## 1 Introduction  
Complexity of the design of contemporary floating objects requires the development of appropriate methods to control their correct operation, which in turn justifies the desirability of developing effective methods for planning diagnostic experiments. Experience shows the need to develop optimal algorithms' research proceedings, in particular for complex (multidimensional) mechanical objects with a high level of interferences [1].  
As a result of diagnostic activities, large sets of measurement parameters are obtained. Therefore, there is a need to develop a database and select useful symptoms. Planning experimental research should provide answers to a number of questions, such as: what means of measurement should be used, how the measurement should be performed, what should be measured and how to infer.  
The mathematical theory of experiment planning proposes scientifically justified methods that allow one to plan the experiment procedure in such a way as to receive the maximum amount of anticipated information at the lowest possible cost and time [2]. Planning for diagnostic experiments in the application of internal combustion engines dealt with include authors in the works [1; 3; 4] and if appropriate ISO 3534-3 standard. Facing the challenge of planning diagnostic experiments to be applied to internal combustion engines, the authors proposed a new approach to building the diagnostic model of complex mechanical objects.  
The applied procedures of planning diagnostic experiments included the selection of features of the object's state, diagnostic parameters and observation sites, as well as diagnostic symptoms. It results from the strategy of operation of objects based on their technical state aimed at in order to rationally plan diagnostic tests [1; 4; 5; 6] and the ISO 3534-3 standard. This applies to both the optimization of the periodicity of diagnosed and the scope of diagnosis [6; 7].  
The literature describes many methods and plans for conducting research [5; 6]. A typical experiment plan consists of the following elements [2]:  
* formulation of a research problem
* definition of restrictions based on preliminary information about the test object
* the proposal of a mathematical model
* choosing a research plan based on the mathematical theory of experiment planning
* test plan execution
* analysis of the obtained results and implementation of the mathematical model by determining unknown parameters
* verification of the mathematical model or a new model proposal
* using the model to further study the object's properties, including the optimal conditions for its functioning  
The above-mentioned works in the field of experimental planning provide a significant contribution within the scope of research limitations [1], planning and performing an optimal experiment [2], pre-selection of diagnostic parameters and choice of principal test conditions [3], proposing a new approach to building the diagnostic model [4], determining of the points of conducting a factor experiment in a specific order [5] and application in the creation of a new quality [6]. The selection of measured quantities, locations of signal receiving points and conditions of testing combustion engines is typically made on the basis of literature-based knowledge, experience or intuition.