QinetiQ Australia's Stability Program is designed to manage the compliance and validation process and the interaction between three major components: Stability, Weight Management and Safety During Docking.
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PLATFORM STABILITY
MANAGEMENT PROGRAM
Violeta Gabrovska
June 2015
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Contents
1. Introduction
2. Stability program governance and management
๏ฏ Stability compliance
๏ฏ Weight management and various interfaces
๏ฏ Docking and slipping
3. Conclusion
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1. Introduction
Stability - critical safety characteristic failure of which may
result in:
loss of life,
early cancellation of a mission and
total loss of a vessel
Maintain low risk of failure - compliance with designated
set of rules
Influencing factors -
lightship growth and
weight distribution
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1. Introduction
Stability Program is
designed to manage the
compliance and validation
process and the interaction
between three major
components:
Stability
Weight management
Safety during docking
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1. Introduction
Stability Management Program :
identifies requirements and their application
provides structure and management tools
assures vessels will have sufficient stability and
structural strength to operate in the defined service
category, environment and during maintenance periods
demonstrate compliance with the DEF (AUS) 5000
regulations or other designated rules as a minimum
assurance for safe operation
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2. Stability program governance and management
Program management plan โ governing document
Management structure โ dynamic, allows flexibility in priorities
and can be amended as the needs change
Work instructions โ describe the process
Custom tailored supporting tools:
compliance matrix;
activity schedule;
activity templates and check lists;
calculation spread sheets; and
vessel specific continuous compliance monitoring tools
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2. Stability program governance and management
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Governing structure
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2.1 Stability
Stability compliance - KG (VCG) curve
Limiting KG curve is developed for each RAN class of ships -
trialling the highest KG for various intact and damage criteria
while still complying with all stability requirements
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Once approved by the NA,
the Limiting KG Curve
becomes the stability
standard
Example โ refer to the
chart
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2.1 Stability
Compliance margins
With aging, platformโs KG (VCG) and displacement margins
will be reduced due to capability upgrade, change in
operational requirements or various reasons and in some
cases those margins can be depleted, which may require
limitations on operation to maintain compliance, for example:
To reduce VCG โ using ballast, increasing min BFR;
To reduce displacement - limiting fuel, fresh water, other
effects;
Limiting operational environment
Those limitations if not resolved, may limit the vessel ability to
complete the desired mission.
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2.1 Stability
NA controls the compliance margins by assigning a stability
status for each class, which also influences the period at which
the stability compliance is verified and T&S Handbook updated
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Stat D e f i n i t i o n
1 An increase in displacement and rise in KG are acceptable without compensation provided each
change is within the limits, and changes are notified to the Support Authority
2 Neither an increase in displacement nor a rise in KG can be accepted without prior approval of the
Naval Authority. Weight and moment compensation are required for all changes.
3 An increase in displacement is acceptable within the limits specified below, but a rise in KG must
be avoided. Moment compensation only is required. Ships with this status are permitted alterations
up to the limits specified below provided net weight increases occur below the lightship KG given
in the most recent T&S Handbook or net weight reductions occur above the same KG. Changes
shall be notified to Support Authority
4 A rise in KG is acceptable within the limits specified below, but an increase in displacement cannot
be accepted without prior approval of the Naval Authority. Weight compensation is required for all
changes
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2.1 Stability
Management of compliance margins
Management of the stability configuration and changes to the
physical state of the vessels are responsibility of each SPO:
Stability schedule
Weight control
Monitoring of stability compliance
Interim checks
Stability in harbour environment
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2.2 Weight management
Necessity
All RAN ships have to maintain:
limiting displacement (maximum weight a ship can
displace without adversely affecting ship stability,
structure or design speed) and
vertical centre of gravity
to ensure adequate reserves of stability and hull girder strength
Weight management is implemented to ensure the ship
remains below those limits throughout its life
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2.2 Weight management
Contributing factors to weight change
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Configuration change: Operational:
Modifications -
๏ฏ Design enhancement
๏ฏ Upgrade
๏ฏ New capability
Obsolescence
Maintenance
(accumulation of
spare parts)
Personal effects
Recreational sport
Change in loading
conditions
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2.2 Weight management
Managing weight and moments: effort is required from both
sides - SPO and operator
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2.2 Weight management
Weight Register โ
Available for assessment of configuration change proposal and
is updated after implementation
Provides continuous monitoring between compliance validations
Ship check โ
Lightship โ Naval & Ship Stores
Provisions and stores โ food, spare parts & tools etc.
Crew and effects โ incl. recreational sport items
Miscellaneous - rigging, specialised equipment, gym etc.
Change in loading conditions โ trainees, containers etc.
The program offers a link between regulator and operator by
providing up to date information about any changes in stability
configuration
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2.2 Weight management
Weight Register
Developed for each vessel โ example โ
3 vessels in a class, stability status 2,3 or 4, stability check
every 2 years โ each vessel stability is checked once in 6
years
1-st tab โ Instructions and Definitions,
2-nd tab โ Limitations, compliance with the KG curve
3-rd โ Weight Register, entry of weight changes
Lightship measurements - updated after stability check
Loading conditions updated when necessary
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2.2 Weight management
Weight Register
Limitations โ
continuous monitoring of
the compliance with the
KG (VCG) curve
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2.2 Weight management
Weight Register
Recording all weight changes to lightship
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2.2 Weight management
Example
KG (VCG): 3mm margin on VCG
How easy is to exceed this
margin? (2000t displacement vessel)
-1.2t from ER
+0.3t on bridge
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2.2 Weight management
Displacement:
Margin - 3.130t (0.16% of the limiting ๏)
How easy is to monitor this margin?
Tonnes per Centimetre immersion (TPC) ~6.00t
Margin โ less than 5mm draft to limiting draft
For practical reason margin on displacement should not be
less than the TPC
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2.2 Weight management
Additional application of weight management:
Supporting Life of Type Extension (LOTE) programs
Supporting management of the interface between
launching/lifting equipment capacity and lifting loading
condition of small vessels
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2.3 Docking and slipping
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Important aspects for safe and successful docking:
Safety of the vessel during slipping/docking
Adequacy of the facility and qualification
Protection of the vessel during lay period
Adequacy of procedures
Personnel qualifications
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2.3 Docking and slipping
The program can assist with:
Dockyard qualification assessment
Docking calculations and plan - Library of selected
dockyards spread-sheets
Weight management โ WR used for configuration change
implementation during maintenance periods, refer to
Risk management during the docking period โ utilaising
WR & docking spread-sheets for compliance monitoring
Contingency plan
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