EN
This paper descibes the application of the method of logical product to detect changes in sonar picture. It also presents the possibility of joining the orthogonal basis of planes ƒ(x,y) = a1x+b1 and ƒ(x,y) = a2y+b2, with scalar product to improve recognition results. It provides a comparative analysis of the results obtained by the use of scalar product itself and of the combination of both the methods on the ground of real data obtained from the tests carried out by the Akademia Morska /Maritime Academy/ in Szczecin on the fairway Szczecin-Świnoujście.