Free Surface Correction (FSC)

Compute GM correction due to liquids in slack tanks. Simple direct mode or build from tank rectangles. Export PNG/PDF.

Method

Pick based on the data you have.

Δ (t)

ρ (t/m³)

Sea ≈ 1.025; fresh ≈ 1.000.

Notes (optional)

A) Direct ΣFSM

ΣFSM (t·m)

FSC (m) = ΣFSM / Δ. Use this mode if your hydrostatic book already lists tank FSMs for the current condition.

ΣFSM: — t·m

FSC: — m

—

Notes

Definition: FSC = ΣFSM / Δ. Subtract FSC from GM to obtain corrected GM.

Rectangular free surface: \( \mathrm{FSM} = \rho \cdot \dfrac{L\,B^3}{12} \) (t·m). Use breadth B across ship, length L longitudinal.

Baffles/swash: apply a reduction factor \(k \in [0,1]\). If unknown, use k = 1 (no reduction).

Caution: FSM depends on fill level & tank geometry; use hydrostatic book values whenever available.