PIANC 2016

Propeller Action and Berth Scour Protection

Effective scour protection is usually needed to protect berthing structures from vessels actions with increasing size and power. For seagoing vessels, use of propellers is usually the dominant vessel action for berth scour protection and the paper will focus on this and improving understanding & guidance.
Factors affecting scour actions at berths will be explored and a probabilistic method to aid design will be outlined. The results of scale model testing of rock protection will be presented and compared to methods in present guidance. A timescale relationship is proposed which has allowed consideration of scour duration upon rock stability. Suggestions will be presented for improved efficiency in the use of rock, for further testing and also for collection of information from working harbours.
Rock falling edge aprons have also been model tested and compared to deployed apron performance, which has allowed initial guidance to be proposed relating to propeller action.
The performance and constructability of rock, insitu concrete and mattress protection types will be reviewed. The differing performance of ‘sealed’ and ‘open’ protection types will be presented and supported by comparison to relevant testing and design methods. The benefits of a design and constructability approach will be outlined along with the use of a quality control process suitable for construction underwater.