In the January 1977 issue of this Journal an article ‘The new buoyage system’ by the Hydrographer of the Navy was one of the many steps taken during the past two years to explain to chart users what IALA System A is all about. Newspapers, magazines, schools of navigation, yachting clubs and commercial printers have all helped to spread the gospel. There are on the market a variety of booklets, wall charts, plastic models, cassette teaching aids and films. The new symbols used to portray the details on the charts can be found in Navigation Publication NP735, available from Admiralty chart agents.

The traditional Kalman filtering-based transfer alignment methods largely depend on prior information for initialisation. However, the initialisation process is hard to fulfil on a moving base. In this paper, a type of inertial measurement vector integration matching for optimisation-based transfer alignment and calibration is proposed to estimate the misalignment between the Master Inertial Navigation System (MINS) and Slave Inertial Navigation System (SINS), and main inertial sensor error parameters of SINS, including bias and scale factor error. In contrast to filter techniques, the proposed method has the capability of self-initialisation and provides a new idea to solve the alignment and calibration problem. No prior information is needed. Moreover, the integration time interval for the matching inertial measurement vector is selected by considering both the observation degree of inertial sensor error parameters and the noise effect. Simulation results demonstrate that the proposed method has faster convergence and is more accurate than Kalman filter techniques.

These methods were briefly described in the Journal (Vol. 13, No. 2). They were prefaced by some comments designed to draw a comparison between the air and sea problems and collision rates. Statistics are liable to be misleading if not perfectly understood and definitive, and marine collision statistics as much as any. It should be realized that Lloyd's List figures include almost every collision incident to ships of joo tons and over and that a comparable air figure would probably need to include damage to aircraft by aircraft on airfields and in hangars and whether under their own power or in tow.

We propose a novel framework for large-scale maritime ship group surveillance using spaceborne optical imaging satellite data and Electronic Intelligence (ELINT) satellite data. Considering that the size of a ship is usually less than the distance between different ships for large-scale maritime surveillance, we treat each ship as a mass point and ship groups are modelled as point sets. Motivated by the observation that ship groups performing tactical or strategic operations often have a stable topology and their attributes remain unchanged, we combine both topological features and attributive features within the framework of Dempster-Shafer (D-S) theory for coherent ship group analysis. Our method has been tested using different sets of simulated data and recorded data. Experimental results demonstrate our method is robust and efficient for large-scale maritime surveillance.

It is a well-known fact that humans are subject to circadian alterations caused by the action of sunlight. This strongly affects their behaviour and skill, making them change their level of alertness from high at daytime to low at night-time. Taking into account this biological feature, and considering that commercial shipping is one of the oldest round-the-clock activities, raises the question whether bridge watchkeepers can carry out their tasks on night shifts with the same level of alertness as on day shifts. Furthermore, night bridge watchkeeping has to be performed in darkness or very dim light to improve the visual capacity of lookouts. A sample of vessel collisions was analysed and it was find out that this kind of accident tends to be more frequent and more serious during the darkness period of the solar day.

Travel demand models (TDMs) with freight forecasts estimate performance metrics for competing infrastructure investments and potential policy changes. Unfortunately, freight TDMs fail to represent non-truck modes with levels of detail adequate for multi-modal infrastructure and policy evaluation. Recent expansions in the availability of maritime movement data, i.e. Automatic Identification System (AIS), make it possible to expand and improve representation of maritime modes within freight TDMs. AIS may be used to track vessel locations as timestamped latitude–longitude points. For estimation, calibration and validation of freight TDMs, this work identifies vessel trips by applying network mapping (map-matching) heuristics to AIS data. The automated methods are evaluated on a 747-mile inland waterway network, with AIS data representing 88% of vessel activity. Inspection of 3820 AIS trajectories was used to train the heuristic parameters including stop time, duration and location. Validation shows 84⋅0% accuracy in detecting stops at ports and 83⋅5% accuracy in identifying trips crossing locks. The resulting map-matched vessel trips may be applied to generate origin–destination matrices, calculate time impedances, etc. The proposed methods are transferable to waterways or maritime port systems, as AIS continues to grow.

In this paper the role of the helmsman in terms of man–machine systems theory, such as is frequently used in aerospace work is considered and the literature of the subject surveyed in so far as it relates to the control of seagoing vessels. Lieutenant-Commander Sutton is in the Control Engineering Department at the Royal Naval Engineering College, Plymouth, and Professor Towill is head of the Department of Mechanical Engineering at UWIST, Cardiff.

Precise control is a key factor in enabling Unmanned Underwater Vehicles (UUVs) to complete various underwater activities. The development of UUV control rules is mostly based on UUV dynamic models. However, such dynamic models contain unknown hydrodynamic parameters that need to be identified. This paper presents a new method, Laser Line Scanning for Hydrodynamic Parameter Identification (LSHPI), which integrates laser line scanning, decoupled dynamics, and evolutionary optimisation to identify the hydrodynamic parameters of an Autonomous Underwater Vehicle (AUV). In this research, laser images, seen from an on board camera's perspective and created using Open Graphics Library (OpenGL), were used to validate LSHPI's feasibility. The accuracy of the AUV positions and Euler angles obtained by the laser image-based methods were investigated for each decoupled One-Dimensional (1D) motion and the influence of other motion disturbances on the accuracy of the obtained AUV positions or Euler angles was also evaluated. In addition, the accuracy of the surge-related hydrodynamic parameters obtained by LSHPI was investigated under different motion disturbances. Based on the hydrodynamic parameter identification results under different motion disturbances, LSHPI's feasibility was successfully validated.

Over the recent decades, there have been a number of trends that have driven the desire to improve the ability to position and navigate in all environments. While GPS has been the driving factor behind most of these trends, there are limitations to GPS that have become more evident over time as the World has increasingly come to rely on location. These limitations are mostly due to the low transmission power of GPS satellites, where navigation signals broadcast from space are comparatively weak, especially by the time they have travelled to receivers on the ground. This makes the signals particularly vulnerable to fading in difficult environments such as built-up urban areas. The low signal-to-noise ratio (SNR) also means that the signals are susceptible to jamming, both hostile and accidental.

This motivates the need for non-GPS (or, more generally, non-GNSS) navigation technologies, for example, terrestrial based alternatives to GNSS such as eLoran. But, there is also significant interest in the exploitation of other non-navigation signals for positioning and navigation purposes. These so-called ‘Signals of Opportunity’ (SoOP) do not generally require any alterations to existing communications transmission infrastructure and often use alternative multi-carrier modulation techniques to those methods used by most GNSS services. The major challenge of using a SoOP for location purposes is that the transmitter network infrastructure has not generally been designed with positioning as a requirement.

An ongoing project, at the Institute of Engineering Surveying and Space Geodesy (IESSG) of the University of Nottingham, is directed towards an investigation of the potential of the Digital Audio Broadcast (DAB) signal for positioning purposes. A prototype Software Defined Radio (SDR) DAB positioning receiver has been developed and has now been tested. This paper presents a detailed review of the structure of the DAB signals and explains how these signals can be used as the basis of a positioning system. In addition the development of the prototype SDR receiver and the initial results are presented and discussed.

The objective of this paper is to illustrate a methodology for the enhancement of meteorological marine forecasts tailored to the needs of navigation. The study consists of two parts: (1) Theoretical background. Introduction to numerical models for weather forecasting used by meteorological centres. A review of the most reliable equations for prediction of intensity and direction of wind and sea state. In particular, reference is made to the tables for wind forecasting developed by R. Mayençon and A. Pezzoli and the equations for prediction of sea state obtained by K. Haselman and D. J. T. Carter in light of the JONSWAP experiment. (2) Practical application. Application of the methodology to a real-world example: a weather forecast elaborated by the Meteohydrological Laboratory at Dipartimento d'Idraulica Trasporti ed Infrastrutture Civili (DITIC) of the Polytechnic of Turin. The forecast was requested by the Consorzio Prada Challenge 2000 as a meteorological support for the training they held in the Tyrrhenian Sea for the next America's Cup series.

According to comprehensive theories of navigation, animals navigate by using two complementary strategies: (1) dead reckoning informs the subject in a continuous manner on its actual location with respect to an Earthbound or absolute coordinate system; while (2) long-term associations between particular landmarks and specific locations allow the animal to find its way within a familiar environment. If the subject structures familiar space as a system of interconnected places – the so-called ‘cognitive map’ – it may know through dead reckoning where it is located on its map and relate its route-based expectations to the actually perceived scenario of local cues.

This paper summarizes the results of Phase 3 of the Arctic Tanker Risk Analysis Project (ATRA) which provided a prototype Tanker Navigation Safety System (TNSS). TNSS is a ship-board risk management system capable of route planning and decision support based upon a knowledge database. The objective of the project was to provide timely risk assessment information to a mariner or decision-maker in a system capable of integration with existing ECDIS or shipboard PC systems. The historical information was to include: accident location, frequency and type, ice, wind, visibility, environmental sensitivity and other factors. The specifications of the TNSS prototype were expanded so that risk could be assessed for each track in a route plan by applying a predictive accident model patterned after the navigation and collision avoidance process.

The ability of animals to find their way, without the benefit of mechanical or electronic aids to navigation, has fascinated humans for centuries. Relying on innate knowledge, coupled with the extraction of navigational data from the natural features of the universe, animals continually confound humans with their skills in locomotion. The magnetic compass, sun compass, strip maps, snapshots, target maps, temperature charts and star charts are known to feature in the overall animal navigation kit. Each species selects the most appropriate ‘map/chart’ and navigation kit for its environment.

Real multi-Autonomous Underwater Vehicle (AUV) cooperative systems operate in complicated marine environments. The interaction between a multi-AUV cooperative system and its marine environment will affect the reliability of the system. Current is an important influencing factor of multi-AUV cooperative systems. A reliability index of multi-AUV cooperative systems known as System Reliable Probability (SRP) is proposed in this study. A method to calculate SRP is introduced, and the influence of current on SRP is discussed in detail. Current is considered an attack source, and the degree of its influence on SRP is calculated. As an example, the performance of this method is shown on two multi-AUV cooperative systems. Results show that the influence of the same current environment on different structures of the multi-AUV cooperative systems differs. This result provides a reference for the structure selection of multi-AUV systems. This study provides a practical method to estimate the reliability of multi-AUV cooperative systems.

Obstacle avoidance navigation for an unmanned surface vessel is a research focus for ship autonomy in which the real-time requirement in practical application is very serious, and always necessitates a complicated structure model to guarantee real-time performance. This paper proposes the grid cell activation model to reduce the complexity of modelling and to simplify an obstacle avoidance algorithm. Combined with the goal-oriented probability model to design a dynamic positive-loss-rate expectation evaluation function, it produces the proper strategy for obstacle avoidance. Case studies on multi-obstacle layouts and special circumstances are conducted and presented. The results indicate that the grid cell obstacle avoidance algorithm can effectively implement obstacle avoidance planning and ensure real-time requirements. A comparison with the potential field algorithm is performed, which shows good results and verifies the feasibility of the algorithm.

Array antenna beam forming has high potential to improve the performance of the global navigation satellite system (GNSS) in urban areas. However, the widespread application of array antennas for GNSS multipath mitigation is restricted by many factors, such as the complexity of the system, the computation load and conflicts between required performance, cost budget and limited room for the antenna placement. The scope of this work is triplicate. (1) The pre-correlation beam forming structure is first suggested for multipath mitigation to decrease the system complexity. (2) With the pre-correlation structure, the equivalence of adaptive beam forming to quiescent beam forming is revealed. Therefore, the computational load for beam forming is greatly decreased. (3) A theoretical model is established to link the benefits of beam forming with GNSS performance improvement in terms of pseudorange quality. The model can be used by industry to balance the aforementioned restrictions. Numerical results with different array settings are given, and a 2 × 2 rectangle array with $0.4\lambda $ element spacing is suggested as a cost-effective choice in GNSS positioning applications in urban canyon areas.

In a previous paper the writer considered the problems of establishing latitude at sea in the sixteenth century and in part based his conclusions on the results of experiments made with modern replicas of the quadrant, the mariner's astrolabe and in particular the cross-staff, these being the instruments in use at the time. Reference was made to the backstaff or Davis quadrant which, though first described by John Davis in its simplest form in 1595 was not in effective use in its final version until well into the seventeenth century. It remained, together with the cross-staff, the principal altitude-measuring instrument in use at sea until the introduction of instruments of reflection in the eighteenth century and indeed continued in use long after that time, no doubt because it was cheaper than the new instruments, but perhaps also in part because of the ingrained conservatism of seafarers. The name ‘backstaff’ can be used generically to refer to all those instruments with which the observer turns his back on the Sun (e.g. the Gunter's bow), but they all post-dated and derived in concept from the Davis quadrant, which remained the most common in England and elsewhere. (The French knew it as le quartier anglais.) It is in this sense that the term is used here.

Three types of self-contained navigation systems may perhaps be found, operating independently on airliners flying polar routes; doppler, astro and inertial. We may also find hybrid systems with doppler, astro and inertial components. The combination of doppler and astro systems should be the first step towards self-contained automatic navigation and this combination could be used with great advantage by the airlines for global operations. The more sophisticated doppler and inertial combination may be found too expensive for airline operators and may therefore be restricted to military uses.

The object of this paper is to present various practical solutions to the problems of inertia navigation in a descriptive rather than a mathematical form. Inertia navigation is an automatic bump of locality, a dead-reckoning device which, starting from a known point, seeks to find position. Other dead-reckoning devices measure speed, which is only relative to the fluid sea or air. Inertia navigation measures accelerations, which are absolute, and hence builds up a measure of speed. The accelerometer is, therefore, a good starting point for our survey.