Skip to main content

Damage Stability

Oil tankers 
Oil tankers shall be regarded as complying with the damage stability criteria if the following requirements are met:
  • The final waterline, taking into account sinkage, heel and trim, shall be below the lower edge of any opening through which progressive flooding may take place.
  • In the final stage of flooding, the angle of heel due to unsymmetrical flooding shall not exceed 25°, provided that this angle may be increased up to 30° if no deck edge immersion occurs.
  • 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° beyond the position of equilibrium in association with a maximum residual righting lever of at least 0.1 m within the 20° range; the area under the curve within this range shall not be less than 0.0175 m·rad.
  • The Administration shall be satisfied that the stability is sufficient during intermediate stages of flooding
  • Equalization arrangements requiring mechanical aids such as valves or cross-levelling pipes, if fitted, shall not be considered for the purpose of reducing an angle of heel or attaining the minimum range of residual stability to meet the requirements

  • Bulk carriers of 150 m in length and upwards of single side skin construction, designed to carry solid bulk cargoes having a density of 1,000 kg/m3 and above, constructed on or after 1 July 1999 shall, when loaded to the summer load line, be able to withstand flooding of any one cargo hold in all loading conditions and remain afloat in a satisfactory condition of equilibrium
  • Bulk carriers of 150 m in length and upwards of single side skin construction, carrying solid bulk cargoes having a density of 1,780 kg/m3 and above, constructed before 1 July 1999 shall, when loaded to the summer load line, be able to withstand flooding of the foremost cargo hold in all loading conditions and remain afloat in a satisfactory condition of equilibrium
  • The assumed flooding need only take into account flooding of the cargo hold space. The permeability of a loaded hold shall be assumed as 0.9 and the permeability of an empty hold shall be assumed as 0.95, unless a permeability relevant to a particular cargo is assumed for the volume of a flooded hold occupied by cargo and a permeability of 0.95 is assumed for the remaining empty volume of the hold


Popular posts from this blog

Differences between MC/MC-C and ME/ME-C engines

The electrohydraulic control mechanisms of the ME engine replace the following components of the conventional MC engine: Chain drive for camshaft Camshaft with fuel cams, exhaust cams and indicator cams Fuel pump actuating gear, including roller guides and reversing mechanism Conventional fuel pressure booster and VIT system Exhaust valve actuating gear and roller guides Engine driven starting air distributor Electronic governor with actuator Regulating shaft Engine side control console Mechanical cylinder lubricators. The Engine Control System of the ME engine comprises: Control units Hydraulic power supply unit Hydraulic cylinder units, including: Electronically controlled fuel injection, and Electronically controlled exhaust valve activation Electronically controlled starting air valves Electronically controlled auxiliary blowers Integrated electronic governor functions Tacho system Electronically controlled Alpha lubricators

Why is a man hole door elliptical in shape?

Any opening in a pressure vessel is kept to a minimum and for a man entry an elliptical hole  is lesser in size than the corresponding circular hole. More over it is prime concern to have a  smoothed generous radius at the corners to eliminate stress concentration. Hence other  geometrical shapes like rectangle and square are ruled out.  To compensate for the loss of material in the shell due to opening, a doubler ring has to be  provided around the opening. The thickness of the ring depends on the axis length along the  dirrection in which the stresses are maximum and the thickness of the shell. It is important to  align the minor axis along the length of the vessel, as the stress in this direction is  maximum. Longitudinal stress: Pd/2t where P= pressure inside the vessel, d= diameter of the arc, t=  thickness of the shell plating  Circumferential stress: Pd/4t  More over a considerable material and weight saving is achieved as minor is along the  direction of maximum stress.

Shell Expansion Plan

It is a two dimensional drawing of a three dimensional surface of the ship’s hull form. This plan is very useful for the following information:It is used for marking the location of a hull Damage on this plan by identifying the strake number , letter and frame number so that the exact location of the damage and also suggested repairs are marked in a localised copy. The shell expansion can be used for finding areas of painting surfaces such as topside, boot topping and bottom areas by applying Simpsons rules directly.  In the shell expansion the vertical scale used is different from the horizontal scale and a suitable adjustment has to be made when calculating areas. This becomes useful in solving disputes concerning areas of preparation and painting. It gives information on the thickness of the original strake which is indicated by the number in the circle shown in the strake.  The quality of steel used is also shown by letters A,B,D E and AH, BH,DH, EH.