Environmental Engineering Reference
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Fig. 9 Arrows showing where in this case shear forces act; i.e., where two tank sections next to
each other, one being fully ballasted having more gravity ( G ) than the empty tank section, where
the buoyancy ( B ) effect is stronger
Fig. 10 Arrows showing the acting of bending forces with increased buoyancy ( B ) in the amid-
ships and increased gravity ( G ) in fore and aft part, causing longitudinal defl ection of the vessel
hull, so called hogging
Fig. 11 Arrows showing the acting of bending forces with increased buoyancy ( B ) in the fore and
aft part and increased gravity ( G ) in the amidships part, causing longitudinal defl ection of the vessel
hull, so called sagging
ballast-related procedures has to lay special emphasis on safety. The interim phases
in loading and discharging ballast water generate changes that usually exert differ-
ent negative infl uence on a vessel's stability and induce additional static forces on
the vessel hull (see Figs. 9 , 10 and 11 ). Improper management of cargo and ballast
operation may result in structural failure of the vessel hull in the port (see Fig. 12 )
or even results in the vessel to capsize.
When the vessel is sailing, she is exposed to more dynamic conditions as com-
pared to being in a port, infl uenced from the outside by waves and wind (see Figs. 13
and 14 ). One of the undesirable effects is that caused by free surfaces affecting
vessels stability, where ballast water is able to move inside the tanks if these are not
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