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DIFFERENT TYPES OF SHIPS
1.ROLL – ON/ROLL – OFF SHIPS
Roll-on/roll-off (RORO) ships are vessels designed to carry wheeled cargo such as automobiles, trucks,
semi-trailer trucks, trailers or railroad cars that are driven on and off the ship on their own wheels. This is in
contrast to lo-lo (lift on-lift off) vessels which use a crane to load and unload cargo.
RORO vessels have built-in ramps which allow the cargo to be efficiently "rolled on" and "rolled off" the
vessel when in port. While smaller ferries that operate across rivers and other short distances often have
built-in ramps, the term RORO is generally reserved for larger ocean-going vessels. The ramps and doors
may be stern-only, or bow and stern for quick loading.
Various types of RORO vessels include ferries, cruise ferries, cargo ships, and barges. New automobiles that are
transported by ship are often moved on a large type of RORO called a Pure Car Carrier (PCC) or Pure Car Truck
Carrier (PCTC).
Seaworthiness of RORO vessels
The seagoing RORO car ferry, with large external doors close to the waterline and open vehicle decks with
few internal bulkheads has a reputation for being a high risk design. An improperly-secured loading door
can cause a ship to take on water and sink, as happened for example in 1987 with the MS Herald of Free
Enterprise. Water sloshing on the vehicle deck can set up a free surface effect making the ship unstable and
causing it to capsize.
A Roll-On/Roll-Off [RO/RO] ship is specifically designed to carry wheeled and tracked vehicles as all or most of its cargo. Vehicles are driven or towed on and off the ship by means of either the ship's own ramps or shore-based ramps. Because it is designed to accommodate cargoes which cannot be stacked but which vary in height, below-deck space and volume utilization is generally less efficient than on a containership. RO/RO ships are thus commercially viable only in certain specialized trades. However, the RO/RO is the preferred ship type for deployment of military unit equipment.
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2. BULK CARRIER
A bulk carrier, bulk freighter, or bulker is a merchant ship specially designed to transport unpackaged
bulk cargo, such as grains, coal, ore, and cement in its cargo holds. Since the first specialized bulk carrier
was built in 1852, economic forces have fuelled the development of these ships, causing them to grow in
size and sophistication. Today's bulkers are specially designed to maximize capacity, safety, efficiency, and
to be able to withstand the rigors of their work.
Today, bulkers make up 40% of the world's merchant fleets and range in size from single-hold mini-bulkers
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 bulkers have Greek, Japanese, or Chinese owners and more
than a quarter are registered in Panama. Korea is the largest single builder of bulkers, and 82% of these ships
were built in Asia.
A bulk carrier's crew participates in the loading and unloading of cargo, navigating the ship, and keeping its
machinery and equipment properly maintained. Loading and unloading the cargo is difficult, dangerous, and
can take up to 120 hours on larger ships. Crews can range in size from three people on the smallest ships to
over 30 on the largest.
Bulk cargo can be very dense, corrosive, or abrasive. This can present safety problems: cargo shifting,
spontaneous combustion, and cargo saturation can threaten a ship. The use of ships that are old and have
corrosion problems has been linked to a spate of bulker sinkings in the 1990s, as have the bulker's large
hatchways, important for efficient cargo handling. New international regulations have since been introduced
to improve ship design and inspection, and to streamline the process of abandoning ship.
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Definition
There are various ways to define the term bulk carrier. The International Convention for the Safety of Life
at Sea 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."
However, most classification societies use a broader definition where a bulker 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 bulkers from
bulk liquid carriers such as oil, chemical, or liquefied petroleum gas carriers. Very small bulkers 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 bulkers. "OBO" describes a bulker which 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 designations very large crude carrier and ultra large crude carrier.
Cross section of a typical bulker
1. Cargo hold
2. Hatch cover
3. Upper hopper tank for water ballast or oil
4. Double bottom
5. Lower hopper tank, for water ballast
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DESCRIPTIONS OF GENERAL TYPES OF BULK CARRIERS
Geared bulk carriers are typically in the handysize to handymax size range although there are a small number
of geared panamax vessels, like all bulkers they feature a series of holds covered by prominent hatch covers.
They have cranes, derricks or conveyors that allow them to load or discharge cargo in ports without shore-
based equipment. This gives geared bulkers flexibility in the cargoes they can carry and the routes they can
travel. (Photo: A typical geared handysize bulk carrier.)
Combined carriers are designed to transport both liquid and dry bulk cargoes. If both are carried
simultaneously, they are segregated in separate holds and tanks. Combined carriers require special design and
are expensive. They were prevalent in the 1970s, but their numbers have dwindled since 1990. (Photo: The oil
pipeline and dry bulk hold aboard the Maya.)
Gearless carriers are bulkers without cranes or conveyors. These ships depend on shore-based equipment at
their ports of call for loading and discharging. They range across all sizes, the larger bulk carriers (VLOCs) can
only dock at the largest ports, some of these are designed with a single port-to-port trade in mind. The use of
gearless bulkers avoids the costs of installing, operating, and maintaining cranes. (Photo:Berge Athen, a
225,000 ton gearless bulker.)
Selfdischargers are bulkers with conveyor belts, or with the use of an excavator that is fitted on a traverse
running over the vessel's entire hatch, and that is able to move sideways as well. This allows them to discharge
their cargo quickly and efficiently. (Photo: The John B. Aird a self-discharging lake freighter.)
Lakers are the bulkers prominent on the Great Lakes, often identifiable by having a forward house which helps
in transiting locks. Operating in fresh water, these ships suffer much less corrosion damage and have a much
longer lifespan than saltwater ships. As of 2005, there were 98 lakers of 10,000 DWT or over. (Photo: Edmund
Fitzgerald, a Great Lakes bulker.)
BIBO or "Bulk In, Bags Out" bulkers are equipped to bag cargo as it is unloaded. The CHL Innovator, shown in
the photo, is a BIBO bulker. In one hour, this ship can unload 300 tons of bulk sugar and package it into 50 kg
sacks.
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3. PASSENGER SHIPS
A passenger ship is a ship whose primary function is to carry passengers. The category does not include cargo vessels
which have accommodations for limited numbers of passengers, such as the ubiquitous twelve-passenger freighters
once common on the seas in which the transport of passengers is secondary to the carriage of freight. The type does
however include many classes of ships designed to transport substantial numbers of passengers as well as freight.
Indeed, until recently virtually all ocean liners were able to transport mail, package freight and express, and other
cargo in addition to passenger luggage, and were equipped with cargo holds and derricks, kingposts, or other cargo-
handling gear for that purpose. Only in more recent ocean liners and in virtually all cruise ships has this cargo capacity
been eliminated.
While typically passenger ships are part of the merchant marine, passenger ships have also been used as
troopships and often are commissioned as naval ships when used as for that purpose.
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4. DREDGERS
Dredging is an excavation activity or operation usually carried out at least partly underwater, in shallow
seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a
different location. This technique is often used to keep waterways navigable.
It is also used as a way to replenish sand on some public beaches, where too much sand has been lost
because of coastal erosion. Dredging is also used as a technique for fishing for certain species of edible
clams and crabs, see fishing dredge.
A dredger is a device for scraping or sucking the seabed, used for dredging. It is a ship or boat equipped
with a dredge. The terms are sometimes interchanged.
The process of dredging creates spoils (excess material), which are carried away from the dredged area.
Dredging can produce materials for land reclamation or other purposes (usually construction-related), and
has also historically played a significant role in gold mining. Dredging can create disturbance in aquatic
ecosystems, often with adverse impacts.
Types of dredging vessels
Suction
For suction-type excavation out of water, see Suction excavator.
These operate by sucking through a long tube, like some vacuum cleaners but on a big scale.
A plain suction dredger has no tool at the end of the suction pipe to disturb the material. This is often the
most commonly used form of dredging.
Trailing suction
A trailing suction hopper dredger (TSHD) trails its suction pipe when working, and loads the dredge spoil
into one or more hoppers in the vessel. When the hoppers are full, the TSHD sails to a disposal area and
either dumps the material through doors in the hull or pumps the material out of the hoppers. Some dredges
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also self-offload using drag buckets and conveyors. The largest trailing suction hopper dredger in the world
is currently Jan De Nul's Cristobal Colon.
Cutter suction
A cutter-suction dredger's (CSD) suction tube has a cutter head at the suction inlet, to loosen the earth and
transport it to the suction mouth. The cutter can also be used for hard surface materials like gravel or rock.
The dredged soil is usually sucked up by a wear-resistant centrifugal pump and discharged through a pipe
line or to a barge. In recent years, dredgers with more powerful cutters have been built in order to excavate
harder rock without blasting.
Auger suction
This process functions like a cutter suction dredger, but the cutting tool is a rotating Archimedean screw set
at right angles to the suction pipe. The first widely used auger dredges were designed by Mud Cat Dredges
in the 1980s which was run by National Car Rental, but is now a Division of Ellicott Dredges. In 1996, IMS
Dredges introduced a self-propelled version of the auger dredge that allows the system to propel itself
without the use of anchors cables. During the 1980s and 1990s auger dredges were primarily used for sludge
removal applications from waste water treatment plants. Today, auger dredges are used for a wider variety
of applications including river maintenance and sand mining. The most common auger dredge on the global
market today is the Versi-Dredge. The turbidity shroud on auger dredge systems creates a strong suction
vacuum and creates much less turbity than conical (basket) type cutterheads and that is why they are
preferred for environmental type applications. The vacuum created by the shroud and the ability to convey
material to the pump faster makes auger dredge systems more productive than similar sized conical (basket)
type cutterhead dredges.
Jet-lift
These use the Venturi effect of a concentrated high-speed stream of water to pull the nearby water, together
with bed material, into a pipe.
Air-lift
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An airlift is a type of small suction dredge. It is sometimes used like other dredges. At other times, an airlift
is used, handheld underwater by a diver. It works by blowing air into the pipe, and that air, being lighter than
water, rises inside the pipe, dragging water with it.
Bucket
A bucket dredger is equipped with a bucket dredge, which is a device that picks up sediment by mechanical means,
often with many circulating buckets attached to a wheel or chain. Some bucket dredgers and grab dredgers are
powerful enough to rip out coral to make a shipping channel through coral reefs.
Grab
Grab dredger picks up seabed material with a clam shell grab, which hangs from an onboard crane or a crane
ship, or is carried by a hydraulic arm, or is mounted like on a dragline. This technique is often used in
excavation of bay mud. Most of these dredges are crane barges with spuds.
Backhoe/dipper
A backhoe/dipper dredge has a backhoe like on some excavators. A crude but usable backhoe dredger can be
made by mounting a land-type backhoe excavator on a pontoon. The six largest backhoe dredgers in the
world are currently the Vitruvius, the Mimar Sinan, Postnik Jakovlev (Jan De Nul), the Samson (DEME),
the Simson and the Goliath (Van Oord). They featured barge-mounted excavators. Small backhoe dredgers
can be track-mounted and work from the bank of ditches. A backhoe dredger is equipped with a half-open
shell. The shell is filled moving towards the machine. Usually dredges material is loaded in barges. This
machine is mainly used in harbors and other shallow water.
Water injection
A water injection dredger uses a small jet to inject water under low pressure (to prevent the sediment from
exploding into the surrounding waters) into the seabed to bring the sediment in suspension, which then
becomes a turbidity current, which flows away down slope, is moved by a second burst of water from the
WID or is carried away in natural currents. Water injection results in a lot of sediment in the water which
makes measurement with most hydrographic equipment (for instance: singlebeam echosounders) difficult.
Pneumatic
These dredgers use a chamber with inlets, out of which the water is pumped with the inlets closed. It is
usually suspended from a crane on land or from a small pontoon or barge. Its effectiveness depends on depth
pressure.
Bed leveller
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This is a bar or blade which is pulled over the seabed behind any suitable ship or boat. It has an effect
similar to that of a bulldozer on land. The chain-operated steam dredger Bertha, built in 1844 to a design by
Brunel and now the oldest operational steam vessel in Britain, was of this type.
Krabbelaar
This is an early type of dredger which was formerly used in shallow water in the Netherlands. It was a flat-
bottomed boat with spikes sticking out of its bottom. As tide current pulled the boat, the spikes scraped
seabed material loose, and the tide current washed the material away, hopefully to deeper water. Krabbelaar
is Dutch for "scratcher".
Snagboat
A snagboat is designed to remove big debris such as dead trees and parts of trees from rivers and canals.
Amphibious
Some of these are any of the above types of dredger, which can operate normally, or by extending legs, also
known as spuds, so it stands on the seabed with its hull out of the water. Some forms can go on land.
Some of these are land-type backhoe excavators whose wheels are on long hinged legs so it can drive into
shallow water and keep its cab out of water. Some of these may not have a floatable hull and, if so, cannot
work in deep water.
Submersible
These are usually used to recover useful materials from the seabed. Many of them travel on caterpillar
tracks. A unique variant is intended to walk on legs on the seabed. Fishing dredges are used to collect
various species of clams scallops, oysters or crabs from the seabed. These dredges have the form of a scoop
made of chain mesh, and are towed by a fishing boat. Careless dredging can be destructive to the seabed.
Nowadays some scallop dredging is replaced by collecting via scuba diving.
Police drag
In some police departments a small dredge (sometimes called a drag) is used to find and recover objects and
bodies from underwater. The bodies may be murder victims, or people who committed suicide by drowning,
or victims of accidents. It is sometimes pulled by men walking on the bank.
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5. CHEMICAL TANKER
A chemical tanker is a type of tanker designed to transport chemicals in bulk.
Ocean-going chemical tankers generally range from 5,000 metric tons deadweight (DWT) to 40,000 DWT
in size, which is considerably smaller than the average size of other tanker types due to the specialised
nature of their cargoes and the size restrictions of the port terminals where they call to load and discharge.
Chemical tankers normally have a series of separate cargo tanks which are either coated with specialised
coatings such as phenolic epoxy or zinc paint, or made from stainless steel. The coating or cargo tank
material determines what types of cargo a particular tank can carry: stainless steel tanks are required for
aggressive acid cargoes such as sulphuric and phosphoric acid Chemical tankers often have a system for
tank heating in order to maintain the viscosity of certain cargoes - typically this system consists of a boiler
which pumps pressurized steam through so-called 'heating coils' - stainless steel pipes - in the cargo tanks,
thus transferring heat into the cargo which circulates in the tank by convection. Many modern chemical
tankers feature double hull construction and have one tank for each pump with separate piping, which means
that each tank can load a separate cargo without any mixing. Tank cleaning after discharging cargo is a very
important aspect of chemical tanker operations, because tanks which are not properly cleaned of all cargo
residue can adversely affect the purity of the next cargo loaded. Before tanks are cleaned, it is very
important that they are properly ventilated and checked to be free of potentially explosive gases.
Most new chemical tankers are built by shipbuilders in Japan, Korea or China, with other builders in Turkey,
Italy, Germany and Poland.
While 'easier' cargoes - e.g. vegetable oil - can be carried in epoxy coated tanks.
(1 )A Chemical Tanker
(2) The deck of a chemical tanker has a complicated piping system. This is the Saudi chemical tanker of
43,851 metric tons deadweight (DWT) 1986 Built Al Farabi, carrying molasses, in Brest.
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6. CARGO SHIPS A cargo ship or freighter is any sort of ship or vessel that carries cargo, goods, and materials from one port to
another. Thousands of cargo carriers ply the world's seas and oceans each year; they handle the bulk of international
trade. Cargo ships are usually specially designed for the task, often being equipped with cranes and other
mechanisms to load and unload, and come in all sizes. Today, they are almost always built of welded steel, and with
some exceptions generally have a life expectancy of 25 to 30 years before being scrapped.
Cargo ships/freighters can be divided into four groups, according to the type of cargo they carry. These
groups are:
1. General Cargo Vessels
2. Tankers
3. Dry-bulk Carriers
4. Multipurpose Vessels
General Cargo Vessels carry packaged items like chemicals, foods, furniture, machinery, motor vehicles,
footwear, garments, etc.
Tankers carry petroleum products or other liquid cargo.
Dry Bulk Carriers carry coal, grain, ore and other similar products in loose form.
Multi-purpose Vessels, as the name suggests, carry different classes of cargo – e.g. liquid and general cargo
– at the same time.
Specialized types of cargo vessels include container ships and bulk carriers (technically tankers of all sizes
are cargo ships, although they are routinely thought of as a separate category). Cargo ships fall into two
further categories that reflect the services they offer to industry: liner and tramp services. Those on a fixed
published schedule and fixed tariff rates are cargo liners. Tramp ships do not have fixed schedules. Users
charter them to haul loads. Generally, the smaller shipping companies and private individuals operate tramp
ships. Cargo liners run on fixed schedules published by the shipping companies. Each trip a liner takes is
called a voyage. Liners mostly carry general cargo. However, some cargo liners may carry passengers also.
A cargo liner that carries 12 or more passengers is called a combination or passenger-cum-cargo line.
http://en.wikipedia.org/wiki/Cargo_ship
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7. CONTAINER SHIPS The hull, similar to bulk carriers and general cargo ships, is built around a strong keel. Into this frame is set
one or more below-deck cargo holds, numerous tanks, and the engine room. The holds are topped by hatch
covers, onto which more containers can be stacked. Many container ships have cargo cranes installed on
them, and some have specialized systems for securing containers on board.
The hull of a modern cargo ship is a complex arrangement of steel plates and strengthening beams. The hull
is built around the keel. Resembling ribs, and fastened at right-angles to the keel are the ship's frames.The
ship's main deck, the metal platework that covers the top of the hull framework, is supported by beams that
are attached to the tops of the frames and run the full breadth of the ship.The beams not only support the
deck, but along with the deck, frames, and transverse bulkheads, strengthen and reinforce the shell. Another
feature of recent hulls is a set of double-bottom tanks, which provide a second watertight shell that runs
most of the length of a ship. The double-bottoms generally hold liquids such as fuel oil, ballast water or
fresh water.
A ship's engine room houses its main engines and auxiliary machinery such as the fresh water and sewage
systems, electrical generators, fire pumps, and air conditioners. In most new ships, the engine room is
located in the after portion of the ship.
A major characteristic of a container ship is whether it has cranes installed for handling its cargo. Those that
have cargo cranes are called geared and those that don't are called ungeared or gearless. The earliest
purpose-built container ships in the 1970s were all gearless. Since then, the percentage of geared newbuilds
has fluctuated widely, but has been decreasing overall, with only 7.5% of the container ship capacity in 2009
being equipped with cranes.
While geared container ships are more flexible in that they can visit ports that are not equipped with pierside
cranes, they suffer from several drawbacks. To begin with, geared ships will cost more to purchase than a
gearless ship. Geared ships also incur greater recurring expenses, such as maintenance and fuel costs.
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8. OBO CARRIERS
OBO is an abbreviated name for Oil- Bulk- Ore cargo vessel. These are specially designed vessels which
carry cargo in bulk in both liquid and dry form. The OBO vessels are some of the most highly sophisticated
cargo vessels sailing today.
OBO Carrier OBO vessel are expensive to build but because of their capability of carrying wet and dry cargo together
,they provide a more economical option as this feature reduces the number of empty voyages or ballast
voyages.
A bulk carrier can carry only dry cargo and a tanker can carry only liquid cargo. These make these two types
of vessels to ply only on fix voyages with least flexibility. On the other hand, OBO vessels have
multipurpose capability which allows them to ply on different voyages as per the demand and supply of the
market to make the maximum profit.
OBO vessels were very popular in the year 1955-1980 and a sudden rise was seen during this period. One of
the biggest OBO carriers of this period –MV Derbyshire was of approximately 180000 DWT.
Unfortunately, it sank in the Pacific Ocean after fighting a terrific storm while it was carrying ore as cargo.
OBO– Construction and Features OBO is normally constructed with a single deck to impart structural strength to the vessel in addition to
several divisions of transverse bulkheads which divides the cargo holds.
Hatches for cargo hold are generally made in two pieces as larger and single hatches will reduce the
structural strength of the ship. Also unlike bulk carriers, OBO vessel has pipe lines and equipment’s on deck
which are used in operation while carrying liquid cargo. Moreover, a single large cover can hinder the
operation of loading and unloading of oil cargo.
However, OBO vessels are losing their popularity because of the following reasons:
1) They are expensive to construct.
2) Loading of bulk cargo requires conveyors and grabs. Due to small hatch opening, the access for bigger
grab and belts become difficult and take more time to load / unload the cargo.
3) Additional trimming of ship is required as the equipment above the deck can hinder the crane movement.
4) Equipments located above the hatches have to be removed temporarily by means of crane, which
increases the port stay and overall cost of operation.
5) The equipments above deck can be damaged by the cranes and equipment used for loading and unloading
operation of bulk cargo.
6) The load distribution of OBO ship is not even and the overall structure is not stiff which may result in
deformation of bulkhead at rough weather.
7) Another major problem of OBO ship is the movement of cargo in the hold which results in list and
instability of the ship due to the shift in the center of gravity of the ship.
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9. Barge Carrier Ships
The loading and discharging of floating containers or vessels with such ships is as a rule done on free water
by shipborne lifting devices which pick up the floating vessels from the water for transfer to the ship and
vice versa. Such expensive shipborne lifting devices have the common disadvantage that they require an
assembly of a large number of individual parts with a relatively low degree of reliability and in most cases
the loading and unloading operations are impaired by the sea water conditions and the atmospheric
environment of the ship. A further disadvantage is that such vessels usually have to be operated by shore
side personnel because of the prevailing agreements between ship owners and longshoremen unions. Such
personnel are normally unable to operate such gear as carefully and safely as a trained crew of the ship. In
addition with the use of travelling ship cranes for the handling of floating vessels, the cranes sensitivity to
the ship's inclination is a further disadvantage.
Barge ships are designed to carry specially designed barges (lighters) or a combination of such barges and
containers. Thus, they are necessarily large ships with a large heavy lift capability. Their design was
intended to combine the flexibility and self-sustained cargo handling capability of the general cargo ship
with the rapid port turnaround time of the RO/RO and containership. This combination, however, has not
proved commercially viable in most trades.
The search for more economic modes of cargo transportation has led to the introduction of designs of sea-
going transport ships with facility for taking a number of loaded barges on board. Such systems of
transportation afford a number of advantages, notably in simplifying the transfer of cargo from inland sites
to an ocean transport ship via inland waterways and the eventual transport of the cargo to coastal or inland
delivery points. By eliminating the off-loading of cargo from the barges into the transport ship and vice
versa, important labour and energy cost savings are achieved and the speed and general convenience of the
water-borne transportation exercise is enhanced.
In the transport of cargo throughout the world, cargo must often be transported in various types of vessels
depending on the depth of the water in which the vessel travels. For example, when grain from the Midwest
is harvested for transport to foreign countries, the grain must be placed in relatively shallow vessels such as
barges or the like and moved down river, such as the Mississippi River, to grain elevators where the grain is
then unloaded from the barges, into the grain elevators. Subsequently a deep draft vessel, such as a cargo
ship, is then loaded with the grain so that the ship may then transport the grain cargo to foreign ports. Most
grain elevators would be located for example, between New Orleans and Baton Rouge, since any travel
north of Baton Rouge by a deep draft vessel is impossible because of the shallow depth of the Mississippi
River. Even on the occasion where the deep draft vessel can receive the cargo of grain directly from the
shallow draft barge, again time and effort and expenses are incurred when this transfer is undertaken.
Barge Carrier Variants
SEABARGE (SEABEE)
The SEABARGE (SEABEE) is arranged much differently from the LASH in that it has three decks on
which the cargo barges or container flats are stowed. Barges are brought to each deck level by a stern
elevator and are moved internally within the ship by the Transporter (conveyor) System. Two barges can be
loaded or discharged in a cycle of about 40 minutes. SEABEE barge ships can carry up to 38 sea barges
(97'6" long x 35' wide x 16'11" high). The elevator capacity is 2,000 LT. The SEABEE ship is the preferred
ship to transport landing craft, utility, and lighter, amphibious resupply, cargo 60 ton. The military
advantages of barge carriers include their suitability to carry either unit equipment, sustaining supplies, or
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ammunition; the ability to carry amphibious lighter age and the capability to preload the barges before ship
arrival and to discharge cargo from the barges at relatively austere port facilities, after the ship has sailed.
Their military disadvantages include a complete dependence on a single, very complicated mechanical
system for barge discharge; the barge's dependence, once afloat, upon the availability of towage and the
overall unsuitability of the barges for towing outside harbors or other protected waters.
BACO (Barge / Container)
BACO liners (barge/container liners) operate in accordance with the dock principle. In this German-
developed system, the barges are floated through bow doors into the carrier, which has been lowered by
taking on ballast. The special feature of these maneuvers is that fact that these barges float in the ship's
storage area and the ship must open its bow in order for them to float in and out. Empty barges have an
empty height of approx. 7 m. The skipper can look straight out over the barges when pushing, which
requires sure instinct and driving expertise on the part of the crew for this maneuver. Once the bow doors
have been closed, the water is pumped out of the dock and the barges are secured with special fittings. The
special BACO barges measure 24 m x 9.50 m and, at a deadweight of 800 metric tons, have a draft of 4.10
m. However, the particular dimensions of the carrier ships are such that other types of barge and even inland
waterway vessels and lighters can also be carried. Several tiers of containers can be carried on deck and be
loaded and unloaded with on-board lifting gear. The Seereederei Baco-Liner GmbH, based in Duisburg, we
run a regular conventional and Container liner service between North-West-European and West-African
ports and vice versa. BACO Liner with their unique Barge / Container carrying vessels are considered the
No 1 service to West Africa. This system allows the vessels to arrive and discharge midstream in African
Ports, thus avoiding port delays.
CONDOCK
CONDOCK - the synonym for CON tainer-, DOCK-, and Ro/Ro-vessel features the combined versatility for
the marine-transportation of Container, large and heavy loads in the Ro/Ro mode and the wide range of
General cargoes. The special design of these vessels is their capability of the safe loading and transportation
of floating units by semi-submersible dock-operation or utilization as a mobile Dry Dock. The vessels may
trade worldwide with open or removed hatchcovers, resulting in nearly unlimited cargo heights.
Cargo transport ships utilising a so-called float-on cargo-loading principle have been built. In 1978 the
CONDOCK-Type vessel was designed in close co-operation with a German Shipyard. The Condock I of
3,603 dwat featured 2 cranes on the starboard side, each 63 tons at 14,00 m combinable 126 tons, decreasing
gradually to 2 x 30 tons at 24,00 m . The barge capacity was 3 baco / lash. Until 1984, a successive series of
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almost identical sistervessels were delivered and operated together with further company-owned
conventional tonnage in the world-wide freight market. The Condock III is a 4,400 DWT Ro-Ro, Flo-Flo
vessel with dual 63 metric ton cranes combinable for 126-ton lifts and an unobstructed hold that is 87.5
meters long. The ship is ideal for yachts, tugboats, and modules and can successfully load at facilities
primarily designed for barge operations.
The international track record includes the preparation and transport of sensitive prefabricated high-
dimensioned modules and pressure vessels for refineries and offshore plants in the Ro-Ro mode. Further
contracts include the transport of former USSR Foxtrot class submarine from Australia to Long Beach and
the Dutch sailing- replica BATAVIA from Amsterdam to Sydney and back in the float in/out mode.
These ships have a self-lowering capability whereby a cargo space can be flooded through the stern to allow
direct access of floating cargo. By enabling cargo to be floated into the ship, the need for expensive lifting
gear is eliminated. After loading the barges onto the transport ship it is debalasted to cause it to rise in the
water and the cargo space is drained. The barges then lie in the transport ship as in a dry dock.
The number of barges of a given size which can be docked in a transport ship in this way is dependent on the
length and width of the cargo space. In designing the transport ship the extent to which these dimensions can
be increased is limited by numerous factors including of course the maximum permissible length and beam
of the ship.
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10. FERRYS
A ferry (or ferryboat) is a form of transportation, usually a boat, but sometimes a ship, used to carry
primarily passengers, and sometimes vehicles and cargo as well, across a body of water. Most ferries operate
on regular, frequent, return services. A passenger ferry with many stops, such as in Venice, is sometimes
called a water bus or water taxi.
Ferries form a part of the public transport systems of many waterside cities and islands, allowing direct
transit between points at a capital cost much lower than bridges or tunnels. However, ship connections of
much larger distances (such as over long distances in water bodies like the Mediterranean Sea) may also be
called ferry services, especially if they carry vehicles.
Double-ended
Double-ended ferries have interchangeable bows and sterns, allowing them to shuttle back and forth
between two terminals without having to turn around. Well-known double-ended ferry systems include the
Staten Island Ferry, Washington State Ferries, Star Ferry, several boats on the North Carolina Ferry System,
and the Lake Champlain Transportation Company. Most Norwegian fjord and coastal ferries are double-
ended vessels. Some ferries in Sydney, Australia and British Columbia are also double-ended..
Hydrofoil
Hydrofoils have the advantage of higher cruising speeds, succeeding hovercraft on some English Channel
routes where the ferries now compete against the Eurotunnel and Eurostar trains that use the Channe Tunnel.
Passenger-only hydrofoils also proved a practical, fast and relatively economical solution in the Canary
Islands but were recently replaced by faster catamaran "high speed" ferries that can carry cars. Their
replacement by the larger craft is seen by critics as a retrograde step given that the new vessels use much
more fuel and foster the inappropriate use of carsin islands already suffering from the impact of mass
tourism.
Hovercraft
Hovercraft were developed in the 1960s and 1970s to carry cars. The largest was the massive SR.N4 which
carried cars in its centre section with ramps at the bow and stern between England and France. The
hovercraft was superseded by catamarans which are nearly as fast and are less affected by sea and weather
conditions. Only one service now remains, a foot passenger service between Portsmouth and the Isle of
Wight run by Hovertravel.
Catamaran
Catamarans are normally associated with high-speed ferry services. Stena Line operates the largest
catamarans in the world, the Stena HSS class, between the United Kingdom and Ireland. These waterjet-
powered vessels, displacing 19,638 tonnes, are larger than most catamarans and can accommodate 375
passenger cars and 1,500 passengers. Other examples of these super-sizer catamarans are found in the
Brittany Ferries fleet with the Normandie Express and the Normandie Vitesse.
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Turntable ferry
This type of ferry allows vehicles to load from the "side". The vehicle platform can be turned. When
loading, the platform is turned sideways to allow sideways loading of vehicles. Then the platform is turned
back, in line with the vessel, and the journey across water is made.
Pontoon ferry
Pontoon ferries carry vehicles across rivers and lakes and are widely used in less-developed countries with
large rivers where the cost of bridge construction is prohibitive. One or more vehicles are carried on a
pontoon with ramps at either end for vehicles to drive on and off. Cable ferries (next section) are usually
pontoon ferries, but pontoon ferries on larger rivers are motorised and able to be steered independently like a
boat.
Foot ferry
Foot ferries are small craft used to ferry foot passengers, and often also cyclists, over rivers. These are either
self-propelled craft or cable ferries. Such ferries are for example to be found on the lower River Schelde in
Belgium and in particular the Netherlands. Regular foot ferry service also exists in the capital of the Czech
Republic, Prague. Restored, expanded ferry service in the Port of New York and New Jersey uses boats for
pedestrians only.
Cable ferry
Very short distances may be crossed by a cable or chain ferry, which is usually a pontoon ferry (see above),
where the ferry is propelled along and steered by cables connected to each shore. Sometimes the cable ferry
is human powered by someone on the boat. Reaction ferries are cable ferries that use the perpendicular force
of the current as a source of power.
Air ferries
In the 1950s and 1960s, travel on an "air ferry" was possible—aeroplanes, often ex-military, specially
equipped to take a small number of cars in addition to "foot" passengers. These operated various routes
including between the United Kingdom and Continental Europe. Companies operating such services
included Corsair.
Referrances-http://en.wikipedia.org/wiki/Roll-on/roll-off
http://en.wikipedia.org/wiki/OBO_carrier
http://en.wikipedia.org/wiki/Cargo_ship
Ship design and construction by Taggart
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SPECIFIC GRAVITIES OF LIQUIDS
Liquid Temp kg/cu.m
1,1,2-Trichlorotrifluoroethane 25 C 1564.00
1,2,4-Trichlorobenzene 20 C 1454.00
1,4-Dioxane 20 C 1033.60
2-Methoxyethanol 20 C 964.60
Acetic Acid 25 C 1049.10
Acetone 25 C 784.58
Acetonitrile 20 C 782.20
Alcohol, ethyl 25 C 785.06
Alcohol, methyl 25 C 786.51
Alcohol, propyl 25 C 799.96
Ammonia (aqua) 25 C 823.35
Analine 25 C 1018.93
Automobile oils 15 C 880 - 940
Beer (varies) 10 C 1010
Benzene 25 C 873.81
Benzil 25 C 1079.64
Brine 15 C 1230
Bromine 25 C 3120.40
Butyric Acid 20 C 959
Butane 25 C 599.09
n-Butyl Acetate 20 C 879.60
n-Butyl Alcohol 20 C 809.70
n-Butyl Chloride 20 C 886.20
Caproic acid 25 C 921.06
Carbolic acid 15 C 956.30
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Carbon disulfide 25 C 1260.97
Carbon tetrachloride 25 C 1584.39
Carene 25 C 856.99
Castor oil 25 C 956.14
Chloride 25 C 1559.88
Chlorobenzene 20 C 1105.80
Chloroform 20 C 1489.20
Chloroform 25 C 1464.73
Citric acid 25 C 1659.51
Coconut oil 15 C 924.27
Cotton seed oil 15 C 925.87
Cresol 25 C 1023.58
Creosote 15 C 1066.83
Crude oil, 48° API 60 F 790
Crude oil, 40° API 60 F 825
Crude oil, 35.6° API 60 F 847
Crude oil, 32.6° API 60 F 862
Crude oil, California 60 F 915
Crude oil, Mexican 60 F 973
Crude oil, Texas 60 F 873
Cumene 25 C 860.19
Cyclohexane 20 C 778.50
Cyclopentane 20 C 745.40
Decane 25 C 726.28
Diesel fuel oil 20 to 60 15 C 820 - 950
Diethyl ether 20 C 714
o-Dichlorobenzene 20 C 1305.80
Dichloromethane 20 C 1326.00
Diethylene glycol 15 C 1120
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Dichloromethane 20 C 1326.00
Dimethyl Acetamide 20 C 941.50
N,N-Dimethylformamide 20 C 948.70
Dimethyl Sulfoxide 20 C 1100.40
Dodecane 25 C 754.63
Ethane -89 C 570.26
Ether 25 C 72.72
DIFFERENT DRAUGHTS
air
draught the vertical distance measured from the ship'swaterline to the highest point on the
ship; usually comes into consideration when the ship has to sail under overhead
bridges in the river
compare draught
bar
draught maximum draught which a ship can take to pass over a bar or sand bank
design
draught draught as used for design calculation before actual construction, which has a
tendency to distort the final reading
draught
marks figures welded on the bow, midship and sternof each side of a ship's shell plating
to indicatedraught; the distance is read from the lower edge of each
number; draught measured at the bow is called forward draught and at the stern
is called aft draught
draught
survey survey carried out to determine the cargo weight on board by measuring the
ship'sdraught
extreme
draught draught measured to the lowest projecting portion of a ship
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forced
draught combustion air for boiler furnace supplied under pressure from a
forced draught fan
lightship
draught draught when ship is empty and deadweightis zero
Different Types of Cargoes on a Ship
Cargoes are goods transported on different carriers/vehicles/means of transport from one place to another for
economic reasons. Generally cargo is used for goods transported through air or water. There are different
types of cargoes that can be transported through ship for commercial purposes. The cargo’s transported by
ship are handled at seaport terminals. Some of these goods are discussed below:
Heavy Equipments and Machinery: This includes industrial as well as household machinery, automobiles,
technical machinery, engineering machinery, auxiliary machinery; etc. They are packed either on wooden
crates or in heavy steel/iron containers according to their handling instructions.
Dangerous or Hazardous Cargo: They consist of hazardous materials like chemicals, oil, petrol, and
diesel, asbestos which are harmful for human contact. Very careful handling is a must to avoid accidents and
loss to human life.
Inflammable or Combustible Cargo: They include goods like oil seeds, oil, diesel, cotton, jute which are
susceptible to catch fire easily even from a single flame. They can ignite spontaneously and hence must be
handled with double extra care to avoid loss of material and men.
Concentrates/Ores: This type of cargo is of high density and may emit toxic fumes and can deplete oxygen
inside the tank. They are usually present in huge quantities and must be prevented from moisture.
Bulk Cargo: They generally include goods like scrap metal, alumina, grains, wood chips, gypsum, logs,
salt. They are generally large in quantities and need special handling care.
Food Products: They include frozen meat, sea food, frozen fruits and vegetables, canned and tinned food
items, syrups, jams, pickles, jellies and fresh food products, grains etc. Temperature and moisture level to be
regulated as per requirements and proper storage as well to minimize loss.
Military Equipments and Project Cargo like Windmills, Generators, Air conditioners:They are usually
too large to fit into any containers.
Leather Hides: usually such types of cargo produce strong malodors and hence have to be kept in isolation
especially when hides are soaked in salt.
Fragile Items: They include items like glassware, china wear, clay items and small machinery and tools
which need to be loaded, transported and unloaded with extra care. They must be packed too with extra care.
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Ores/concentrates - these are high-density cargoes and are usually loaded in large quantities on a ship. The
main danger from these cargoes is that they could give rise to toxic vapours that could make the atmosphere
of the tank depleted in oxygen. Hence care should be taken while entering such cargo spaces and these
cargoes should be kept separate from other moist cargoes lest they develop a flow state.
Leather Hides -leather can be a very unpleasant cargo to carry on board a ship and it gives out a very strong
smell which is literally unbearable especially in enclosed spaces. When the hides are soaked with salt they
give out a large amount of brine, so this type of cargo has to be kept in isolation from other cargoes.
Foodgrains - ships are used to transport large amounts of food grain from one place to another and these
include grains such as rice, wheat, seeds and so forth. Needless to say such a cargo needs to be stored in very
sanitized conditions and there is no question of a there been any contact between such cargoes and other
cargoes mentioned previously such as leather. Apart from foodgrains ships can also carry other types of
eatables and these may well require refrigeration to keep them fresh throughout the voyage.
Recommended