route traveled all affect the final price. Moving a capesize load of coal from South America to Europe cost anywhere from $15 to $25 per ton in 2005.
Hauling a panamax-sized load of
aggregate materials from the
Gulf of Mexico
The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
to Japan that year could cost as little as $40 per ton to as much as $70 per ton.
Some shippers choose instead to
charter
A charter is the grant of authority or rights, stating that the granter formally recognizes the prerogative of the recipient to exercise the rights specified. It is implicit that the granter retains superiority (or sovereignty), and that the rec ...
a ship, paying a daily rate instead of a set price per ton.
In 2005, the average daily rate for a Handymax ship varied between $18,000$30,000.
A Panamax ship could be chartered for $20,000$50,000 per day, and a Capesize for $40,000$70,000 per day.
[UNCTAD 2005.]
Ship breaking
Generally, ships are removed from the fleet by going through a process known as
ship breaking
Ship-breaking (also known as ship recycling, ship demolition, ship dismantling, or ship cracking) is a type of ship disposal involving the breaking up of ships for either a source of parts, which can be sold for re-use, or for the extraction ...
or scrapping.
Ship-owner
A ship-owner is the owner of a merchant vessel (commercial ship) and is involved in the shipping industry. In the commercial sense of the term, a shipowner is someone who equips and exploits a ship, usually for delivering cargo at a certain freig ...
s and buyers negotiate scrap prices based on factors such as the ship's empty weight (called light ton displacement or LDT) and prices in the scrap metal market.
In 1998, almost 700 ships were scrapped in places like
Alang, India
Alang is a census town in Bhavnagar district in the Indian state of Gujarat. Because it is home to the Alang Ship Breaking Yard, Alang beaches are considered the world's largest ship graveyard.
Demographics
As of the 2001 Indian census, Alan ...
and
Chittagong, Bangladesh
Chittagong ( /ˈtʃɪt əˌɡɒŋ/ ''chit-uh-gong''; ctg, চিটাং; bn, চিটাগং), officially Chattogram ( bn, চট্টগ্রাম), is the second-largest city in Bangladesh after Dhaka and third largest city in B ...
.
This is often done by 'beaching' the ship on open sand, then cutting it apart by hand with gas torches, a dangerous operation that results in injuries and fatalities, as well as exposure to toxic materials such as asbestos, lead, and various chemicals. Half a million deadweight tons worth of bulk carriers were scrapped in 2004, accounting for 4.7% of the year's scrapping.
That year, bulk carriers fetched particularly high scrap prices, between $340 and $350 per LDT.
Operation
Crew
The crew on a bulk carrier typically consists of 20 to 30 people, though smaller ships can be handled by 8. The crew includes the captain or master, the
deck department
The deck department is an organisational team on board naval and merchant ships. The department and its manning requirements, including the responsibilities of each rank are regulated within the STCW Convention, applicable only to the merchant ...
, the
engine department
An engine department or engineering department is an organizational unit aboard a ship that is responsible for the operation, maintenance, and repair of the propulsion systems and the support systems for crew, passengers, and cargo.
These includ ...
, and the
steward's department
Seafaring is a tradition that encompasses a variety of professions and ranks. Each of these roles carries unique responsibilities that are integral to the successful operation of a seafaring vessel. A ship's crew can generally be divided into ''f ...
. The practice of taking
passenger
A passenger (also abbreviated as pax) is a person who travels in a vehicle, but does not bear any responsibility for the tasks required for that vehicle to arrive at its destination or otherwise operate the vehicle, and is not a steward. The ...
s aboard cargo ships, once almost universal, is very rare today and almost non-existent on bulk carriers.
During the 1990s, bulk carriers were involved in an alarming number of
shipwreck
A shipwreck is the wreckage of a ship that is located either beached on land or sunken to the bottom of a body of water. Shipwrecking may be intentional or unintentional. Angela Croome reported in January 1999 that there were approximately ...
s. This led ship-owners to commission a study seeking to explain the effect of various factors on the crew's effectiveness and competence.
The study showed that crew performance aboard bulk carriers was the lowest of all groups studied.
Among bulk carrier crews, the best performance was found aboard younger and larger ships.
Crews on better-maintained ships performed better, as did crews on ships where fewer languages were spoken.
Fewer
deck officer
The deck department is an organisational team on board naval and merchant ships. The department and its manning requirements, including the responsibilities of each rank are regulated within the STCW Convention, applicable only to the merchant ...
s are employed on bulk carriers than on similarly sized ships of other types.
A mini-bulk carrier carries two to three deck officers, while larger Handysize and Capesize bulk carriers carry four.
Liquid natural gas tankers of the same size have an additional deck officer and
unlicensed mariner.
Voyages
A bulk carrier's voyages are determined by market forces; routes and cargoes often vary. A ship may engage in the
grain trade
The grain trade refers to the local and international trade in cereals and other food grains such as wheat, barley, maize, and rice. Grain is an important trade item because it is easily stored and transported with limited spoilage, unlike other ...
during the
harvest
Harvesting is the process of gathering a ripe crop from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most labor-i ...
season and later move on to carry other cargoes or work on a different route. Aboard a
coastal carrier in the
tramp trade
A boat or ship engaged in the tramp trade is one which does not have a fixed schedule, itinerary nor published ports of call, and trades on the spot market as opposed to freight liners. A steamship engaged in the tramp trade is sometimes called ...
, the crew will often not know the next port of call until the cargo is fully loaded.
Because bulk cargo is so difficult to discharge, bulk carriers spend more time in port than other ships. A study of mini-bulk carriers found that it takes, on average, twice as much time to unload a ship as it does to load it.
A mini-bulk carrier spends 55 hours at a time in port, compared to 35 hours for a lumber carrier of similar size.
This time in port increases to 74 hours for Handymax and 120 hours for Panamax vessels.
Compared with the 12-hour turnarounds common for container ships, 15-hour turnarounds for car carriers, and 26-hour turnarounds for large tankers, bulk carrier crews have more opportunities to spend time ashore.
Loading and unloading
Loading and unloading a bulk carrier is time-consuming and dangerous. The process is planned by the ship's
chief mate
A chief mate (C/M) or chief officer, usually also synonymous with the first mate or first officer, is a licensed mariner and head of the deck department of a merchant ship. The chief mate is customarily a watchstander and is in charge of the shi ...
under the direct and continued supervision of ship's
captain
Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police department, election precinct, e ...
. International regulations require that the captain and terminal master agree on a detailed plan before operations begin.
Deck officer
The deck department is an organisational team on board naval and merchant ships. The department and its manning requirements, including the responsibilities of each rank are regulated within the STCW Convention, applicable only to the merchant ...
s and
stevedore
A stevedore (), also called a longshoreman, a docker or a dockworker, is a waterfront manual laborer who is involved in loading and unloading ships, trucks, trains or airplanes.
After the shipping container revolution of the 1960s, the number o ...
s oversee the operations. Occasionally loading errors are made that cause a ship to capsize or break in half at the pier.
The loading method used depends on both the cargo and the equipment available on the ship and on the dock. In the least advanced ports, cargo can be loaded with shovels or bags poured from the hatch cover. This system is being replaced with faster, less labor-intensive methods.
Double-articulation cranes, which can load at a rate of 1,000 tons per hour, represent a widely used method,
and the use of shore-based
gantry crane
A gantry crane is a crane built atop a gantry, which is a structure used to straddle an object or workspace. They can range from enormous "full" gantry cranes, capable of lifting some of the heaviest loads in the world, to small shop cranes, us ...
s, reaching 2,000 tons per hour, is growing.
A crane's discharge rate is limited by the bucket's capacity (from 6 to 40 tons) and by the speed at which the crane can take a load, deposit it at the terminal and return to take the next. For modern gantry cranes, the total time of the grab-deposit-return cycle is about 50 seconds.
Conveyor belts offer a very efficient method of loading, with standard loading rates varying between 100 and 700 tons per hour, although the most advanced ports can offer rates of 16,000 tons per hour.
[International Maritime Organization, 1999:7.] Start-up and shutdown procedures with conveyor belts, though, are complicated and require time to carry out.
Self-discharging ships use conveyor belts with load rates of around 1,000 tons per hour.
Once the cargo is discharged, the crew begins to clean the holds. This is particularly important if the next cargo is of a different type.
[Hayler, 2003:5–11.] The immense size of cargo holds and the tendency of cargoes to be physically irritating add to the difficulty of cleaning the holds. When the holds are clean, the process of loading begins.
It is crucial to keep the cargo level during loading in order to maintain stability.
As the hold is filled, machines such as
excavator
Excavators are heavy construction equipment consisting of a boom, dipper (or stick), bucket and cab on a rotating platform known as the "house". The house sits atop an undercarriage with tracks or wheels. They are a natural progression fro ...
s and
bulldozer
A bulldozer or dozer (also called a crawler) is a large, motorized machine equipped with a metal blade to the front for pushing material: soil, sand, snow, rubble, or rock during construction work. It travels most commonly on continuous track ...
s are often used to keep the cargo in check. Leveling is particularly important when the hold is only partly full, since cargo is more likely to shift. Extra precautions are taken, such as adding longitudinal divisions and securing wood atop the cargo.
If a hold is full, a technique called tomming is used,
which involves digging out a hole below the hatch cover and filling it with bagged cargo or weights.
Image:Bulldozer loaded on bulk carrier.jpg, 1. A bulldozer is loaded into the hold.
Image:Bulker-unload-sequence-2.jpg, 2. The bulldozer pushes cargo to the center of the hold.
Image:Velox cargo ship unloading rapeseed.jpg, 3. The gantry crane picks up the cargo.
Image:Bulker-unload-sequence-4.jpg, 4. The gantry crane removes the cargo from the ship.
Image:Grab unloaded into hopper.jpg, 5. The gantry crane moves the cargo to a bin on the pier.
Architecture
A bulk carrier's
design
A design is a plan or specification for the construction of an object or system or for the implementation of an activity or process or the result of that plan or specification in the form of a prototype, product, or process. The verb ''to design'' ...
is largely defined by the cargo it will carry. The cargo's density, also known as its
stowage factor, is the key factor. Densities for common bulk cargoes vary from 0.6 tons per cubic meter for light grains to 3 tons per cubic meter for iron ore.
The overall cargo weight is the limiting factor in the design of an ore carrier, since the cargo is so dense. Coal carriers, on the other hand, are limited by overall volume, since most bulk carriers can be completely filled with coal before reaching their maximum draft.
For a given tonnage, the second factor which governs the ship's dimensions is the size of the ports and
waterway
A waterway is any navigable body of water. Broad distinctions are useful to avoid ambiguity, and disambiguation will be of varying importance depending on the nuance of the equivalent word in other languages. A first distinction is necessary b ...
s it will travel to. For example, a vessel that will pass the Panama Canal will be limited in its
beam
Beam may refer to:
Streams of particles or energy
*Light beam, or beam of light, a directional projection of light energy
**Laser beam
*Particle beam, a stream of charged or neutral particles
**Charged particle beam, a spatially localized grou ...
and
draft
Draft, The Draft, or Draught may refer to:
Watercraft dimensions
* Draft (hull), the distance from waterline to keel of a vessel
* Draft (sail), degree of curvature in a sail
* Air draft, distance from waterline to the highest point on a vessel ...
. For most designs, the ratio of length-to-width ranges between 5 and 7, with an average of 6.2.
The ratio of length-to-height will be between 11 and 12.
Machinery
The
engine room
On a ship, the engine room (ER) is the compartment where the machinery for marine propulsion is located. To increase a vessel's safety and chances of surviving damage, the machinery necessary for the ship's operation may be segregated into vari ...
on a bulk carrier is usually near the
stern
The stern is the back or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite the bow, the foremost part of a ship. Ori ...
, under the
superstructure
A superstructure is an upward extension of an existing structure above a baseline. This term is applied to various kinds of physical structures such as buildings, bridges, or ships.
Aboard ships and large boats
On water craft, the superstruct ...
. Larger bulk carriers, from Handymax up, usually have a single
two-stroke
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a Thermodynamic power cycle, power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being comple ...
low-speed
crosshead
In mechanical engineering, a crosshead is a mechanical joint used as part of the slider-crank linkages of long reciprocating engines (either internal combustion or steam) and reciprocating compressors to eliminate sideways force on the piston. ...
diesel engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...
directly coupled to a fixed-pitch
propeller
A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...
. Electricity is produced by auxiliary
generators and/or an
alternator
An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.Go ...
coupled to the propeller shaft. On the smaller bulk carriers, one or two
four-stroke
A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directio ...
diesels are used to turn either a fixed or
controllable-pitch propeller via a reduction
gearbox
Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...
, which may also incorporate an output for an alternator.
The average design ship speed for bulk carriers of Handysize and above is .
The propeller speed is relatively low, at about 90 revolutions per minute, although it depends on the size of the propeller.
As a result of the
1973 oil crisis
The 1973 oil crisis or first oil crisis began in October 1973 when the members of the Organization of Arab Petroleum Exporting Countries (OAPEC), led by Saudi Arabia, proclaimed an oil embargo. The embargo was targeted at nations that had supp ...
, the
1979 energy crisis
The 1979 oil crisis, also known as the 1979 Oil Shock or Second Oil Crisis, was an energy crisis caused by a drop in oil production in the wake of the Iranian Revolution. Although the global oil supply only decreased by approximately four per ...
, and the resulting rise in oil prices, experimental designs using coal to fuel ships were tested in the late 1970s and early 1980s. The Australian National Lines (ANL) constructed two 74,700-ton coal-burner ships called ''River Boyne'' and ''River Embely''.
along with two constructed by TNT called ''TNT Capricornia'' and ''TNT Capentaria'' and renamed ''Fitzroy River'' and ''Endeavor River''. These ships were financially effective for the duration of their lives, and their
steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be trans ...
s were able to generate a shaft-power of .
This strategy gave an interesting advantage to carriers of
bauxite
Bauxite is a sedimentary rock with a relatively high aluminium content. It is the world's main source of aluminium and gallium. Bauxite consists mostly of the aluminium minerals gibbsite (Al(OH)3), boehmite (γ-AlO(OH)) and diaspore (α-AlO(O ...
and similar fuel cargoes, but suffered from poor engine yield compared to higher maintenance cost and efficient modern diesels, maintenance problems due to the supply of ungraded coal, and high initial costs.
Hatches
A hatch or hatchway is the opening at the top of a
cargo hold
120px, View of the hold of a container ship
A ship's hold or cargo hold is a space for carrying cargo in the ship's compartment.
Description
Cargo in holds may be either packaged in crates, bales, etc., or unpackaged (bulk cargo). Access to ho ...
. The mechanical devices which allow hatches to be opened and closed are called hatch cover. In general, hatch covers are between 45% and 60% of the ship's breadth, or beam, and 57% to 67% of the length of the holds.
To efficiently load and unload cargo, hatches must be large, but large hatches present structural problems. Hull stress is concentrated around the edges of the hatches, and these areas must be reinforced.
Often, hatch areas are reinforced by locally increasing the
scantling
Scantling is a measurement of prescribed size, dimensions, or cross sectional areas.
Shipping
In shipbuilding, the scantling refers to the collective dimensions of the framing (apart from the keel) to which planks or plates are attached to form th ...
s or by adding structural members called stiffeners. Both of these options have the undesired effect of adding weight to the ship.
As recently as the 1950s, hatches had wooden covers that would be broken apart and rebuilt by hand, rather than opened and closed. Newer vessels have hydraulic-operated metal hatch covers that can often be operated by one person.
Hatch covers can slide forwards, backwards, or to the side, lift up or fold up. It is essential that the hatch covers be watertight: unsealed hatches lead to accidental cargo hold flooding, which has caused many bulk carriers to sink.
Regulations regarding hatch covers have evolved since the investigation following the loss of the . The Load Line Conference of 1966 imposed a requirement that hatch covers be able to withstand load of 1.74 tons/m
2 due to sea water, and a minimum scantling of 6 mm for the tops of the hatch covers. The
International Association of Classification Societies
The International Association of Classification Societies (IACS) is a technically based non-governmental organization that currently consists of eleven member marine classification societies. More than 90% of the world's cargo-carrying ships’ to ...
then increased this strength standard by creating its ''Unified Requirement S21''
[International Association of Classification Societies 2007, p. 21-1.] in 1998. This standard requires that the pressure due to sea water be calculated as a function of freeboard and speed, especially for hatch covers located on the forward portion of the ship.
Hull
![CSL TECUMSEH](https://upload.wikimedia.org/wikipedia/commons/8/89/CSL_TECUMSEH.jpg)
Bulk carriers are designed to be easy to build and to store cargo efficiently. To facilitate
construction
Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and com ...
, bulk carriers are built with a single
hull curvature.
Also, while a
bulbous bow
A bulbous bow is a protruding bulb at the bow (or front) of a ship just below the waterline. The bulb modifies the way the water flows around the hull, reducing drag and thus increasing speed, range, fuel efficiency, and stability. Large ships ...
allows a ship to move more efficiently through the water, designers lean towards simple vertical bows on larger ships.
Full hulls, with large
block coefficient
A hull is the watertight body of a ship, boat, or flying boat. The hull may open at the top (such as a dinghy), or it may be fully or partially covered with a deck. Atop the deck may be a deckhouse and other superstructures, such as a funnel, d ...
s, are almost universal, and as a result, bulk carriers are inherently slow.
This is offset by their efficiency. Comparing a ship's carrying capacity in terms of deadweight tonnage to its weight when empty is one way to measure its efficiency.
A small Handymax ship can carry five times its weight.
In larger designs, this efficiency is even more pronounced: Capesize vessels can carry more than eight times their weight.
Bulk carriers have a cross-section typical of most merchant ships. The upper and lower corners of the hold are used as
ballast tank
A ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide hydrostatic stability for a vessel, to reduce or control buoyancy, as in a submarine, to correct trim or list, ...
s, as is the
double bottom
A double hull is a ship Hull (watercraft), hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull ...
area. The corner tanks are reinforced and serve another purpose besides controlling the ship's trim. Designers choose the angle of the corner tanks to be less than that of the
angle of repose
The angle of repose, or critical angle of repose, of a granular material is the steepest angle of descent or dip relative to the horizontal plane to which a material can be piled without slumping. At this angle, the material on the slope fac ...
of the anticipated cargoes.
This greatly reduces side-to-side movement, or "shifting," of cargo which can endanger the ship.
The double bottoms are also subject to design constraints. The primary concern is that they be high enough to allow the passage of pipes and cables. These areas must also be roomy enough to allow people safe access to perform surveys and maintenance. On the other hand, concerns of excess weight and wasted volume keep the double bottoms very tight spaces.
Bulk carrier hulls are made of steel, usually
mild steel
Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states:
* no minimum content is specified or required for chromium, cobalt ...
. Some manufacturers have preferred high-tensile steel recently in order to reduce the tare weight.
[International Maritime Organization, 1999:8.] However, the use of high-tensile steel for longitudinal and transverse reinforcements can reduce the hull's rigidity and resistance to corrosion.
Forged steel is used for some ship parts, such as the propeller shaft support.
Transverse partitions are made of
corrugated iron
Corrugated galvanised iron or steel, colloquially corrugated iron (near universal), wriggly tin (taken from UK military slang), pailing (in Caribbean English), corrugated sheet metal (in North America) and occasionally abbreviated CGI is a bu ...
, reinforced at the bottom and at connections.
The construction of bulk carrier hulls using a
concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
-steel sandwich has been investigated.
Double hull
A double hull is a ship hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is some dis ...
s have become popular in the past ten years.
Designing a vessel with double sides adds primarily to its breadth, since bulk carriers are already required to have
double bottom
A double hull is a ship Hull (watercraft), hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull ...
s. One of the advantages of the double hull is to make room to place all the structural elements in the sides, removing them from the
holds
A hold (abbreviated HLD, H or HD) is awarded to a relief pitcher who meets the following three conditions:
:1. Enters the game in a save (baseball), save situation; that is, when all of the following three conditions apply:
:: (a) He appears i ...
. This increases the volume of the holds, and simplifies their structure which helps in loading, unloading, and cleaning. Double sides also improve a ship's capacity for ballasting, which is useful when carrying light goods: the ship may have to increase its draft for stability or seakeeping reasons, which is done by adding ballast water.
A recent design, called Hy-Con, seeks to combine the strengths of single-hull and double-hull construction. Short for Hybrid Configuration, this design doubles the forward-most and rear-most holds and leaves the others single-hulled.
This approach increases the ship's solidity at key points, while reducing the overall tare weight.
Since the adoption of double hull has been more of an economic than a purely architectural decision, some argue that double-sided ships receive less comprehensive surveys and suffer more from hidden corrosion. In spite of opposition, double hulls became a requirement for Panamax and Capesize vessels in 2005.
Freighters are in continual danger of "breaking their backs"
[George, 2005:217.] and thus longitudinal strength is a primary architectural concern. A
naval architect This is the top category for all articles related to architecture and its practitioners.
{{Commons category, Architecture occupations
Design occupations
Architecture, Occupations ...
uses the correlation between longitudinal strength and a set of hull thicknesses called
scantling
Scantling is a measurement of prescribed size, dimensions, or cross sectional areas.
Shipping
In shipbuilding, the scantling refers to the collective dimensions of the framing (apart from the keel) to which planks or plates are attached to form th ...
s to manage problems of longitudinal strength and stresses. A ship's hull is composed of individual parts called ''members.''
[George, 2005:218.] The set of dimensions of these members is called the ship's scantlings.
Naval architects calculate the stresses a ship can be expected to be subjected to, add in safety factors, and then can calculate the required scantlings.
These analyses are conducted when traveling empty, loading and unloading, when partially and fully loaded, and under conditions of temporary overloading.
Places subject to the largest stresses are studied carefully, such as hold-bottoms, hatch-covers, bulkheads between holds, and the bottoms of ballast tanks.
Great Lakes bulk carriers also must be designed to withstand
springing Springing as a nautical term refers to global (vertical) resonant hull girder vibrations induced by continuous wave loading. When the global hull girder vibrations occur as a result of an impulsive wave loading, for example a wave slam at the bow ...
, or developing
resonance
Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillatin ...
with the
waves
Waves most often refers to:
*Waves, oscillations accompanied by a transfer of energy that travel through space or mass.
* Wind waves, surface waves that occur on the free surface of bodies of water.
Waves may also refer to:
Music
* Waves (ban ...
, which can cause
fatigue fractures.
Since 1 April 2006, the International Association of Classification Societies has adopted the ''Common Structural Rules.'' The rules apply to bulk carriers more than 90 meters in length and require that scantlings' calculations take into account items such as the effect of corrosion, the harsh conditions often found in the
North Atlantic
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe and ...
, and dynamic stresses during loading. The rules also establish margins for corrosion, from 0.5 to 0.9 mm.
Safety
The 1980s and 1990s were a very unsafe time for bulk carriers. Many bulk carriers sank during this time; 99 were lost between 1990 and 1997 alone.
Most of these sinkings were sudden and quick, making it impossible for the crew to escape: more than 650 sailors were lost during this same period.
Due partly to the sinking of , a series of international safety resolutions regarding bulk carriers were adopted during the 1990s.
Stability problems
Cargo shifting poses a great danger for bulk carriers. The problem is even more pronounced with grain cargoes, since grain settles during a voyage and creates extra space between the top of the cargo and the top of the hold.
Cargo is then free to move from one side of the ship to the other as the ship rolls. This can cause the ship to list, which, in turn, causes more cargo to shift. This kind of chain reaction can capsize a bulk carrier very quickly.
The 1960 SOLAS Convention sought to control this sort of problem.
[International Maritime Organization, 1999:2.] These regulations required the upper ballast tanks designed in a manner to prevent shifting. They also required cargoes to be leveled, or trimmed, using excavators in the holds.
[https://www.google.com/books/edition/Cargo_Handling_and_Stowage/Q1ofCwAAQBAJ?hl=en&gbpv=1&dq=%27trimming+of+cargo%22&pg=PA120&printsec=frontcover ''Cargo handling and stowage'' by Peter Grunau retrieved 8/9/21] The practice of trimming reduces the amount of the cargo's surface area in contact with air
[International Maritime Organization, 1999:4.] which has a useful side-effect: reducing the chances of spontaneous combustion in cargoes such as coal, iron, and metal shavings.
Another sort of risk that can affect dry cargoes is absorption of ambient moisture.
When very fine concretes and aggregates mix with water, the mud created at the bottom of the hold shifts easily and can produce a
free surface effect
The free surface effect is a mechanism which can cause a watercraft to become unstable and capsize.
It refers to the tendency of liquids — and of unbound aggregates of small solid objects, like seeds, gravel, or crushed ore, whose behavior ap ...
.
The only way to control these risks is by good ventilation practices and careful monitoring for the presence of water.
Structural problems
![Seledang Ayu](https://upload.wikimedia.org/wikipedia/commons/3/3d/Seledang_Ayu.jpeg)
In 1990 alone, 20 bulk carriers sank, taking with them 94 crewmen. In 1991, 24 bulk carriers sank, killing 154.
[International Maritime Organization, 1999:5.] This level of loss focused attention on the safety aspects of bulk carriers, and a great deal was learned. The
American Bureau of Shipping
American(s) may refer to:
* American, something of, from, or related to the United States of America, commonly known as the "United States" or "America"
** Americans, citizens and nationals of the United States of America
** American ancestry, pe ...
concluded that the losses were "directly traceable to failure of the cargo hold structure"
and
Lloyd's Register of Shipping
Lloyd's Register Group Limited (LR) is a technical and professional services organisation and a maritime classification society, wholly owned by the Lloyd’s Register Foundation, a UK charity dedicated to research and education in science and ...
added that the hull sides could not withstand "the combination of local corrosion, fatigue cracking and operational damage."
The accident studies showed a clear pattern:
# Sea water enters the forward hatch, due to a large wave, a poor seal, corrosion, etc.
# The extra water weight in hold number one compromises the partition to hold number two,
# Water enters hold number two and alters the trim so much that more water enters the holds
# With two holds rapidly filling with water, the bow submerges and the ship quickly sinks, leaving little time for the crew to react.
Previous practices had required ships to withstand the flooding of a single forward hold, but did not guard against situations where two holds would flood. The case where two after (rear) holds are flooded is no better, because the engine room is quickly flooded, leaving the ship without propulsion. If two holds in the middle of the ship are flooded, the stress on the hull can become so great that the ship snaps in two.
![Seledang Ayu 2](https://upload.wikimedia.org/wikipedia/commons/b/bc/Seledang_Ayu_2.jpeg)
Other contributing factors were identified:
* Most shipwrecks involved ships over 20 years in age. A glut of ships of this age occurred in the 1980s, caused by an overestimate of the growth of international trade. Rather than replace them prematurely, shipping companies were compelled on cost grounds to keep their aging vessels in service.
* Corrosion, due to a lack of maintenance, affected the seals of the hatch covers and the strength of the bulkheads which separate holds. The corrosion is difficult to detect due to the immense size of the surfaces involved.
[International Maritime Organization, 1999:5,6.]
* Advanced methods of loading were not foreseen when the ships were designed. While the new processes are more efficient, loading is more difficult to control (it can take over an hour just to halt the operation), occasionally resulting in overloading the ship. These unexpected shocks, over time, can damage the hull's structural integrity.
* Recent use of high-tensile steel allows building a structure with less material and weight while retaining similar strength. However, because it is thinner than regular steel, HT steel can corrode more easily, plus it can develop metal fatigue in choppy seas.
* According to Lloyd's Register, a principal cause of sinkings was the attitude of ship-owners, who sent ships with known problems to sea.
[International Maritime Organization, 1999:7,8.]
The new rules adopted in the 1997 annexes to the
SOLAS convention focused on problems such as reinforcing bulkheads and the longitudinal frame, more stringent inspections (with a particular focus on corrosion) and routine in-port inspections.
The 1997 additions also required bulk carriers with restrictions (for instance, forbidden from carrying certain types of cargoes) to mark their hulls with large, easy-to-see triangles.
Crew safety
![Rettungsboot2](https://upload.wikimedia.org/wikipedia/commons/0/03/Rettungsboot2.jpg)
Since December 2004, Panamax and Capesize bulk carriers have been required to carry free-fall
lifeboats
Lifeboat may refer to:
Rescue vessels
* Lifeboat (shipboard), a small craft aboard a ship to allow for emergency escape
* Lifeboat (rescue), a boat designed for sea rescues
* Airborne lifeboat, an air-dropped boat used to save downed airmen
A ...
located on the stern, behind the deckhouse.
This arrangement allows the crew to abandon ship quickly in case of a catastrophic emergency.
One argument against the use of free-fall lifeboats is that the evacuees require "some degree of physical mobility, even fitness" to enter and launch the boat.
Also, injuries have occurred during launches, for example, in the case of incorrectly secured safety belts.
In December 2002, Chapter XII of the SOLAS convention was amended to require the installation of high-level water alarms and monitoring systems on all bulk carriers. This safety measure quickly alerts watch standers on the bridge and in the engine room in case of flooding in the holds.
In cases of catastrophic flooding, these detectors could speed the process of abandoning ship.
See also
*
''Berge Stahl'', the largest bulk carrier from 1986 until 2011
*
''Bright Field''
*
''Edmund Fitzgerald''
*
''Flare''
*
''Lake Illawarra''
* ''
New Carissa
MV ''New Carissa'' was a freighter that ran aground on a beach near Coos Bay, Oregon, United States during a storm in February 1999 and broke apart. An attempt to tow the bow section of the ship out to sea failed when the tow line broke, ...
''
*
''Ore Brasil'', the largest bulk carrier in service
*
''Paul R. Tregurtha'', the largest bulk carrier on the
Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...
*
''Sygna''
Notes
References
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External links
Bulk Carriers @ United Nations Atlas of the OceansBulk Carriers at MRI Netherlands
{{DEFAULTSORT:Bulk Carrier
Ship types
1852 introductions