Acoustic transponders are employed in underwater navigation in situations in which a high degree of accuracy is required. Typical applications include underwater search, mapping, photography by a submersible or a towed vehicle and positioning of underwater work systems. The network of transponders, of which there may be only two or three, or which may be very extensive, is implanted by a support ship or by a submersible. The network can be located geographically by a satellite navigation equipment to an accuracy of 0·25 nm. This accuracy (or even accuracy within ± 1 mile) is sufficient to locate the network after a period of disuse. Acoustic navigation of a vehicle is accomplished relative to the network, to accuracies of the order of several feet.

This paper, which discusses a preliminary development of a microcomputer-based navigation system for the fishing industry, was presented at the Oceanology International Congress at Brighton in March. Dr Coates is at the University College of North Wales, Mr Dye and Mr Knox with the Sea Fish Industry Authority.

The history of the sea-fishing industry is one in which success has only been achieved at the price of experience, painfully gathered as a consequence of abortive fishing trips or damaged gear. A detailed knowledge of conditions on the sea-bed, in particular preferred fishing areas and sea-floor obstacles such as wrecks or sand-pinnacles, is clearly of paramount importance in maintaining commercial viability. At the present time, for the requirements of the UK Sea-Fishing Fleet, such specialist information is available in the form of the widely used ‘Kingfisher’ chart series. With the advent of cheap, yet powerful microcomputer systems, the possibility now exists to create a data-base version of the Kingfisher Charts, thus offering the advantages of rapid updating of information and convenient wheelhouse presentation of user-selected chart features by means of a video monitor.

Recent advances in the speed and capability of miniature computers have made possible a strapped-down mechanization for airborne inertial navigation systems. The implementation of this mechanization is critically dependent on the availability of suitable accelerometers and gyroscopes able to measure, and yet withstand, the effects of vehicle motion. The laser gyroscope is now considered a major contender for angular measurement in that it offers the possibility of a cheap, reliable instrument with the wide dynamic range required for strapped-down implementation.

In this note, we propose to enquire into how far it may in principle be possible to employ zenith-photography for astro-navigation in the air, also to touch on the question of whether the mechanical difficulties can be adequately overcome. The question of principle seems in fact quite clear, but the practical side will undoubtedly demand much care and study by engineers and by practical navigators if the method is ever in fact to be adopted; we hope to show that the method has advantages sufficient to make the problem worthy of attention.

It might reasonably be considered that any discussion of interplanetary navigation at the present moment is slightly premature. So of course it is, from the practical point of view, since no well-informed person seriously imagines that space-travel will be possible for at least twenty or thirty years, despite the colossal efforts which are now being devoted (unfortunately for quite other purposes) to the solution of its engineering problems. Nevertheless the subject is one of peculiar fascination—which is a completely sufficient excuse for discussing it—and the navigation of guided missiles into astronomical space, which will precede the manned exploration of the planets, has of course already begun and will continue on an ever-increasing scale during the next decades.

For more than a century and a quarter ships' crews of the world's voluntary observing fleet have made meteorological and surface current observations. Those observations recorded in the ships' logbooks are the backbone of the Marine Archive now held in the Meteorological Office, Bracknell, UK. Much use is made of computer processing for providing suitable statistical data which form the basis of maps and current roses. This article outlines the method of processing used in the Netherlands, illustrating various situations the observer at sea may encounter. The supposition that the use of modern navigation equipment could hamper the making of current observations is discussed, and situations that could cause the reduction of accuracy and reliability of current mean values are mentioned. In essence: how reliable are surface current observations from ships collected in the past few years, and particularly those that will be collected in the years to come?

In this paper, which was presented at a symposium on electronic aids to air navigation held in Paris in November 1977 (and subsequently published in the Journal of the French Institute of Navigation), the authors first analyse in detail the mental processes of an aircraft pilot and the ergonomic factors that should underlie the design of any flight data display. They then describe a cathode-ray tube display designed for use in civil transport aircraft and the modifications they found desirable in the light of simulator trials.

The preliminary to the Steering and Sailing Rules state: ‘Risk of collision can, when circumstances permit, be ascertained by carefully watching the compass bearing of an approaching vessel. If the bearing does not appreciably change, such risk shall be deemed to exist.’ What is to be taken as ‘appreciable’ when considering a change of bearing is not defined, but the watchkeeper at sea in clear weather has his accumulated experience to call upon and no difficulty is normally encountered in deciding on the degree of risk, except in the case of using radar in thick weather, when the watchkeeper has not the benefit of long experience. The purpose of this note is to consider the conditions under which the nearest approach can be estimated and to determine the accuracy of the estimate.

At 2215 hours GMT on 21 September 1947 the U.S.A.A.F. All-Weather Flying Centre's Automatic C54 took off automatically from Stephenville, Newfoundland, and twelve hours and five minutes later landed at Brize Norton, England. Neither pilot nor navigator had interfered with the automatic equipment during the entire flight. What, briefly, is the navigation equipment and procedure employed on such a flight?

Equipment. The navigation equipment consists of three magnetic heading selectors, two air log units or AMUS and a radio compass which will automatically switch to a number of preselected frequencies.

The paper by Spencer and Blades, both of the Department of Psychology in the University of Sheffield, was presented on 14 March 1984 at an Institute meeting held in London to discuss Psychology and Navigation.

From its earliest moments, the young organism has a need to track and integrate into some scheme of knowledge the location of salient objects and places; and thence to develop navigational strategies for efficient movement through space. In the case of human young, their initially limited mobility constrains the extent of their active explorations, and thus their range of experience; and adult protectiveness (somewhat heightened in the modern, suburban nuclear family setting) continues to limit such explorations even when the child is fully capable of extensive movement round the local area (Pick and Acredolo, 1983).

To fulfill any specific task a certain navigation accuracy is in general required. If this requirement can be achieved by different systems the cost effectiveness will be decisive. Apart from missions which allow large position errors, medium or high navigation accuracies will normally be desired, obtained either by high technological standards or by an unsophisticated system with an updating procedure. The cost of highly sophisticated systems increases exponentially with increasing accuracy, so that our object was to find an appropriate updating system.

Automatic collision avoidance systems are being installed on board more and more ships and this necessitates verifying their characteristics, as compared with postulated requirements. The requirement for such anti-collision systems may be specified as follows:

(i) Radar echoes should be tracked automatically, regardless of weather conditions, the number of echoes, or the relative distance between tracked targets.

(ii) The system should be operable by a single observer, assuming that the information given is used efficiently.

(iii) The information should be displayed in the clearest and the most comprehensible form.

(iv) The system should facilitate alterations of course and speed.

(v) Information relating to collision risk should be provided in ample time if the system is to operate in dense traffic.

(vi) The system should include alarm devices which operate in pre-determined circumstances.

The design of a route through Dover Strait to Europoort for very large carriers (VLCs) with a draught of up to 22 metres is described. The results are compared with established international safety criteria. A number of subjects for further study by institutes of navigation are mentioned. Van Riet (DG Shipping and Maritime Affairs), Kaspers (Public Works, North Sea Directorate) and Buis (Hydrographic Service, Royal Navy) participated in this design process. The views expressed, however, are those of the authors and not necessarily those of their organizations.

Since 1974 deep-draught ships of up to 20·70 metres (68 feet) have been navigating the English Channel and the Dover Strait with destination Europoort in the Netherlands. To a lesser extent ships with these large draughts have been passing through the Strait with destinations in Scandinavian countries.

Dynamic trajectory prediction is an important topic in the field of navigation and positioning. Due to the drawbacks of a Global Navigation Satellite System (GNSS) receiver, the trajectory of the position always lags behind the dynamic platform's actual position, especially in highly dynamic situations. In order to solve the prediction of a dynamic trajectory, a generalised extension extrapolated model is proposed in this paper. The model utilises the current motion state and a priori position data of the platform, combines the interpolation and fitting method, adds the angle information as a constraint condition and solves the platform position prediction. In this paper, the feasibility of the generalised extended extrapolation algorithm is analysed theoretically and practically. Simulation results show that the prediction error is within 0.2 metres and experimental results show that the algorithm still has high prediction accuracy when a land vehicle platform is turned through a large angle.

This paper was the basis of a presentation given on 9 November 2004 at Church House, London during the Institute's NAV 04 Conference. The author argues that AIS has been proven as a valuable aid to safe navigation, but requires comprehensive training to ensure its proper and effective use. Furthermore, he supports those concerned that using AIS in support of “homeland security” will make ships more vulnerable to attack.

This paper outlines a technique to represent terrain using tree structures, based on Morton ordering to avoid the use of pointers. This approach enables terrain data to be organised in a hierarchical form affording a trade-off between the speed of access to the terrain database and resolution of the terrain data extracted from the tree. A set of database access algorithms is developed that form the basis of path extraction needed for real-time mission management. Several examples are presented to illustrate the performance of the routeing algorithms developed in the paper.

A great deal has been written, especially in the last few years, on the subject of collision at sea. The increase, however, in the speed of ships and in the density of traffic so magnifies the complexity of the problem that even closer and more earnest study is still called for. Three fields of inquiry demand our attention: technical advances, procedure, and the human factor. Of these, the widest and most promising might seem to be the first. Its importance is undeniable, and I am by no means the only one to have pointed out that with the new difficulties it raises it supplies also the appropriate solution. Even wider, however, and more complex is the field of human study; this covers both the others, for in this the final objective is to enable men to master what they have won for themselves, and this they cannot do—here we meet the familiar problems of philosophy, ethics and religion—unless they first learn to master themselves.

Compared with these two fields, the technical and the human, that of procedure must at first seem quite insignificant. Can one seriously imagine that there is in fact some new method of avoiding collisions, so abstruse that no one has yet been able to discover it? In my small book on the use of radar I wrote: ‘The Regulations envisage two ways of avoiding collision:

1. A movement carried out in concert with the other vessel.

2. A reduction of speed, if necessary to zero.

In the mid-16th century the English began to expand their merchant and fighting navies to sail beyond the waters of north-west Europe. This necessitated mathematical navigation, charts, and written and illustrated sailing directions; all, from the 1580s, were embodied in the printed ‘waggoners’ of the Dutch and were used in translation by the English seamen.