Given:

$$Lenght,\:L=140m$$

$$Breadth,\:B=18.5m$$

$$Draught,\:d=8.1m$$

$$Displacement,\:\Delta=17025tonnes$$

$$Pitch\:ratio,\:p=0.673\operatorname{}$$

$$Diameter\:of\:Propeller,\:D=4.8m$$

$$\operatorname{Real\:Slip,\:R_{s}=30\%\:or\:0.3}$$

$$Wake\:fraction,\:W=0.5C_{b}-0.05$$

$$Consumption,\:C_2=\:20t\:per\:day\:$$

$$Ship\:Speed,\:V_2=13\:knots$$

$$\operatorname{Revolution,\:N}=110rpm$$

$$cons\:per\:day\:\alpha\:V^3$$

To find Fuel Consumption C1=?

We know that,

$$Displacement,\:\Delta=\nabla\times\rho$$

$$17025=\nabla\times1.025$$

$$\nabla=16609.76m^3$$

$$Block\:Coefficient,\:C_{b}=\frac{\nabla}{L\times B\times d}$$

$$C_{b}=\frac{16609.76}{140\times18.5\times8.1}$$

$$C_{b}=0.792$$

$$Wake\:Fraction,\:W=0.5C_{b}-0.05$$

$$W=0.5\times0.792-0.05$$

$$W=0.346$$

$$Pitch\:ratio,\:p=\frac{P}{D}$$

$$0.673=\frac{P}{4.8}$$

$$P=4.8\times0.673$$

$$P=3.23m$$

$$Theoretical\:Speed,\:V_{t}=\frac{P\times N\times60}{1852}$$

$$V_{t}=\frac{3.23\times110\times60}{1852}$$

$$V_{t}=11.51knots$$

Using, Real slip equation.

$$\operatorname{\operatorname{Real\:Slip,\:R_{s}=\frac{V_{t}-V_{a}}{V_{t}}}}$$

$$0.3=\frac{11.51-V_{a}}{11.51}$$

$$V_{a}=11.51-11.51\times0.3$$

$$V_{a}=11.51\left(1-0.3\right)$$

$$V_{a}=11.51\times0.7$$

$$V_{a}=8.057knots$$

$$Wake\:fraction,\:W=\frac{V-V_{a}}{V}$$

$$0.346=\frac{V-8.057}{V}$$

$$0.346V=V-8.057$$

$$V=\frac{8.057}{0.654}$$

$$V=12.32knots$$

$$cons\:per\:day\:\alpha\:V^3$$

$$\frac{C_1}{C_2}=\left(\frac{V_1}{V_2}\right)^3$$

$$\frac{C_1}{20}=\left(\frac{12.32}{13}\right)^3$$

$$C_1=20\times\left(\frac{12.32}{13}\right)^3$$

$$C_1=20\times0.851$$

$$C_1=17.02t\:per\:day$$