HomeCalculatorsITTC-57 Friction Coefficient

ITTC-57 Friction Coefficient

Friction coefficient Cf from Reynolds number using the ITTC-57 correlation line. The foundation of every hull-resistance method that distinguishes frictional from residual resistance.

DesignResistanceITTC

Inputs

Ship speedknWaterline length (Lwl)mKinematic viscositym²/sSea water at 15 °C = 1.189 × 10⁻⁶; fresh water = 1.139 × 10⁻⁶.

Reynolds Re

1,297,790,111–

Friction Cf

0.001482–

Formula, assumptions, and limits

$$\text{Re} = \frac{V \cdot L_\text{pp}}{\nu}, \quad C_F = \frac{0.075}{(\log_{10} \text{Re} - 2)^2}$$

ITTC-57 is the agreed model-to-ship correlation line. It's an engineering compromise, not exact turbulent-plate theory. Hull roughness is added as a separate increment ΔCf (see appendage-and-roughness calculator).

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