QUANTITATIVE EVALUATION OF A STABILIZED PLATFORM SHIPBOARD GRAVITY METER

Abstract

A new LaCoste and Romberg surface‐ship gravity meter mounted on a stabilized platform was tested over the known gravity field of the San Luis Pass salt dome, about twenty miles southeast of Freeport, Texas. A 100 ft boat was used in sea conditions considered average for the shallow offshore areas, waves running from 2 to 6 ft high. An average repeatability of 0.7 mgal was determined for 18 line intersections, of which 14 had differences 1.0 mgal or less. A line by line comparison with the known gravity field indicates an average difference between the known field and the surface meter results of 0.5 mgal. Systematic errors of less than 1.0 mgal were recognized. The platform meter was tested simultaneously with a LaCoste and Romberg gimbal‐supported meter, which proved to be more sensitive to the course direction of the boat and could not make adequate horizontal acceleration corrections in rough seas about 15–20 percent of the total time. The meter on the stabilized platform operated at all times in all six directions.