For the analysis of Large Angle Stability, displacement and centre of gravity are specified in the loadcase. A range of heel angles are specified and Hydromax calculates the righting lever and other hydrostatic data at each of these heel angles by balancing the loadcase displacement against the hull buoyancy and, if the model is free-to-trim, the centre of gravity against the centre of buoyancy such that the trimming moment is zero.

Large angle stability requirements

§   Range of heel angles to be analysed

§   Trim (fixed or free)

§   Loadcase

§   Tank definition in the case of tank loads being included in the Loadcase (and/or for the definition of damage)

Large angle stability options

§   Fluid Densities

§   Treatment of fluids in tanks: fluid simulation or corrected VCG

§   Wave form

§   Hog and sag

§   Damage

§   Compartment definition (in case of damage)

§   Key points

§   Margin line and deck edge

§   Analysis of stability criteria

The key output value is GZ (or righting lever), the horizontal distance between the centres of gravity and buoyancy. A graph of these values at the various heel angles forms a GZ curve. Various other information is often overlaid on the GZ curve, including upright GM, curves for wind heeling and passenger crowding levers and the angle of the first downflooding point. These additional data depend on which (if any) stability criteria have been selected.

The sectional area curve at each of the heel angles tested may also be displayed.

If large angle stability criteria have been selected for analysis, these results will also be reported in the criteria results table and they may lead to additional curves being displayed on the GZ curve.

Downflooding angles for any key points, margin line and deck edge will also be computed and tabulated.

For more detailed information please see: Large Angle Stability on page 67.