The paper presents an algorithm of recommended waterway parameters determination based on relationships derived from actual empirical research (a combination of PIANC and Canadian methods). These relationships are mostly discontinuous functions (e.g.: of ship type variable, speed, method of determining the position, etc.), which can be approximated by continuous spline functions. Application built in the C# allows determining the recommended minimum width of the waterway, width increase due to the accuracy of the vessel positioning method, and the radius of waterway bends for the five input variables of the ship and from ten to sixteen input variables of the area