PROBABILITY ESTIMATION DEGREE OF DANGER VESSELS RAPPROCHEMENT

In the article is specified, that a decision-making process contains the following stages: control of environment, including relative position and parameters of relative motion, the exposure of situation of rapprochement of vessels, in the case of rapprochement of vessels it is necessary to produce estimation of degree of his danger, at dangerous rapprochement is needed to define the type of co-operation, depending on the degree of danger of situation of rapprochement the choice of strategy of divergence is produced. On the first stage of process of decision-making surrounding mobile objects come to light by ARPA or AIS, for which is measured parameters of motion and relative position. It is shown that on the second stage of process of decision-making, using the measured parameters, it is necessary to expect the value of speed of change of distance between vessels, taking into account that at its negative value ships are drawn together. On the third stage of process of decision-making at rapprochement of vessels estimation of degree of his danger is produced, what development of situation of rapprochement to the moment of time of their shortest rapprochement is forecast for. On the fourth stage of decision-making it is necessary to define the type of cooperation of the drawn together vessels, taking into account principle their process control of divergence. It is especially substantial for principle of locally-independent management by the process of divergence, when coordination of co-operation of vessels at dangerous rapprochement is needed. The fifth stage of decision-making is characterized by the choice of strategy of divergence, thus at the locally-independent process control of divergence the choice of strategy of divergence is produced depending on the degree of danger of situation of rapprochement, by the standard maneuver of divergence or for excessive rapprochement of vessels it is necessary to use the maneuver of urgent divergence. In work as the index of efficiency of the analytical collision avoidance systems vessels probability of safe completion of process of divergence, which is work of probabilities of successful end of stages of process of decision-making on the choice of strategy of divergence, is offered. It is shown that first three stages of decision-making on the choice of strategy of divergence are characterized by general probability of absence of danger of collision on condition that distance of the shortest rapprochement is equal to the set minimum-possible distance of rapprochement. For determination of the mentioned probability the error of distance of the shortest rapprochement is considered and expression is got for the closeness of its distributing. To that end collected dependence of error of distance of the shortest rapprochement from the errors of measuring of distance and bearing. By the got expression for the closeness of distributing of error of distance of the shortest rapprochement probability is certain of that at equality of distance of the shortest rapprochement with limit-possible distance of rapprochement there will not be the collision.

TAKING INTO ACCOUNT THE DYNAMICS OF THE BOTTOM RELIEF FOR TECHNOLOGIES RIS

Science and technology achievements in the 21st century have qualitatively changed the traditional methods and techniques of Earth's surface research. Nowadays, remote methods have been used widely, when an observer or a measuring device is located at a certain distance from the study object in order to increase the observation area by several times. These materials can expand horizons of researchers, lead to increasing the flow of valuable information about already known objects and phenomena of the Earth.In presented research, there are some explanations about mechanisms of using natural processes to make forecast of changes in bottom topography in shallow water under navigation conditions. The key factor is the development of programs that can track changes in natural processes with displaying and fixation on electronic devices. Any research should preferably be carried out considering changes of the object over time and under the influence of various factors simultaneously and dynamically. In the article dynamic processes are divided into "significant" and "insignificant". This dependence is determined by the scale of space and time, where and when they occur. The concept of "scale factor" is introduced in order to determine significance of dynamic processes influence during research. Presented in the research dynamic map modelling method enables to make a forecast of siltation of the sea / river bottom for a given period of time. After comparing the forecast with the actual result, you can make corrections of the selected function, i.e. constantly improving the model. As a result of the research, we came to the following conclusions: 1. The “scale factor” should be entered in dynamic navigation map research and compilation with using different-scale data of the water surface and bottom topography; 2. It is recommended to enter a dynamic component into the information block of the navigation cartographic systems ECDIS and Inland ECDIS, allowing the skipper to see the position of the vessel, considering the wave height relative to the bottom in real time; 3. Above methods of parallel bottom topography transferring are based only on the data of statistical observations with using iterations. These methods usually give proper results on sandy and silty soils, where the relief has distinct wave-like forms, as well as relatively often repeated external influences with following the general main direction.

CALCULATION OF THE RELEVANT COLREG VARIANTS OF THE COMBINED ACTION TO AVOID COLLISION

An algorithm is proposed for determining the set of corresponding to the COLREG variants of combined action (alteration course with the speed) to avoid collision with several vessels. When establishing compliance with COLREG, 11 types of meeting of the dangerous target and own ship and four stages (planning of maneuver, early, possible and urgent measures) at the segment of COLREG performance in relation to this target were distinguished. It was assumed that the action to prevent a collision is determined at the first stage. We used the general and particular indicators of the COLREG compliance for each of possible variants of combined action. Due to the large number of such options, the formulas used in their analysis for forecasting, assessment of safety and other goals were simplified so that the calculation time was acceptable. On this basis, the danger domain for the targets was selected simple, circular in shape, with the center shifted relative to the target to take into account the greater risk of crossing its course along the bow than at the stern. It was supposed acceptable to replace the trajectories of combined actions with a combination of a straight segment and an arc of a circle; to represent the change in speed during braking by a second-order polynomial; to consider as unrelated the course and speed changes in the joint operation. An algorithm has been developed for obtaining a matrix of general COLREG compliance estimates of possible combined action variants and flow chart of this algorithm is given. By the elements of this matrix, it is possible to search for an effective variant of the passing by under various assumptions and criteria. As an example, an algorithm for calculating the combined action to avoid a collision with a minimum reduction of the speed is given. The reliability of the proposed algorithms was confirmed by simulation modeling of ships collision avoiding processes in various situations. Key words: collision avoidance, combined action, compliance with COLREG, collision avoidance algorithm.

COORDINATE METHOD FOR DETERMINING THE GROUND SPEED OF THE VESSEL BY VECTORS AND DISPLACEMENT OF RELATIVE SPEEDS

During the movement of the vessel along the route there is a problem of observation of natural and man-made obstacles, which is solved by modernizing the management using enavigation. Intensification of the movement process is provided by increasing the number and frequency of observations according to static criteria. In this case, the methods of graphical and analytical calculation of the path are the basis of navigation, forcing a return to the local criterion, which reflects the full physical nature of the process. The calculation of the vessel's path on the route is carried out according to the rule of the polygon, the sides of which are the vectors of the speed of the path, the vessel and perturbations (wind, waves, current). The main problem is the accuracy of determining the magnitude of the perturbation vector. The inaccuracy of the definition leads to the extension of the vessel's path, which contributes to energy and financial losses for transport support and maintenance of the vessel. The aim of the study is to create a reliable, fast and accurate (innovative) way to determine the characteristics of rectilinear gradual uniform motion of the vessel, which features three speed vectors: perturbation, relative and absolute velocities. The object of study was the process of ship movement, and the subject - the elements (parameters) of movement. The article determines the forecast parameters with a minimum of a priori information at the beginning of the vessel: the sequence of determining the angles of the speed triangle is determined, the sides (modules) of the speed triangle are determined, the order of determining the coordinates of the vertices of the velocity triangle is established. This allows to solve more complex problems of graph-analytical and mechatronic calculus and observation of translational and rotational motion of the vessel along the route and to improve control to reduce risk on the course of disturbances in "big" real time, with variable intervals of observations, approaching invariant and robust control. The advantage of the coordinate method is to solve the problem of determining the parameters of vectors by methods of analytical geometry more accurate, proven and simple in comparison with empirical dependencies, as well as geometric constructions

EPENDENCE OF PARAMETERS OF VIRTUAL REGION FROM SUBSTANTIAL FACTORS

In the article is specified, that marine ships considerable part of the operating time work in the straitened districts, in which the width of free passage-way for vessels is limited in the navigation relation by dangers, or intensive navigation. It is marked that in the case of dangerous rapprochement of vessels in the straitened waters at the choice of maneuver of divergence by an operating ship besides a dangerous target it is necessary to take into account preventing ships and navigation dangers in the district of maneuvering, and the existent methods of simultaneous account of dangerous aims and navigation dangers carry analytical character and are bulky and ineffective. The necessity of development of operative and evident methods of warning of collisions of vessels at sailing in the straitened waters is caused to these. The analysis of the last achievements and publications is resulted in work, the decision of the considered problem and selection of parts unsolved before is begun in which. It is shown that binary coordination is the basic method of description of cooperation of pair of the dangerously drawn together vessels, urgent strategies of divergence are considered, the structure of which depends on the conduct of target in the process of divergence, the analysis of procedures of account of navigation dangers is also produced by an analytical method for different types of navigation dangers. Procedure of transformation of the ship safe region set in space of relative motion is offered, in space of veritable motion, a virtual region is formed as a result. It is indicated, that basic properties of virtual regions are: rapprochements of ship with a target dangerous, when the current area of programmatic trajectory of motion of ship gets in the virtual region of target; distance of the shortest rapprochement of ship with a dangerous target will be equal to the set minimum-possible distance of rapprochement, if direction of current area of programmatic trajectory of motion of ship is tangent to the border of virtual region; equality of distance of the shortest rapprochement of ship with a target and set minimum-possible distance of rapprochement is saved at the following of ship on a virtual region tangent to the border to the moment of the shortest rapprochement. It is shown in the publication, that by the computer program dependences of position and form of virtual region on the relation of speeds of ship and target were explored, from distance between a ship and target, and also from bearing on a target. It is shown that depending on distance between a ship and target at the unchanging bearing a virtual region occupies unchanging position in relation to the line of programmatic way of ship, and position and sizes of virtual region depend on bearing on a target.

ANALYTICAL MODELLING OF SEAKEEPING QUALITIES OF CONTAINER VESSEL

The design of ships or any other floating systems intended to operate on or close to the surface of the sea is controlled to a large extent by what is usually referred to as seakeeping, or, in more common terminology, safety at sea. This is a primary consideration and criteria, which has to be fully met. Safety of a ship naturally includes the crew, cargo and the hull itself. Seakeeping is, indeed, a generalized term and reflects the ship's capability to survive all hazards at sea such as collision, grounding, fire, as well as heavy-weather effects related to the environment in general and waves in particular. The two most likely types of failure under these conditions are due to structural causes and capsizing resulting from insufficient stability under severe weather conditions. Such criteria as economical navigation of the ship as related to speed-keeping abilities, fuel consumption, avoidance of damage to ship components and cargo, and comfort to crew or passengers, or both, are key items. The operational limits of electronic equipment, mechanical components and weapon systems on board warships are other aspects of sea keeping. In this work it is highlighted that seakeeping is a generalized term that includes a wide variety of subjects such as ship motions (amplitudes, accelerations, phases), deck wetness, slamming, steering in waves, added resistance, hydrodynamic loadings (pressures, forces, moments) and transient loads. Since the ship environmental operability or its sea keeping characteristics are closely linked to the severity of the sea, the description of the seaway is usually considered as an integral part of sea keeping. It is taken into consideration that the severity of the sea cannot be considered in absolute terms, since for each floating system, be it a ship, a platform or a buoy, the intensity of the sea state can only be determined in terms of the system's responses. Hence, different thresholds apply to different problems, and sea state 4 may be just as severe for a small patrol craft as sea state 8 may be for a larger containership. Hence, the characteristics and frequency of occurrence of waves in specific sea zones are required if a possible reduction in the system environmental operability is expected. It is demonstrated that most texts or papers, which deal with the overall question of sea keeping, devote some attention to the basic phenomena, that is, the seaway and the motions of the ship or other floating platforms as a result of the excitation imposed by the seaway. Ship motions, as such, do not always constitute the criteria for sea keeping, and much more often other responses directly related to the magnitude and phasing of the motions or the resulting velocities and accelerations constitute the prime cause for exhibiting good or bad sea keeping qualities. Such responses could be a function of the motion only, as in the case of added resistance or hydrodynamic pressures, or they could be a function of motion and other design parameters, such as freeboard in the case of deck wetness or the longitudinal weight distribution in the case of vertical bending moments. In this work, latest methods of modeling and computation for body-wave interactions described and compared with data observed for container carrier. The foregoing calculation routine Судноводіння | Shipping & Navigation ISSN 2306-5761 | 2618-0073 30-2020 Національний університет «Одеська морська академія» 79 is fairly well accepted today among naval architects specializing in the sea keeping aspects of the ship design process. Differences between the results obtained by various techniques as presented by the available computer programs are insignificant. However, since the regular-wave results are of little or no value except as input for the more realistic long- and short-term response predictions in a real seaway environment, it is important to determine which wave data information and what statistical extrapolation techniques are used to obtain the latter. The format used to describe the seaway in most ship response calculations is the wave spectrum. However, since measured spectrum for a specific sea zone or route are very rarely available, it is often necessary to use spectrum measured in one location for predictions in another location. In such a case, while the basic spectruml shape and scatter remain unchanged, the percentage of wave height distribution would vary to represent realistic conditions for the sea area in question. Such data usually are based on observations, and assuming the sample is large enough the distribution of expected wave heights should be quite reliable. An alternative approach often used in ship design is to utilize one of several theoretical spectruml formulations [2, 3, 4] such as the Pierson-Moskowitz one-parameter spectrum, the ISSC spectrum, the JONSWAP spectrum, and other. In each of these cases, some input parameters are required usually in the form of wave height, period, peak frequency, fetch, etc. The reliability of the wave data depends in these cases both on the quality of the input parameter and the adequacy of the theoretical formulation.

IMPACT OF THE CROSS-TRACK ERROR DISTRIBUTION LAW ON SAFE NAVIGATION IN NARROW WATERS

The paper indicates that navigation in narrow waters requires navigators to use means of passage safety assessment prior to choosing a route. It is pointed out that a relevant factor when assessing the safe passage probability is the cross-track error distribution law, whose impact is the subject of the research. The article analyses recent developments and publications that have begun investigating this subject, and highlights previously unsolved parts of the general problem. The results revealed two equivalent approaches, as well as a navigational safety parameter, which are used to determine the probability of safe navigation in narrow waters on the chosen route. The need to develop advanced predictive vessel motion models is noted, while many researchers study the design of an information system for vessel motion simulation with complex dynamic models and an intelligence system for vessel motion prediction that imitates the learning process of an autonomous control unit created with the use of the artificial neural network. Methods for identification of vessel manoeuvring models are shown. Based on the analysis of vessel hydrodynamics, a nonlinear model frame of vessel manoeuvring is established. The available publications suggest using compound laws of the first and second types for describing random errors in navigation measurements as an alternative to the normal distribution law. The article examines the dependence of the safe narrow waters passage probability on the cross-track error distribution law. The normal law and compound laws of the first and second types are considered as the cross-track error distribution laws. A formula for estimating the safe passage probability in the manoeuvring area is given, and expressions for the distribution function of the normal law and compound laws of both types are obtained. To assess the impact of the cross-track error distribution law for the same route, the safe passage probability for the normal distribution law, as well as compound laws of the first and second types, was calculated. For the same route, the probability of safe passage was calculated with the use of onedimensional and two-dimensional density models. It is shown that the average relative difference between the estimated safe passage probability for both models is 0.3%, which confirms the validity of using a one-dimensional cross-track error distribution density.

NEW MATHEMATICAL MODELS OF LONGITUDINAL HYDRODYNAMIC FORCES ON THE SHIP’S HULL

Development of modern ship's automatic steering systems, navigation simulators, research of ship maneuvers stipulates the necessity of adequate mathematical models of the ship propulsion complex. The main components of the non-inertial forces of the ship propulsion complex are the hydrodynamic forces on the hull. Therefore, the improvement of mathematical models of these forces refers to important scientific and practical problems. This paper proposes a general approach to the construction of mathematical models of hydrodynamic forces on the hull. The approach is based on a multivariate quasilinear regression analysis, considering the values of the multiple correlation coefficient, the significance of the model, and the significance of each explanatory factor (regressor). In particular, the Fisher's criterion was used to test the significance of the models, and the statistical significance of each regressor was checked with the help of the Student's criterion. In addition, the standard error of each regressor was investigated. We also checked the absence of multicollinearity of the obtained models. The inadequacy of many existing mathematical models of hydrodynamic derivatives of longitudinal hydrodynamic forces on the hull is shown. In particular, it was found that one-factor correlation analysis cannot provide the construction of adequate models with high significance for all hydrodynamic derivatives. It has also been proven that applying only the AIC minimum criterion (Akaike Information Criterion) cannot ensure that all the regression analysis criteria are met. New adequate models of hydrodynamic derivatives have been constructed for longitudinal hydrodynamic forces on the hull with a high level of correlation, high indicators of significance of the models as a whole and of each regressor separately. The models are built for the whole range of variation of the block coefficient: (0.5; 0.9) and separately for the two ranges: (0.5; 0.7) and (0.7; 0.9). As regressors, we used the relations of the basic geometric parameters of the vessel, such as length, breadth on the current waterline, draught and the value of the block coefficient.

MARINE RAM-TYPE STEERING GEAR DETAILS LOAD TRANSFER FEATURES

he article deals with steering gears, used on marine and river ships, namely with ram-type steering gears. Article topicality due to the fact that ship controllability and sailing safety depends of steering gears reliability. Reliability could be increased through the refinement of processes, which took place during the perception and transfer of load. Process of lateral force perception by plungers and guide beams is studied theoretically. It is shown that perception depends of gap size between plunger and sleeve and could pass in one, two or three stages. Those stages are characterized changing in the loading process plungers fixing conditions, and respectively plunger lateral load proposed to determinate by three design schemes. Received expressions for calculation ultimate gaps of «plunger-sleeve» pare landing, that gives the limits of application each of three design schemes. Ratios for determination load of plunger and guide beam are received trough consideration their joint deformation for each design schemes. On the example of YOOWON-MITSUBISHI YDFT-335-2 ram-type steering gear is shown that in new gear, where landing gap is minimal and conditioned by tolerances of plunger and sleeve diameters, guide beam can take only 2.0…6.5% of lateral force, which applied to it and plunger from tiller. In steering gear with partially worn out plunger and sleeve in time of rudder feather shifting from diametric plane to board (when α = 5…35º), guide beam could take 4.7…6.8% of lateral force. The source of origin significant loads on plungers in ram-type steering gears is application of sinus-type mechanism for transformation progressive plunger motion to rotating tiller motion. Decreasing lateral loads on plunger through using unloading guide beams, with considering low unloading percent is ineffective. Guide beams availability complicates steering gear construction, increasing number of friction surfaces and trough this complicates steering gear maintenance.

PRACTICAL FEATURES OF ECDIS SAFETY DEPTH CALCULATION

The safety of marine navigation in coastal areas and narrow waters, which account for 80% of total navigational accidents, remains a pressing concern. These circumstances indicate the need to improve traditional and automated methods of passage planning and control of navigation and traffic management processes, based on the assessment of the actual navigation accuracy and navigation safety parameters. According to current industry recommendations, the main parameters of safe navigation are safety depth, safety contour, permissible cross-track limit, and accuracy of position fixing. This study deals with the development of a general practical approach to the calculation of the safety depth, as one of the main safety parameters in the ECDIS system, with an increased focus on those aspects of calculation where navigators tend to make mistakes. Analysis of data obtained during the training on the ECDIS simulator for navigators directly involved in the passage planning process (master, navigation officer) showed systematic mistakes in assessing the route safety, which can lead to ship grounding in real world. At the same time, navigators often do not recognize the danger, misinterpret it or make mistakes when checking the passage plan for safety. The results of the competence assessment showed that 40% of masters and 30% of navigation officers make mistakes in calculating the safety depth. The most common mistakes are the incorrect application of category zones of confidence (CATZOC), miscalculation of the minimum depth on the route, miscalculation of the tide height, tidal window period, the neglect of corrections for increased draught due to roll and pitch. The paper suggests that the UKC (under keel clearance) company policy shall take into account the accuracy of chart information. Furthermore, the research further develops the method of calculating the safety depth, implemented in the software, which makes it possible to systematically assess the safety of a route with multiple legs with heterogeneous parameters.