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2 Polish Maritime Research

2 2018

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The imaging of Gdansk Bay seabed by using side sonar

Grelowska G., Kozaczka E., Witos-Okrasińska D., Szymczak W.

Polish Maritime Research

2018

S 1

111--118

This paper is mainly aimed at presentation of an impact of environmental conditions on imaging accuracy by using hydro-acoustic systems in waters of a high non-uniformity of spatial distribution of hydrological parameters. Impact of refraction on erroneous estimation of range, in case of wave radiation into water under a large angle, like in side sonars or multi-beam echo-sounders, is especially important. In this paper seasonal changes in sound speed and its impact on acoustic beam refraction is discussed. And, examples which illustrate errors in determination of side sonar range occurred during last investigations carried out in Gdansk Bay waters are presented.

Influence of natural conditions on the imaging of the bottom of the Gdańsk Bay by means of the side scan sonar

Witos-Okrasińska D., Grelowska G., Kozaczka E.

Polish Maritime Research

2018

S 1

104--110

The interest in underwater resources is the reason for the development of modern hydroacoustic systems, including side sonars, which find numerous applications such as: research of seabed morphology and sediment characteristics, preparation of sea sediment maps, and even in special cases of biocenoses such as sea grass meadows, detection of specific targets at the bottom such as shipwrecks, mines, identification of suitable sites for maritime infrastructure. Such applications require precise information about the position of the objects to be observed. Errors affecting the depiction of the bottom using hydroacoustic systems can be divided into errors associated with improper operation of measuring and support devices, systematic errors and random errors. Systematic errors result from the changing conditions prevailing in the analyzed environment affecting the measurement system. The errors affecting the correct operation of hydroacoustic systems can include: changing angle of inclination of the beam caused by the vessel’s movement on the wave or refraction connected to changes in the sound speed as the depth function.