Ship effects at the bankline of navigation channels

Abstract

Ship effects at the bankline are most significant in confined channels and many ship channels contain a shallow berm on one or both sides of the channel. The shallow berm has a large impact on the ship effects at the bank-line. The dominant ship effects in confined channels are caused by the displacement effects of the ship and include long-period effects of drawdown, return velocity, transverse stern wave, and surge. Ships generally operate at 80–90% of limit speed and the displacement effects of the ship vary significantly with speed in this range. Analytical/empirical methods cannot address ship effects where shallow berms exist or complex channels. A numerical model, HIVEL2D, is used to determine ship effects in complex confined channels. Model-prototype comparisons show agreement of long-period effects such as drawdown. An empirical relationship is developed for determining surge magnitude but is limited to the waterway on which it was developed until additional data can be collected.