STABILITY TOOLS

Stability Calculators

Professional stability calculators for GM, free surface effect, list, trim, angle of loll and all key stability parameters.

8Calculators

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IMO A.749Standards-based

All Stability Calculators

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GM Calculator

Calculate metacentric height for vessel stability assessment and verification

Stability

GM = KM − KG | KM = KB + BM

KM (m)KG (m)Draft (m)

Free Surface Effect

Calculate virtual rise in G due to free surface in partially filled tanks

Correction

GG₁ = (ρ_liquid × i_free surface) ÷ Δ

Tank Length (m)Tank Breadth (m)Liquid Density (t/m³)Displacement (MT)

Displacement Calculator

Determine vessel displacement from draft readings and hydrostatic tables

Hydrostatics

Δ = TPC × Mean Draft (cm) | or from hydrostatic curves

Mean Draft (m)TPC (MT/cm)Block CoefficientLBP (m)Beam (m)

List Calculator

Calculate list angle from transverse weight shift or off-centre loading

List

tan(θ) = (w × d) ÷ (Δ × GM)

Weight Shifted (MT)Distance (m)Displacement (MT)GM (m)

Trim Calculator

Calculate fore and aft trim change from loading or discharging operations

Trim

Change in Trim = (w × d) ÷ MCTC | BG = (w × d) ÷ Δ

Weight (MT)Distance from LCF (m)MCTC (MT·m/cm)LBP (m)

Angle of Loll

Calculate angle of loll when initial GM is negative (unstable equilibrium)

Stability

tan(θ_loll) = √(−2 × GM ÷ BM)

GM (m) [negative]BM (m)Displacement (MT)

BM Calculation

Calculate transverse metacentric radius BM from vessel dimensions

Hydrostatics

BM = I_waterplane ÷ Volume = (L × B³) ÷ (12 × ∇)

LWL (m)Beam (m)Draft (m)Block Coefficient (Cb)

Shift of G

Calculate rise or fall of G when moving, loading or discharging a weight

Stability

GG₁ = (w × d) ÷ Δ | Rise of G = (w × KG_item) ÷ (Δ + w)

Weight (MT)Distance from G (m)Displacement (MT)Item KG (m)

About Stability Calculators

Ship stability calculations are critical for vessel safety and compliance with SOLAS Chapter II-1. These calculators follow IMO Resolution A.749(18) — Code on Intact Stability for All Types of Ships. They are intended as reference tools for deck officers, stability engineers and marine surveyors alongside vessel-specific stability booklets.