Quay structures can be reduced by design using thinner scour protection. The performance of thinner protections as ‘Sealed’ or ‘Open’ to flow entry is described.

Established design methods for insitu concrete mattress and rock protections under single propeller action are reviewed. These methods are extended to twin propeller action based upon scale model testing undertaken. Comparison is made to current guidance by PIANC (2015) and PIANC (1997).

Vessels with twin propellers are outlined along with design implications for berths.