What are MARPOL regulations for Damage Stability ?

Location of Damage:

Tankers of  more than 225 metres in length, anywhere in the ship’s length. In tankers of more than 150 metres, but not exceeding 225 metres in length, anywhere on the ship’s length except involving either after or forward bulkhead bounding the machinery space located aft. The machinery space shall be treated as a single floodable compartment.
In tankers of less than 150 metres in length anywhere on the ship’s length between the adjacent transverse bulkheads with the exception of the  machinery space.

Meaning of Extent Of Damage
Side Damage 
  1. Longitudinal Extent 1/3(L 2/3) or 14.5 Metres
  2. Transverse Extent B/5 or 11.5 metres which ever is less
  3. Vertical extent – From the bottom to full height


Bottom Damage

0.3 L from ford Other part
Longitudinal extent or 5 m 1/3(L 2/3) or 14.5 1/3(L 2/3)
Transverse extent B/6 or 10m B/6 or 5 M
Vertical extent B/15 or 6M B/15 or 6M
Stability Criteria  Of Vessel
  1. The final water line taking into account sinkage, heel and trim, shall be below the lower edge of any opening through which progressive may take place.
  2. The final stage of flooding, the angle of heel due to unsymmetrical flooding shall not exceed 25 degrees provided that this angle may be increased up to 30 degrees if no deck immersion occurs.
  3. The stability in the final stage of flooding shall be investigated and may be regarded as sufficient if the righting lever curve has at least a range of 20 degrees beyond the position of equilibrium in association with a maximum residual righting lever of at least  1 metre within the 20 degrees range; the area under the curve within this range shall be not less than  0.0175 metre radians.