Assessment of the vessel position dead reckoning method error

A method of the calculation of vessel dead reckoning coordinates with the accuracy assessment is proposed. It is based on previously derived formulas for the assessment of the uncertainty boundaries for vessel geodetic latitude and longitude during its motion along the ellipsoid surface. The above formulas are used as follows. At first, the latitude and its precision index are calculated. After, they are used for the calculation of the longitude and its precision index. As the result, it is possible to determine uncertainty intervals for vessel coordinates derived with dead reckoning. The implementation of this method for testing an electronic chart display and information system Navi-Sailor 4000 as to the calculation of vessel dead reckoning coordinates with it is shown. The provision of the information about vessel heading and speed through water is carried out to the system in real-time mode by means of a signal simulator. The speed and heading are remaining unchanged during one-hour time interval. During the above time interval, the data about dead reckoning coordinates are recording into a log-file, then the data are converted in a text format and used for the test. The dead reckoning coordinates, calculated by the system, are in the limits of uncertainty assessed with the proposed method. A limitation of the method is that it does not take into account the influence of errors due to rounding because of the finiteness of the computer bit grid. After the elimination of the above limitation, it seems to be possible to use a modernized version of the method as a part of a procedure for testing the navigational systems which give the information about vessel dead reckoning coordinates.