Re-visiting the requirement to introduce amended collision regulations to meet the developing threat in encounters between high-speed craft and slower, mainly smaller vessels. This paper looks at the requirements of different types of encounter and the ability to identify high-speed craft through AIS. It introduces proposed changes to the Colregs that could help to reduce the perceived threat to small, slow craft.

The objective of this work was to assess whether the implementation of a bridge resource management (BRM) unit into the simulator-based nautical training of the German Navy is effective in improving non-technical skills and navigation performance. To this end, questionnaire data, observations of behaviour and performance outcomes were compared between a control group and an experimental group. Data of 24 bridge teams (126 sailors) were used for the analyses. Ten teams received BRM training and 14 teams served as the control group with unchanged simulator training. Reactions to simulator training were positive in both groups but more favourable in the control group. In the BRM group, significantly more positive attitudes towards open communication and coordination, more frequent sharing of information and fewer collisions were found than in the control group. Effect sizes were rather small. This may be due to the limited scale of the BRM unit, which consisted of only one instruction-training-feedback cycle. The extension of BRM-related feedback to all simulator runs of the nautical training can be expected to produce larger effects on attitudes, behaviour and performance.

A system which yields the automatic positioning of a ship from computer analysis of marine radar images of nearby coastlines has been tested on data from the survey vessel Maxwell while proceeding in and out of Halifax harbour. Differences between radar-determined position fixes and those obtained by a microwave navigation system with an error of the order i o m show little evidence of additional error when the origin of the radar images used as ‘reference map’ is within 500 m of the actual position. As the distance increases the accuracy slowly decreases.

I am honoured that the Royal Institute of Navigation has invited me to give the E. G. R. Taylor lecture for 1992. These lectures, held annually, were funded by well-wishes in various societies to celebrate Professor Eva Taylor's 80th birthday. As a scholar, Professor Taylor moved in many spheres. I have chosen a subject which seems appropriate to her pioneering work in the history of navigation and the marine sciences.

Rule 25 of the Collision Regulations lays down that, when it is safe and practicable, ships in narrow channels shall keep to the starboard side. The idea behind routing is to extend this type of organization to areas where, because of the concentration of traffic, the problem begins to resemble that of narrow channels. In the open sea a busy route presents no great problem. But where shipping lanes converge the collision problem often becomes serious. This is to a large extent a modern problem which has arisen not only with the increase in maritime traffic, but also with the ability of ships to navigate where they will. Further, the average speed of ships, in all conditions, has greatly increased.

Both the argument and the geometry in this paper require careful study before they can be appreciated; it is hoped that the following notes, which are restricted to purely geometrical considerations, will assist readers to understand them.

The author's fundamental argument is that it is geometrically impossible for ships A and B, at distance r apart and moving with constant speeds v and u, to approach each other more closely than distance d (less than r) if the courses of ships A and B are each restricted to a semi-circular anti-collision sector, depending only on the angle δ sin δ = d/r, and on an agreed universal convention. This is illustrated in Fig. 1 in which the two sectors are indicated by vv' for ship A and uu' for ship B. Adopting the convention that the ships pass ‘port to port’, the permissive anti-collision sector for each ship is, relative to the bearing of the other ship, from δ to starboard, increasing to 180° and to port from 180° to 180° −δ . This is equivalent to restricting the course so that the other ship bears more than δ to port or more than 180°−δ to starboard.

The Safety Level Approach (SLA) is a structured application of risk-based methodologies for the International Maritime Organization's (IMO's) rule-making process. When the SLA is applied, safety goals have to be provided. In order to set appropriate levels for safety goals, it is necessary to measure the tolerance degree of the current safety level. Based on the consistency with individual risk criteria and the principle of continuous improvement, this paper proposes an approach to establish the societal risk criteria, which can be used for setting safety goals in the context of the IMO's SLA. Furthermore, by defining dynamic factors to express risk aversion, a method for tolerance measurement of the current societal risk is developed. Finally, a case study into the societal risk evaluation of cruise ships and Roll-On Roll-Off (RO-RO) passenger ships is conducted.

Motion compensation is a significant part of an airborne remote sensing system. A Position and Orientation System (POS) can directly measure the motion information of an airborne remote sensing payload that can improve the quality of airborne remote sensing images. Gravity disturbance, information on which is often ignored due to being difficult to acquire in real-time, has become the main error source of POS in the development of inertial components. In this paper, a new real-time gravity compensation method is proposed, which includes the gravity disturbance as the error states of a POS Kalman filter, and an accurate gravity disturbance model is constructed using a time-varying Gaussian-Markov model based on a high-precision gravity map, whose resolution is enhanced by a new interpolation method based on Gaussian Process Regression (GPR). A flight experiment was conducted to evaluate the efficiency of the proposed method and the results showed that the proposed method performs well when compared with other real-time gravity compensation methods.

In this work, a new concentric circles detection method for object detection is proposed. It has been applied to the images of a commercial radar, captured with a Charge-Coupled Device (CCD) camera. The processing includes the detection of centres and concentric circles in the images and the identification of the radar scale. Several methods found in the literature have been applied and compared with our novel proposal for multiple concentric circles detection, called “Propagation Method based on Circular Regression”. This methodology has been validated with real radar images, proving its efficiency in obtaining the distance of any object to a marine vessel, with high accuracy and low computational cost, in real time. This system can not only be applied to most existing radars in the market by adjusting the parameters of each model but our proposal for concentric circle detection can be also applied to other sensing applications.

This study consists of an investigation of the point at which ships' masters make decisions to avoid collisions, with regard to the time and distance separation from the other ship. The objective of the study is to find out what factors influence them to make their decisions to manoeuvre at this point rather than at any other; this involves the examination of various factors which could be relevant to the decision-making process, such as the speeds of the two ships, the relative bearing of the other ship, and the length of sea experience of the navigator.

Several computer simulation models for marine traffic systems have been built but various subjective assumptions have had to be made about the criteria on which a decision to make a collision avoidance manoeuvre is based. This study represents the first systematic investigation of the statistical relationships among the factors affecting these criteria.

The estimation of collision danger is often required by harbour authorities and others for planning fairways or for increasing the safety of navigation. Fujii1 gives an approximate formula for the probability of collision in a waterway where the density of traffic, the size distribution of ships and the average speed are known. Fujii's formula is however only applicable where the traffic has been surveyed and traffic patterns are well known. Some simple method is required for estimating collision danger, especially for harbours where traffic patterns are complicated and the information available on marine traffic engineering is comparatively small.

The Global Positioning System, Navstar, is an advanced satellite-based navigation system which is currently under development and evaluation in the United States of America. Progress has been very fully reported in the open literature and a definitive paper on the concept has in fact been published in this Journal. The concept has now been experimentally validated and much of the evidence which supports this validation has in turn been published.

The impact of Navstar on navigation in the period beyond 1985 is potentially very great indeed in that it offers, worldwide, a navigation capability to surface and aerospace users of a standard of accuracy combined with continuous availability which is currently associated only with short-range aids.

This paper has the objective of presenting (a) a general introduction to the physical principles on which Navstar is based, followed by (b) a survey of its potential relevance to the operational needs of various classes of user. Finally there is some more speculative matter in the form of (c) a discussion of the potential impact of successful implementation of Navstar on current and projected future navigation systems.

Knowledge of surface currents is of fundamental importance in many diverse marine activities; for example in navigation, offshore engineering and operations, and in the prediction and monitoring of the movement of pollutants. In those areas of scientific research directed towards improved understanding of climate, and towards the modelling and prediction of currents, studies of exchanges of heat and momentum between atmosphere and ocean also require detailed knowledge of mean and fluctuating components of near-surface flow.

Most of the radar systems used in operating marine vessel traffic management services experience problems, such as track loss and track swap, which may cause confusion to the traffic regulators and lead to potential hazards in the harbour operation. The reason is mainly due to the limited adaptive capabilities of the algorithms used in the detection process. The decision on whether a target is present is usually based on the amplitude information of the returning echoes. Such method has a low efficiency in discriminating between the target and clutter, especially when the signal-to-noise ratio is low. With modern signal processing techniques more information can be extracted from the radar return signals and the tracking parameters of the previous scan. The objectives of this paper are to review the methods which are currently adopted in radar target identification, identify techniques for extracting additional information and consider means of data analysis for deciding the presence of a target. Instead of employing traditional two-state logic, it is suggested that the radar signal should be allocated in terms of threshold levels into fuzzy sets with its membership functions being related to the information extracted and the environment. Additional signal processing techniques are also suggested to explore pattern recognition aspects and discriminate features which are associated with a return signal from those of clutter.

What are we doing it for? Datatrak designed, built and prepared for the transport market, a complete Automatic Vehicle Location and Reporting System (AVLRS) that covers 95 percent of the road system of Great Britain.

We were amused by the Cross Track Distance at Mid-Longitude problem posed by Paul Hickley in The Journal of Navigation 57, 320. Two professors, John Ponsonby and Peter Hoare, replied to the invitations immediately. Both their solutions to the original article give superb accuracy. The two solutions are certainly ingenious and creative and encouraged us to develop new formula for building the Mid-Longitude Equation on great circle. Regrettably, the original author doesn’t think that the two were the solution that ATPL examiners were looking for. I also think that the two solutions would be beyond the capacity of the average undergraduate. Our method gives a good understanding logically and easily to be mnemonic, and the derivation process is found without any need to appeal to any formula of spherical trigonometry.

The normal Great Circle method of computing the shortest distance between two positions on the Earth – e.g. from an aircraft's present position (PP) to a waypoint (WP) – is not accurate enough to meet present-day requirements for aircraft Nav–Attack systems.

On the surface of an Ellipsoid (or Spheroid), the true ‘shortest distance’ is along a geodesic curve between the two points, but the computation of this curve is complex, and as shown by R. Williams at Reference, the difference between the geodesic and Great Ellipse distances between two points is negligible (<0·01 nm).

The Great Ellipse through two points on a spheroid is defined as the ellipse that passes through the two points and the centre of the spheroid; it therefore has a major axis equal to the Earth's, and a minor axis that is between the Earth's major axis (for two points on the Equator) and minor axis (for two points on the same, or diametrically opposite, longitudes). Thus the problem of deciding on which Great Ellipse the two points lie is equivalent to determining the magnitude of the minor axis β of the ellipse on which they both lie.

This paper, and the following six papers, were presented during the NAV 98 Conference held at Church House, Westminster, London on 9th and 10th December 1998. A full listing of the Conference, and how to obtain a copy of the proceedings, is shown on Page 300.

The existing Loran-C and Chayka infrastructure can, with some minor changes, become a very powerful augmentation system for GNSS (GPS, GLONASS and the future Galileo). Delft University initially proposed the Eurofix concept in 1989. Although the necessary modification to the LF navigation systems are minimal, the GNSS user may get significant benefits from the Eurofix signals in terms of accuracy, integrity and availability. The reason is the high signal structure, signal propagation, and the operations dissimilarity of both systems. The broadcast correction and integrity data improves GNSS accuracy down to the metre level. In this way, the measured Loran-C and Chayka ranges are continuously updated. Thus, in the case of GNSS signal interruptions, highly calibrated Loran-C/Chayka may take over the navigation function. Tests carried out in Europe at the Loran-C station at Sylt (Germany) drew large international attention, leading to further tests in the USA by the US Coast Guard in 1998. Recently, a Dutch–Russian consortium implemented Eurofix on the Chayka transmitter at Bryansk (Russia) which is now successfully broadcasting DGPS as well as DGLONASS correction data. This paper highlights some on-air Eurofix DGPS performance experiments carried out in Europe and the USA. With all the European Loran-C and Chayka transmitters modified, Eurofix can be used all over the European continent. As multiple stations can normally be received simultaneously, the user may locally apply networked DGNSS, which may reduce spatial decorrelation effects significantly. Post- processed results of this Regional Area Augmentation System are presented.

This paper considers the development of three autopilots for controlling the yaw responses of an autonomous underwater vehicle model. The autopilot designs are based on the adaptive network-based fuzzy inference system (ANFIS), a simulated, annealing-tuned control algorithm and a traditional proportional-derivative controller. In addition, each autopilot is integrated with a line-of-sight (LOS) guidance system to test its effectiveness in steering round a series of waypoints with and without the presence of sea current disturbance. Simulation results are presented that show the overall superiority of the ANFIS approach.

A novel autonomous positioning approach based on X-ray pulsars is proposed in this paper. First, the principles of the pulsar–based measurement model and the inter-satellite range model in the autonomous positioning of satellite constellations are presented. The observability of the pulsar-based measurement model is then shown. Second, the autonomous positioning algorithms, including measurement models and orbital dynamics models, are formulated using an unscented Kalman filter to estimate the position vectors of satellites. Finally, the feasibility of the proposed measurement scheme compared with an inter-satellite range scheme is illustrated by numerical simulation. The results show that the proposed approach can keep the satellite state convergent, and achieve position accuracies of 2 m. The proposed scheme provides a promising approach for autonomous absolute positioning of constellation systems by using X-ray pulsars.