Dans le livre "MODERN RHINE SEA SHIPS" concernant les petits
cargos de type "fluvio-maritime", on trouve :
"A more recent innovation assisted by the presence of side ballast
tanks is the fitting of moveable steel bulkheads. Side tanks can present
a uniform shape throughout a hold which enables large portable steel bulkheads
to be both easily moved and easily fitted at appropriate slots in the
cargo holds. These cargo bulkheads have a number of advantages to both
shippers and shipowners. The shipper is able to ship multiple parcels
of the varying qualities of bulk cargo (or even different cargo) and yet
retain the quality and integrity of these various cargo parcels. As the
bulkhead positions are not fixed the parcel sizes are variable from voyage
to voyage. Prior to this type of arrangement, shippers were frequently
reluctant to ship multiple parcels of bulk cargoes of varying qualities
as their usual method of separation was by tarpaulin or heavy plastic
sheeting, which however carefully fitted and removed, invariably lead
to some cargo contamination or degradation. This new type of cargo separation
also avoids unnecessary time and cost of labour intensive manual separation.
The introduction of the moveable bulkheads in vessels has been particularly
well received in the grain trade as properly used they can avoid the need
to bag the surface of the cargo. Heavy grain such as wheat or barley is
prone to shifting, particularly in heavy weather as a result of free surface
effect upon the cargo. Other agricultural products (such as soya bean
meal) need a greater hold space capacity to deadweight ratio in order
to load a vessel with the same tonnage. The advent of moveable bulkheads
has enabled the same vessel to load to her load line with a higher cubic
cargo and yet use the moveable bulkheads to exclude ullage space but fill
the remaining hold completely. This avoids free surface and removes the
need for bagging cargo which is very labour intensive, time consuming
and relatively expensive compared with handling the same quantity of cargo
in bulk.
The use of portable bulkheads for the carriage of cereals has been extended
to benefit cargo interests wishing to reach ports having a restricted
draft below that required for a fully laden coaster.
Moveable bulkheads can also be utilised to enable vessels to load a full
quantity of homogenous cargo but to maintain an even trim fore and aft.
This is a particular advantage when working to restricted draft locations
on rivers and canaIs. Many vessels tend to trim by the head when loaded
with a cargo having a stowage factor equivalent to the ratio of the vessel's
deadweight to cubic capacity. By creating a small amount of ullage space
aft of the most forward fixed bulkhead, this tendency can be overcome."
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