ABSTRACT
This paper presents an analytical hydrodynamic modeling tool developed to predict the performance of a very large crude carrier (VLCC), the Exxon Valdez, which ran aground on Bligh Reef in Prince William Sound.
The model consists of simplified hydrodynamic equations of motion with coefficients calibrated from sea trials. The model also incorporates hydrographic data of Prince William Sound to include shallow-water effects, data from a survey of Bligh Reef, current effects, the vessel geometry, and the tanker’s draft and trim on the night of the grounding.
The final form of the hydrodynamic equations derived for the model are presented, along with the derived values of the six coefficients that characterize the dynamic properties of the vessel in water.
Full-scale sea trials of the vessel were conducted over a range of rudder and speed inputs at various vessel drafts. A matrix optimization was employed to determine the derivatives that best characterize the Exxon Valdez based on a systematic comparison of model-predicted positions with data collected during sea trials.
For inputs of rudder position and engine shaft speed, the model predicts vessel position and heading as functions of time for various trackline reconstructions, including the one followed by the vessel prior to grounding.
