IMPROVED PASSAGE PLANNING USING WEATHER FORECASTING, MANEUVERING GUIDANCE, AND INSTRUMENTATION FEEDBACK

ARCO Marine currently operates ten tankers which move crude oil from V aldez, Alaska to West Coast ports of the United States, These tankers range in size from 70 000 to 265 000 dwt and operate throughout the ye ar in the harsh environment of the North Pacific Ocean. All of the shi ps have experienced fatigue and slamming related structural-damage, Fa tigue damage of structural details occurs from cyclic loading as the s hip hull girder flexes in response to the seaway. Damage to local bow structure results from slamming, which is a high magnitude impulse loa d that induces a high frequency response in the hull girder. Because o f this high frequency response, slamming also contributes significantl y to fatigue damage. With the goal of minimizing this structural damag e, ARCO Marine initiated the Hull Monitoring Frog ram with Ocean Syste ms Inc, in mid-1992 to develop an onboard computer-based Decision Supp ort System (DSS) that conveys information to the shipmaster to aid in avoiding encounters with ship damaging seas. There are three basic sou rces of information to the DSS: weather forecasting, analytic and empi rical seakeeping computations, and instrumentation feedback. An instru mentation package was installed on the ARCO California and continuousl y recorded ship motion and hull girder responses throughout its five 1 992/93 winter-voyages. Analysis of the recorded data resulted in sever al significant findings that validate the needfor an onboard DSS. The Hull Monitoring Program built on the success of the 1990 ARCO Tanker S lamming Study [1] and has resulted in the conceptual design of a proto type DSS ready for implementation during the 1993/94 winter voyages. T his paper describes the 1992/93 instrumentation package and data acqui sition process, presents many of the significant findings, introduces the-concept of improved passage planning, and discusses plans for the onboard implementation of the prototype system.