The author is Professor of Oceanography in the School of Engineering and Science of New York University and this paper was prepared for the Imco joint ad hoc group for the study of external forces affecting ships. Reviewing the circumstances attending the loss of the trawlers Blue Crusader and Boston Pionair in 1965 he attributes them to high pyramidal seas caused by the crossing of wave trains refracted in water of varying depth. The use of model experiments, air photography and laser altimeters is suggested for verifying the theoretical conclusions, in the light of which corrective measures might be taken when navigating under such conditions.

The paper which follows was presented at an Ordinary Meeting of the Institute held in London on 26 January with the President, Rear-Admiral G. S. Ritchie, C.B., D.S.C, F.R.I.C.S. in the Chair.

In a survey of navigational aids which considers both the navigational problems and the means for their solution it is first worth looking back in history because the problems as well as the solutions have changed. It is difficult to decide at what point in time to start, though without any doubt the greatest changes have come in the past fifty years. Even the ancients had their problems; it appears that the Greek general, historian, and apparently sailor, Thucydides was disgraced and exiled in about 400 B.C. because he lost seven of his ships and failed to reach Thrace from Thasos in time to save it from the Spartans. His navigation may have been faulty and perhaps better navigational aids might have changed the course of history!

When advancing years put the Himalaya out of reach my thoughts turned to sailing and the chances of combining this with climbing, two activities that have much in common. After an apprenticeship in the form of two voyages with Bobby Somerset—whom I still regard as the maestro in small boat matters—I acquired Mischief solely with a view to crossing the Patagonia ice-cap. The ice-cap had not then been crossed and since all attempts from the Argentine side had failed I thought of tackling it from the sea. Mischief, 45 ft. long, 13 ft. beam, 7 ft. 6 in. draught, of about 30 tons T.M., had been built in 1906 as a Bristol Channel pilot cutter.

In January 1971 the liner Antilles sailing among the islands of the same name ran aground in the neighbourhood of the Grenadines, between the islands of Mustique and the Pillories. Nobody was injured but the ship was lost. An inquiry by a maritime court in the following October acquitted the Captain and this came as a great relief to the seafaring fraternity because it was difficult to see how a sailor at the top of his profession could knowingly have navigated with such imprudence. The fatal rock was not shown on the chart and everyone knows that charts are not perfect: the Master had been the victim of the inevitable.

‘There are two kinds of Instruments by which Artificers have conceived that the figure of this so beautifull and various fabricke of the whole Universe might most aptly be expressed, and as it were at once presented to the view. The one exhibiting this Idea in a round solid is called a Globe. The other, expressing the same in a plaine, they tearme a Planisphaere or Map.… The Planisphaere, indeed, is a fine invention.… But yet that Other, being the more ancient, hath also the priority in Nature, and is of the most convenient forme; and therefore more aptly accommodated for the understanding and fancy (not to speake any of the beauty and gracefulnesse of it), for it representeth the things themselves in proper genuine figures.’

The following discussion took place at an open session of the Technical Committee held at the Royal Aeronautical Society in London on 19 January 1972 with Mr. H. E. Smith in the Chair.

The Chairman: Relative navigation has a wide connotation, but for the purpose of our discussion it may be applied firstly to aircraft management in the positive or passive sense, arising from an air-to-air navigational interrogation capability, and secondly to the means whereby this capability may be realized.

This is a survey of a subject for which there are few positive conclusions on the reasons for existing controls and control practices. The position of the operator of a vehicle or craft, the preferred side for the control or conning position and the ‘rules-of-the-road’ for land and water transport and also air transport seemed to have evolved through innate and conditioned human preferences such as ‘handedness’, through customs and traditions and, possibly to a lesser extent, by arbitrary rule making. In general, man is outwardly laterally symmetrical but has a dominant side and a preferred-hand. Within the majority of ethnic groups right-hand preferring people make up 90 per cent of a population. However, despite innate preferences about which there is inconclusive evidence and the influences of a ‘right-handed’ world imposed upon the maturing child, man can acquire through learning and training a sufficient degree of ambidexterity to operate effectively the controls of complex man/machine interfaces. As long as tools, vehicles and all other artifacts remained essentially simple to use or operate they could be controlled, governed or steered by either hand or by one hand—usually the preferred—or by both hands. However, the preferred hand with any of these combinations would ‘lead’ and would provide precision or ‘fine’ control. The introduction of writing and similar tasks requiring coordination of mind, hand and eye has always reinforced the ‘right-handed’ world. For convenience this survey is divided into three major evolutionary paths: sword, steering oar and left-hand circuit.

After reading the first two reports on the surveys of marine traffic in the Dover Strait conducted by the National Physical Laboratory, it was decided to investigate the possibility of applying the results to two points raised in recent issues of the Journal.

The first question studied was one suggested by Beattie, in his article on the first of the above traffic surveys. It was noted that there was quite a variation in the number of ships per hour passing through a given area. This could have been caused by a systematic tendency for ships to come through in clusters or could be a perfectly random variation. If the variation was completely random then the frequency distribution of ships per hour should follow a standard statistical distribution known as the Poisson distribution. For each of six separate distributions obtained from the results of the surveys on 26 February to 1 March 1971 and 27 April to 29 April 1971, the appropriate theoretical Poisson distribution was fitted and tests made to assess how close the theoretical and observed distributions were. The results of the calculations are summarized below in the table.

Yachtsmen, like other mariners, are being encouraged to ‘think metric’—to become accustomed to metres in Tide Tables, Pilots and Light Lists, and to make use of the new metric charts as and when these become available. Along with these changes to books and publications we can expect the introduction of metric tide gauges, and of echo sounders calibrated not in feet or fathoms but in metres. In a few years time even those yachtsmen who normally never correct their charts, or who do not think about renewing them until they are covered with cocoa stains, will be forced to work in metres.

It may come as a surprise to many navigators that the interesting and valuable, although seemingly little-used, method in which three successive bearings of a single fixed mark are used to find course made good, has a history of not more than about half a century.

When two or more suitably placed marks are in sight the course made good may readily be found from a series of fixes by cross bearings, and this technique is commonly used by coastal navigators. When, however, a single mark alone is available the reliability of running fixes depends upon the accuracy of estimations of courses and distances made good in the intervals between successive bearings. A table for finding the distance of a mark from two bearings and the distance run in the interval between observations was inserted in the first edition of Raper's Practice of Navigation in which the author informs his readers that the table was constructed at the suggestion of Sir Francis Beaufort and that it first appeared in the Nautical Magazine.

It is interesting to consider navigation and the problem of traffic control with the common underlying concept of randomness, though Anderson's presentation seems more oriented to thermodynamics than to information theory. But the underlying philosophy is the same: entropy never increases.

In order to decrease entropy without the help of Maxwell's demon we have to introduce work or energy, that is we measure the state of a specific object and control that state with the aid of the information gained.

The principal purposes of this introductory paper are to identify and describe the main aspects of marine traffic engineering, and to suggest ways in which traffic engineering principles and methods developed for land and air transport systems may be applied to marine problems. Traffic engineering is a relatively new branch of engineering science, but it was quickly and widely recognized as essential in ensuring that all forms of land and air transport operate safely and efficiently. However, although sea transport is a long established activity, it is only during the past few years that marine traffic engineering has begun to emerge as a separate aspect of this broader scientific discipline.

A general programme of work with the overall aim of reducing the incidence of collisions in the Dover Strait has been commissioned by the Marine Division, Department of Trade and Industry. As part of the programme the Operational Research Unit in DTI is developing mathematical models of traffic flow, using inputs of data provided from the surveys mounted by NPL and described in the paper by Johnson and Wheatley.

The paper describes and reviews some of the work done by NPL over a period of twelve months in a climate of growing concern about the present and future safety of marine traffic, especially in narrow and restricted waters. The increase in number, size and speed of ships in the last decade emphasizes the need for information on the characteristics of marine traffic affecting safety of navigation, while the use of very large tankers and new types of carrier has increased the potential consequences of pollution to the environment in the event of a serious casualty. The situation in the Dover Strait is further complicated by crossing traffic and by the existence of fishing grounds.

As vessels become more efficient and shipping demands continue to grow the population explosion of vessels at sea is outdistancing even its famous human counterpart. This increases the risk of accidents, particularly in confluence areas and straits, and to avert future disaster it is important to predict trends in global traffic flows so that appropriate measures may be taken in time. This poses a difficult problem. Due to the diversity of nationalities involved, the autonomy of ships and competitive secrecy, it is only possible to account for the present at-sea ship population within about 16 per cent. Geographical distribution is even more doubtful and predicting changes more speculative still.

A Marine terminal influences the flow of traffic which sails at a lower speed and is congested. Navigation must be in accordance with the total amount of traffic and not, as in the open sea, in accordance with one or two other ships. Shore based authority must be accepted. The flow of traffic along the coast passing a terminal meets this congestion, certainly if the terminal is in shallow water frequented by large vessels. Crossing also adds to the congestion for the passing flow of traffic. The congestion will be less if the marine terminal and outer channel can accommodate the total traffic flow.

Although the economic theory of congestion as applied to road traffic has been known since at least the time of Pigou its application to marine problems has been much slower. It is the purpose of this paper to remedy this somewhat by interpreting the theory in a marine context and to suggest some of the practical implications of taking proper account of congestion effects.

A Survey of marine accidents has been carried out as part of a study aimed at predicting the probable future frequency of accidents likely to result in pollution of the United Kingdom coastline. The survey covers all marine accidents in the North-western European area, i.e. North Sea, English Channel, Irish Sea &c, and all tanker accidents world-wide; it covers the 10-year period 1959–68 inclusive.