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The metacentric height (GM) is the primary indicator of initial transverse stability. A positive GM means the vessel will right herself when heeled; a negative GM means she is unstable and will loll or capsize. This tool calculates the key stability parameters using a rectangular box approximation.
The block coefficient (Cb) for a real ship is typically 0.55–0.85 and the waterplane coefficient (Cw) is typically 0.70–0.90. Using a box (Cb = Cw = 1.0) overestimates BM and therefore KM, which means estimated GM will be higher than the actual value.
Enter all four dimensions to compute.
Scenario: Panamax bulker B = 32 m, drought d = 12 m, KG (from loading computer) = 8.5 m.
Calculate: BM = 32² ÷ (12 × 12) = 1024 ÷ 144 = 7.11 m. KB = 12 ÷ 2 = 6.00 m. KM = 6.00 + 7.11 = 13.11 m. GM = 13.11 − 8.5 = 4.61 m.
Interpretation: Well-positive GM. However this is box-approximation; real bulker Cb ≈ 0.85 + Cw ≈ 0.88, so actual BM ~15% lower, actual GM ~4.0 m. Still comfortable. On a real voyage, verify against the loading computer output.