284-Vessel Stability / 748
Vessel Stabilit
y
BOS-PRD-07.900601
4
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Si
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When using simplified calculations, the
Maste
r
shall
ensure that the vessel vertical height of the centre of
gravity (VCG or KG) falls on or below the maximum allowed max Vertical Centre of Gravity (VCG) curves or
tables and that the draft at the load line mark is not exceeded.
VCG curves are a set of curves for various combinations of displacements and trims and can be calculated
showing VCG for which all required criteria are satisfied. They do not take into account any free surface
effect so the actual loading case VCG value
shall
be corrected for the free surface moment before being
compared with the curve.
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4
F
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If the
Maste
r
has any doubts about the simplified assessment or finds actual VCG close to the VCG
maximum, a full direct calculation
shall
be carried out by manual calculations using tank tables and
hydrostatic data. When loading software is provided on board, it
should
be used in place of manual
calculations.
Before carrying heavy loads, performing crane or anchor handling operations and any other operation with
potential to have a severe effect on the vessel, special stability calculations
shall
be carried out to ensure
that the condition fulfils the stability criterion.
Any loading condition calculated by the
Maste
r
shall
comply with the limiting criteria.
4
.1.
5 L
o
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stabilit
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lati
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All vessels (other than crew boats)
shall
be equipped with loading software for stability calculations. The
software
shall
match with current applicable statutory and class requirements. In particular, software,
calculations and installation on board
shall
be subject to Class review and approval.
4
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6
Stabilit
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of
twa
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stallati
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a
nd u
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The loading software
shall
be installed on board with a redundancy.
Hardware is not subject to Class approval providing that the redundancy can be demonstrated.
Performance of the loading software is included in class survey scope. Class approval is subject to class
tolerances regarding differences between software results and full direct calculations results.
The system
shall
be tested against Class approved Loading Conditions on a regular basis to ensure
operational compliance, accuracy and performance standards. After installation, the approved loading
conditions are to be calculated onboard by the vessel’s personnel with a class society surveyor.
Load testing is the process of putting demand on a system or device and measuring its response. Load
testing is performed to determine a system’s behaviour under both normal and anticipated peak load
conditions.
Records of the tests
shall
be maintained. The time and relevant details of all stability calculations
shall
be
clearly recorded in the vessel’s logbook.
Software manufacturers may differ between vessel types and therefore the software manufacturer reference
manual and integrated ‘HELP’ menu
shall
be used for guidance on completing stability calculations and
assessments.
The system
shall
be used whenever a stability calculation is required and the results compared with the
results from the
Stability Booklet
.
Version 04. Original date: 22/06/2012. Version date: 31/12/2014. Valid version only on QMS site. Uncontrolled document when printed.
Procedure prepared by: BOS Operations Department Project Coordinator. Approved by: BOS Head of Operations. Validated by: BOS Quality Representative.
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