Although the Admiralty pilots have been regularly revised every 10 to 12 years as well as being kept corrected by supplement, there has been remarkably little change in the general style and content for over 100 years. As a major step has recently been taken to modernize and metricate the Admiralty chart, it was considered opportune to study the pilots at the same time. Therefore towards the end of 1968 a small committee was formed within the Hydrographic Department to review these books. The first action by the committee was to initiate some market research. All members of the Chart Users' Panel were invited to answer a questionnaire of twelve questions, but a few weeks later it was considered desirable to spread the research over a wider field and the same questions were sent out as a Notice to Mariners (No. 1737/68). The response was most encouraging and by the closing date at the end of December about 780 replies had been received and these have all been analysed. A few replies still come in, which puts the total at over 800$quite a good proportion of the regular users.

In 1945, when the end of hostilities restored freedom of commercial traffic, it seemed as though technical advances would enable it to acquire an ever increasing measure of safety. Soon, however, it became apparent that if ships were immune from the dangers of the past, it was only to meet other dangers which had been introduced by those very advances.

In a valuable paper published in July 1960 (Journal, 13, 253) Hanssen and James described the system developed by the U.S. Hydrographic Office (now U.S. Navy Oceanographic Office) for selecting the optimum track for transoceanic crossings by applying long-range predictions of wind, waves and currents to a knowledge of how the routed vessel reacts to these variables. In the present paper the authors, both of the Marine Sciences Department of the U.S. Navy Oceanographic Office, propose a method, based on this earlier work, of using climatic charts on the North Atlantic to avoid regions of high frequency storm conditions and thus improve ship efficiency. Essentially this method is for ships not being routed by a central forecasting office. An earlier version of the paper appeared on the verso of the U.S. North Atlantic Pilot Chart for March 1969.

Using a Kelvin-Hughes radar photoplot an investigation of sea-clutter patterns on the radar screen was carried out during two voyages in the Atlantic during 1964 and 1965. A physical explanation of sea clutter has not yet been produced. The Use of Radar at Sea states (page 101): ‘In almost all sea conditions there will be an area of sea clutter around the ship. The fronts of waves give stronger echoes than the backs and therefore the clutter area will not be symmetrical about the ship.… If the movement of the sea is largely due to swell there will be a wider space between echoes although they will extend to some distance. Lines of rollers sometimes produce very distinct echoes.’

On 1 June 1967 routing was established in the Dover Strait. In the two years since then much experience has been gained and some of this has been reported already. The most significant fact to emerge so far is the sharp reduction in the number of accidents especially in relation to the amount of fog.

In the years 1961–7 before routing there was an average 14·3 collisions per annum, the lowest years being 1962 and 1965 with only 12 and the worst being 1961 with 23. In the first year since routing between 1 June 1967 and 31 May 1968 there were only 5 collisions, an all time low, and in the second year between 1 June 1968 and 31 May 1969 13 collisions with two after the 31 May 1969. Since most accidents in this area, but not as a whole, occur in fog it has long been established that a good measure of the safety record here is to examine the collisions per fog day. To do this in the Dover Strait, the amount of fog reported at the South Goodwin and Varne light vessels has been established from Trinity House and averaged to give an index for the Strait.

By means of a Notice to Mariners dated 10 August 1968, and in November of the same year with the collaboration of the Comité Central des Amateurs de France, the French Hydrographic Service conducted an inquiry among the Masters of French ships into the traffic separation schemes in force in the Dover Strait and other areas. The following is the report submitted to the Secretary General to the Marine Marchande. It is reproduced here without its appendices.

To help him in his use of radar as an aid to avoiding collision in fog, the watch officer needs to be sure which targets appearing on the radar screen are potential hazards, including those with which the collision risk will be increased by alteration of his own course and/or speed made to avoid other ships or in the course of navigation. In the commonly encountered multi-ship situation there are therefore likely to be at any particular instant several ships, perhaps 10 or more constantly changing, concerning which detailed and up-to-date information is highly desirable. This detailed information is of two kinds, namely information concerning the motions of other ships relative to own ship, and information concerning the true motions of other ships.

My first reaction on being invited by the Editor to contribute a ‘twenty-first birthday’ article on the above subject for the Journal was that there is little new to say. However, it is now 13 years since I prepared the presidential address on ‘The Place of Astronomy in Navigation’ (this Journal, 9, 1, 1956) and, apart from any other developments, space navigation has since become established as an operational science as well as a theoretical discipline. There have, in fact, been many developments and much progress in these 21 years; and, although these appear in the Journal and elsewhere mainly as gradual changes, a comparison over the whole interval reveals drastic changes, particularly in outlook and appreciation.

Position finding and hydrography—the plotting of coasts, channels and dangers to navigation—are the most obvious applications of science to the oceans, and they are the basis of well-established professions in which the use of accurate methods and the presentation of precise information are of paramount importance. Navigators can also make good use of knowledge of waves, tides and currents, but these are more variable in time and space, and, needing to be understood as well as charted, offer plenty of scope for academic study as well as a professional approach.

The following analysis of collisions in the Dover Strait has been made by J. H. Beattie for the International Committee on the Organization of Traffic at Sea (Icotas).

Tentative arrangements have now been made for the International Maritime Consultative Organization (Imco) to call an International Conference in 1972 to examine the international regulations for prevention of collision at sea and to make proposals for change where appropriate. It would therefore seem timely for members of the Institute with views on how the Collision Regulations might be amended to air these views so that all the aspects of the problem can be considered prior to the Revision Conference.

It would seem essential first to consider whether the rules as at present structured are broadly correct, which would indicate simply a review of each rule to see whether and to what extent amendments or improvements may be desirable, or alternatively whether some of the underlying basic premises on which the present rules are based are in need of revision, which would obviously mean very much more radical change. In the author's opinion the rules as now drafted do not seem to be correctly structured for modern navigation by the great bulk of ships on the high seas.

This paper describes the four main functions of radar in the Merchant Navy, expresses views on the controversial matter of mode of display and indicates possible solutions to the problem. Mention is also made of the desirability of properly engraving the relative bearing ring and the necessity of being able to take true and relative bearings at one and the same time if required.

Although the merchant navy is one of the earliest users of navigation, it is today by no means the most spectacular user, especially in comparison with present-day hovercraft and the coming supersonic civil aircraft. This absence of the spectacular is, however, not due to lack of imagination or progressiveness, but stems from very natural circumstances. These circumstances are the relatively low-if not the lowest-transportation speed, the application of the laws of Archimedes to obtain the required carrying capacity, and the laws of economics which dictate a delicate balance between investments and net revenue.

This study by the United States National Transportation Safety Board was undertaken to determine why ship collisions persist despite the use of radar and what recommendations could usefully be made to prevent collisions between radar-equipped vessels. The samples analysed cover the fiscal years 1963–7. An Appendix giving details of these collisions is omitted.

1. Introduction. The National Transportation Safety Board's review of the investigation of the collision between the S.S. Arizona and the M.V. Meiko Maru directed attention to collisions of vessels equipped with radar. In this case, the Masters of both vessels were navigating by radar to the exclusion of the Rules of the Road and the requirements of good seamanship, and neither was utilizing properly the radar to best advantage by plotting the relative motion of targets.

A previous paper, developing the idea of automated routing of vessels stated ‘the full scope of automated systems at sea is inconceivable in terms of compliance with the old (collision) Regulations. Only an entirely new code of manœuvre will give the dimensions and scope needed.’ Again, it was suggested that the Collisions Regulations would need to be completely re-thought and re-written in the light of present capabilities and possibilities. This paper, while not endeavouring completely to re-write the Collision Regulations, tries to outline the form the new Regulations should take without entering into too much detail, with particular relevance to the traffic separation schemes presently under consideration by Imco and leading to the future prospect of complete automation as envisaged in the article under reference.

It may be useful to outline the progress made in the field of inertial navigation for civil transports made since the last meeting of the Institute held to discuss the subject. After experimental evaluation work, mainly in the U.S.A. but also in this country, the first production equipment made specifically for civil use was the Sperry SGN 10 equipment made for Pan American Airways and first fitted in 1965.

‘Navigation demonstrateth how, by the shortest good way, by the aptest direction, and in the shortest time a sufficient ship between any two places may be conducted.’ To our Elizabethan forebears it was evident that the best way to conduct a ship was by the shortest passage of time which engendered least risk of catastrophe and avoided excessive wear and tear on ship, equipment and possibly passengers and crew. In the age of value-engineering and cost-effectiveness we are required to quantify these conflicting criteria. This is a matter of economics, which is concerned with applying the finite resources of mankind to the satisfaction of its infinite wants.

This paper outlines possible applications in the terminal area of an ILS based on hyperbolic geometry and correlation detection.

1. Introduction. A recent contribution to this Journal has surveyed the terminal area problem at London and outlined the research which is necessary to improve traffic handling capability. It was shown that contributions from many different development efforts will need to be integrated in order to achieve a worthwhile result. A fundamental aspect is that the problem of traffic congestion begins and ends at the runways and that the performance of the instrument landing system is of major importance. This paper will indicate how an approach and landing aid based on hyperbolic geometry and using correlation detection techniques can offer solutions to many of the known causes of traffic delay. The same principles can be used to integrate data links and monitoring into a complex which should be designed to aid the pilot as well as the controller.

It took three years to gain acceptance for the provision, in crowded waters, of two parallel channels for the main traffic, each reserved for streams travelling in opposite directions. It then took another four years to obtain the corresponding marking in the Dover Strait, which served as a testing ground for the system. However, since this came into operation in 1967, there has been an amazingly rapid expansion of the organization of crowded waters. At a time when new schemes are being brought to the attention of seamen, it is important to take a close look at the authority which such regulations possess.

The basic concept of case and cluster rotation in inertial navigation (IN) systems is introduced, and the reduction in the errors caused by changes in gyro and accelero-meter biases is illustrated. The general properties of cluster rotated systems are summarized and it is concluded that, although errors inside the Schuler loops may be drastically reduced by rotation, care must be taken to avoid error sources outside the loops.