Requirements Concerning Load Line: International Association of Classification Societies
Requirements Concerning Load Line: International Association of Classification Societies
Requirements concerning
LOAD LINE
                                     CONTENTS
L1 Deleted
L3 Intact stability of tankers during liquid transfer operations Deleted May 2001
L1       Deleted
(cont)
                                 End of
                                 Document
                   Page 1 of 1
                                                                                                   L2
L2
L2        Intact stability – matter of class
(1988)
 (cont)
(Rev.1    All new ships with a length of 24 m and above will be assigned class only after it has been
June      demonstrated that their intact stability is adequate for the service intended.
2000)
(Rev.2    Adequate intact stability means compliance with standards laid down by the relevant
Apr       Administration or those of the Classification Society taking into account the ship’s size and
2013)     type. The level of intact stability for ships with a length of 24 m and above in any case should
          not be less than that provided by Part A of IMO Resolution MSC.267(85) as applicable to the
          type of ship being considered.
          Where other criteria are accepted by the Administration concerned, these criteria may be
          used for the purpose of classification.
          Evidence of approval by the Administration concerned may be accepted for the purpose of
          classification.
NOTES
          2.   The "contracted for construction" date means the date on which the contract to build the
               vessel is signed between the prospective owner and the shipbuilder. For further details
               regarding the date of "contract for construction", refer to IACS Procedural Requirement
               (PR) No. 29.
                                                                                             End of
                                                                                             Document
                                                            ▲
                                                            ▲
                                                                                                              L4
L4
S18       Closure of Chain Lockers
(Nov
(cont)
2002)     This Unified Requirement is applicable to ships with a length of 24 m and above built in
(Rev.1    accordance with the 1966 Load Line Convention or the 1988 Protocol to the Load Line
July      Convention and the keels of which are laid or which are at a similar stage of construction on
2003)     or after 1 July 2003.
(Rev.2
Nov       1.    Spurling pipes and cable lockers are to be watertight up to the weather deck.
2005)     Bulkheads between separate cable lockers (see Arrangement 1), or which form a common
(Rev.3    boundary of cable lockers (see Arrangement 2), need not however be watertight.
Mar
2011)     2.    Where means of access is provided, it is to be closed by a substantial cover and
(Corr.1   secured by closely spaced bolts.
Aug
2011)     3.     Where a means of access to spurling pipes or cable lockers is located below the
          weather deck, the access cover and its securing arrangements are to be in accordance with
          recognized standards* or equivalent for watertight manhole covers. Butterfly nuts and/or
          hinged bolts are prohibited as the securing mechanism for the access cover.
          4.    Spurling pipes through which anchor cables are led are to be provided with
          permanently attached closing appliances** to minimize water ingress.
Notes:
          2.      The “contracted for construction” date means the date on which the contract to build the vessel
          is signed between the prospective owner and the shipbuilder. For further details regarding the date of
          “contract for construction”, refer to IACS Procedural Requirement (PR) No. 29.
                                                                                                        End of
                                                                                                        Document
            Active and passive systems are defined in paragraph 2. This UR covers passive systems and
            the off-line operation mode of active systems only.
            The requirements in this UR apply to stability software on ships contracted for construction on
            or after 1 July 2005.
1. General
Note:
            1. The “contracted for construction” date means the date on which the contract to build
               the vessel is signed between the prospective owner and the shipbuilder. For
               further details regarding the date of “contract for construction”, refer to IACS Procedural
               Requirement (PR) No.29.
           -        The onboard computer software for stability calculations is to be ship specific and
                    the results of the calculations are to be only applicable to the ship for which it has
                    been approved.
2. Calculation Systems
           an active system replaces the manual entry with sensors reading and entering the contents of
           tanks, etc.; and
           a third system, an integrated system, controls or initiates actions based on the sensor-
           supplied inputs and is not within the scope of this UR.
           Four types of calculations performed by stability software are acceptable depending upon a
           vessel’s stability requirements:
Type 1
           Software calculating intact stability only (for vessels not required to meet a damage stability
           criterion).
Type 2
           Software calculating intact stability and checking damage stability on basis of a limit curve
           (e.g. for vessels applicable to SOLAS Part B-1 damage stability calculations, etc.) or checking
           all the stability requirements (intact and damage stability) on the basis of a limit curve.
Type 3
           Software calculating intact stability and damage stability by direct application of pre-
           programmed damage cases based on the relevant Conventions or Codes for each loading
           condition (for some tankers etc.).
Type 4
           Software calculating damage stability associated with an actual loading condition and actual
           flooding case, using direct application of user defined damage, for the purpose of providing
           operational information for safe return to port (SRtP).
           Damage stability of both Type 3 and Type 4 stability software shall be based on a hull form
L5         model, that is, directly calculated from a full three-dimensional geometric model.
(cont’d)
           4.      Functional requirements:
           4.1.1   The calculation program shall present relevant parameters of each loading
                   condition in order to assist the Master in his judgement on whether the ship is
                   loaded within the approval limits. The following parameters shall be presented for
                   a given loading condition:
- deadweight data;
- lightship data;
- trim;
                   - compliance with stability criteria: Listing of all calculated stability criteria, the limit
                     values, the obtained values and the conclusions (criteria fulfilled or not fulfilled) (not
                     applicable for Type 2 software which uses limit curve for checking all the stability
                     requirements. However, if intact stability criteria are given in addition to the limit
                     curve, the limit values, the obtained values and the conclusion shall be indicated).
           4.1.2   A clear warning shall be given on screen and in hard copy printout if any of the
                   loading limitations are not complied with.
- Restrictions to the stowage height for timber where timber load lines are assigned.
           4.1.3   Type 3 software is to include pre-defined relevant damage cases according to the
                   applicable rules for automatic check of a given loading condition.
           4.1.4 The date and time of a saved calculation shall be part of the screen display and hard
                 copy printout.
           4.1.5 Each hard copy printout shall contain identification of the calculation program
                 including version number.
           4.1.6   Units of measurement are to be clearly identified and used consistently within a
                   loading calculation.
           4.1.7   For Type 3 and Type 4 software, the system shall be pre-loaded with a detailed
L5                 computer model of the complete hull, including appendages, all compartments, tanks
(cont’d)           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, as applicable
                   and according to the type of stability software.
           4.1.8   For Type 1 and Type 2 software, in case a full three dimensional model is used for
                   stability calculations, the requirements of the computer model are to be as per
                   paragraph 4.1.7 above to the extent as applicable and according to the type of
                   stability software.
           4.2.1   The normal (Type 1, 2 and 3) and SRtP (Type 4) software need not be “totally
                   separated”. Where the normal and SRtP software are not totally separated:
                   • the function of switching between normal software and Type 4 software shall be
                     provided.
                   • the actual intact loading condition is to be the same for both functions (normal
                     operation and SRtP); and
           4.2.2   In passenger ships which are subject to SRtP and have an onboard stability computer
                   and shore-based support, such software need not be identical.
           4.2.3   Each internal space shall be assigned its permeability as shown below, unless a more
                   accurate permeability has been reflected in the approved stability information.
                                                              Permeability
                        Spaces           Default           Full     Partially filled       Empty
                      Container           0.95             0.70           0.80              0.95
                        Spaces
                      Dry Cargo           0.95             0.70                0.80         0.95
                        spaces
                    Ro-Ro spaces          0.95             0.90                0.90         0.95
                    Cargo liquids         0.95             0.70                0.80         0.95
                     Intended for         0.95             0.95                0.95         0.95
                     consumable
                        liquids
                        Stores            0.95             0.60            (0.60)           0.95
                     Occupied by                                   0.85
                      machinery
                     Void spaces                                   0.95
                     Occupied by                                   0.95
                   accommodation
           4.2.4   The system shall be capable of accounting for applied moments such as wind, lifeboat
                   launching, cargo shifts and passenger relocation.
           4.2.5   The system shall account for the effect of wind by using the method in SOLAS
L5                 regulation II-1/7-2.4.1.2 as the default, but allow for manual input of the wind
(cont’d)           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).
           4.2.6   The system shall be capable of assessing the impact of open main watertight doors
                   on stability (e.g. for each damage case provided for verification, additional damage
                   stability calculation shall be done and presented, taking into account any watertight
                   door located within the damaged compartment(s)).
           4.2.7   The system shall utilize the latest approved lightship weight and centre of gravity
                   information.
           4.2.8   The output of the software is to be such that it provides the master with sufficient clear
                   unambiguous information to enable quick and accurate assessment of the stability of
                   the vessel for any actual damage, the impact of flooding on the means of escape and
                   the controls of devices necessary for managing and/or controlling the stability of the
                   ship.
                   When the actual loading condition is input in the SRtP software, the following output
                   (intact stability) shall be available:
- deadweight data;
- lightship data;
- trim;
- heel;
- free surfaces;
- GM value;
                   - GZ values relevant to an adequate range of heeling (not less than 60°) available
                     indicatively at the following intervals: 0 5 10 15 20 25 30 40 50 60 deg;
                   - compliance with relevant intact stability criteria (i.e. 2008 IS Code): listing of all
                     calculated intact stability criteria, the limiting values, the obtained values and the
                     evaluation (criteria fulfilled or not fulfilled);
                   When the actual loading condition is associated to the actual damage case(s) due to
                   the casualty, the following output (damage stability) shall be available:
- trim;
- heel;
- GM value;
                   - GZ values relevant to an adequate range of heeling (not less than 60°) available
                     indicatively at the following intervals: 0 5 10 15 20 25 30 40 50 60 deg;
                   - compliance with stability criteria: listing of all calculated stability criteria, the limit
                     values, the obtained values and the conclusions (criteria fulfilled or not fulfilled);
                   - the survivability criteria for Type 4 software (SRtP) are left to the discretion of the
                     Administration;
                   - relevant flooding points (unprotected or weathertight) with the distance from the
                     damage waterline to each point;
                   - a profile view, deck views and cross-sections of the ship indicating the flooded water-
                     plane and the damaged compartments.
           4.2.9   For ro-ro passenger ships there shall be algorithms in the software for estimating the
                   effect of water accumulation on deck (WOD) (e.g. 1. In addition to the predefined
                   significant wave height taken from the approved stability document, there shall be
                   possibility for the crew to input manually the significant wave height of the ship
                   navigation area in the system, 2. In addition to the predefined significant wave height
                   taken from the approved stability document, calculations with two additional significant
                   wave heights shall be submitted for checking the correctness of the algorithms in the
                   software for estimating the effect of WOD). *
           * This paragraph applies to Ro-Ro Passenger ships subject to the Stockholm Agreement
           (IMO Circular Letter No. 1891)
           5.      Acceptable Tolerances
L5
(cont’d)   Depending on the type and scope of programs, the acceptable tolerances are to be
           determined differently, according to 5.1 or 5.2. Deviation from these tolerances shall not be
           accepted unless the Society considers that there is a satisfactory explanation for the
           difference and that there will be no adverse effect on the safety of the ship.
Hydrostatic data: Displacement, LCB, LCF, VCB, KMt and MCT versus draught.
           Compartment data:           Volume, LCG, VCG, TCG and FSM/ Grain heeling
                                       moments vs level of the compartment’s contents.
           Hydrostatic data:          Displacement, LCB, LCF, VCB, KMt and MCT versus
                                      draught as well as actual draughts, trim.
           Stability data:            FSC (free surface correction), GZ-values, KG, GM, KG/GM
                                      limits, allowable grain heeling moments, derived stability
                                      criteria, e.g. areas under the GZ curve, weather criteria.
           Compartment data:          Calculated Volume, LCG, VCG, TCG and FSM/ Grain
                                      heeling moments vs level of the compartment’s contents.
           The computational accuracy of the calculation program results shall be within the acceptable
           tolerances, specified in 5.1 or 5.2, of the results using an independent program or the
           approved stability information with identical input.
           5.1     Programs which use only pre-programmed data from the approved stability
                   information as the basis for stability calculations, shall have zero tolerances for
                   the printouts of input data.
                   Additionally differences associated with the use of hydrostatic and stability data
                   for trims that differ from those in the approved stability information, are
                   acceptable subject to review by the individual Society.
           5.2    Programs which use hull form models as their basis for stability calculations,
                  shall have tolerances for the printouts of basic calculated data established
                  against either data from the approved stability information or data obtained using the
                  approval authority’s model. Acceptable tolerances shall be in accordance
                  with Table 1.
           Table 1
L5
(cont’d)
           Hull Form Dependent
           Displacement                                                                             +/- 2%
           Longitudinal center of buoyancy, from AP                                            +/- 1% / 50 cm
           Vertical center of buoyancy                                                          +/- 1% / 5 cm
           Transverse center of buoyancy                                                    +/- 0.5% of B / 5 cm
           Longitudinal center of flotation, from AP                                           +/- 1% / 50 cm
           Moment to trim 1 cm                                                                      +/- 2%
           Transverse metacentric height                                                        +/- 1% / 5 cm
           Longitudinal metacentric height                                                     +/- 1% / 50 cm
           Cross curves of stability                                                               +/- 5 cm
Compartment dependent
Notes:
           2.       When applying the tolerances in Table 1 having two values, the allowable tolerance is the greater of the
                    two values.
           3.       Where differences in calculation methodology exist between the programs used in the comparison, this
                    may be a basis for accepting deviations greater than that specified in Table 1 provided a software
                    examination is carried out in sufficient detail to clearly document that such differences are technically
                    justifiable.
           4.       Deviation from these tolerances shall not be accepted unless the Society considers that there is a
                    satisfactory explanation for the difference and that it is clearly evident from the Society’s stability
                    calculations that the deviation does not impact compliance with the required stability criteria for the ship
                    under consideration.
           6.     Approval Procedure
L5
(cont’d)   Conditions of approval of the onboard software for stability calculations
The onboard software used for stability calculations is subject to approval, which is to include;
           -      verification that the data used is consistent with the current condition of the ship.
                  (Refer to paragraph 6.2);
           -      verification that the software is appropriate for the type of ship and stability
                  calculations required;
           The satisfactory operation of the software with the onboard computer(s) for stability
           calculations is to be verified by testing upon installation. (Refer to paragraph 8). A copy of the
           approved test conditions and the operation manual for the computer/ software are to be
           available on board.
           Upon application to the Society for general approval of the calculation program, the Society
           may provide the applicant with test data consisting of two or more design data sets, each of
           which is to include a ship’s hull form data, compartmentation data, lightship characteristics
           and deadweight data, in sufficient detail to accurately define the ship and it’s loading
           condition. Acceptable hull form and compartmentation data may be in the form of surface
           coordinates for modeling the hull form and compartment boundaries, e.g: a table of offsets, or
           in the form of pre-calculated tabular data, e.g: hydrostatic tables, capacity tables, etc.,
           depending upon the form of data used by the software being submitted for approval.
           Alternatively, the general approval may be given based on at least two test ships agreed
           upon between the society and the applicant.
           In general, the software is to be tested for two types of ships for which approval is requested,
           with at least one design data set for each of the two types. Where approval is requested for
           only one type of ship, a minimum of two data sets for different hull forms of that type of ship
           are required to be tested. For calculation software which is based on the input of hull form
           data, design data sets shall be provided for three types of ships for which the software is to
           be approved, or a minimum of three data sets for different hull forms, if approval is requested
           for only one type of ship. Representative ship types which require different design data sets
           due to their hull forms, typical arrangements, and nature of cargo include: tanker, bulk carrier,
           container ship, and other dry cargo and passenger ships. The test data sets shall be used by
           the applicant to run the calculation program for the test ships. The results obtained (together
           with the hydrostatic data and cross-curve data developed by the program, if appropriate) shall
           be submitted to the Society for the assessment of the program’s computational accuracy. The
           Society shall perform parallel calculations using the same data sets and a comparison of
           these results will be made against the applicant’s submitted program’s results.
           -      Upon application to the Society for data verification, the Society and the
                  applicant shall agree on a minimum of four loading conditions, taken from the
                  ship’s approved stability information, which are to be used as the test conditions. For
                  ships carrying liquids in bulk, at least one of the conditions shall include
                  partially filled tanks. For ships carrying grain in bulk, one of the grain loading
                  conditions shall include a partially filled grain compartment. Within the test
                  conditions each compartment shall be loaded at least once. The test
                  conditions normally are to cover the range of load draughts from the
                  deepest envisaged loaded condition to the light ballast condition and shall
                  include at least one departure and one arrival condition.
                  For Type 4 stability software for SRtP, the Society shall examine at least three
                  damage cases, each of them associated with at least three loading conditions taken
                  from the ship’s approved stability information. Output of the software is to be
                  compared with results of corresponding load / damage case in the approved damage
                  stability booklet or an alternative independent software source.
           -      The Society is to verify that the following data, submitted by the applicant, is
                  consistent with arrangements and most recently approved lightship
                  characteristics of the ship according to current plans and documentation on file
                  with the Society, subject to possible further verification on board:
                  - The position of the forward and after perpendiculars, and if appropriate, the
                    calculation method to derive the forward and after draughts at the actual position of
                    the ship’s draught marks;
                  - Ship lightweight and centre of gravity derived from the most recently approved
                    inclining experiment or light weight check;
                  - Lines plan, offset tables or other suitable presentation of hull form data if necessary
                    for the Society to model the ship;
           Verification by the Society does not absolve the applicant and shipowner of responsibility for
           ensuring that the information programmed into the onboard computer software is consistent
           with the current condition of the ship.
           7.      Operation Manual
L5
(cont’d)   A simple and straightforward operation manual is to be provided, containing descriptions and
           instructions, as appropriate, for at least the following:
- installation
- function keys
- menu displays
- list of warnings
8. Installation Testing
           To ensure correct working of the computer after the final or updated software has been
           installed, it is the responsibility of the ship’s Master to have test calculations carried out
           according to the following pattern in the presence of a Society surveyor:
           From the approved test conditions at least one load case (other than light ship) shall be
           calculated. Note: Actual loading condition results are not suitable for checking the correct
           working of the computer.
Steps to be performed:
           -       Retrieve the test load case and start a calculation run; compare the
                   stability results with those in the documentation.
           -       Change several items of deadweight (tank weights and the cargo weight)
                   sufficiently to change the draught or displacement by at least 10%. The
                   results are to be reviewed to ensure that they differ in a logical way from
                   those of the approved test condition.
           -       Revise the above modified load condition to restore the initial test
                   condition and compare the results. Confirm that the relevant input and output data
                   of the approved test condition have been replicated.
           -       Alternatively, one or more test conditions shall be selected and the test
                   calculation performed by entering all deadweight data for each selected test
                   condition into the program as if it were a proposed loading. The
                   results shall be verified as identical to the results in the approved copy of
                   the test conditions.
           9.     Periodical Testing
L5
(cont’d)   It is the responsibility of the ship’s master to check the accuracy of the onboard computer for
           stability calculations at each Annual Survey by applying at least one approved test condition.
           If a Society surveyor is not present for the computer check, a copy of the test condition
           results obtained by the computer check is to be retained on board as documentation of
           satisfactory testing for the surveyor’s verification.
           At each Special Survey this checking for all approved test loading conditions is to be done in
           presence of the surveyor.
           The program shall monitor operation and activate an alarm when the program is incorrectly or
           abnormally used.
           The program and any data stored in the system shall be protected from corruption by loss of
           power.
           Error messages with regard to limitations such as filling a compartment beyond capacity, or
           exceeding the assigned load line, etc. shall be included.
                                                                                          End of
                                                                                          Document