**NAVIGATION AND
HYDROGRAPHY №48/2017**

**Method of
Quantitative Evaluation of Navigation Safety. **S. N. Nekrasov. –
Navigation and Hydrography. – 2017. – No. 48. – Р. 7–13.

The article deals with the problem of navigation safety of seafaring vesselʹs. The method of quantitative evaluation of navigation safety is considered. The vessel, as distinct from the existing approaches, is considered as a spatial object; the position of each point of the object is fully enough is described by the width of the maneuvering lane of movement and by divergence of the vesselʹs center of mass from some standard trajectory. The essence of the method is reduced to statistical evaluation of changeability of the stated navigation parameters that depend on the navigation-hydrographic, hydrometeorologic conditions and quality of the ship control. The quantitative evaluation of the navigation safety is defined as the probability of leaving the set traffic lane.

Key words: navigation safety, navigation risks, identification of navigation risk models, shift of the vesselʹs center of mass, width of the maneuvering lane of a vessel, complex statistical analysis, imitation modelling.

**Prospects
for Employment of the Earth’s Magnetic Field to Determine the Speed and
Co-ordinates of the Autonomous Unmanned Submarine Vehicles. **P. I.
Maleyev, V. Y. Bakhmutov. – Navigation and Hydrography. – 2017. – No. 48. – Р. 14–19.

The autonomous unmanned submarine vehicles (AUSV) are actively developed in recent years. The effectiveness of their employment depends, to a considerable degree, on the used aids to navigation. The known methods of fixing the position of the AUSV are briefly analyzed. The method of fixing the position of the vehicle and its absolute speed by the Earth’s magnetic field is considered in detail. The actuality of the method is connected with considerable success in creating the marine shipboard magnetometric systems. The specific features and advantages of this method over the already known methods are shown. Also the results of the sea field tests of the mock-up units of the shipboard magnetometric systems are presented confirming the prospects for their employment in solving the problems considered here.

Key words: autonomous unmanned submarine vehicles, navigation systems, co-ordinates, speed error, correction, magnetometric aids devices.

**Evaluation of the Expected Accuracy of the Position Co-ordinates
Produced by Navigation Complex of a Moving Object with Irregular Flow of
Navigation Fixes.**** **S. A. Yaroshenko. –
Navigation and Hydrography. – 2017. – No. 48. – Р. 20–26.

The formula for evaluation of the expected accuracy of navigation fixes produced with the irregular flow of navigation fixes, is proposed. By means of the formula the evaluation of the expected accuracy of the position co-ordinates using the same initial data and most often occurring distributions of the time internals between the observations, are calculated. The obtained evaluation allows to make a grounded decision on the observation fixes periodicity, as well as the accuracy of the observation aids planned to be used.

Key words: navigation complex, moveable object, error of position fixes, flow of observations, expected accuracy, chance event, the law of distribution, time interval.

**Approach to
Formation of the Subsystem for Monitoring the Automated Infocommunications
Control Systems. **K. E. Legkov, A. V. Yemelyanov. – Navigation and
Hydrography. – 2017. – No. 48. – Р. 27–34.

The article deals with the problems of designing the the operative monitoring subsystems of the automated control systems of special-purpose infocommunications navigation complexes. The variants of structural organization of these subsystems are suggested.

Key words: infocommunications systems, monitoring subsystem, formation of structure, automated control system.

**Evaluation
of Tidal Variations of Gravity Acceleration for the Barents Sea. **K. G.
Stavrov, O. A. Gasnikov, V. I. Guseva. – Navigation and Hydrography. – 2017. –
No. 48. – Р. 35–41.

The distribution of tidal variations of gravity acceleration in the Barents Sea water area is evaluated. The forms of representing this information in the handbooks and information-reference systems on natural environment parameters of the World Ocean are proposed.

Key words: earth tides, oceanic tides, gravimetric survey, variations of gravity acceleration, corrections for tides.

**Method of
Hydrolocation Evaluation of Parameters for the Submerged Part of Icebergs in
Order to Provide the Navigation Safety for the Shipping Lines of the North Sea
Route. **A.
A. Anokhin, A. M. Sharkov. – Navigation and Hydrography. – 2017. – No. 48.
– Р. 42–46.

The method of hydrolocation survey of the submerged part of an iceberg by multibeam echosounders is considered. During the experimental work, 19 icebergs were studied. Using its results, the volumes were considered and 3D models of the submerged part of the explored icebergs were designed.

Key words: icebergs, provision of safety, multibeam echosounder, towing the iceberg, submerged part of an iceberg.

**Development
of International Concept of the Common Chart Datum for the Baltic Sea
Countries. Vertical Reference Systems of Depths and Heights of the Baltic Sea
Countries. **S.
V. Reshetnyak, L. G. Shalnov. – Navigation and Hydrography. – 2017. – No. 48. –
Р. 47–56.

The materials of the Working Group for Chart Datum of the Hydrographic Commission of the Baltic Sea for development of the concept of the common chart datum of the Baltic Sea are considered. The international and national terms and requirements for the chart datum based on the average multiyear sea level and height reference system used in the Baltic Sea countries and their ambiguousness are analyzed. The main causes and advantages for choosing the European Vertical Reference System (EVRS) as the common chart datum of the Baltic Sea are discussed.

Key words: the Baltic Sea, chart datum, average multiyear sea level, navigation chart, European Vertical Reference System.

**Method of
Calculation of Vertical Distribution of Sound Velocity and Depth by the
Measurement Data of ARGO Drifting Buoys. **Y. N. Zhukov. –
Navigation and Hydrography. – 2017. – No. 48. – Р. 57–62.

The results of comparison of the velocity in sea water calculation by the methods of Wilson and UNESCO, as well as the comparison of depth calculation by the sea water pressure by the 280 Chart Division of the Navy and Leroy method, are presented. The comparison results show that Wilson and UNESCO methods practically coincide. However to solve the hydroacoustic problems of the Navy it is always necessary to use one and the same method, for example, Wilson method. To calculate the depth by the pressure (or vice versa) the Leroy method should be used.

Key words: sound velocity in sea water, methods of calculation of sound velocity in sea water, calculation of depth by water pressure.

**Method of
Calculation of Tidal Harmonic Constants by Observations with Intervals. **Y. N.
Zhukov, E. V. Fedorova. – Navigation and Hydrography. – 2017. – No. 48.
– Р. 63–69.

The method of calculation of the harmonic tidal constants by Dudson method using the hourly sea level observations with intervals is presented. The method is based on the calculation algorithm of Matching Pursuit (adjustment of the problem solution by the directional running over the parameters) that generalizes the known method of the principal components (principal components analysis).

Key words: tides, intervals in observations, Matching Pursuit, method of Dudson.

**Optimization
of Multicycle Process of Pollution Assimilation in Sea Water by the Method of
Increasing Time Intervals. **H. G. Asadov, S. A. Askerova. – Navigation
and Hydrography. – 2017. – No. 48. – Р. 70–76.

The method of optimizing of the multicycle process of pollution assimilation in sea water area is suggested. The principal positions of theory and practice in calculation of the assimilation capacity of the sea water areas are stated. The model of pollution assimilation processes and self clearance of the nearshore water area is suggested. The basic parameters of the developed model are determined. As a result the optimization of the developed model using the variation optimization method enabled to calculate the optimum regime of the pollutants entering the water area at which the summary accumulation capacity for the multicycle assimilation process reaches the maximum value.

Key words: sea water area, assimilation, pollution, optimization, model, ecosystem.

**Tallinn
Recollections or One of those Days. **V. V. Starozhitsky. –
Navigation and Hydrography. – 2017. – No. 48. – Р. 77–81.