Accuracy improvement in depth measurements taken using one-beam echosounder under ship pitching and rolling

Abstract

In order to ensure accuracy of depth measurements on small hydrographic ships in the paper an analysis of errors in depth measurements, taken with a one-beam echosounder under ship rolling and pitching is made, along with the comparison of methods used to decrease the impact of pitching and rolling on the accuracy of those measurements. Data obtained as a result of the analysis made indicate that depth measurement error induced by ship pitching and rolling depending on pitch and roll angles can take on a value up to 3,1% on a flat bottom; in order to ensure that error value is acceptable for precise measurements, the magnitude of pitching and rolling angles should be less than 2°. On a basis of the comparison of three basic methods used to decrease impact of pitching and rolling on depth measurements (i.e. using of ship stabilizers, gyrostabilization of echo sounder measurement head and electronic stabilization of an acoustic beam) it’s evident, that in the view of cost-effectiveness and acoustic noise reduction, use of a gyrostabilized echo sounder measurement head is optimal for small hydrographic ships. In the paper author proposes the scheme of mounting of such a head on the ship, and also recommends the method for gyrostabilizer synthesis.