In his Presidential Address Admiral Ritchie referred to the two series of charts in 79 small-scale sheets which 16 member states of the International Hydrographic Organization have undertaken to produce; some of them will be published this year. This new development, and how it will affect mariners who now use our Admiralty charts, may be of some interest.

The two small-scale charts for ocean and offshore navigation require a comparatively limited effort and with the enthusiasm and interest shown by all participating nations it is expected that both could be completed within a reasonable period, probably before the end of 1974. When these charts are published it will be possible to withdraw many small-scale Admiralty charts, some of which were originally published more than a century ago and have subsequently received only partial correction, and much criticism as being out-of-date. But it will not usually be possible to replace them chart for chart as each individual new International Chart is published, because replacement of existing charts can best be made when the whole scheme or at least a complete regional area has been completed. This applies not only to the United Kingdom but to all the world charting authorities and will result in their still having to maintain many existing charts until the new coverage is complete. This problem of ‘block’ replacement, rather than individual chart replacement, will assume serious proportions in the subsequent larger-scale stages of the International Chart.

Navigation safety at sea is vital for each autonomous surface vehicle (ASV), which involves the problem of motion planning in dynamic environments and their robust tracking through feedback control. We present a practical path-planning method that generates smooth trajectories for a marine vehicle traveling in an unknown environment, where obstacles are detected in real time by millimetre wave (mmWave) radar. Our approach introduces a polynomial curve to describe the lateral and longitudinal trajectories in the Frenet frame, known as the ‘motion primitives’, whose combination ensures that the planning area is properly covered. In addition, we can select a feasible, optimal and collision-free trajectory from such a set of motion primitives that is generated by considering the vehicle dynamics and comfort. The capabilities of proposed algorithm are demonstrated in the experiment with static and dynamic obstacles.

As Mr. Sadler points out, there can be no conflict between mathematicians and navigators, provided the mathematicians have adequately fulfilled their job. If, however, the navigators fail to follow the mathematics, or even to check the results by taking a few examples, then there will be plenty of misunderstandings; to bring ‘philosophy’ into the discussion is to return to the attitudes of the Middle Ages, and to obscure technical issues which are perfectly clear and simple.

In 1963, in addition to examining the characteristics of the Omega system, we were also very concerned with a comprehensive navigation system study which was designed to examine all aspects of a world-wide navigation system operating in a B.O.A.C. type environment. This concerned a study of dead reckoning as well as externally referenced sources of information. You have the choice of an all dead reckoning system probably employing multiple sensors of the same type, triple IN is typical, or you could have a mixture of externally referenced and self-contained, in other words dead reckoning sensors. Occasional reference could be made to short-range aids or even a satellite system if available to increase the integrity of the position-fixing information. The inertial and computer aspects have been examined by the Avionics Department at R.A.E. whereas the radio sensors, which are externally referenced, and the relevant software have been the responsibility of the Radio Department.

This country, and the marine industry in particular, is in the throes of a change that it has been decided shall be called metrication. It is evident from what is both written and spoken that not everyone is aware of what metrication means, that many people assume that it is simply a change from imperial units to metric units. However, what is really intended is the adoption of the S.I. system of units and this implies much more than just the use of metric dimensions. The two main points of the S.I. system are (i) that every dimension is measured in decimal multiples of a basic unit and (ii) that the system of units is a coherent one. The educational advantages of such a system are too well known to require restating here. Antagonists of change usually point out that time does not conform to condition (i) and while this is true, nevertheless the S.I. system will be a great improvement on our present one and the non-conformity of time should not be used as an excuse for other non-conformities.

IN the course of a systematic search for tables or graphs using the principles appealed to in the Experimental Astronomical Navigation Tables (see p. 333), I examined a copy of the above tables, whose full title follows:

‘Margetts's Horary Tables for shewing by Inspection the Apparent Diurnal Motion of the Sun, Moon and Stars, the Latitude of a Ship and the Azimuth, Time or Altitude corresponding with any Celestial Object.

‘London. Printed for and sold by the Author. “Published as the Act directs 1st July 1790.”’

These tables (or diagrams) do not appear to be well known and they seem to possess sufficient interest to warrant notice. The author's own description is so precise that I can do no better than to repeat it verbatim with a few added notes of explanation. The accompanying photograph, reproduced from the copy in the collection of navigational books and tables in the Admiralty Library by kind permission of the Admiralty Archivist, shows a typical opening of the tables.

I have been unable, in the course of an admittedly hurried and incomplete search, to find any biographical information about Margetts. Perhaps some reader of the Journal can supply the deficiency.

With the comparative absence of navigation aids in the earlier days of flying, up to about ten years ago, the navigator was constantly engaged in associating observations, calculations and chart work in what was essentially a high-class guessing game. The low speeds (just over 100 knots on flying boats and just under 200 knots on landplanes) provided enough time for this rather intriguing exercise to be carried out in a fairly relaxed atmosphere, conducive to an individualistic approach that could be justified by results. The navigator's performance was largely (at that stage of aviation) judged on the neatness of his plotting, the accuracy of E.T.A.'s and the absence of late course corrections before arriving at destination or a check point. If there is anything in the view that navigation is an art, this particular yardstick certainly induced considerable artifice in the navigator.

A GEC Marconi Avionics/MoD joint–funded integrated, digital terrain system called ' PENETRATE ' (passive enhanced navigation with terrain referenced avionics) is in its fourth year of flight trials on a Hunter fast–jet aircraft at the Defence Research Agency, Farnborough. Although originally designed to enable military aircraft to penetrate enemy defences at low level in poor weather conditions and at night, the system also has a direct read across to civil air transport operations. The heart of the PENETRATE system is a digital data–store housing a three–dimensional model of the terrain including cultural details, obstructions and tactical intelligence information.

PENETRATE incorporates terrain-referenced navigation to provide accurate position information relative to the ground contours. A sophisticated digital map displays navigation information and includes intelligence and intervisibility overlays. Head-up visual enhancement options are provided which can be tailored to the outside visibility. These comprise monochrome skeletal perspective displays which are superimposed on the outside world view and also on the forward-looking infra-red (FUR) scene. The display enhancements range from obstruction cues through ridge line overlays to skeletal perspective terrain presentations.

This paper covers the philosophy and architecture of PENETRATE together with details of the demonstration system. It also discusses the capability of this digital terrain system to enhance the safety of civil aircraft approaches into difficult airports such as Kathmandu and Hong Kong.

Modern ship control and navigation systems involve a complex variety of intricately interwoven electronic, electrical, mechanical and hydraulic devices. It has become appropriate therefore to devise a convenient method for representing mathematically the dynamic characteristics of these systems and the elements which comprise them, so that block-diagram modelling can be implemented. This is ideal for displaying the interrelationships of such systems pictorially and has the added advantage of simplicity and of indicating realistically the actual processes which are taking place, as the models refer to the relationship between mathematics and the real world.

To optimize the man-machine relationship different approaches are possible, the adaptation of man to the machine or of the machine to man. The first relates to training and selection, the second is generally called ‘human engineering’, now of great interest both in the naval and merchant marine context. Changing factors like the density of traffic in harbours, the harbour environment, the speed of ships and problems of manning and automation have all contributed to that interest. A ship designer is increasingly confronted with design problems where the man/machine relationship involves the operator as a controller. The desired increase in performance is achieved only if human possibilities are put to their best use.

Pressure pattern flying embraces a number of air navigation techniques all of which have one common feature: they relate pressure distribution along an aircraft's flight path to that component of the wind which acts at right angles to the aircraft's heading. My intention is to give a brief outline of the theory underlying these techniques.

Wind is brought about by horizontal pressure differences in the earth's atmosphere. Air tends to move from an area of high pressure towards an area of low pressure under the influence of the pressure gradient force. The direction of its motion is, however, affected by the earth's rotation in space. Considering this rotation in the horizontal plane only, it is at a maximum at the poles and zero at a point on the equator. At any intermediate point of latitude ϕ, the speed of rotation in the horizontal plane is proportional to the sine of the latitude. In the northern hemisphere the rotation is anticlockwise; in the southern hemisphere it is clockwise with reference to outer space.

This paper, which was presented at a meeting of the Deutsche Gesellschaft für Ortung und Navigation held in Berlin on 24 April 1963, briefly discusses some of the factors which will affect navigation and control of supersonic transport aircraft. Attention is directed to the special problems of determining optimum flight path and estimating position and E.T.A. during three phases of the flight: acceleration, supersonic cruise and deceleration.

Accepting the technical fact of automatic landing, an examination is made of the basic human problems in its application to commercial air transport. This examination starts with an analysis of the use of human operators and automatic machines applied to operational tasks. Consideration is given to both control and monitoring functions, and conclusions are drawn about the correct approach to man/machine system design.

The required standard of safety for commercial automatic landing is briefly reviewed, with particular reference to the official British attitude. It is shown that automatic landing can be a tool for improving safety in future. The role of the pilot is considered. It is concluded that there is no real conflict between man and machine: that the automatic system will not affect the crew complement, or the basic responsibilities of an airline pilot: and that the potential of automatic systems can only be realized by a proper understanding of their true implications.

The original paper, of which this is an abbreviated version, was presented at the Institute of Aerospace Sciences National Meeting held in Seattle, Washington, on 10 and 11 August 1962.

Automatic landing systems are already in full production in Britain for Bomber and Transport aircraft of the Royal Air Force, and many thousands of successful landings have been made in both jet and propeller driven aircraft in all sorts of weather conditions. Second generation equipment is now clearing the prototype stage and entering production for application to passenger carrying aircraft at a civil standard of safety. This equipment is destined initially for application to the De Havilland Trident for British European Airways, and to the Short Belfast heavy transport for the Royal Air Force.

A variety of different techniques has been developed for the weather routeing of sailboats. These have varied according to whether the technique is intended for yachts or for sail-assisted powered vessels, whether the routeing is for long or short time periods, and whether the routeing is used for navigation or design purposes.

The techniques that have been implemented to date are reviewed, comparing their strengths and weaknesses. Ways in which these problems may be overcome in future implementations of weather routeing are also discussed

It is always reassuring to find a kindred spirit thinking along the same lines as oneself. R. Williams's proposal for a table of latitude parts (34, 247) is a reiteration of my paper of twelve years ago (23, 233).

The equations of a rhumb-line track were established by Sadler (9, 371) and it always seemed to me to be a more elegant solution to solve the equations themselves rather than to apply corrections to inaccurate equations, hence the approach suggested in my paper.

Until its nationalization in 1956, the physical limitations of the Canal had greatly influenced world shipowners with regard to the sizes of ships built, particularly oil tankers. Following nationalization, in an era of cheap oil and transport costs, shipowners took the initiative and began to build large tankers. Mindful of the effect that such changes would have on the tonnage of oil transported through the Canal, the Suez Canal Authority began a programme of expansion in 1958 which was to be executed in two stages. The first stage was completed by February 1964 and consisted of widening and deepening the Canal so that ships with draughts of 38 ft could be accommodated, thus allowing vessels of 60,000 d.w.t. to transit fully loaded. The second stage of development was intended to deepen the Canal to accept vessels of draughts up to 40 ft, corresponding to ships of 70,000 d.w.t. This work was scheduled to be completed by the end of 1967, but the project was not finished due to the start of the Arab–Israeli war.

The institute of navigation has been formed to promote the interests of science and of practical navigation, by uniting together in a scientific body those who are concerned with or are interested in the science and art of navigation. For navigation is both a science and an art, whose development must be based upon the knowledge and experience of many different types of persons. The formation of the Institute was stimulated by the formation in 1945 in the United States of an Institute with the same aims; it is likely that similar Institutes will be formed in other countries also. Arrangements are in hand whereby the members of either the British or the American Institute will have the privileges of both, and it is planned to form an international committee to co-ordinate the work of the various separate Institutes. In navigation, as in other branches of science, there is much to be gained by international co-ordination and co-operation.