Offshore positioning methods in engineering applications

Abstract

Marine civil engineering projects in India are in a stage of a major upsurge due to the large oil finds on the continental shelf, improvements and developments of coastal loading/unloading and port facilities. These projects vary in distance from the nearest land from near-coastal to far-offshore, viz., 150-250 km. Accurate position fixing for these jobs requires optical (visual), radio-nav and underwater acoustic systems. Selection of an optimum method is made considering the specific job requirements and for the economics. The important criteria for the adoption of a particular system normally are the range and accuracy required, repeatability, duration and frequency of operations, number of users, climatic conditions and the coastal terrain, etc. The deciding economic factors are the costs towards mobilisation/demobilisation, geodetic surveys, equipment costs or rentals, operating and maintenance costs, etc. A study of these factors and an approach to selection of the most advantageous systems in varying Indian conditions, has been dealt in light of EIL's experience through several projects