Resistance

$R_t$ = Total resistance $R_f$ = frictional resistance $R_r$ = Residual resistance (Wave and eddy making resistance)

$$R_t= R_r+ R_f$$

Frictional Resistance

Where $f$= coefficient of friction $A$= wetted surface area $V$= ship’s speed $n$= coefficient dependent on roughness of hull

$$f = \frac{0.441}{L_s^0.0088}$$$$R_f = f \times A \times V^n$$

Froude’s Speed Length Law

Velocity of ship = $V_s$ Velocity of model = $V_m$ Length of ship = $L_s$ Length of model = $L_m$

[\frac {V_s}{\sqrt {L_s}} = \frac{V_m}{\sqrt {L_m}}]

Residual Resistance

$R_{rs}$= Residual resistance of ship $R_{rm}$= Residual resistance of model $L_s$= Length of Ship $L_m$= Length of model

$$\frac{R_{rs}}{R_{rm}}{{\frac{L_s}{L_m}}^3}$$

Wetted Surface Area

$$\frac{WSA_{ship}}{WSA_{model}}={\frac{L_s}{L_m}}^3$$