5.3 Calculation of outflow in case of bottom damage
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Statutory Documents - IMO Publications and Documents - Resolutions - Marine Environment Protection Committee - Resolution MEPC.64(36) - Guidelines for Approval of Alternative Structural or Operational Arrangements as Called for in Regulation 13G(7) of Annex I of MARPOL 73/78 - (adopted on 4 November 1994) - Annex - Guidelines for Approval of Alternative Structural or Operational Arrangements as Called for in MARPOL 73/78, Annex I, Regulation 13G(7) - Methodology for calculation of the hypothetical oil outflow - 5.3 Calculation of outflow in case of bottom damage

5.3 Calculation of outflow in case of bottom damage

 Calculation of the outflow from bottom damages should be done as follows:

Length in meters between the forward and after extremities of the cargo tanks = L t (m)
Width of the cargo tank area = B t (m)
Length of tank number i = l i (m)
Width of tank number i = b i (m)
Height of a double bottom = h i (m)
Cargo volume in tank number i = V i (m3)
Length of a bottom damage according to subparagraph 5.1.2 = l s (m)
Width of a bottom damage according to subparagraph 5.1.2 = b s (m)
Vertical extent of a bottom damage according to subparagraph 5.1.2 = v s (m)

  • Probability factor for breaching tank number i due to bottom damage

Nominal density of the cargo according to para 4 = p c(t/m3)
Density of the sea water (normally 1.025) = p s(t/m3)
Loaded condition draft = d (m)
Height of cargo column above the cargo tank bottom = h c (m)
Highest normal overpressure in the inert gas system (normally 0.05 bar) = Δp (bar)
Margin for average transient loss, swell and tide effects = 1.1
Standard acceleration of gravity - g = 9.81 m/s2

  • Outflow factor due to hydrostatic overpressure in tank number i

    Outflow from tank number i

    Total hypothetical outflow in case of a bottom damage

In case the ship is equipped with a double bottom the calculated outflow from tanks located above such double bottom may be assumed to be reduced by 50% of the total capacity of the affected double bottom tanks but in no case by more than 50% of the calculated outflow from each tank.

Parent topic: Methodology for calculation of the hypothetical oil outflow
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