Free tool
Hydrostatics calculator
The everyday hydrostatics arithmetic — displacement and volume, hull-form coefficients, TPC and sinkage, and fresh/dock water allowances. Every formula is shown with its substitution and reference.
- ρ · ∇
1.025 × 9,756.1 m³
Standard hydrostatic relations (Barrass & Derrett, Ship Stability; Tupper, Naval Architecture). TPC/FWA/DWA assume constant waterplane area over small changes — the ship's approved hydrostatic tables and load-line certificate govern. Register: hydro.displacement-from-volume v1.0 (verified).
Scope
What this covers — and what it does not.
Covered
Relations that need only supplied values: Δ = ρ·∇, Cb = ∇/(L·B·T), Cm = Am/(B·T), Cp = ∇/(Am·L), TPC = ρ·Awp/100, sinkage = w/TPC, FWA = Δ/(4·TPC), DWA and the constant-displacement density rule T₂ = T₁·ρ₁/ρ₂.
Not covered
KM, BM, LCB, hydrostatic curves and anything needing the ship's geometry. Those come from the vessel's approved hydrostatic tables — enter values from them here rather than approximating.
Verify before use
Results are planning arithmetic. Load-line marks, the stability book and flag/port requirements govern any operational decision.