Loading condition · learning model
Educational illustration only. Not a shipboard stability calculator or loading instrument. Do not use these values for voyage, cargo, ballast, or safety decisions. Real GZ curves require approved hydrostatic/cross-curve data and full corrections.
Small-angle model (0–10°): corrected GM = GM − free-surface correction; approximate GZ = corrected GM × sin(heel). Righting moment in tonne-metres = displacement (t) × GZ (m). Negative values indicate a destabilizing tendency in this simplified model.
Live stability display
Corrected GM1.00 m
Approx. GZ0.105 m
Moment (t·m)3136
Heel illustration
Approx. righting arm, 0–10°
Adjust a slider to explore the initial stability approximation.
Reading the numbers
Positive corrected GM produces a positive small-angle righting arm. A free-surface correction reduces the effective GM, potentially changing its sign. At 0° the approximate arm and moment are zero even when GM is positive. The plot is limited to 10° on purpose: extrapolating this formula to large heel angles is unsafe.