Part II - Damaged Stability

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Application

5. (1) This Part applies to passenger vessels of more than 15 gross tonnage or carrying more than 12 passengers.

(2) Instead of complying with sections 6 to 15 of this standard, the following vessels may demonstrate an equivalent level of safety by complying with the alternative standard listed as follows:

  1. Undecked vessels with length of less than 24 metres and carrying less than 50 persons may show compliance with the requirements of ISO 12217-1.
  2. Rigid inflatable boats (RIBs) with length of less than 8 metres may show compliance with the requirements of ISO 6185-3. RIBs with length of more than 8 metres and less than 24 metres and carrying less than 50 persons may show compliance with the requirement of ISO 6185-4.
  3. High speed craft (HSC) may show compliance with IMO 2000 HSC Code (International Code of Safety for High Speed Craft, 2000)
  4. Small Multiple-pontoon vessels may show compliance with the “Stability, Subdivision, and Load Line Standards”, TP 7301 STAB 5, Appendix B, provided they meet the Application section of Appendix B.
  5. Small vessels of unusual configuration carrying less than 50 persons may show compliance with a recognized standard acceptable to Transport Canada for this type of vessel.

(3) Except as specified in paragraph (4), any passenger vessel to which this part applies must also be inclined and meet the requirements for intact stability specified in the “Stability, Subdivision, and Load Line Standards”, TP 7301 as amended from time to time.

(4) Instead of complying with the requirements of TP 7301, vessels listed in paragraph (2) may show compliance with the intact stability requirements of the applicable alternative standard.

(5) A vessel that was considered a new vessel for the application of the previous edition of these Standards and that was required to be subdivided at least to a degree of one compartment must continue to meet the requirement of the previous edition until:

  1. an increase in subdivision is required for an existing vessel according to subsection 16(4); or
  2. the vessel undergoes a major modification, the number of persons carried is increased or the area of operation is changed in which case the vessel will be considered a new vessel for the application of the present edition of this standard.

Standard of Subdivision – All Vessels

6. (1) Except as specified in paragraph (2), (3) and (4), for vessels carrying more than 12 passengers, sufficient stability shall be provided in all service conditions so as to enable the vessel to withstand the final stages of flooding of any one main compartment1. Whether or not specifically required by this section to meet at least a one-compartment standard of subdivision, every vessel shall be fitted with at least 3 transverse watertight bulkheads2.

(2) To provide the required stability, vessels subject to subsection (1) carrying less than 50 persons may be fitted with a suitable closed-cell buoyant material, or subdivided into watertight compartments.

(3) Where the vessel is certified to carry 400 or more persons stability shall be adequate to withstand the flooding of any main compartment as follows:

  1. new vessels: any two adjacent main compartments;
  2. existing Ro-Ro passenger vessels: any two adjacent main compartments;

(4) For existing passenger vessels other than Ro-Ro sufficient stability shall be provided to withstand flooding as follows:

NUMBER OF PERSONS CARRIED SUBDIVISION REQUIREMENTS
< 50 unberthed or ≤ 12 berthed 3 transverse watertight bulkheads3
≥ 50< 400 unberthed or
> 12 < 400 berthed
Any one main compartment
≥ 400 < 600 Any two adjacent main compartments flooded within at least 40 percent of the vessel length forward.
Any one main compartment elsewhere
≥ 600 < 800 Any two adjacent main compartments flooded within at least 60 percent of the vessel length forward.
Any one main compartment elsewhere
≥ 800 Any two adjacent main compartments

(5) The requirements of paragraphs (1), (2), (3) and (4) shall be determined by calculations which are in accordance with sections 7, 12, 13, 14 and 15 of this Part and which take into consideration the proportions and design characteristics of the vessel and the arrangement and configuration of the damaged compartments. In making these calculations the vessel is to be assumed in the worst anticipated service condition as regards stability and/or freeboard.

Stability In Swamped Condition

(6) For all new vessels which may be subject to swamping, the stability of the swamped vessel shall be deemed to be sufficient, if the calculation shows that, after open wells or cockpits have been flooded, the final condition of the vessel is as follows:

  1. the metacentric height is positive, but not less than 0.05 metres, and
  2. the minimum freeboard to the top of the well or cockpit is 150 mm.

(7) For all existing vessels that may be subject to swamping, the swamped stability shall be evaluated as specified in paragraph (6) in all cases where the vessel undergoes a major modification, the number of persons carried is increased or the area of operation is changed

Stability Of Passenger Vessels In Damaged Condition – All Vessels

7. (1) Unsymmetrical flooding is to be kept to a minimum consistent with efficient arrangements. Where it is necessary to correct large angles of heel, the means adopted shall, where practicable, be self-acting, but in any case where controls to cross-flooding fittings are provided they shall be operable from above the bulkhead deck. These fittings together with their controls shall built and installed to a recognized standard. The maximum angle of heel after flooding but before equalization shall not exceed 15°.

Where cross-flooding fittings are required, the time for equalization shall not exceed 15 minutes4. Suitable information concerning the use of cross-flooding fittings shall be supplied to the Master of the vessel5.

(2) The final condition of the vessel after damage and, in the case of unsymmetrical flooding, after equalization measures have been taken shall be as follows:

  1. in the case of symmetrical flooding there shall be a positive residual metacentric height of at least 0.05m as calculated by the constant displacement method6;
  2. in the case of unsymmetrical flooding, the equilibrium angle of heel (өEQ) for one-compartment flooding shall not exceed 7°. For the simultaneous flooding of two or more adjacent compartments, the equilibrium angle of heel shall not exceed 12°;
  3. in no case shall the margin line be submerged in the final stage of flooding. vessel

8. (1) In intermediate stages of flooding, the maximum righting lever shall be at least 0.05 m and the range of positive righting levers shall be at least 7°7.

(2) In intermediate stages of flooding, taking into account sinkage, heel and trim, any one of the following shall not occur:

  1. immersion of any vertical escape hatch in the bulkhead deck;
  2. any controls intended for the operation of watertight doors, equalization devices, valves on piping or on ventilation ducts intended to maintain the integrity of watertight bulkheads from above the bulkhead deck become inaccessible or inoperable;
  3. immersion of any part of piping or ventilation ducts carried trough a watertight boundary that is located within any compartment included in damage cases, if not fitted with watertight means of closure at each boundary8.

Sufficiency of Stability in Damaged Condition – New Vessels

9. (1) In addition to Sections 7 and 8 for vessels that:

  1. are certified to operate in Near Coastal Voyage, Class 1 (Home Trade Voyage Class I and II or Inland Waters Voyage Class I)9 or
  2. are certified to carry 50 or more persons and certified to operate in Near Coastal Voyage, Class 2 (Home Trade Voyage Class III or Inland Waters Voyage Class II)9
    The stability required in the final condition after damage and after equalization where provided, shall be determined as follows:
  3. The positive residual righting lever curve shall have a minimum range of 15° beyond the angle of equilibrium. This range may be reduced to a minimum of 10°, in the case where the area under the righting lever curve is that specified in (1)(d) of this section, increased by the ratio:
    15 ÷ range
    where the range is expressed in degrees.
  4. The area under the righting lever curve shall be at least 0.015 metre-radians, measured from the angle of equilibrium to өPF, defined as the lesser of:
    (i) the angle at which progressive flooding occurs;
    (ii) 22° (measured from the upright) in the case of one-compartment flooding, or 27° (measured from the upright) in the case of the simultaneous flooding of two or more adjacent compartments.
    (e) The maximum righting arm shall be at least 0.04m greater than the heeling arm resulting from the greatest of the following heeling moments, calculated as specified in section 15 of this Part:
    (iii) the crowding of all passengers towards one side;
    (iv) the launching of all fully loaded davit-launched survival craft on one side;
    (v) wind pressure.
    (f) The maximum righting arm shall not be less than 0.10m.

10. (1) In addition to sections 7 and 8 for vessels that:

  1. are certified to operate on Sheltered Water Voyage (Home Trade Voyage Class IV, Minor Waters Class I and Minor Waters Class II)9, or
  2. are certified to operate on Near Coastal Voyage, Class 2 (Home Trade Voyage Class III or Inland Waters Class II)9 and carry less than 50 persons.

shall have a maximum righting arm greater than the heeling arm resulting from the greatest of the following effects, calculated as specified in section 15 of this Part:

  1. the crowding of all passengers towards one side;
  2. the launching of all fully loaded davit-launched survival craft on one side;
  3. wind pressure.

Sufficiency of Stability in Damaged Condition – Existing Vessels

11. (1) The area under the righting lever curve of vessels that is specified in (2) of this section, shall be measured from the angle of equilibrium to the lesser of:

  1. the angle at which progressive flooding occurs;
  2. 22° (measured from the upright) in the case of one-compartment flooding, or 27° (measured from the upright) in the case of the simultaneous flooding of two or more adjacent compartments.

(2) In addition to Sections 7 and 8 the area under the righting lever curve for vessels carrying 50 or more persons certified to operate on:

  1. Near Coastal Voyage, Class 1 (Home Trade Voyage Class I and Home Trade Voyage Class II)9 shall be greater than 0.015 metre-radians;
  2. Near Coastal Voyage, Class 2 (Home Trade Voyage Class III and Inland Voyage Class I and II)9 shall be greater than 0.0075 metre-radians

(3) In addition to Sections 7, 8 and 11(2) the maximum righting arm for all existing vessels shall be greater than the heeling arm resulting from the greatest of the following effects, calculated as specified in section 15 of this Part:

  1. the crowding of all passengers towards one side;
  2. the launching of all fully loaded davit-launched survival craft on one side;
  3. wind pressure.

Principles for Calculations

12. (1) In all cases, only one breach in the hull and only one free surface need be assumed.

(2) Where it is proposed to fit decks, inner skins or longitudinal bulkheads of sufficient tightness to seriously restrict the flow of water, proper consideration shall be given to such restrictions in the calculations, as follows:

  1. Intermediate stages of flooding shall be evaluated where the flooding water is limited to the outside of the decks, inner skins or bulkheads in consideration;
  2. The provisions of 7(1) and 8(1) concerning intermediate stages of flooding shall be applied to these cases.

13. (1) For the purpose of making damage stability calculations, the volume and surface permeabilities shall be as follows:

SPACES PERMEABILITY
Appropriated to cargo, coal or stores 60
Occupied by accommodation 95
Occupied by machinery 85
Intended for liquids 0 or 9510

Higher surface permeabilities are to be assumed in respect of spaces which, in the vicinity of the damage waterplane, contain no substantial quantity of accommodation or machinery and spaces which are not generally occupied by any substantial quantity of cargo or stores.
14. (1) The assumed extent of damage shall be as follows:

  1. longitudinal extent: 10% the length of the vessel; 3 m plus 3% of the length of the vessel; or 11 m, whichever is the less11;
  2. transverse extent (measured inboard from the vessel's side at right angles to the centreline at the level of the deepest subdivision load line): a distance of one fifth of the breadth of the vessel; and
  3. vertical extent: from the base line upwards without limit;
  4. if any damage of lesser extent than that indicated in this subsection would result in a more severe condition regarding heel or loss of metacentric height, such damage shall be assumed in the calculations.

15. (1) Heeling moments shall be calculated according to the following:

  1. Moments due to crowding of passengers:
    • four passengers per square metre;
    • a mass of 75 kg for each passenger;
    • passengers shall be distributed on available deck areas towards one side of the vessel on the decks where muster stations are located and in such a way that they produce the most adverse heeling moment.
  2. Moments due to launching of all fully loaded davit-launched survival craft on one side:
    • all lifeboats and rescue boats fitted on the side to which the vessel has heeled after having sustained damage shall be assumed to be swung out fully loaded and ready for lowering;
    • for lifeboats which are arranged to be launched fully loaded from the stowed position, the maximum heeling moment during launching shall be taken;
    • a fully loaded davit-launched liferaft attached to each davit on the side to which the vessel has heeled after having sustained damage shall be assumed to be swung out ready for lowering;
    • persons not in the lifesaving appliances, which are swung out, shall not provide either additional heeling or righting moment;
    • lifesaving appliances on the side of the vessel opposite to the side to which the vessel has heeled shall be assumed to be in a stowed position.
  3. Moments due to wind pressure:
    • a wind pressure of 120 N/m2 to be applied;
    • the area applicable shall be the projected lateral area of the vessel above the waterline corresponding to the intact condition;
    • the moment arm shall be the vertical distance from a point at one half of the mean draught corresponding to the intact condition to the centre of gravity of the lateral area.

(2) For the purpose of calculating the heeling arm in section 9(1)(e) of this Part, the heeling arm shall be calculated as follows:
Heeling arm = Heeling moment ÷ displacement

(3) For the purpose of constructing a heeling arm curve to show compliance with sections 10(1) or 11(3) the heeling arm shall be calculated as follows:
Heeling arm = (Heeling moment ÷ displacement) . cos (θ)
where: θ = angle of heel.

The following GZ curve is provided to illustrate the criteria defined in this Part.

Click on the image for a larger view.

Righting Arm Curve

Compliance Schedule for Existing Vessels12

16. (1) Existing vessels certificated to operate on Near Coastal Voyage, Class 1 and Class 2 (Home Trade Voyage Class I, II and III and Inland Waters Voyage Class I and II)9 shall comply with sections 7, 8 and 11 of this Part not later than the date of the first periodical survey after the date of compliance prescribed in (3)(a), (3)(b), or (3)(c) of this section, whichever occurs the latest.

(2) Existing vessels certified to operate on Sheltered Water Voyage (Home Trade Voyage Class IV and Minor Waters Voyage Class I and II)9 shall comply with sections 7, 8 and 1113 of this Part not later than the date of the first periodical survey after the date of compliance prescribed in (3)(b), or (3)(c) of this section, whichever occurs the latest.

(3) Compliance schedules for existing vessels:

(a) Degree of compliance of GZ Area

Formula - GZ Area DATE OF COMPLIANCE
< 50% 6 months after pub
< 70% 18 months after pub
< 90% 36 months after pub
< 100% 60 months after pub

(b) Number of persons certified to be carried

NUMBER OF PERSONS DATE OF COMPLIANCE
≥ 1500 6 months after pub
≥ 1000 < 1500 12 months after pub
≥ 600 < 1000 18 months after pub
≥ 400 < 600 24 months after pub
≥ 200 < 400 36 months after pub
≥ 50 < 200 48 months after pub
< 50 60 months after pub

(c) Existing vessels that will be less than 20 years of age on the date of compliance as specified by (1) or (2) shall comply with Section 11 of this part not later than the date of the first periodical survey after the vessel’s age is greater than 20 years. The age of the vessel means the time counted from the date on which the keel was laid or the date on which it was at a similar stage of construction.

(4) All existing vessels carrying 400 persons or more shall comply with sections 6(3), 6(4) and 6(5) of this Part not later than the date of the first periodical survey after the date of compliance below:

PERSONS CARRIED COMPLIANCE DATE
≥ 1500 48 months after pub
≥ 1000 < 1500 60 months after pub
≥ 600 < 1000 72 months after pub
≥ 400 < 600 96 months after pub

Alternative Compliance Approach For Existing Vessels14

17. (1) For existing Ro-Ro passenger vessels with enclosed or partially enclosed vehicle decks an equivalent level of safety may be demonstrated through the application of the Static Equivalent Method as described in Appendix 1.

(2) Existing vessels Ro-Ro and other than Ro-Ro may also demonstrate compliance with the probabilistic method stated in paragraph 18(1).

Alternative Compliance Approach for Vessels Built After 1 January 2009

18. (1) For new vessels built on or after 1 January 2009 an equivalent level of safety may be demonstrated through the application of the damage stability requirements (probabilistic method) as defined in Annex 2 of Resolution MSC.194(80) adopted on 20 May 2005.

Footnotes

1 “main compartment” means any one of the compartment between two main transverse watertight bulkheads.

2 One collision bulkhead and one bulkhead forward and aft of the main engine room.

3 Existing passenger vessels other than Ro-Ro and carrying less than 50 persons are not required to meet section 7 to 15, but must have a minimum of 3 transverse watertight bulkheads.

4 Compartments fitted with cross flooding arrangement shall also be fitted with adequate venting arrangement to avoid over pressurization and adequate cross-flooding.

5 Refer to the Recommendation on a standard method for establishing compliance with the requirements for cross-flooding arrangements in passenger ships adopted by IMO by resolution A.266(VIII).

6 Lost buoyancy method

7 The added weight method, taking into account the actual shifting of the center of gravity of the flooded water for each percentage of flooding and angle of heel calculated, shall be used for calculation of intermediate stages of flooding.

8 If pipes, ducts or tunnels are situated within assumed flooded compartments, arrangements are to be made to ensure that progressive flooding cannot extend to compartments other that those assumed flooded.

9 This equivalent voyage classification applies only to this TP and should not be used in the interpretation of other Regulations or TP.

10 Whichever results in the more severe requirements.

11 10% of the length will apply to vessels under 43 m.

12 Some compliance date examples are shown below.

Vessel 16(3)(a) 16(3)(b) 16(3)(c) 16(4) Compliance required by
49 persons, HT4, keel laid October 1989 Not applicable 60 months = 1 October, 2012 October 1989 + 20 = October 2009 Not applicable Section 6(4)13 – First Periodical survey after October 2012
199 persons, MW1, keel laid May 2000 Not applicable 48 months = 1 October, 2011 May 2000 + 20 = May 2020 Not applicable Sections 7,8 & 11 - First periodical survey after May 2020
500 persons, HT1, keel laid June 1965, GZ area ratio 80% 36 months = 1 October, 2010 24 months = 1 October, 2009 June 1965 + 20 = June 1985 96 months = 1 October, 2015 Sections 7,8 & 11 - First periodical survey after 1 October, 2010
Section 6 - First periodical survey after 1 October, 2015
800 persons, MW2, keel laid Dec 1995 Not applicable 18 months = 1 April, 2009 Dec 1995 + 20 = Dec 2015 72 months = 1 October, 2013 Section 6, 7, 8 & 11 – First periodical survey after 1 October, 2013

13 These vessels must meet the criteria of 7, 8 and 11 at their current subdivision level. Any vessels carrying 50 persons or more and that do not have subdivision must be upgraded to one compartment subdivision as required in 6(1) to meet the requirements of 7, 8 and 11. Vessels carrying not more than 49 persons must have at least 3 transverse watertight bulkheads as required by 6(4). For vessel carrying 400 persons or more section 16(4) will determine if their level of subdivision needs to be upgraded further and when.

14 The compliance schedule in section 16 is also applicable to the alternative methods.

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