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1
Content available Practical aspects of using radar in maritime navigation with analysis of its potential errors and limitations
Rutkowski Grzegorz
Scientific Journal of Gdynia Maritime University
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2020
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nr 113
17--28
EN
In this article, the author will try to explain the basic principles of the practical focus of using radar in maritime navigation, analysing its potential errors and limitations. An attempt will also be made to describe the basic seamanship practice of how to set up the radar, determine the radar blind sectors, calculate the radar position accuracy, generate a basic anti-collision radar report, calculate CPA, TCA, BCR, BCT etc., and verify the effectiveness of a trial anti-collision manoeuvre by using the radar in the different radar modes when navigating in restricted sea areas.
2
Content available Comparative Study of the Accuracy of AIS and ARPA Indications. Part 1. Accuracy of the CPA Indications
Wawruch R.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2018
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Vol. 12, no. 3
439--443
EN
According to the IMO recommendation when the target data from radar tracking and AIS are both available and the association criteria are fulfilled such that the radar and AIS information are considered as for one physical target, then as a default condition in radar equipment should be automatically selected and displayed the AIS target symbol and the alphanumerical AIS target data only. The article presents research conducted in real sea conditions on the reliability of information presented by the ship's AIS and ARPA about the passing distance with the other vessel tracked by radar equipment and fitted with AIS.
3
Content available Comaparative study of the accuracy of AIS and ARPA indications. Part 2. Accuracy of the opposite vessel true course and true speed indication
Wawruch R.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
|
2018
|
Vol. 12, no. 4
673--678
EN
The article presents analysis of the automatic radar plotting aid (ARPA) and automatic identification system (AIS) indications reliability performed on the base of the results of measurements conducted on merchant vessels at sea. In the first part of the article titled “Comparative study of the accuracy of AIS and ARPA indications. Part 1. Accuracy of the CPA indications” are described: vessels on which the tests were carried out, AIS and radar equipment installed on them, observed meeting situations and accuracy of the CPA indication. In this article are discussed, for the same meeting situations, accuracy of the information on true course and true speed of the opposite vessel presented by ARPA and AIS and correlation between this accuracies and errors of the CPA indication.
4
Content available Ability to test shipboard automatic identification system instability and inaccuracy on simulation devices
Wawruch R.
Zeszyty Naukowe Akademii Morskiej w Szczecinie
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2017
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nr 52 (124)
128--134
EN
According to the International Maritime Organisation (IMO) recommendation, when the target data from the automatic identification system (AIS) and radar tracking are both available and the association criteria are fulfilled such that the AIS and radar information are considered for one physical target, then as a default condition of radar equipment, the AIS target symbol and the alphanumerical AIS target data, including information on the closest point of approach (CPA) and time needed to reach the CPA (TCPA) should be automatically selected and displayed as this is more accurate than radar tracking data as the current values of true and relative vectors of a manoeuvring object can be presented without time delay which is characteristic for radar tracking. Research conducted at sea on two ships using real navigational equipment has shown that sometimes onboard AIS presents CPA of other vessels equipped with this device as unstable and inaccurate as the automatic radar plotting aid (ARPA). The source of these instabilities and inaccuracies is to be discovered and thus implemented into radar-navigational simulators used for radar training at operational and management levels. This article briefly describes the encountered inaccuracy and instability of the values of the CPA of the encountered vessel presented by AIS, on current shipboard systems, and the possibilities of their demonstration on simulation devices.
5
Content available Ship domain model for multi-ship collision avoidance decision-making with COLREGs based on artificial potential field
Wang T.F., Yan X.P., Wang Y., Wu Q.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2017
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Vol. 11, no. 1
85--92
EN
A multi-ship collision avoidance decision-making and path planning formulation is studied in a distributed way. This paper proposes a complete set of solutions for multi-ship collision avoidance in intelligent navigation, by using a top-to-bottom organization to structure the system. The system is designed with two layers: the collision avoidance decision-making and the path planning. Under the general requirements of the International Regulations for Preventing Collisions at Sea (COLREGs), the performance of distributed path planning decision-making for anti-collision is analyzed for both give-way and stand-on ships situations, including the emergency actions taken by the stand-on ship in case of the give-way ship’s fault of collision avoidance measures. The Artificial Potential Field method(APF) is used for the path planning in details. The developed APF method combined with the model of ship domain takes the target ships’ speed and course in-to account, so that it can judge the moving characteristics of obstacles more accurately. Simulation results indicate that the system proposed can work effectiveness.
6
Content available Ship domain as a safety criterion in a precautionary area of traffic separation scheme
Pietrzykowski Z., Magaj J.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2017
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Vol. 11, no. 1
93--98
EN
The ship domain is one of the criteria for navigational safety assessment. It is particularly important in restricted areas with high intensity traffic, where the criteria of closest point of approach (CPA) and time to CPA are difficult to apply. This research continues to examine ship domains in Traffic Separation Schemes (TSS). We have analyzed precautionary areas established within TSSs in connection with changed arrangements of vessel traffic. Besides, we have defined ship domains in a precautionary area of a specific TSS, and compared them to domains of vessels proceeding along traffic lanes.
7
Content available Evaluation method of collision risk by using true motion
Imazu H.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2017
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Vol. 11, no. 1
65--70
EN
It is necessary to develop a useful application to use big data like as AIS for safety and efficiency of ship operation. AIS is very useful system to collect targets information, but this information is not effective use yet. The evaluation method of collision risk is one of the cause disturb. Usually the collision risk of ship is evaluated by the value of the Closest Point of Approach (CPA) which is related to a relative motion. So, it becomes difficult to find out a safety pass in a congested water. Here, Line of Predicted Collision (LOPC) and Obstacle Zone by Target (OZT) for evaluation of collision risk are introduced, these values are related to a true motion and it became visible of dangerous place, so it will make easy to find out a safety pass in a congested water.
8
Content available Approach parameters in marine navigation - graphical interpretations
Lenart A. S.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2017
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Vol. 11, no. 3
521--529
EN
In this paper approach parameters widely used collision avoidance systems such as the distance at closest point of approach and time to the closest point of approach and less known and used as the distance on course, the distance abeam and any distance and the times intervals to their occurrences are derived, analyzed and graphically interpreted in the combined coordinate system for position and motion. They can be used in collision avoidance systems and for reversed purposes - manoeuvring to required approach parameters, intentional approaches and naval tactical manoeuvres.
9
Content available An assessment of ship encounter situations based on predicted points of collision
Galor W.
Zeszyty Naukowe Akademii Morskiej w Szczecinie
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2016
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nr 46 (118)
82--87
EN
A number of factors affect the safety of navigation, the collision of two ships being one of them. In ship encounter situations, certain principles of behaviour set forth by regulations are in force. Traditionally, a navigational situation is evaluated by identifying the closest point of approach for the passing ships and by comparing it with the assumed safe distance. Then it is necessary to use technical aids: radar and Arpa (depending on the regulations). In Arpa, navigational situation information is mainly presented in the form of vectors. The other presentation that can be used in an encounter situation is the predicted point of collision (PPC). This is the point or points toward which one’s own ship should steer at her present speed (assuming that the target does not manoeuvre) in order for a collision to occur. This paper presents original results of a study into the assessment of ship encounter situations based on PPC. The methods (analytical and graphical) of PPC as a set of circles are elaborated and an analysis of a ship encounter situation performed.
10
Content available Manoeuvring to required approach parameters - CPA distance and time
Lenart A. S.
Annual of Navigation
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1999
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No. 1
99-108
EN
The predicted object CPA (Closest Point of Approach) distance DCPA and, to a lesser extent, the time interval to its occurrence TCPA are well established criteria for collision threat. They are approach parameters widely used as well in collision avoidance systems featuring computer - aided tracking (ARPAs) as in manual radar plots. The scope of this paper is aimed at the problem which although it can be and it is connected with collision avoidance manoeuvres, but it is rather reversed and can be applied for intentional approaches or in naval tactical manoeuvres - what own speed and/or course manoeuvre should be undertaken to achieve the required CPA distance and/or time?
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