Free Surface Correction (FSC)

Free-surface correction for a slack tank - reduction in effective GM caused by liquid shifting in a partially-filled compartment.

StabilityFree surface

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

i = \tfrac{l \cdot b^3}{12}, \quad \text{FSC} = \frac{i \cdot \rho_\text{liquid}}{\Delta}

Symbol	Meaning	Unit
$l, b$	Tank length and breadth at free surface	m
$\rho_\text{liquid}$	Liquid density	t/m³
$\Delta$	Ship displacement	t
$i$	Second moment of tank free surface	m⁴
$FSC$	Effective GM loss	m

Source: IMO IS Code Part B Ch.3; Derrett & Barrass Ch.13

Compute the loss of effective GM from a slack tank's free surface moment.