Stability openings definition (MOSES)

Dear Sirs,

Could you let me know how to define downflooding points in the stability calculation in MOSES ?


Non-Tight openings connect to Hull

X=1, Y=2, Z=3


Non-Tight openings connect to COMP1

X=4, Y=5, Z=6

In the intact stability analysis, GZ curve has to be stopped at that point dowiflood.

In the damaged stability analysis, GZ curve not to be stopped in case COMP is damaged.

How to define the openings and how to treat the openings in the GZ curve evaluation ?

An example with simple and basic command for the CIF is very helpful for me.

Best Regards  

  • Dear Yuki,

    I have prepared simple stability files to explain how to define the now water-tight points. Please note that the downflooding points to check submergence during stability can be modeled in the hull as well as compartments in MOSES.

    In the example below, I have modeled a vessel named "barge" with two compartments, namely "bow" and "stern," as shown in the figures below. Six points (*PT1,...,*PT6) are defined in the model file. Points *PT1 and *PT2 are associated with the "bow" compartment, points *PT5 and *PT6 are associated with the "stern" compartment, and *PT3 and *PT4 are associated with the "barge" hull compartment. Please refer to the DAT file for details on how to associate downflooding points with respective compartments.

    Now, intact and damage stability analysis is performed using the STAB_OK macro. The MOSES plot for intact stability will show the downflooding angle to be about 17.17 degrees. If you look at the MOSES output, you will see the critical downflooding point to be *PT6. In this case, since all the downflooding points are at the same elevation, MOSES is just showing the last point it reads (*PT6) to be the critical downflooding point that goes into the water at heel angle of 17.16deg.

    However, when you damage the "bow" compartment and perform the damage stability, you will see that the downflooding angle is now 14.16 degrees, and the critical downflooding point is *PT3. The reason for this is that MOSES identifies that the "bow" compartment is damaged, and therefore, *PT1 and *PT2 become irrelevant for stability (since the whole compartment ("bow") is damaged, and those points (*pt1&*pt2) belong to that compartment). Therefore, MOSES will identify the most critical downflooding point, which will be *PT3. This is expected since when the "bow" compartment is damaged, the point *PT3 will go down (due to trim) and be closest to the water among all the remaining downflooding points. Therefore, MOSES reports *PT3 as critical and also gives the user the angle (14.16deg) at which *PT3 goes underwater.

    I hope the above explanation and attached files (and output) clear your doubts. Let me know if you have further questions.


    Rahul Kanotra