Bulk Carrier Ships
The global dry cargo market is served by numerous ships of all sizes, ranging from small coasters up to giant Very Large Ore Carriers (VLOC) capable of hauling a quarter of a million tonnes of iron ore. Currently, dry cargo ships are highly sophisticated, fuel-efficient, and cargo-friendly ships.
Some ships are highly specialized and able to transport only one type of cargo, other ships are flexible in design and able to transport numerous types of cargoes.
We will explain dry cargo ship types, their basic design, and their suitability for particular cargoes and businesses.
Bulk Carrier Ship Types
Some fundamental ship designs are adapted to enable the dry cargo ships to become involved in more than one business. Therefore, modern designs of certain multi-deck ships, originally designed to carry general cargoes, are also capable of carrying containers or, bulk cargoes, in addition to or instead of break-bulk cargoes.
Additionally, If these ships are fitted with high-capacity cranes or derricks, capable of safely lifting from shore to cargo hold and vice versa, these ships have ultimately another facility of advantage to the Ship Owners or Ship Operators. Some cargo ships are designed specifically for heavy project cargoes in mind. Therefore, ships with this cargo flexibility can intrude upon the specialized heavy-lift markets, in addition to the transportation of bagged and baled goods.
Some ships are designed to engage in specialist businesses such as the transportation of timber in cargo holds and on deck. On the other hand, some ships are designed to trade to certain geographical regions such as the Great Lakes. Some ships are designed to engage in both wet and dry markets such as Combination Carriers. Combination Carriers are furnished to transport cargoes of crude-oil or dry-bulk commodities, such as iron ore, coal, or grain.
The idea behind dry cargo ship design has changed dramatically since 1945. Nowadays, ships must be cargo-friendly primarily designed and fitted to speed cargo handling at loading and discharging ports within a minimum of time and with a minimum of shore labor but with the capacity of efficiently transporting the highest amount of freight earning cargo. The increasing cost of bunkers (fuel) has also meant that modern main engines have been developed to consume less during sea voyages than was once the issue. Furthermore, hull designs have been improved, such as the introduction of the bulbous bow. Developments are still taking place in both engine and hull design. Currently, ship design aims to lower carbon emissions. Ships are obliged under international conventions to minimize their polluting effect. Developed ports are furnished with sophisticated cargo-handling equipment, so naval architects have been required to incorporate modern port requirements into ship design, and to design larger ships, capable of maximizing revenues for the shipowners and of hauling commodities at the lowest unit costs.
Bulk Carrier Ship Types are divided into:
1- Bulk Carriers
2- General Cargo Ships
4- Ro-Ro Ships
5- Specialised Ships
6- Short-Sea Ships (Coaster Bulk Carrier Ships)
1- Bulk Carriers
All modern bulk carriers are mandated to be built with double hulls just as all modern tankers are. Single skin bulk carriers phased out. There are some advantages from double-hull design, not least a quicker discharge because cargo will not stick between the frames of the bulk carriers’ sides and a decline in mechanical damage driven by the practice of dislodging stuck cargo using cargo grabs as hammers and swinging them at the hull. Another change in modern bulk carriers’ design is the re-introduction of the forecastle which is the raised spot at the front of the bulk carriers.
Most modern deepsea bulk carriers up to panamax bulk carrier size are fitted with cranes. The majority of modern bulk carriers over panamax bulk carrier size and the majority of modern Short-Sea Ships (Coaster Bulk Carrier Ships) are gearless, having no cargo-handling equipment on board and reliant on onshore cranes to be loaded and discharged. As their name implies, bulk carriers are intended mainly for dry bulk cargoes, although bulk carriers can be adapted for the carriage of other cargoes.
Bulk Carrier Ship Sizes
Classification Size (DWT) Length (meters)
Coaster Bulk Carriers 1,000- 10,000 –
Handysize Bulk Carriers 10,000 – 39,999 <160
Handymax Bulk Carriers 40,000 – 59,000 <190
Panamax Bulk Carriers 60,000 – 99,999 <240
Capesize Bulk Carriers 100,000 – 199,999 <310
Very Large Ore Carriers (VLOC) 200,000 – 299,999 >310
Ultra Large Ore Carriers (ULOC) 300,000 – 399,999 >310
Chinamax (Valemax) >400,000 >310
Coaster Bulk Carriers (1,000-10,000 DWT): Coaster Bulk Carriers operate around coastlines, usually within the domestic seas. Coaster Bulk Carriers have shallow drafts, and cargo holds are is infrequently divided into different bulkheads. Coaster Bulk Carriers are important to coastline trading for countries, notoriously so when domestic seas cover an extensive geographical area.
Handysize Bulk Carriers (10,000-39,999 DWT): Handysize Bulk Carriers are the most versatile class of bulk carriers. Handysize Bulk Carriers operate for deep-sea trading. As the definition is not straightforward, Handysize Bulk Carriers can also comprise sub-categories Handymax, Supramax, Ultramax bulk carriers. Handysize Bulk Carriers have a shallower draft than other large bulk carriers. Most Handysize Bulk Carriers are equipped with cranes. Consequently, Handysize Bulk Carriers can operate in most ports and terminals. Most Handysize Bulk Carriers are built with five (5) Cargo Holds.
Handymax Bulk Carriers (40,000-59,999 DWT): Handymax Bulk Carriers are well-suited for small ports with length and draught limitations, or ports lacking transshipment infrastructure. Most Handymax Bulk Carriers are built with five (5) Cargo Holds and four (4) cranes of approximately 30 tonnes SWL (Safe Working Load).
Panamax Bulk Carriers (60,000-99,999 DWT): Panamax Bulk Carriers are built with a beam and draft suitable for limitations imposed by the old dimensions of the Panama Canal Locks. Panamax Bulk Carriers will still be the common vessel for coal and grain for years to come. Most Handysize Bulk Carriers are built with seven (7) Cargo Holds. The maximum ship dimensions allowed:
Length Width Draft
Panamax 294.13 m 32.31 m 12.04 m
Neo Panamax 366 m 51.25 m 15.2 m
Capesize Bulk Carriers (100,000-199,999 DWT): Capesize Bulk Carriers are unable to use the Panama Canal and Suez Canal, not necessarily for their tonnage, but because of their size. Capesize Bulk Carriers sail around Cape Horn or the Cape of Good Hope (COGH). Capesize Bulk Carriers operate remarkably deepwater terminals and predominantly carry iron ore and coal. There is a relatively small number of ports with the infrastructure to accommodate Capesize Bulk Carriers.
Very Large Ore Carriers (VLOC) (200,000-299,999 DWT) / Ultra Large Ore Carriers (ULOC) (300,000-399,999 DWT): VLOC/ULOC carry iron ore primarily between Brazil and China. Because of its tremendous size, there is only a small number of ports around the world with the infrastructure to accommodate Very Large Ore Carriers (VLOC) and Ultra Large Ore Carriers (ULOC).
Bulk Carrier Ship Sub-Classes
Supramax Bulk Carriers: (50,000-60,000 DWT): Supramax Bulk Carriers are strongly favored by charterers due to the larger cargo carrying capacities and cranes. Supramax Bulk Carriers operate in a considerably wider range of world ports and terminals. Most Supramax Bulk Carriers are built with five (5) Cargo Holds and four (4) cranes of approximately 30 tonnes SWL (Safe Working Load).
Ultramax Bulk Carriers: (60,000-65,000 DWT): Ultramax Bulk Carriers are the largest of the handy class bulk carriers. Ultramax Bulk Carriers are Supramax Bulk Carriers with a ship length 10 meters longer. Ultramax Bulk Carriers offer a better all-around investment for charterers and shipowners due to its higher cargo carrying capacity and better bunker (fuel) efficiency than Supramax Bulk Carriers. Ultramax Bulk Carriers are considered an upgrade over the Supramax Bulk Carriers. Ultramax Bulk Carriers are upsized Handymax and Supramax Bulk Carriers.
New Panamax Bulk Carriers (Neopanamax Bulk Carriers): Neopanamax Bulk Carriers are built with a beam and draft suitable for limitations imposed by the new dimensions of the Panama Canal Locks. Effective on 1 June 2018, with the new Panama Canal Locks, the new Panama Canal can handle ships up to LOA (Length Overall) of 366 meters, 51.25 meters beam, 15.2 meters draft. The New Panamax (Neopanamax) standard accommodates ships up to 120,000 DWT (Deadweight Tonnage).
Kamsarmax Bulk Carriers: Kamsarmax Bulk Carriers are Panamax Bulk Carriers of about 82,000 DWT (Deadweight Tonnage) and with increased length up to 229 meters. Kamsarmax Bulk Carriers’ name comes from the name of Port Kamsar (Equatorial Guinea). Kamsarmax Bulk Carriers’ dimensions are given by the limitations of Port Kamsar’s bauxite terminal.
Newcastlemax Bulk Carriers: Newcastlemax Bulk Carriers have a maximum beam of 50 meters and a length of 300 meters. Newcastlemax Bulk Carriers’ name is based on the largest bulk carrier that can operate in the terminal of the Port of Newcastle (Australia). Newcastlemax Bulk Carriers are ships of about 209,000 DWT (Deadweight Tonnage). Newcastlemax Bulk Carriers mainly carry iron ore between Australia and Asia.
Setouchmax Bulk Carriers: Setouchmax Bulk Carriers are the largest ships that can navigate the sea of Setouchi (Japan). Setouchmax expresses the maximum possible vessel size with which all appropriate ports of the Japanese Seto Inland Sea with its large number of iron ore and coal discharging ports can be reached. Setouchmax Bulk Carriers are up to slightly under 300 m long and have a maximum draft of 16.1 m and around 205,000 DWT (Deadweight Tonnage). Setouchmax Bulk Carriers belong to the main capesize category of bulk carriers.
Seawaymax Bulk Carriers (Lake-Fitted Bulk Carriers): Seawaymax Bulk Carriers with a maximum length of 226 meters and a maximum drought of 7.92 meters is the largest vessel that can pass through the St. Lawrence Seaway Canal (Great Lakes, Canada).
Malaccamax Bulk Carriers: Malaccamax Bulk Carriers with a maximum length of 330 meters, a maximum drought of 20 meters, and around 300,000 DWT (Deadweight Tonnage) refers to the maximum dimensions of the bulk carriers able to cross the Strait of Malacca.
Dunkirkmax Bulk Carriers: Dunkirkmax Bulk Carriers with a maximum length of 289 meters, a maximum beam of 45 meters, and around 175,000 DWT (Deadweight Tonnage) refers to the maximum dimensions of the bulk carriers able to operate in the eastern dock of the Port of Dunkirk (France).
Bulk Carriers’ Cargo Holds
Bulk carriers have a straightforward design, where the bridge, superstructure, and engine room are located aft in almost every case, leaving moderately unobstructed access to cargo hatchways. Most bulk carriers are built with Upper Wing Tanks (Topside Tanks). Upper Wing Tanks (Topside Tanks) provide self-trimming facilities on their underside.
Self-Trimming Bulk Carriers require sloping areas located fore and aft of the hatchway openings, as well as to port and starboard. Self-Trimming Bulk Carriers bypass the pricey shore labor and ensure that bulk cargo is safely trimmed (cargo fills extremities of the holds). Upper Wing Tanks (Topside Tanks) are used to carry ballast water when the ship is Laden (Empty) or Partly Laden (Party Empty) at sea. Most bulk carriers take ballast water to the tanks located forward (fore-peak tanks) and aft (after-peak tanks) and, possibly, floodable-holds (midship).
Some bulk cargoes are moderately light, such as grain, and therefore a ship’s hold can be filled before the ship comes down in the water to her permissible load-line marks. Small bulk carriers utilize the space in Upper Wing Tanks (Topside Tanks) for certain cargoes, such as grain, that are fairly free-flowing. Upper Wing Tanks (Topside Tanks) can be drained of ballast water, washed through, cleaned, and dried, the free-flowing cargo is then loaded into the empty tanks, which reduces the wasted deadweight capacity. At discharge ports, the free-flowing cargo is bled into the cargo hold directly beneath through openings that are sealed. This operation is called Bleeding Wing Tanks.
Some maritime experts dispute that there are no true Self-Trimming Bulk Carriers, and the expression is misleading. In truth, shipping professionals are completely aware of the limitations of Self-Trimming Bulk Carriers although, to be fair, there may be legal problems when using this expression, with some cargoes in rare circumstances giving rise to serious disagreements. Therefore, some shipowners prefer to utilize the less burdensome expression Easy-Trimmer when representing their bulk carriers.
In the bottoms of the Cargo Holds are tanktops covering double bottom tanks. Some bulk carriers have Lower Wing Tanks (Side Tanks). The upper sides of Lower Wing Tanks (Side Tanks) in the cargo hold give rise to the expression Hoppered Holds. Some bulk carriers are designed to have square-bottomed (flat hold floors), especially Con-Bulkers (Container-Bulk Carriers) are planned to serve in both the bulk cargo and container market sectors. Some bulk carriers, such as Colliers, are designed to have Hoppered Holds. Hoppered Holds assist the safe security of the bulk cargoes and minimize bulk cargoes movement at sea.
Bulk Cargo Stowage
Bulk cargoes can vary broadly in their stowing properties. For example, iron ore stows around 12 cubic feet for every metric tonne, whereas barley stows around 57 cubic feet per metric tonne. Apparently, in the cases of iron ore, total deadweight (DWT) will be reached with cargo holds little more than a third full, whilst a cargo of barley will fill cargo holds to capacity and the bulk carrier may theoretically be losing possible earnings because of shortage of space in cargo holds. For heavy commodities (low stowage cargoes), bulk carriers must be loaded so they do not become too stiff. Therefore, cargo is normally loaded in adjacent holds, for example, Holds 1, 3, 5 of supramax bulk carrier. Some bulk carriers are particularly hold-strengthened to carry heavy commodities (low stowage cargoes). Carrying cargo in adjacent holds with others empty is especially advantageous for loading or discharging at more than one port when carrying cargoes other than heavy ores.
Bulk Carrier Ships’ Cargo Gear
Some bulk carriers are furnished with discharging equipment and they are called Self-Discharging Bulk Carriers. Some bulk carriers carry their Cargo Grabs (Grab-Fitted Bulk Carriers). These Cargo Grabs can be fitted to the bulk carrier’s derricks or cranes and utilized to load/discharge cargo. Some bulk carriers are fitted with Gantry Crane. Gantry Crane is simply a traveling crane that moves longitudinally the length of a bulk carrier along a gantry rail.
Some Self-Discharging Bulk Carriers are fitted with a sophisticated discharging device that operates on a Conveyor Belt and/or Screw System (such as Siwertell System), loading being left to shore-based equipment. Generally, Conveyor Belt and/or Screw System (such as Siwertell System) fitted bulk carriers are tailored for a precise cargo type and business.
For big bulk carriers, ship’s gear is a substantial disadvantage. Therefore, most big bulk carriers such as panamax, capesize, VLOC (Very Large Ore Carriers) are Gearless. For big bulk carriers, businesses have evolved around sophisticated and speedy shore equipment which requires clear, unhindered access to cargo holds.
Bulk Carrier Ships’ Cargo Fittings
Most bulk carriers are not fitted with electric ventilation, but many have Fire-Smothering (CO2-Fitted Bulk Carriers) facilities serving cargo holds. Most bulk carriers are fitted with Steel Hydraulic Hatch-Covers, opening fore and aft on the majority of handysize bulk carriers. Most big bulk carriers are fitted with Side-Rolling Hatch-Covers. Side-Rolling Hatch-Covers open sideways when, in the open position Side-Rolling Hatch-Covers surround the deck between coamings and the bulk carrier’s rail, reinforced by a steel framework to allow bulk carrier’s crew members and shore workers to pass underneath when moving about the bulk carrier’s decks. Side-Rolling Hatch-Covers facilitate a greater open hatchway space to speed cargo handling.
Specialized Bulk Carrier Ships
Woodchip Carriers: Woodchip Carriers can be as large as 40,000-50,000 DWT (Deadweight Tonnage). Woodchip Carriers are developed for the carriage of high-stowing wood-chip products. Usually, Woodchip Carriers are unsuitable for the carriage of heavy, dense commodities such as iron ores. Regularly, Woodchip Carriers are chartered on regular operations from the West Coast of the United States (WCUS) and Canada to the Far East (FEAST). Principally, Woodchip Carriers have to steam a Ballast Leg (Return Trip) from discharging port.
Timber Carrier (Lumber Carrier): The purpose of the ship architect of a Timber Carrier (Lumber Carrier) is to create sufficient space in holds and on deck and hatch covers for the ultimate amount of this high-stowing cargo to be hauled. Timber Carriers (Lumber Carriers) have stanchions as the Loggers (Log Carriers). Nevertheless, in the construction of Timber Carrier (Lumber Carrier), the chains and tackles are of a lighter construction so as not to damage the timber (lumber) cargo. Shifting of timber (lumber) cargoes at sea is a risk. Stowing and securing the timber (lumber) cargoes must always be to the Ship Master’s complete satisfaction. Timber Carriers (Lumber Carriers) have unobstructed squarish holds and wide hatchways. When a full cargo of timber (lumber) is carried, certain regulations regarding load-lines are applied, which signifies that an optional lumber load-line (timber load-line) can be used, allowing deeper loading. With a full and secure timber (lumber) deck cargo, ship buoyancy, and inherent safety have improved, and the freeboard can be adjusted to improve cargo intake.
Logger (Log Carrier): Loggers are usually around 15,000-35,000 DWT (Deadweight Tonnage). Loggers are usually fitted with cranes around 25 tonnes SWL (Safe Working Load), capable of loading and supporting heavy logs. Furthermore, Logger (Log Carrier) can carry conventional bulk cargoes. Logs may also be loaded on the deck, secured by Stanchions (Stanchions-Fitted Bulk Carrier) alongside bulwarks, and by chains and securing tackle. There are two (2) types of Stanchions: Permanent Stanchions and Collapsible Stanchions. Collapsible Stanchions are along bulwarks adjacent to cargo hatches so Collapsible Stanchions can be lowered to lie horizontally on the deck and allow clear unhindered access between shore and hatchways. When a Logger (Log Carriers) is not equipped with steel stanchions, Temporary Wooden Stanchions are occasionally used by shaving down suitable logs from the cargo, to enable Temporary Wooden Stanchions to fit into Stanchion Sockets in the edge of the weather-deck adjacent to the bulwarks.
Ore-Carriers: Ore-Carriers have consolidated cargo spaces because Ore-Carriers are designed to carry heavy-dense mineral cargoes. Today, ore-carriers tend to be over 200,000 DWT DWT (Deadweight Tonnage) and the largest dry-cargo bulk carriers in the world are ore-carriers, such as Valemax 400,000 DWT (Deadweight Tonnage). Due to draft restrictions, most Ore-Carriers can operate at certain ports. Ore-Carriers are designed for precise cargo operations. Ore-Carriers are built with specially reinforced holds and tank-tops and with no need for self-trimming facilities.
Bulk Cement Carriers: Bulk Cement Carriers are built with sophisticated mechanical and pneumatic systems. Some Bulk Cement Carriers act as Mother Ship (Factory-Ship), off-loading from other bulk carriers and storing or even bagging bulk cement aboard. Formerly, Bulk Cement Carriers were converted from appropriately dimensioned bulk carriers. Usually, Bulk Cement Carriers operate on a certain trade route or are positioned in a certain area, to fulfill the cement demands of a nearby market. Furthermore, Ordinary Bulk Carriers can be readily adapted for the carriage of bulk cement or clinker by the cutting of Cement Holes (small holes on hatch covers) to facilitate loading and/or discharge without producing inappropriate dust pollution. Cement Holes must be approved by the Classification Society before the bulk carrier departs. Generally, Cement Holes are covered by a suitable Charter Party Clause that stipulates Charterers to reimburse the Shipowner for the expense of the hole-cutting and rewelding operation. Commonly, time used for hole-cutting and rewelding operation counts as laytime, if the bulk carrier is employed on a voyage basis.
2- General Cargo Ships
General Cargo Ships fulfill the same roles as their predecessors hundreds of years ago. General Cargo Ships adapt to international trades and carry miscellaneous cargoes. Nowadays, General Cargo Ships are called Multi-Purpose Ships (MPP).
General Cargo Ships were first mass-built in the mid of 19th century when the well-known 10,000 DWT (Deadweight Tonnage) Liberty-type ships were constructed. After WW2, Liberty-type ships were sold to shipowners. Liberty-type ships remained in popularity until the 1960s. Afterward, new designed General Cargo Ships, primarily the British SD14 and the American designed but Japanese made Freedom, as well as the German Liberty Replacement (the GLR), were introduced. Today, there remain a few old General Cargo Ships at sea with bridge and engines located amidships, modern General Cargo Ships have aft-superstructure, bridge, and engines, and with cargo-friendly, unobstructed hatchways and holds between these and the forecastle; and without the inconvenience of a shaft-tunnel wrapping a prolonged propeller shaft linking the midships main engine and the ship’s propeller. Shipbrokers still encounter Charter Party Clauses positioning the onus of damage to a shaft tunnel on the Shipowner, if that shaft tunnel is not sufficiently covered.
General Cargo Ships: Cargo Liners and Tramps
Multi-Purpose Ships (MPP) operating in the deep-sea markets tend to be relatively small by today’s benchmarks. Today, most Multi-Purpose Ships (MPP) are built around 10,000-25,000 (Deadweight Tonnage). General Cargo Ships operated on scheduled routes are usually more sophisticated and sometimes are built to custom-serve that operation, being termed, perhaps, Cargo-Liners. However, Cargo-Liners are diminishing in numbers. Usually, line-operators chartering-in conveniently positioned and priced tramp-ships from the chartering market.
General Cargo Ships and Liquid Cargoes
After the introduction of parcel tankers and containers, there is nowadays less demand for liquid cargoes to be transported in cargo-liners. However, there is improved demand for ships with holds and decks equipped for carrying several tiers of containers. Therefore, designs of Multi-Purpose Ships (MPP) and General Cargo Ships have been modified in recent years and these modifications may be clarified by examining miscellaneous aspects applicable and, in some cases, peculiar to these ships.
General Cargo Ships’ Holds
Modern General Cargo Ships are almost built with two decks and can therefore be termed Tweendeckers. Tweendeckers’ upper deck is called the main-deck (weather-deck) and the lower deck is called the tweendeck. Most Tweendeckers have just one tweendeck is built relatively closer to the main-deck (weather-deck) overhead than to the bottom of the cargo hold beneath. In other words, tweendeck is built about two-thirds up the height of the holds. Therefore, the cargo area enclosed between the tweendeck and the main-deck (weather-deck) is called the Tweendeck Space. The cargo area, the space beneath the tweendeck down to the bottom of the cargo area is called the Hold-space. Tweendeckers are appropriate for the carriage of bagged, baled, and drummed cargoes, the support of the tweendeck meaning that a high tier stowage of these cargoes can be safely accommodated. Conventional bulk carriers may lead to splitting of lower stowed bags or crumpling of drums due to the weight pressing down from above.
Most General Cargo Ships have a considerable number of separate cargo spaces which is another advantage when encountered with several cargoes to be transported at the same time. General Cargo Ships’ separate cargo spaces keep separated the cargoes from each other which avoids tainting by smell or enables loading and discharging at several ports during a voyage, without extra-handling of cargoes. Most Tweendeckers are designed for the carriage of bulk commodities and containers, in addition to traditional tweendeck-cargoes. Today, the Tweendeckers can more accurately be termed Multi-Purpose Ships (MPP).
The bottom of a cargo hold is not the bottom of a ship. Between the cargo hold and the ship’s bottom, there are miscellaneous tanks, planned to transport water ballast or bunkers. These tanks are called Double-Bottom Tanks. The top (ceiling) of the Double-Bottom Tanks forms the bottom of the cargo hold built directly above and, therefore, the top (ceiling) of the Double-Bottom Tanks are Tank-Tops.
General Cargo Ships’ Cargo Fittings
General Cargo Ships require built-in installations to handle safely a whole variety of cargoes, as well as gear to load, stow, secure and discharge cargoes. Most cargo holds are equipped with Fire-Smothering Equipment (CO2 Fitted-Ship) which are employed to prevent outbreaks of fire. Particular cargoes are prone to spontaneous combustion such as bagged fishmeal or easily combustible such as baled jute.
Some General Cargo Ships are equipped with Mechanical Ventilation or, more probably Electrical Ventilation in the cargo holds. Ventilation is practical, especially for cargoes that sweat heavily such as bagged rice.
Vintage Tweendeckers had Tweendeck Hatch Camings around tweendeck hatchways, planned as a safety component to protect the crew members operating in the tweendeck spaces from the risk of falling into the holds below. Nevertheless, with the introduction of forklifts that are employed to facilitate cargo handling, Tweendeck Hatch Camings have been virtually dispensed with, the Tweendeck Hatch Covers fitting level with the surrounding tweendeck floor and furnish a flat unobstructed area. Such General Cargo Ships, unobstructed by Tweendeck Hatch Coamings, are called Flush Tweendeckers.
Other obstructions likely in a tweendecker’s cargo holds are columns or pillars supporting overhead decks. It is important to examine the place of such obstructions before chartering in the Tweendecker.
Some Tweendeckers are equipped with Cargo-Battens. Cargo-Battens are strips of lumber (timber) fixed at intervals usually horizontally along the sides of holds. Cargo-Battens are developed to keep baled and bagged cargoes from being damaged by touching the sides of a vessel which are consistently wet through condensation and/or little seepage via tiny faults in the shell plates. Furthermore, Cargo-Battens boost ventilation and reduce damage from moisture or sweating. Nevertheless, Cargo-Battens are repeatedly damaged and have to be removed completely and stowed elsewhere when handling bulk cargoes. Cargo-Battens are costly to preserve in good condition and Cargo-Battens are labor-intensive to maintain repairing and remove. Nowadays, it is really rare to encounter General Cargo Ships fully fitted with Cargo-Battens. Instead of Cargo-Battens, Cargo-Nets might be utilized in General Cargo Ships. Commonly, cargo is protected when required by a combination of kraft paper and dunnage materials. Dunnage can be of miscellaneous materials. However, Dunnages are usually loose woods of miscellaneous types and sizes laid at the bottom of a cargo hold to preserve lower-stowed cargoes clear of bilge water and from blocking drainage, and also wedged between parts of the cargoes to keep the stow secure and safe. Traditionally, particular businesses utilize local materials as a Dunnage. For instance, Cargo-Mats and Bamboo are utilized as dunnage material for the export of bagged rice from South-East Asia.
It may also be required to secure some cargoes with Lashings. Lashing Pad-Eyes may be welded to tank-tops or cargo hold’s sides to furnish safe anchorages for the Lashing Material. Commonly, the expense and time of welding and removing Lashing Pad-Eyes are for the account of the Charterer, with Charter Party Clauses drafted accordingly. Additionally, if Lashing Pad-Eyes are not removed after the completion of cargo discharging operation, the Shipowner has to be compensated. Charter Party Clause may stipulate that the Shipowner has to ensure that crew members take care of Lashing Materials provided by the Charterers and hand them over to Charterers’ representatives in good condition at the end of the voyage.
Nowadays, General Cargo Ships are obliged to carry a Cargo Securing Manual which describes what Cargo Fittings are attached to the ship and Cargo Fittings’ loading limits. Extra Cargo Fittings can still be attached, however, Extra Cargo Fittings’ loading limits may have to be certified by a surveyor before Extra Cargo Fittings can be utilized. Furthermore, Cargo Securing Manual must incorporate details of Lashing Materials such as wire ropes, twist locks, shackles, and turnbuckles. The Lashing Materials list should be revised regularly and therefore deliver a proper reference for Charterers involved in disagreements over damage to Lashing Materials.
General Cargo Ships and Bulk Cargoes
Extra special fittings might be required for some General Cargo Ships before a bulk cargo can be hauled safely to protect against the cargo shifting dangerously when at sea. Most modern Multi-Purpose Ships (MPP) and Tweendeckers are planned to carry bulk cargoes without special cargo fittings. Some modern Multi-Purpose Ships (MPP) and Tweendeckers are fitted with permanent Partial Center-Line Bulkheads, preventing the sideways shift of cargo. Vintage General Cargo Ships engaging had temporary Wooden Center-Line Bulkheads before authorization would be delivered to sail. Generally, modern bulk carriers are fitted with Self-Trimming (Self-Trimmed Bulk Carriers) facilities for high stowing bulk cargoes.
General Cargo Ships and Containers
With the revolution in cargo handling, the design of General Cargo Ships has had to adapt and fit new approaches. Therefore, the cargo spaces of modern Multi-Purpose Ships (MPP) tend to be as square as is possible, to assist the stowage of containers and palletized-cargo, whilst on the weather-decks, contemporary ship designs allow for storage of containers, often two or more tiers high, taking into account the ship stability, visibility from the ship’s bridge, and deck strengths.
General Cargo Ships’ Ballast and Bilges
Vintage General Cargo Ships were designed to haul quantities of liquids such as palm oil. Vintage General Cargo Ships had little Deep-Tanks equipped with Heating Coils. Sometimes cargo holds are flooded to provide additional stability when the ship is in ballast or partly-laden condition may be termed Deep-Tanks, although it is more reasonable to refer to these cargo holds as Floodable-Holds to distinguish their purpose. Vintage General Cargo Ship SD14 had Floodable-Hold (Cargo-Hold No. 3). Some modern Multi-Purpose Ships (MPP) have been fitted with older-style Deep-Tanks, however, this business has been taken over almost entirely by Parcel-Tankers. After washing Cargo Holds, dirty water is drained away from the hold bottoms into bilges through strum-boxes which serve as filters and stop the solid subjects from clogging bilge pipes and damaging pumps. Before loading bulk commodities, these bilge openings might be purposefully covered over for identical grounds.
Shelter Decker (What is Shelter Decker?)
Shelter Decker term might be encountered predominantly in the Short-Sea Market (Coaster Market) sector. Shelter Decker refers to a ship design particularly adapted to overcome severe tonnage rules, by which ships could maximize cargo capacity and cargo intake, and therefore maximize revenues, yet limit the registered tonnage evaluated against the ships and therefore lower costs and liabilities which are based on the ship’s Registered Tonnage. By Shelter Decker designs, port costs, and crew numbers are reduced. The tonnage rules forming these innovative designs have long been modified and there is now no need for innovative naval architecture to overcome this legislation. However, the Shelter Decker term remains on in particular market sectors, and where the term Shelter Decker is used today it should be taken to indicate Tweendecker.
General Cargo Ships’ Cargo Gear
Derricks are fairly simple. Derricks are easy to rig and maintain. Furthermore, Derricks are reasonably inexpensive. There are three parts to a derrick:
- Vertical Supporting Pillar (Samson Post)
- Rigging (Wire Ropes, Blocks, and Tackles)
Derricks are operated by electrically or hydraulically driven winches. Cargo lifting equipment must be strictly and regularly inspected with certificates issued testifying to the SWL (Safe Working Load). Cargo lifting equipment inspections can be carried out by Classification Societies or by specific other internationally recognized authorities. Undoubtedly, Charter Party should incorporate a warranty by the Shipowner that a ship’s gear certificates are up to date and will remain so during the voyage or time-charter. Delinquency may cause shore employees to refuse to handle a ship or, worse, injury or death resulting from faulty or uncertificated gear. Furthermore, the shipowner may have to pay tremendous financial penalties.
Derricks Union Purchase
Derricks can be exceptionally versatile and adapt to certain businesses. Union Purchase is a technique of binding derrick booms to a particular rigging method, straightforward to operate and fast in operation so that cargoes can be moved speedily from shore to cargo hold, or vice versa. The difficulty with this technique is that once the rigging is set up it has to be changed to adjust the locations of lifting and setting down of each load. Therefore, cargo has to be moved to a precise position before lifting and taken away from another exact position at the end of each movement cycle. Therefore, Union Purchase is a labor-intensive technique. Union Purchase is convenient for the less-developed ports. Furthermore, the Union Purchase technique reduces the SWL (Safe Working Load). Union Purchase technique has its benefits for the discharge of bagged goods in less-developed areas. Where heavy cargoes are concerned, the Union Purchase technique is not the solution.
The winch arrangement of particular ships allows two parallel derricks to be linked together with two adjacent cargo winches in a technique termed Swinging Derricks. Swinging Derricks maintain the speed of operation of Union Purchase, however, enable liftings up to the maximum capacity of the smallest derrick or cargo winch involved, using in place of a third cargo winch a Deadman, a suspended deadweight on one line such as a mass of old wire, the purpose of which is merely to deliver tension. One winch is used to swing the boom from over the hatchway to the quayside, a second winch being used to swing the boom back to its initial position.
Self-Swinging Derrick or Crane-Derrick
Self-Swinging Derrick or Crane-Derrick is a single derrick system that operates in the identical technique as a crane, by operating only its own directly associated winches and therefore does not interfere with cargo-handling at adjacent hatchways. Commonly, Self-Swinging Derrick or Crane-Derrick is to be located in isolation at a hatchway and, just like a crane, is capable of incredibly fast operation by only one, a professional driver using a joystick control. A commercial example of a Self-Swinging Derrick or Crane-Derrick is the Velle Type.
Commonly, cargo derricks lift between 5 and 15 tonnes SWL (Safe Working Load), however, conventional-type derricks can be adapted for lifts of up to 50 tonnes SWL (Safe Working Load). Some general-cargo ships are fitted with Stulcken Derricks which, in some cases, can safely lift weights of up to 450 tonnes SWL (Safe Working Load), having the added advantage of operating two hatchways directly fore and aft of the location of its Samson Posts.
Naturally, when chartering General Cargo Ships or Multi-Purpose Ships (MPP), the location, SWL (Safe Working Load), and capabilities of the ship’s derricks may be of crucial matter, and the shipbroker should be completely familiar with the needs of the principal and can properly assess the ships cargo gear. For ship charter purposes, the term Double-Rigged indicates that two (2) derricks serve each hatchway.
Electrically Powered Cranes
Most modern Multi-Purpose Ships (MPP) are usually equipped with Electrically Powered Cranes. Electrically Powered Cranes have the advantage over most derricks of being more versatile and capable of accurately placing and picking up cargoes. Electrically Powered Cranes are more sophisticated and costly to maintain. Electrically Powered Cranes require more efficient handling than derricks. Cranes are self-contained in their units, not requiring supporting Samson Posts like Derricks. Customary lifting capacities of ship cranes range from 5 to 40 tonnes SWL (Safe Working Load). Most modern ships are built with higher capacity cranes, possibly having the structure to unite the lifting capacity of two adjacent cranes, thereby substantially boosting the maximum crane capacity. Most new-building bulk carriers are equipped with cranes of around 25 to 60 tonnes SWL (Safe Working Load). Derricks are still being used to deliver a heavy-lift facility.
Ships’ Hatch Covers
Most ships are equipped with steel hatch covers of what is known as Macgregor Type Hatch Covers. Macgregor is a company that pioneered and patented hatch cover designs in the 1950s. Furthermore, Macgregor designs cargo-handling gear. Macgregor Type Hatch Covers open and close with a concertina-like movement. Side-Rolling Hatch Covers roll either to the end of the hatch or on big bulk carriers to the side where Side-Rolling Hatch Covers provide some protection for crew members working on the deck during loading or discharging operations. Some ships have Piggy-Back Hatch Covers where the Hatch Covers stack on top of one another and for container ships, Pontoon Hatch Covers, which are lifted on and off using similar fitting as found on the containers, are most typically employed.
Modern hatch covers are driven by electric or hydraulic power. Old hatch covers are driven by winches and chains. Modern hatch covers are relatively labor-free. Hatch Covers are subject to rigorous testing by Classification Societies to ensure that Hatch Covers remain safe and watertight. Cargo damage by moisture may well be encountered to result from water ingress through Hatch Covers. Usually, Charter Party Clauses stipulate that Shipowners will keep hatch covers in an efficient, watertight condition.
Depending upon the design of the ship, cargo holds may be served by one or more hatchways. For example, vintage Freedom Type Ships’ Cargo Hold/Tweendeck No.1 can be seen to be served by Hatchway No.1, whereas Cargo Hold/Tweendeck No.2 is served by Hatchways 2 and 3, Hatchway No.2 located above the forward part of the cargo hold/tweendeck and Hatchway No.3 located above the after part. An identical pattern will be observed over Holds 3 and 4. Consequently, the Charter Party description of Freedom Type Ships should incorporate the expression 4 Holds and 6 Hatches. Like modern bulk carriers, vintage SD14 General Cargo Ships would be described as having 5 Holds and 5 Hatches.
Some Multi-Purpose Ships (MPP) are built with Twin-Hatches, in other words, hatchways are located side by side rather than fore and aft. The purpose of Twin-Hatches is to provide easy access to the sides of a ship’s holds and tweendeck areas to ease the handling of heavy and bulky cargoes. The major disadvantage of Twin-Hatchways is the requirement for a supportive center-line beam running longitudinally between the two hatchway openings.
Most Tweendeckers, Tweendeck-Hatchways are located precisely beneath Weatherdeck-Hatchways, thereby easing cargo handling operation. Commonly, Tweendeck-Hatchways and Weatherdeck-Hatchways have the exact dimensions. Nevertheless, this may not be the case, particularly with vintage ships. Therefore, shipbrokers should double-check Ships’ Hatchways when chartering Tweendeckers.
Containerships are specially designed for the transportation of containers. Containerships are the contemporary equivalent of the Cargo-Liner Ships. Containerships are operated on scheduled voyages on fixed routes, steaming at high speeds. Commonly, containerships operate sophisticated container terminals where comprehensive shore gear is available. Therefore, most of the big containerships are gearless. Usually, containerships turn-round time in port is extremely short.
Containerships are virtually solely chartered by Containership Operators, such as MSC, Maersk, CMA CGM, Hapag-Lloyd, COSCO Container, Ocean Network Express (ONE), etc., in the liner trades. Usually, most Containership Operators completely charter in containerships. The more significant part of the daily containership market activity is in the short sea (coaster)and middle distance businesses, the largest containerships sizes are fixed almost exclusively on long-term time charter with the main liner operators.
Containers are stowed below the weather-deck in Cell Guides (Cellular Steel Frameworks), and also a few tiers on weather-deck. Most coaster containerships have large hatchway openings of the identical width and length as the holds they serve, and the hatch-covers are frequently Pontoon Hatches (Steel Slabs) lifted on and off by shore gear.
Generally, the size of almost all merchant ships is expressed in tons, however, the capacity of containerships is expressed in terms of the number of containers, TEU (Twenty-Foot Equivalent Units), the containership is planned to carry. Short Sea Containerships (Coaster-Feeder Containerships) carry around 500 TEU. Modern Large Containerships carry around 23,000 TEU. In a containership, each container space is called a Container Slot. Containerships may carry a mixture of 20 TEU (Twenty-Foot Equivalent Units) and 40 FEU (Forty-Foot Equivalent Units) containers.
Small Containerships are employed as Feeder Containerships. Feeder Containerships feed the hinterland around major container terminals with loaded containers inbound from abroad, before feeding containers for export back to the container terminal on the return trip. Usually, Feeder Containerships operate at undeveloped container ports, Feeder Containerships may well be geared which enables Feeder Containerships to load and to discharge containers.
Hatchless Containership: Most large containerships are designed without hatch covers. Hatchless Containerships’ cell guides extend above the weather deck.
Shiptainer: Container gantries are called shiptainers. A ship-borne gantry-crane.
Fully Cellular Containership: A containership fully equipped with Cell Guides.
Fully Fitted Containership: A containership fully equipped with Container Securing Equipment, such as lashings, twist-locks, etc., and with Strengthened Decks.
4- Ro-Ro Ships
Ro-Ro Ships (Roll On – Roll Off Ships) range from an extremely straightforward River Ferry that is designed for inland waters to some of the most sophisticated Passenger Ferries. Mostly, Ro-Ro Ships operate at ports with limited port facilities. Ro-Ro Ships’ self-sustaining ability to load and discharge provides an outstanding method of transportation.
Deepsea Ro-Ro Ships are fitted with forklift trucks and tractors. Most Deepsea Ro-Ro Ships are fitted with a crane or two. Deepsea Ro-Ro Ships can handle an entire range of wheeled vehicles as well as palletized and containerized goods. Usually, access to the interior of Deepsea Ro-Ro Ships is via a stern ramp. Deepsea Ro-Ro Ships’ stern ramp can be slewed around and raised or lowered to fit whatever berth permits.
Inside Ro-Ro Ships, ramps or lifts lead up or down to miscellaneous deck levels. Inside Ro-Ro Ships, a wide variety of cargoes may be stowed.
Ro-Ro Ships’ decks and tank-tops are strengthened to take heavy cargoes. Ro-Ro Ships (Roll On – Roll Off Ships) or LO/LO (Lift On/Lift Off) system can carry all kinds and most sizes of rolling commodities and cargoes that can be placed on wheels.
Ro-Ro Ships constitute an extension to the road transportation for wheeled vehicles, especially for lorries which can unhitch and deposit the trailer on board.
Some types of Ro-Ro Ships are referred to as Trailer-Carriers. Trailer-Carriers’ capacity is expressed in terms of the length of available Lane Metres.
Some types of Ro-Ro Ships are referred to as Railway-Ferries or Train-Ferries. Railway-Ferries or Train-Ferries carry a variety of passengers, wheeled cargoes, and have rail tracks on decks to accommodate railway carriages. Railway-Ferries or Train-Ferries are fitted with a sophisticated ballast system to allow the ships’ rail tracks to be safely and securely connected to the shore rail system.
Another type of Ro-Ro Ships is the Pure Car Carriers (PCC). Pure Car Carriers (PCC) are designed with fixed decks and sophisticated ventilation systems for the carriage of motor cars and nothing else. Furthermore, thousands of vehicles can be driven on or off in a matter of hours. The main players of Pure Car Carriers (PCC) are the automotive companies.
Another type of Ro-Ro Ships is the Pure Car and Truck Carriers (PCTC). Pure Car and Truck Carriers (PCTC) are developed from the basic design of Pure Car Carriers (PCC). Pure Car and Truck Carriers (PCTC) are designed with clearances of some decks that can be altered to accommodate larger vehicles, such as trucks, as well as cars.
5- Specialised Ships
5.1- Livestock Carriers
Livestock Carriers can be divided into two (2) types Livestock Sheep Carriers and Livestock Cattle Carriers. Livestock Sheep Carriers are designed to carry sheep and Livestock Cattle Carriers are designed to carry larger animals such as cattle. The apparent design distinction is the additional deck height needed for the larger animals. Both Livestock Carrier types require fodder storage, comprehensive water supply, outstanding ventilation, appropriate techniques of animal waste disposal, non-slip decks, carefully organized ramps. Most Livestock Carriers were converted from existing ships. Occasionally, specialized Livestock Carriers are constructed.
5.2- Refrigerated Ships (Reefers)
Refrigerated Ships (Reefers) are designed and constructed to haul numerous cargoes such as fruits, vegetables, meats, and fish which would rapidly deteriorate in standard hold conditions. Modern Refrigerated Ships (Reefers) are constructed with holds and decks furnishing adequate access for standard-sized pallets and fork-lift trucks. Most modern Refrigerated Ships (Reefers) are equipped with Side-Ports Openings allowing direct access to cargo decks. Furthermore, the design of Refrigerated Ships (Reefers) makes them suitable for the carriage of motor cars that fit under the limited deck-heights, as well as for other non-refrigerated and palletized cargo, although many Refrigerated Ships (Reefers) operate exclusively in the refrigerated markets on long-term charters. Lately, Refrigerated Containers are getting the market share of Refrigerated Ships (Reefers).
5.3- Heavy Lift Ships
There are General Cargo Ships or Multi-Purpose Ships (MPP) equipped with heavy-lift derricks. However, there are specific cargoes that are far too heavy for even heavy-lift derricks capable of supporting lifts of around 2,000 tonnes. To fulfill this demand, there are specialized Heavy-Lift Ships.
There are two (2) types of Heavy-Lift Ships, the smaller capacity unit reliant on lifting cargo on and off with its gear, and capable of supporting lifts of around 2,000 tonnes unit weight. Commonly, smaller Heavy-Lift Ships are of a traditional appearance and from the outside look like Multi-Purpose Ships (MPP).
The second type is the Semi-Submersible Heavy-Lift Ships that are furnished with a robust ballasting system by which tanks are flooded as required, sufficient to submerge the Semi-Submersible Heavy-Lift Ships’ cargo area, which can be positioned under the object to be hauled such as an oil drilling platform or another vessel. When Semi-Submersible Heavy-Lift Ships are secured in the carriage position, the ballast tanks are pumped dry and the Mother-Ship – the Semi-Submersible Heavy-Lift Ship itself – surfaces from the water-bearing the weight of the cargo. To release the cargo, the process is reversed.
5.3- Barge Carrying Ships
There are several designs of Barge Carrying Ships. Barges can be compared with containers. Barges are self-contained units capable of being loaded and discharged at the ports of origin and destination of their cargoes, being hauled between the two ports by Mother-Ships. Nevertheless, the capacity of a barge is considerably greater than that of containers. Barges are floating units that lend themselves to the carriage of large unit cargoes. The barge units are called Dumb. The barge units are unable to self-propel. The barge units are planned for ease of transport under one of several carrying methods.
Lighter Aboard Ship (LASH) and SeeBee both operate a system by which lighters are lifted on and off Mother-Ships, being compiled and distributed along waterways by towing vessel. BACO (Barge Aboard Catamaran) uses a system of floating barges into the mother ship through large bow doors. Mother-Ships are capable of hauling individual barges of over 1,000 tonnes DWT (Deadweight Tonnage). Despite the obvious attractions of this type of ship for certain trades, it is possible to remain an impressive but extremely niche market.
5.4- Combination Carriers
There are two (2) types of Combination Carriers. Combination Carriers are employed both at the dry-bulk and wet-bulk trades markets.
The most common type of Combination Carrier is the OBO (Ore/Bulk Oiler). OBO (Ore/Bulk Oiler) has an adequate cubic cargo-carrying capacity to carry not only heavy, dense ore cargoes, but also low stowing cargoes such as coal and grains. The unique characteristic of an OBO (Ore/Bulk Oiler) is that the same cargo hold that has been employed to carry a dry-bulk commodity can be discharged and then prepared for the carriage of crude oil. Charterers in the dry and wet businesses may prefer to charter specialized bulk carriers or tankers. However, OBO (Ore/Bulk Oiler) shipowners have an in-built freighting advantage over their specialized competitors, in that ballast legs can be decreased because of OBO (Ore/Bulk Oiler) ability to operate in both markets. Maintenance of OBO (Ore/Bulk Oiler) is often higher than for a more straightforward vessel specializing in exclusively one market sector, encouraging earnings can be gained from OBO (Ore/Bulk Oiler) with efficient voyage planning.
The second most common type of Combination Carrier is the O/O (Ore/Oiler). O/O (Ore/Oiler) is designed to have an individual small cargo compartment for the carriage of heavy ores, the crude oil is carried separately in oil tanks. O/O (Ore/Oiler) can carry dry-bulk cargoes other than ores, however, low stowing cargoes would fill the cargo holds very fast and be unable to use the full deadweight. Furthermore, O/O (Ore/Oilers) are not built with self-trimming installations, extra time and cost would be required to trim the cargo surface level. Therefore, it is exceptionally unusual for O/O (Ore/Oilers) to be employed in the transportation of other than iron-ore or crude oil. Generally, O/O (Ore/Oilers) are not designed more than 100,000 DWT (Deadweight Tonnage).
6- Short-Sea Ships (Coaster Bulk Carrier Ships)
Short-Sea Ships (Coaster Bulk Carrier Ships) are not simply smaller versions of deep-sea ship types, Short-Sea Ships (Coaster Bulk Carrier Ships) have modifications peculiar to their employment. The modern Short-Sea Ships (Coaster Bulk Carrier Ships) require the flexibility of intake of cargoes to survive in an extremely competitive industry. Therefore, Short-Sea Ships (Coaster Bulk Carrier Ships) are usually built with only one hold operated by a large open-hatch steel hatch cover. Commonly, Short-Sea Ships (Coaster Bulk Carrier Ships) are designed with box-shaped hold.
Modern Short-Sea Ships (Coaster Bulk Carrier Ships) are constructed with steel bottoms to their cargo hold. Vintage Short-Sea Ships (Coaster Bulk Carrier Ships) may have concrete, wooden, or tarmacadam sheathing as protection to the tank-tops.
Occasionally, vintage Short-Sea Ships (Coaster Bulk Carrier Ships) are built with self-trimming facilities so that free-flowing bulk cargoes, which are susceptible to shift dangerously at sea, were secured by a variety of bagging and strapping part of the cargo at the top of the stow.
Modern Short-Sea Ships (Coaster Bulk Carrier Ships) are usually furnished with at least two moveable bulkheads facilitating the ship to arrange for a full cargo hold comprising 80 to 90% of the ship’s capacity and a small cargo hold where the balance can be slack without the requirement for bagging and strapping.
Low-profile Short-Sea Ships (Coaster Bulk Carrier Ships) are designed to steam rivers and canals by lowering the mast or superstructure and enabling the vessel to pass under bridges and other overhead obstructions.