The agreed frictional-resistance coefficient in model-to-ship correlation.
Formula
$$ \text{Re} = \frac{V \cdot L_\text{pp}}{\nu}, \quad C_F = \frac{0.075}{(\log_{10} \text{Re} - 2)^2} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $\text{Re}$ | Reynolds number | - | intermediate |
| $V$ | Ship speed | m / s | derived from kn × 0.5144 |
| $L_\text{pp}$ | Length between perpendiculars (or LWL) | m | hydrostatics |
| $\nu$ | Kinematic viscosity of water | m² / s | ITTC table - sea 15 °C = 1.189 × 10⁻⁶ |
| $C_F$ | Frictional-resistance coefficient | - | result |
ITTC-57 is an engineering compromise, not a first-principles turbulent-plate formula. Hull-roughness and bilge-keel allowances are added as separate $\Delta C_F$ increments in the Appendage & Roughness calculator.
Sources
- ITTC - Recommended Procedures and Guidelines (7.5-02-03).
- Molland, Turnock & Hudson - Ship Resistance and Propulsion.