The present paper describes the analysis of ferry wake wash along a proposed route between San Francisco and a new ferry terminal at Hercules. The steady wave field generated by a candidate catamaran ferry was calculated for a range of vessel speeds and water depths, using established computational fluid dynamics (CFD) techniques. The matrix of cases analyzed span the range of vessel speeds (5 to 35 knots) and water depths (3 to 32 m) anticipated for ferry service along the proposed route. The cases analyzed span the sub-critical, trans-critical, and super-critical flow regimes, based on whether the depth-based Froude number is less than, equal to, or greater than one, respectively. The free-wave spectra which fully characterize the ship-generated wave system in the far field are also calculated and presented, including for shallow-water cases. The calculated ferry wakes and the free-wave spectra enable the propagation and transformation of the wave system into the far field over varying bathymetry, so that the impact of ferry wakes on the shoreline may be studied. The analysis is part of a broader “shoreline and biological response” approach to wake wash impact analysis. The approach contains site-specific elements, but the process may also be applied to evaluate wake wash impact of specific, yet-to-be-built ferries on other future routes.
Authors: S. Anil Kumar (Glosten); Justus Heimann (FRIENDSHIP Systems GmBH); Bruce L. Hutchison (Glosten); Scott W. Fenical (Coast & Harbor Engineering)