Maximum allowable heeling moments for grain cargo are listed below
In addition to the intact criteria and the damage criteria, the vessel shall comply with the rules for maximum heeling moment due to grain shift, SOLAS 1974, Chapter VI.
- The metacentric height, after correction for free surfaces, is to be 0.30 m or greater.
- The angle of heel due to grain shift shall be 12 degrees or less.
- In the statical stability diagram, the net or residual area between the heeling arm curve and the GZ curve up to the angle of heel where the maximum difference between the two curves occur, or up to 40 degrees of heel or up to the angle of flooding, whichever is less of the three, shall be 0.075 mrad or more.
These criteria have been taken into account in the preparation of the table of maximum permissible heeling moment due to grain shifting.
The table is presented for draught, trim and KG values covering the vessels operating range.
In short, when the vessel is carrying grain, the master has to ensure that the sum of the heeling moment due to grain shift is smaller than the value obtained from the limiting tables .
Finally the vessel has to comply with the intact and damage stability criteria according to the Stability Information Manual.
You may also know about Grain Heeling Moments :
The stability calculations are based on the assumption that the centre of gravity in a filled compartment is at the volumetric centre of the whole cargo space.
In the stowage arrangements covered by this Manual a filled compartment means any compartment which after loading and trimming is filled with bulk grain to the maximum possible extent, i.e. to the top of the hatch coaming.
All necessary and reasonable trimming shall be performed to minimize the effect of grain shifting.
For partly filled holds the adverse effect of the vertical shift of grain surface is taken into account by an addition of 12% and for filled holds the adverse effect of the vertical shift of grain surface is taken into account by an addition of 0%.
All additional is incorporated in the presented shifting moments.
The table is presented with ullage reference from the top of the hatch coaming and/or height reference above the tank top