6 — Guidance on subdivision and damage stability calculations Internationaal Verdrag van Torremolinos voor de beveiliging van vissersvaartuigen, 1977
Guidance on subdivision and damage stability calculations
(1) Conditions of equilibrium
(a) The final waterline after damage to any one compartment should be either:
(i) to the line of openings at which progressive flooding to spaces below would occur and to the requirements of the Administration; or
(ii) to the after end of the top of the poop superstructure deck at the centreline, subject to paragraph (3)(a) below.
(b) Unsymmetrical flooding shall 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.
(2) Damage assumptions
The following assumed damage should apply:
(a) The vertical extent of damage in all cases is assumed to be from the base line upwards without limit.
(b) The transverse extent of damage is equal tot B/5 metres, measured inboard from the side of the vessel perpendicularly to the centreline at the level of the deepest operating waterline, where B (in metres) is as defined in Regulation 2(7).
(c) If damage of a lesser extent than specified in sub-paragraphs (a) and (b) above results in a more severe condition, such lesser extent should be assumed.
(d) The flooding should be restricted to any single compartment between adjacent transverse bulkheads. If there are steps or recesses in a transverse bulkhead of not more than 3.05 metres in length located within the transverse extent of assumed damage as defined in sub-paragraph (b) above, such transverse bulkhead may be considered intact and the adjacent compartments may be floodable singly. Where there exists a step or recess within the transverse extent of assumed damage of more than 3.05 metres in length in a transverse bulkhead, the two compartments adjacent to this bulkhead should be considered as flooded. The step formed at the junction of the afterpeak bulkhead and the afterpeak tank top should not be regarded as a step.
(e) Where a main transverse bulkhead is situated within the transverse extent of assumed damage and is stepped in way of a double bottom or side tank by more than 3.05 metres, the double bottom or side tanks adjacent to the stepped portion of the main transverse bulkhead should be considered as flooded simultaneously.
(f) Main transverse watertight bulkheads should be spaced at least 1/3 L2/3 metres apart where L (in metres) is as defined in Regulation 2(5).
Where transverse bulkheads are spaced at a lesser distance, one or more of these bulkheads should be assumed as non-existent in order to achieve the minimum spacing between bulkheads.
(g) If pipes, ducts or tunnels are situated within the assumed extent of damage penetration as defined in sub-paragraph (b) above arrangements are to be made so that progressive flooding cannot thereby extend to compartments other than those assumed to be floodable in the calculation for each case of damage.
(h) Where operating experience has shown that other values for sub-paragraphs (b) and (f) above are more appropriate those values should be used.
(3) Survival assumptions
The vessel is considered to survive the conditions of damage specified in paragraph (2) above provided the vessel remains afloat in a condition of stable equilibrium and satisfies the following stability criteria:
(a) The stability in the final condition of flooding may be regarded as sufficient if the righting lever curve has a minimum range of 20 degrees beyond the position of equilibrium in association with a residual righting lever of at least 100 millimetres. The area under the righting lever curve within this range should be not less than 0.0175 metre-radians. Consideration should be given to the potential hazard presented by protected or unprotected openings which may become temporarily immersed within the range of residual stability. The unflooded volume of the poop superstructure around the machinery space casing, provided the machinery casing is watertight at this level, may be taken into consideration in which case the damage waterline should not be above the after end of the top of the poop superstructure deck at the centreline.
(b) The angle of heel in the final condition of flooding should not exceed 20 degrees.
(c) The initial metacentric height of the damaged vessel in the final condition of flooding for the upright position should be positive and not less than 50 millimetres.
(d) Relaxation from the damage stability requirements should be permitted only if the proportions, arrangements and other characteristics of the vessel are more favourable to stability after damage.
(4) Permeabilities
The permeabilities employed are to be those as calculated or estimated for the individual spaces in question.
(5) Initial condition of loading
The subdivision and stability calculation should be carried out in the worst operating condition in respect of the residual buoyancy and stability in the non-icing condition.
- Regeling
- Internationaal Verdrag van Torremolinos voor de beveiliging van vissersvaartuigen, 1977
- Soort
- Verdrag
- Geldend vanaf
- 02-04-1977
- BWB-id
- BWBV0003251
- Versie
- 1977-04-02_0