We describe a new type of radio navigation and tracking system which, unlike conventional systems, does not depend on a costly infrastructure of coherent radio transmitters. This new system measures positions using spatial, rather than temporal, coherence and can therefore use any existing radio transmitters set up for any purpose. We describe the principles of operation, applications and present results obtained with a demonstration unit (in Cambridge) which can measure the position of a motor vehicle to a precision of about 5 m using local medium-wave public broadcast transmitters.

One of the major concerns in the operation of an air traffic system is the maintenance of adequate separation between aircraft. The assurance of an ‘acceptably low’ risk of collision is a crucial element in the system design. A number of factors need to be assessed in this process. What is the navigational performance of the aircraft in the system ? What are the possibilities for radar surveillance ? Are procedural arrangements together with position reporting a suitable mechanism? What difference would be made by collision avoidance or warning systems? Given that any combination of these or other factors has an implication on the minimum separation between aircraft, the level of safety ‘assured’ has to be balanced against the costs of the various alternatives which may present themselves.

In planning for change the implications of new operating practices or devices have to be assessed carefully. For most changes the process is one of evolution rather than revolution, although collision avoidance devices may have more of the latter's characteristics. Even for ‘revolutionary’ changes it may be possible to model the new system. Thus the existing situation is studied and its characteristics observed, then there are hypotheses of the ways in which the change alters the mechanisms in the system and finally the likely effects on system performance through mathematical and computer (often fast-time simulation) modelling.

Waves, tides and ocean currents might not be expected to produce electric currents, but by moving water, as a conductor, through the Earth's magnetic field they do in fact produce measurable voltages and flows of electricity. Young, Gerrard and Jevons, who made the first detailed study of this phenomenon, thought it conceivable that measurements of electric potential gradient might be used to estimate the drift of a ship at sea, and Von Arx showed how indications from electrodes towed behind the Research Vessel Atlantis were used to keep her on a direct course from Bermuda to Woods Hole, across the Gulf Stream. In recent years the method has been used extensively in studies of ocean currents and more ships might use it if the necessary equipment were readily available.

Concentrating on a surface vessel with input saturation, model uncertainties and unknown disturbances, a path following the adaptive backstepping control method based on prescribed performance line-of-sight (PPLOS) guidance is proposed. First, a prescribed performance asymmetric modified barrier Lyapunov function (PPAMBLF) is used to design the PPLOS and the heading controller, which make the path following position and heading errors meet the prescribed performance requirements. Furthermore, the backstepping and dynamic surface technique (DSC) are used to design the path following controller and the adaptive assistant systems are constructed to compensate the influence of input saturation. In addition, neural networks are introduced to approximate model uncertainties, and the adaptive laws are designed to estimate the bounds of the neural network approximation errors and unknown disturbances. According to the Lyapunov stability theory, all signals are semi-globally uniformly ultimately bounded. Finally, a 76$\,{\cdot }\,$2 m supply surface vessel is used for simulation experiments. The experimental results show that although the control inputs are limited, the control system can still converge quickly, and both position and heading errors can be limited to the prescribed performance requirements.

Numerous collisions over the years have emphasized the need for rapid and efficient ship-to-ship voice communication systems. Such systems, set up to satisfy the demand for more and better channels through which messages can be sent, should guarantee that both sender and receiver come to share the same thoughts and feelings. ‘It can be said that two expressions have the same meaning if their utterance results in the same change of behaviour.’ Recognizing that voice communication systems cannot be effective until all parties speak and understand the same ‘language’, the Maritime Safety Committee of IMCO has developed the Standard Marine Navigational Vocabulary, a significant landmark in the attempt to achieve the maximum safety to navigation and the most appropriate conduct of ships at sea. This paper will concentrate on the objectives of the Vocabulary and will try to ascertain if such objectives have been achieved. The analysis will emphasize the viewpoint of ‘non-English speaking people’ using English ‘for the interchange of intelligence between individuals of all maritime nations’, and will take linguistic considerations into account.

When designing a bridge for a naval vessel the designer faces a number of requirements which are quite different from those of a merchant vessel. Besnard states that besides a good view, the officer of the watch requires by him the instruments for determining direction and distance or speed, position finding instruments and other electronic aids, and the means of communicating with the helmsman and engine room as well as some check on these communications. He concludes that a cockpit arrangement of the instruments would suit the requirements. Rees, on the other hand, doubts whether the officer of the watch would remain alert for long periods when sitting in an enclosed compartment, and suggests that a cockpit arrangement is only appropriate where there is little space. Further he argues that the duties of the officer of the watch extend beyond those of simply directing the ship.

There have been two distinct phases in the development of radio aids to navigation. The first, which must be regarded as the true pioneer period, followed rapidly upon the development of wireless telegraphy by Marconi and others; it was soon realized that the early aerials employed had directional properties and that this phenomenon could be used to obtain a bearing.

This paper and the following five papers were presented at the NAV90 Conference on Land Navigation and Information Systems. The Conference was organized by the Institute in September at the University of Warwick. Complete sets of the proceedings are available from the Director, Royal Institute of Navigation, price £60 (to RIN members).

This paper takes a global overview of technical developments in vehicular navigation. From this vantage point, the author gives his perception of some of the critical issues involved in the major shakeout and consolidation which he expects to occur during the next one or two decades, and he speculates on the outcome.

A simple method is described for estimating the angle of misalignment of a two-component electromagnetic log, using the covariance properties of the measured components when a ship is steered in a constant cross wind at a number of different speeds. It is shown that, with the present accuracy of radar fixing, allowing for misalignment has a very small effect on the determination of sensitivities for an absolute calibration. However the effect of misalignment is important when cross-calibrating the athwartships components of two electromagnetic logs.

In the sixteen years since the last paper on this subject was published in the Journal (1951, 4, 288), some notable changes have taken place in the design and capabilities of submarines. Nautilus, the world's first nuclear submarine, was laid down in 1952 and completed in 1955. Since then a further 120 nuclear submarines have been commissioned. Now, a large proportion of the world's submarines are ‘true’ submersibles, self-sustaining over periods of months in everything except food; capable of proceeding submerged faster than the average surface ship; and rarely requiring to surface or even to come to periscope depth.

Disasters result from the breakdown of navigational faculties. Those concerned with the ‘practical’ aspects of navigation naturally assume a standard and infinitely flexible nervous system by which the individual can adjust to the stresses created by great speeds in the absence of habitual sense information. This paper outlines the nervous basis of adjustment to environment (personal navigation), the forms of breakdown in disease, and the nature of hallucinations. Some forms of disturbing experiences likely to be felt in modern navigation are predicted and explained. Such problems are seen as integral matters of aviation planning, design and practice.

‘The main aim … is to enable interested persons with quite different backgrounds of knowledge and experience, to come together and consider collectively a subject of common interest from their various standpoints.’

(A. M. A. Majendie, ‘The Significance of Blunders’, this Journal, 12, 28.)

The requirements of navigation entering or leaving harbour or in narrow waters are exacting, and a very accurate position is usually essential. For this reason it is believed that inertial techniques should be applied in the first instance only to ocean navigation as, although the system will give the ship's position continually, the accuracy will be of the order of one mile.

The latitude and vertical references are absolute, but the longitude reference is relative to a known starting point. Besides position, an inertial system can also provide course, sidereal time and roll and pitch and, by comparison of successive positions, course and speed made good, and leeway. Furthermore the system could be used to feed position into an automatic plotting table, with a chart of suitable scale superimposed, so that the vessel's geographical location would be visible at a glance.

This paper, with Dr Lyon's was presented in Paris in November 1983 at an international colloquium organized by the Centre d'Etudes Arctiques of the Centre National de la Recherche Scientifique, by whose kind permission they are here reproduced. The theme of the conference, at which some 35 papers were presented, was the Conquest of the North Pole; the subjects covered included both the history of Arctic exploration and contemporary problems and the future of polar transport, sea and air. Mr Kerr is Director of the Canadian Hydrographic Service's Atlantic Region; both he and his co-author are at the Bedford Institute of Oceanography in Dartmouth.

This paper by the Principal Scientific Officer of Trinity House was presented at an Institute meeting in London on 28 April 1976 with Mrs. Mary Pera in the Chair.

Mr. Reynolds describes the use of lights to convey positional and other information by the assignment of characteristics of rhythm and colour and discusses the problems of visual discrimination, the choice of light intensities and the effect of atmospheric conditions on the ranges of lights. He also describes the new buoyage system and other moves towards international agreement. A paper on the IALA system by the Hydro-grapher of the Navy appears at p. 94.

Lighting is used in various ways in maritime applications. For operations at night in vessels, in harbours or on drilling platforms general lighting is necessary; such lights may also be of value in indicating a hazard or suggesting a route to be followed but are not expressly intended for that purpose. Fixed lights in vessels are arranged in a spatial pattern and employ colour to give indications of the presence and aspect of the vessel to other vessels. Indirect lighting is also sometimes used, as in the floodlighting of lighthouse towers to reduce bird deaths by collision.

The rapid developments of mini-computer technology and the introduction of integrated navigational electronic equipment in ships calls for a reappraisal of bridge design as a matter of urgency. Several research projects have been carried out in recent years and all have concluded that ‘a completely fresh outlook is required rather than work on existing designs and on methods which are regarded as both accepted and acceptable’. Shipowners and shipbuilders need to understand the requirements of the men who will be responsible for the safe handling and navigation of the ship and to choose between stagnant inefficiency and economical gain through proficiency. The standard central command-post layout design should comprise flexible units adaptable to every type of merchant ship, except of course such specialized vessels as oil rigs.

As air traffic is expanding rapidly, more and more people are exposed to the possibility of accident. Although safety per passenger-seat mile continues to improve; because of the increasing capacity of aircraft this does not necessarily mean that the accident rate per trip follows the same pattern. The majority of accidents happen during take-off and landing but they are not necessarily associated with loss of life. The application of crash survival factors to structure and improvement in the restraint equipment for crew and passengers; the provision of rapid exit facilities and the reduction of the chances of conflagration have all played their part in improving the chances of survival.

Accidents involving collision with high ground on the other hand are almost always catastrophic and usually fatal to all the occupants. The statistics issued by I.A.T.A. show that some 40 per cent of all passenger deaths, in the airlines contributing figures, are due to this cause. Because of this it is imperative to consider every aspect of them that might lead to their reduction.

In this paper, which was read at an Institute meeting in London on 11 February 1976 with Mrs. Mary Pera in the Chair, Captain Cockcroft examines the incidence of collisions in relation to the numbers and classes of ships at risk and their trends, pre-war and post-war. Total and partial losses are included and compared with other forms of loss, e.g. strandings.

In several previous papers statistics of marine collisions have been given for particular areas such as the Dover Strait, Western European rivers, the Baltic Sea and Japanese waters. This paper is concerned with worldwide statistics with particular reference to sea collisions. The information is mainly derived from the Statistical Tables published by Lloyd's Register of Shipping and from the casualty reports compiled by the Corporation of Lloyd's. Statistics of shipping casualties must obviously be related to the number or tonnage of vessels at risk; for insurance purposes loss ratios are usually expressed in terms of tonnage lost to tonnage afloat but navigators are more concerned with the number of casualties and number of vessels at risk in various categories.

Collision statistics indicate that many collisions at sea occur after one or both vessels take action to avoid collision. It is worth considering why this should be so. Is the action taken contrary to the requirements of the Regulations for Preventing Collisions at Sea or are the Rules unsatisfactory in not stating clear and effective requirements? It is necessary to consider the principles of collision avoidance to determine whether a more effective solution can be obtained. This investigation relates to all types of craft, not necessarily only marine craft.

In 1874, the Austrian arctic scientist, Weyprecht, on his return from an Austro-Hungarian polar expedition stated that, though many countries had sent expeditions into the polar regions at great expense and involving appreciable hazards to those participating, no important contributions to knowledge had resulted from them. They had done a certain amount of mapping and obtained a few meteorological observations but the primary object had been, as a matter of national prestige, to plant the flag nearer to the Pole than had been reached before. In his opinion what was needed for the advancement of knowledge about the polar regions was that nations should collaborate in sending expeditions to various parts of the arctic region to make observations throughout the whole of one year. Largely because of his persistent advocacy of this view, the value of the proposal came to be recognized, and as a result the enterprise known as the First International Polar Year was developed. A number of countries combined to send expeditions to establish observing stations at selected points in the arctic region to make observations throughout the year 1882–3 in meteorology and geomagnetism and also of the aurora. The observations made during this Polar Year contributed appreciably to knowledge of geomagnetism and of meteorology.