Question

3. A ship travels in seawater at a speed of 15 knots and expends 7000 hp. The ship's hull is 150 m long and has a surface area of 5000 m2. Assume that all of the ship's drag is due to skin friction and that the ship's hull can be treated as a flat plate with equivalent length and surface area. A) The ship's hull has barnacles which contribute to the drag. Find the roughness due to the barnacles. B) If the barnacles are now removed, the hull can be treated as a smooth surface. Determine the maximum speed the ship can achieve with the same propulsive power.

Please don't copy the answers from different people because most of them on here do the same thing.

Answer 1

Solution given data, . .. and Exis A ship travels in Seawater at a speed = 15 khots and expands' = 1000 hp . The ship bull long s isotni . surface area = 5000 int By using Power equation drag.coefficient as P= 80 1 / CAV) la in CDla i Substitute I CAV3 given values 7000 745.7. Ź (1020) (5000) (1što. Siuu? CD - DE ,5219900 1171031336.1243 = CD- 0.00445 The Reynolds number for the flow over Plate. Re= V2 = (Isxo. 5144) (150) 10.80lxco 6 il 574 0.8014106 luustio 9 Re =

... Find relative roughness value using graph for flat po for given drag coefficient and reynolds number &= nxios - Txios E = Axios) (150) TE= 0.0105 ml The maximum speed for Smooth Surface using Power equations. Pasol Cay) v = colten v² = 2 2 va (eaco VE 12P13 substitute the given values: va ſ 2 (1000x745.7) 3 11020) (5000) 1043980073 VE L 5100000 J VE (2.0470) 3 VE 1269 m/s ĮV- 2.468 knots