It does indeed give me great pleasure to have been honoured by the request to give this lecture. And it is with a little trepidation that I have chosen my subject, the very title of which could frighten off many people, and I am very glad to see that your Institute consists of people made of sterner stuff. On the other hand, I did feel that the subject in question met the nature of this lecture. It was generally cultural and it relates to navigation. And so let me start on this subject which has a reputation for being difficult. And let me assure you that Einstein's work on relativity is not at all difficult. It is very simple. But it rests on the extremely difficult, abstract theories that we owe to Galileo and to Newton.

The paper by Captain Cotter on Edward Johnson and the early history of ship's magnetism published in the September Journal sets the scene for the birth, in 1842, of the Compass Department of the Admiralty. Commander Fanning, a former Deputy Director of the Admiralty Compass Observatory, as it later became, here relates its subsequent history. The paper was presented to an Ordinary Meeting of the Institute held in London on 19 December 1979 with Dr J. F. Kemp in the Chair.

This paper traces the fortunes and development of a small department, one of the oldest Admiralty technical departments, from its early struggles with the magnetic compass, through many vicissitudes, economies, defence cuts, wars, intrigues, take-overs and even human frailties. We shall see how technical advances have led to ever more demanding requirements and I hope to show how, by meeting each new challenge, there has emerged the lively, forward-looking organization that today is still responsible for ‘everything that matters’ in navigation equipment, as it was at its inception in 1842.

The Fastnet Race of 1979, over the classic course from Cowes round the Fastnet Rock and back to Plymouth, proved to be the most disastrous in the history of the race, or indeed of ocean racing itself. A storm of exceptional violence, of which the meteorological analysis by itself has provided an inadequate explanation, decimated the fleet causing the loss of 15 lives and the abandonment of many boats. The Royal Ocean Racing Club, which organizes the race, has (with the RYA) issued its own report and the progress of the weather pattern over those fateful days has by now become familiar. In this article Adlard Coles, a highly experienced small-boat seaman (and Institute Gold Medallist), author of Heavy Weather Sailing describes the chaos wrought by the unusually violent and steep seas and attempts to draw conclusions from his own investigation of the affair.

In the first six months of 1979 there were six collisions in the area of the Dover Strait (extending from the Greenwich meridian to 2° 30′ E and from 50° 30′ N to 51° 30′ N) that involved at least one vessel of 500 grt or more. (Two further collisions took place during the next four months.) Collisions have not occurred in these waters at a rate of one a month since 1969. Yet since then there have been several notable changes that should have led to greater safety. The IMCO traffic separation scheme has been made compulsory for ships of all nations through the coming into force of the new Collision Regulations on 15 July 1977. Secondly, the Channel Navigation Information Service was established in England in 1972, and it and its counterpart in France have been monitoring the traffic by radar and making regular broadcasts for more than five years. Finally, traffic discipline has steadily improved, as measured by the number of ‘rogue’ vessels that are held to contravene the routing scheme (Fig. 1).

To decide whether this spate of collisions represents a marked deterioration in navigational standards it is necessary to do rather more than merely count occurrences (Fig. 2). In the first place, any evaluation must take account of the amount of damage to the ships involved and to the environment, and of deaths and injuries to personnel.

This study consists of an investigation of the point at which ships' masters make decisions to avoid collisions, with regard to the time and distance separation from the other ship. The objective of the study is to find out what factors influence them to make their decisions to manoeuvre at this point rather than at any other; this involves the examination of various factors which could be relevant to the decision-making process, such as the speeds of the two ships, the relative bearing of the other ship, and the length of sea experience of the navigator.

Several computer simulation models for marine traffic systems have been built but various subjective assumptions have had to be made about the criteria on which a decision to make a collision avoidance manoeuvre is based. This study represents the first systematic investigation of the statistical relationships among the factors affecting these criteria.

This paper outlines the concept of a domain and an evasion area, called an arena, around a ship which are then applied to produce a computer model of ship behaviour. The arena determines when a ship takes avoiding action, as does the land arena which reacts with a discrete series of coastal points to prevent the ship running aground.

The increase in the number and size of ships has resulted in the introduction of traffic routing schemes and the need to understand ship behaviour more thoroughly. The concept of ‘the effective area around a ship which a navigator would like to keep clear with respect to other ships and stationary objects’ has been used by various authors including Goodwin, Fujii and Lewison with varying names such as domain, collision diameters and encounter area. There has been no fixed shape for these areas. Some are circular, others elliptical, while Goodwin's has three segments each with its own portion of a circle. By developing the theory of the domain, it was hoped to be able to produce a model of traffic behaviour which could be used to simulate traffic flows, or specific incidents, in order to study them more fully.

For a circular contour, which is one of the methods for indicating an error boundary, the author has studied the conditions for the probability of a ship's position (fixed by two position lines) lying within a 95 per cent circle by probability integration. In this case, the coefficient in the equation to indicate the radius is a function of an intersecting angle and an accuracy ratio between two position lines. The author has examined several accuracy ratios and applied the system to the error boundary of a ship's position fixed by three equally accurate position lines. However, as interpolation involves both angle of cut and accuracy ratio, the process is somewhat troublesome.

In this paper it is shown that the accuracy contour for a fix is an ellipse, whether the accuracies of the position lines are the same or not, and a method is developed to replace an error ellipse for two position lines of unequal accuracy with an ellipse formed by two equal-accuracy position lines. The method is extended to three position lines of unequal accuracy. It then becomes possible to indicate an error boundary by a 95 per cent probability circle.

This paper, by the Deputy Operations Manager of the Marine Department of Hunting Surveys Limited, was presented on 15 November 1979 at a meeting of the Solent Branch of the Institute held at the College of Nautical Studies, Warsash. It deals with the operation of semi-submersible laybarges based on experience in the northern North Sea from 1975 to 1979. It covers, from the survey contractor's point of view, the different phases of operation from the time the oil company selects the route until the line is laid and surveyed on the seabed. Some aspects of the work described would not normally be associated with surveying or navigation but have been carried out by survey teams in laybarges.

The two papers which follow (Jones and Ratcliffe) were presented in the course of a seminar sponsored jointly by the Institute with the Nautical Institute and held at the City of London Polytechnic on 13 December 1979. The purpose was to examine the usefulness of transponders for marine purposes. Seven papers were presented and these may be obtained at £7.50 (£5 for Members) from the Nautical Institute.

The term transponder is usually interpreted by practising mariners as the simple inband swept frequency device, called Racon, with which those mariners are most familiar. It is this concept which largely colours the mariner's views on the topic, and is perhaps the reason for the obvious reluctance to accept expanding use of transponders which is apparent in the marine industry. Their personal recollected experiences of the clutter caused by Racon and the possible problems that could result from proliferation of such beacons give justifiable cause for this hesitancy.

Air transport is characterized by a rapid and fairly steady growth in the size, numbers and speed of the vehicles. The systems for navigation and control of this traffic have evolved with the changing problem, and heavy demands have been, and are being, made on electronic technology. At the same time, heavy emphasis is laid on the need for evolutionary changes; old and new systems must be compatible. The present investment, world-wide, in civil air transport is about £100000M. World-wide compatibility is essential between air and ground electronic subsystems, and such systems and operating procedures are, eventually, the subject of international agreements. It follows that any system changes must be heavily influenced by past history, and for that reason it is proposed to discuss airborne secondary radar transponders on a historical basis.

The shipping industry is faced with unilateral legislation proposed by the United States of America covering navigational equipment and, in the interests of harmonization, IMCO is compiling performance specifications and carriage requirements for navigational equipment including collision avoidance systems; the establishment of type approval procedures can be anticipated. The shipowner has reservations, in respect of the need for adequate training in the use of advanced systems and the risk of navigators placing reliance on such devices as collision avoidance systems when their constant availability cannot be guaranteed.

The aerospace industry has demonstrated very effectively the accuracy and reliability of both manned and unmanned vehicles on extensive and sophisticated missions. There is little doubt that the next two or three decades will see the rapid introduction of further automated and computerized techniques into ship operations and there is a great deal that the shipping industry can learn from civil aviation – in particular, traffic regulation, automated navigation, accident investigation, and training techniques. Three accidents which illustrate some of the problems associated with the operation of merchant ships are cited, and comparisons made with the operational procedures used in aviation.

The motor vessel Blythe Star of 321 grt sailed at 1830 on 12 October 1973 from Hobart, Tasmania, bound for King Island with a cargo of bagged superphosphate. At 0800 on 13 October she heeled over to starboard and sank. The weather was fine, with light winds, slight seas, and very low swell. All of the ten persons aboard abandoned ship in an inflatable life-raft. One died at sea and two others died after reaching shore in southern Tasmania. The remainder, after landing on 21 October, made their way to a logging contractor and safety on October 24. The accident resulted in the biggest search and rescue operation ever conducted in Australia.

As sea traffic grows, so too does the problem of the acoustic pollution of fishing grounds. This paper describes the measurement and analysis of ship-produced underwater sounds and their effect on the behaviour of certain fishes. It would seem that their influence on marine organisms is a growing problem and should not be ignored by navigators, for the sounds produced by large or high-speed vessels, or even fishing boats, can frighten fish shoals or cause them to change their migration routes.

After a series of tests to measure and analyse the underwater sound, the output of submerged loud-speakers, either at sea or in an aquarium, was adjusted to ensure that the sound intensity near the fish was at the required level and the fish behaviour was carefully observed. For these experiments a hydrophone was connected to a pre-amplifier. A signal amplified by the pre-amplifier is attenuated before being sent to the main amplifier, the sound level being read directly on an indicator using the sound analysing character ‘C’. A tape recorder registers the sound signal in a flat response from 20 to 50 Hz to within 3 dB. A tracing recorder was also sometimes used and the two methods gave almost the same results.

It is expected that the number of military and civil aircraft operating supersonically all over the world may remain the same during the next decade. The problem of sonic boom, which has been by-passed for military aircraft through the assignment of specially allocated ranges for supersonic operation, is still with us and is likely to influence the operation of supersonic transport (SST) aircraft, the Concorde and the Tupolev 144. Concorde is still short of reaching the break-even point, despite the large traffic gain registered on the routes to North and South America. The problem is to get overland routes; the difficulties encountered by the UK in the discussions with India and Malaysia for the establishment of a London–Bahrain–Singapore route are well known.

Before presenting the effects of the sonic boom on the ecology it may be well to summarize the nature and the main features of this phenomenon.

(i) The N-wave signature. A complex body like an aircraft, moving in supersonic flight, generates a pattern of local shock waves which tend to coalesce in two main shock cones, the front (or bow) and tail, as the distance from the aircraft increases. A shock wave is a discontinuity surface for the thermodynamic characteristics of the fluid, the most important being the static pressure jump responsible for the N-shaped pressure signature characteristic of the sonic boom. Other parameters are of minor importance to the environment. A shock signature is denned by the following parameters:

The recent death of Philip Van Horn Weems, at the advanced age of 90, has removed from the field of navigation one of its most outstanding and colourful personalities. His contributions, made over a period of more than half a century, have ranged over almost every aspect of navigation: practising navigator, instrument inventor, pioneer of the GHA form of Nautical Almanac and of the first Air Almanac, introducer of the Star Altitude Curves, brilliant expositor (as his books so clearly demonstrate), successful business man who trained many thousand navigators through his training schools and correspondence courses – he devoted his whole life to navigation with boundless energy and contagious enthusiasm.

This is not the place to give the factual details of his life, or to put on record his many achievements, both inside and outside his professional career. Many of his most lasting and significant contributions to the practice of navigation, although so familiar to myself, can only be appreciated by a detailed study relative to the contemporary ‘state of the art’; Weems was, above all else, an innovator of ideas many of which were developed by others and which deserve a fuller and more technical treatment.

A brief summary of his career follows. Weems, left an orphan at an early age, had a hard life on the family farm in Tennessee, with little formal education.

A tedious problem which confronts many a yachtsman is determining the deviation of his magnetic compass. He can hardly justify the expensive services of a professional compass adjuster, so this necessary but difficult operation must be carried out by himself. Should he decide to use bearings of shore objects when swinging ship he is faced with the difficulty of observing these bearings on his compass. A small-boat compass is hardly likely to come equipped with azimuth mirror and sight vanes. The alternative equipment for taking the bearings is a pelorus, but the expense of this instrument could hardly be justified for such rare and intermittent use.

The favourite way out of the difficulty appears to be to use a hand bearing compass. This method suffers from two disadvantages in particular:

(i) The hand bearing compass should be situated in precisely the same position as the main compass if it is to reproduce the latter's readings precisely. Not only is this impossible to achieve in practice – the nearest they can be brought together is side by side – but when brought close together their mutual magnetic reaction can produce errors of an unknown amount.

(ii) The use of bearings to shore objects naturally entails being offshore. Stationary small boats are notoriously unstable observation platforms and even a light chop would make it impossible to read the main compass with the accuracy necessary for a good deviation card.

I note with interest Dr Barrass' comment in the January issue of the Forum (33, 139). He deals with three subjects: (i) the ultimate trim of tankers in shallow water; (ii) the question of increasing rpm in interaction situation; and (iii) the final turning diameter in shallow water.

Dr Barrass' curves (p. 140, Fig. 1) are useful approximations to squat and to ship characteristics but cannot be treated as definitive.

Fig. 2 is a particular interpretation of practice and not necessarily universally accepted, particularly in respect of the LCB position. In some recent VLCC work benefits have been obtained by moving the LCB aft in association with a buttock-flow stern. Furthermore, the dependence of block coefficient upon Froude number is not realistic, especially in the finer vessels; it is the prismatic coefficient that is dependent upon Froude number. It cannot be taken, therefore, that absolute curves for these factors exist as inferred from Fig. 2.

Turning to Fig. 1, the curves showing sinkage in confined channels are for the blockage ratio bracketing 0·1–0·3. This is a large range of blockage and as a result the curves can significantly underestimate and overestimate sinkage, depending upon where in this bracket a particular example falls. Similarly, the solid curves show sinkage in open water conditions over depth/draft ratios 1·1 – 1·2. This is quite a large range and a unique curve cannot represent these two values.