The study of the Modification of the Ro-Ro Ferry’s Angle of the Entrance Using Statistical Methods and Ship Model Resistance Tests

Abstract

Aspects of speed and its correlation to ship resistance greatly affect the performance of ferry ro-ro ships. The fixing of the ship’s resistance is very significant when related to the ship’s economic costs. BTH-BRIN has carried out resistance tests and calculations using the Holtrop statistical method where the resistance result is considered too large. To reduce the resistance, modifications are made, one of which is by changing the angle of the entrance of the ship bow. Again, the Holtrop statistical calculations are then employed to determine the effective angle of the entrance after the ship is modified. Reducing the angle of the entrance of water at the ship’s bow is expected to reduce the resistance in terms of the bow wave. It also needs paying attention to the amount of ship payload that has been planned. This paper describes the process of resistance reduction due to the change of the angle of the entrance of the ferry ro-ro ship. Firstly the resistance of the original ship is predicted using the statistical method and a scaled ship model is made and tested in BTH towing tank. Second, the angle of the entrance of the ferry ro-ro ship is modified. Finally, the modified one is predicted statistically based on the Holtrop method. The results of the statistical analysis of the modified angle of entrance showed that the resistance is smaller than the original one.

Numerical Analysis of Modified Angle of Entrance and Ducktail Addition of the 1,500 Gt Ro-Ro Ferry Hull Validated With Ship Model Resistance Test

“…Various efforts have been made to reduce the total resistance of the ship. Some of them are modifying the hull form [6], installing the undership fin to improve the direction of the fluid flow under the hull to the propeller [7], providing the bulbous bow to decrease wave interference which contribute to reduce ship wave resistance [8,9], attaching stepped hull to reduce the wetted surface area [10,11], sharpening the bow AoE [12,13,14,15] and the addition of the ducktail at the transom stern [16,17,18] to reduce viscous and wave resistance.…”

“…The shape of the bow hull with a sharper AoE allows waves to follow the bow more smoothly. Reducing AoE serves to minimize wave resistance [12,13,14,15,19] and improve flow patterns [20]. The movement of the ship always causes waves.…”