The permissible minimum accuracy of OBN's positions calculation is estimated by help of direct water wave's first breaks (FB) from ordinary shots - based upon record parameters (sample rate - first of all) of reflection method. The article contains the methods&soft of receiver positioning and list of record's parameters, which are especially sensitive to receiver-coordinates errors by reflection method's processing. The position's calculation criterion is formulated; relying on this the minimum necessary accuracy of OBN's positions was estimated (Barents and Kara Seas shelf's areas, typical records) - up to 8m. The article contains the calculation's method, man-hour and result's accuracy. The corrections necessity of "mirror" solutions by 2D seismic survey is considered expressly. The basic conclusion: The seismic survey (reflection method) is all-sufficient instrument both for data acquisition and for bottom receiver's positioning. Under this circumstance the purchase and use of hydro acoustic systems providing the seismic survey is not necessary.