Single deck ships designed to carry homogeneous unpacked dry cargoes such
as sugar or cereals. Such ships have large hatchways to facilitate cargo handling,
hopper sides and wing tanks. The latter are used either for the carriage
of grain, other bulk cargoes or water ballast. Bulk carriers, or bulkers as they
are sometimes called, are built in a wide range of sizes and are generally gearless,
although smaller vessels may have their own gear.
A variety of specialised types of bulk carrier have evolved, and a number are
mentioned here.
Alumina carrier: typically having four holds, she is fully enclosed because
of the amount of alumina dust generated by conventional systems. Loading
is effected by means of a chute lowered into the holds. Self- discharging is
achieved by opening gates in the floor of the holds, which allows the cargo
to drop on to conveyor belts leading to one end. Mechanical or pneumatic
equipment elevates it to deck level.
Bulk newsprint carrier: designed to carry rolls of newsprint, having
gantry cranes to lift the cargo on and off, such ships may also be suitable for
the carriage of timber cargoes and containers, thus reducing the number of
voyages in ballast.
Bulk/container carrier: multi- purpose ship designed to carry a full cargo
of containers or dry bulk such as grain, coal and ore. This capability enables the
ship to operate in a wider range of trades and reduces the number of voyages
in ballast. It is also referred to as a container/bulk carrier or conbulker.
Bulk- ore carrier: having wide hatchways and a high centre of gravity, this
ship has self- trimming holds, that is, she is shaped in such a way that the cargo
levels itself. This makes such ships suitable for the carriage of grain.
Capesize vessel: bulk carrier of over 80,000 tonnes deadweight, not able
to transit the Suez Canal or Panama Canal so must round the Cape of Good
Hope or Cape Horn.
Cement carrier: type of bulk carrier specially designed for the carriage of
cement. Self- unloading ships, they have one or more conveyor belts running
fore and aft which carry the cargo to the stern where one of several means of
elevating bring the cargo to deck level where it is transferred to a boom for
discharging. Because of the problems with dust, special terminal facilities
are required. Cement is also carried on general cargo ships and small bulk
carriers.
Chinamax: bulk carrier of 400,000 tonnes deadweight, designed for the
trade in iron ore between Brazil and China. This type of vessel is included in
the category of very large ore carrier (VLOC).
Collier: normally with three, four or five holds, she has large hatchways to
give rapid discharge by allowing the grabs easy access to all parts of the holds.
Loading is effected by gravity from chutes. Some colliers have conveyor belts
for discharging, in which case they are said to be self- unloaders.
Handymax: bulk carrier of 35,000–50,000 tonnes deadweight, so called
because it is suitable for many different trades.
Handysized bulker or handysized bulk carrier: bulk carrier at the
smaller end of the range of sizes associated with this type of ship, of 10,000–
35,000 tonnes deadweight. Within this category are ships which are intended
to trade into the Great Lakes of North America; their dimensions are within
the constraints of the St Lawrence Seaway which is the limiting factor in this
trade. Also spelled handy- sized.
Ice- breaking bulk carrier: bulk carrier whose hull is strengthened to
enable her to navigate in conditions of ice, particularly in the ore trade carried
on in the Canadian Arctic.
Laker: ship specially designed to trade in the North American Great Lakes
system. Lakers are normally geared and possess an unusually large number
of hatches. Some lakers never leave the Lakes and indeed a few are too large
to negotiate the St Lawrence Seaway’s locks which lead to the St Lawrence
River and thence to the Atlantic. Others trade worldwide to avoid being laid
up in the Lakes during the winter when the Seaway closes. Lakers are used
principally to carry iron ore from the St Lawrence and from ore terminals
within the Lakes to steel mills in the US mid- West and grain from the western
Lakes to the St Lawrence.
Log carrier: any bulk carrier used for carrying logs; this ship requires a
high cubic capacity because of the stowage factor of this cargo.
Mini- bulker: vessel of about 3,000 tonnes deadweight which has the constructional
features of a bulk carrier, having a single deck, hoppered holds and
wing tanks, but which is smaller. As with the larger bulk carriers, the minibulk
carrier may be geared or gearless. Equally, she may have hatch covers
capable of taking timber deck cargo or shipping containers.
Open hatch bulk carrier: type of bulk carrier whose hatch openings correspond
in size to the floor of the holds. This allows the crane to position
cargo for stowage directly into its location for the voyage and enables it to
be lifted out without first being moved sideways. This configuration speeds
up cargo handling and reduces damage. Such vessels are widely used for the
carriage of reels of paper.
Ore carrier: large ship, generally gearless and with large hatchways,
designed to be used for the carriage of various types of ore. Because of the
high density of ore, ore carriers have a relatively high centre of gravity to
prevent them being stiff when at sea, that is, rolling heavily with possible stress
to the hull. This high centre of gravity is achieved by having relatively small
cargo holds (small because the cargo takes up relatively little space) built over
deep double- bottoms.
Ore pellet carrier: ship which must be equipped with suitable fire- fighting
equipment since this type of cargo is prone to spontaneous combustion.
Panamax bulk carrier: vessel of about 60–70,000 tonnes deadweight,
capable of transiting the Panama Canal.
Sail- assisted bulk carrier: bulk carrier which is conventionally constructed
except for having two rectangular rigid sails mounted athwartships in
a position forward of, and consequently out of the way of, the forward- most
hatch covers. Savings in fuel and exhaust gas emission combined with greater
stability are claimed for this design, which involves an on- board computer
determining the most efficient angle for the sails.
Self- trimming ship or self- trimmer: ship whose holds are shaped in
such a way that a bulk cargo loaded into her will level itself.
Self- unloader: ship equipped with gear to enable her to discharge without
using shore equipment. Vessels of this type are used in the iron ore and coal
trades. Typical gear is a boom conveyor, which is capable of a high rate of discharging
from ship to shore or from ship to ship. Often, this is fed by opening
gates on the floor of the holds, thus allowing the cargo to drop onto conveyor
belts. It is then taken to one end where it is elevated to deck level by mechanical
or pneumatic means.
Timber carrier: ship which is usually geared and with large hatchways.
Sometimes referred to as a forest products carrier.
Universal bulk carrier: early bulk carrier designed to carry a wide range
of bulk cargoes (but only one at a time). She has separate upper holds which
could be used for ballast or for dense cargoes such as iron ore, while the main
holds carry less dense cargoes.
Valemax: proprietary name for a bulk carrier of 400,000 tonnes deadweight,
designed to carry iron ore from Brazil to China. This vessel is included
in the category of very large ore carrier.
Very large ore carrier: largest of the bulk carriers, of no official size, but
often described as being of 250,000 tonnes deadweight or above.
Woodchip carrier: vessel designed to carry woodchips in bulk. Normally
in the size range 20,000 to 60,000 tonnes deadweight, such vessels have a high
cubic capacity because of the high stowage factor of this commodity which
enables them to be loaded to their marks. Discharging is effected in one of
various ways, for example pneumatic conveyor belts or buckets. The advantage
of woodchips over other timber products, as far as shipping is concerned,
is that they are quicker to handle and are consequently more economic to
transport.
Woodpulp carrier: ship whose holds are box- shaped, that is, with vertical
sides and having no obstructions, so as to allow the cargo, which is presented
in large blocks, to be stowed efficiently. Some ships have side doors to allow
loading of these blocks of wood pulp when they are palletised. If the ship is also
used to carry paper rolls, she must have adequate dehumidifying equipment.
Which is better container or bulk carrier?
Bulk carriers receive a lot of headline attention because they carry major commodities such as steel and iron, but container purchases and delivery rates are arguably more indicative of broader economic conditions.