Estimating Berthing Performance of Twin Shaft Ship by means of CFD

Estimating ship low-speed manoeuvrability is a crucial and challeng-ing task especially in early design sign stage. It is essential in case of cruise ships or ferries because they have to be able to operate in harbours without tugs assistance. Their crabbing ability (moving sideways in order to approach or leave a quay) is critical. The integral part of the crabbing for twin screw ships is a push-pull manoeuvre, which is a combination of pulling and pushing action of propellers coupled with rudders causing the sideway motion of the ship. To bet-ter understand the complex flow features during a push-pull manoeuvre and help to estimate crabbing ability CFD simulations can be used. In this paper results of CFD simulations of a push-pull manoeuvre are present-ed. The simulations are carried out in different environmental conditions: be-ginning with unrestricted waterways and ending with confined spaces. The re-sults are analysed in detail and interactions between hull, rudders, propellers, and channel bottom are studied. Additionally, effects caused by the presence of a quay are discussed.