General
1 When an onboard stability computer is provided in accordance with regulation II-1/8-1.3.1.1, the system referred to in these
Guidelines should comprise an onboard stability computer capable of receiving and
processing manual and electronic data to provide the master with regularly updated
operational information on the residual damage stability of the ship after a flooding
casualty. Two-way communication links to shore-based support should also be available to
provide the master with post-damage residual structural strength information.
2 When shore-based support is provided in accordance with regulation II-1/8-1.3.1.2, the system referred to in these
Guidelines should comprise two-way communication links to the shore-based support with a
stability computer capable of receiving and processing manual and electronic data to
provide the master with regularly updated operational information on the residual damage
stability of the ship after a flooding casualty. In addition, the shore-based support
should also have the capability to provide the master with post-damage residual
structural strength information.
3 The stability computers should utilize software with the following
capabilities:
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Using the pre-damage loading condition, software calculating the
residual damage stability following any flooding casualty by processing data from
both manual entry and from sensor readings to compute operational information
required by the master using an accurate and detailed computer model of the entire
hull, including superstructures and appendages, all internal compartments and
tanks, etc. together with up-flooding/down-flooding points, cross-flooding
arrangements, escape routes, ship profile and watertight door status (i.e. open or
closed).
System overview
4 At least two independent stability computers should be available at all
times (either two onboard, or two through shore-based support, or one each), which are
capable of receiving and processing the data necessary to provide operational
information to the master.
5 The onboard system should have an uninterruptible power supply (UPS)
connected to both main and emergency switchboards.
Input
6 The system should be pre-loaded with a detailed computer model of the
complete hull, including appendages, all compartments, tanks and the relevant parts of
the superstructure considered in the damage stability calculation, wind profile,
down-flooding and up-flooding openings, cross-flooding arrangements, internal
compartment connections and escape routes. Each internal space should be assigned its
standard regulation
II-1/7-3 permeability, unless a more accurate permeability has been
calculated.
7 The system should utilize the latest approved lightship weight and centre
of gravity information.
8 Details of the damage location(s) and extent(s) or the damaged
compartments should be input manually by the ship's staff and combined with data from
electronic sensors such as draught gauges, tank level devices, watertight door
indicators and flooding level sensors.
9 If it is considered at any time that a sensor or sensors are faulty, or
have been damaged, the ship's staff should be able to override the sensor data with
manual data. The system should clearly indicate to the operator if a sensor that should
be available is being manually overridden.
10 The system should always be updated to the current loading condition
which will form the basis of any damage stability calculation.
Calculation methods
The system should:
11 Utilize software (see paragraph 3) capable of analysing the damage
stability following any real flooding casualty including multi-compartment, non-linked
breaches.
12 Use the actual pre-damage loading state obtained from the routine
operations mode.
13 Be capable of accounting for applied moments such as wind, lifeboat
launching, cargo shifts and passenger relocation.
14 Account for the effect of wind by using the method in regulation II-1/7-2.4.1.2 as the default, but allow for manual
input of the wind speed/pressure if the on-scene pressure is significantly different (P
= 120 N/m2 equates to Beaufort 6; approximately 13.8 m/s or 27 knots).
15 Be capable of assessing the impact of open main watertight doors on
stability.
16 Have the capability of using the same detailed hull model for damage
control drills or to assess potential damage and stability scenarios during a flooding
casualty. This should not interfere with the ability of the onboard computer or
shore-based support to monitor the actual situation and provide operational information
to the master.
Output
17 The system should output the residual GZ curve both graphically and
numerically. It should also provide the following information: draught (forward,
midships and aft), trim, heel angle, GZ max, GZ range, angle of stability, down-flooding
immersion angles and escape route immersion angles.
18 The output format and units of the information supplied by the ship's staff or
shore-based support team should be consistent with the format and units of the approved
stability booklet in order to facilitate easy comparison. The output should be within
the tolerances specified in the Guidelines for the approval of stability instruments
(MSC.1/Circ.1229).
19 The system should show a profile view, deck views and cross-sections of the ship
indicating the flooded water-plane and the damaged compartments.
Other issues
20 An operation manual should be provided for the system software printed in a language
in which the ship's staff are fully conversant. The manual should also indicate the
limitations of the system.
21 At least two crew members should be competent in the operation of the system
including the communication links to the shore-based support. They should be capable of
interpreting the output of the system in order to provide the required operational
information to the master.
22 When shore-based support is provided in accordance with regulation II-1/8-1.3.1.2, there should be a
contract for the supply of shore-based support at all times during the validity of the
ship's certificate.
23 When shore-based support is provided in accordance withregulation II-1/8-1.3.1.2, the shore-based support
should be manned by adequately qualified persons with regard to stability and ship
strength; no less than two qualified persons should be available to be on call at all
times.
24 When shore-based support is provided in accordance with regulation II-1/8-1.3.1.2, the shore-based support
should be operational within one hour (i.e. with the ability to input details of the
condition of the ship, including structural damage, as instructed).
Strength
25 The system should have the capability of two-way communication with the shore-based
team with an agreed method of specifying and transmitting details of structural loss
and/or degradation.
26 The strength aspects of the shore-based computer should be in compliance with the
requirements of a classification society which is recognized by the Administration.
Ro-ro passenger ships
27 There should be algorithms in the software for estimating the effect of water
accumulation on deck (WOD).
Approval and testing
28 The stability aspects of the system should be initially approved and periodically
checked against validated test conditions based on a number of loading/damage scenarios
from the approved stability information book to ensure that it is operating correctly
and that the stored data has not been subject to unauthorized alteration.
Limitations of the system
29 The system is not intended to compute transient asymmetrical flooding whereby the
ship could capsize under the immediate inrush of floodwater before there is time for
equalization measures to take effect.
30 The system is not intended to make any allowance for the motion of the ship in a
seaway, including the effects of tide, current or wave action.
Equivalence
31 Equivalent arrangements for the provision of operational information to the master
following a flooding casualty may be employed to the satisfaction of the
Administration.