One of the essential steps in the operations of war is to know where your enemy is, so that you may either make contact with him or avoid him: the same applies to any friendly force with which you may be operating. And in parallel with these steps you need also to establish your position relative to any natural hazards that you may have either to avoid or exploit. If you can establish the positions of yourself, your friends, the enemy, and the hazards relative to the Earth's surface, you can use the information to control your own movements as you wish; alternatively you can sometimes, by one means or another, directly establish the enemy's position relative to your own and proceed accordingly—a process equally useful in ‘homing’ or evasion.

Experience gained in the automation of air traffic control is of interest from more than one point of view, and not only because of the range and diversity of new and delicate problems to which this application of automation has given rise, and for which it is necessary to find simultaneous solutions. It has been necessary to design and develop new methods for the acquisition, processing and display of information and to link them with digital computers, for which a complex and voluminous ‘real-time’ software has had to be compiled and brought up to date without interrupting the procedure. But it is when it comes to visualizing the total pattern that the most difficult problems arise because the major decisions determining the success or failure of the operation have had to be taken without the possibility of acquiring any preliminary experience.

Man and the computer have to work together in real time as harmoniously as possible to obtain the best results from the modern data processing systems that it was proposed to employ; it was therefore essential to consider very deeply the complementary roles which each was intended to play.

To describe this research in detail or the solutions arrived at would not be of great interest to those other than specialists.

F. J. North reminds us that the well defined geographical entity now called the Bristol Channel should, on historical grounds, be called the Severn Sea. This was the name used by Giraldus Cambrensis (1146?–1223) in his Topographic Hibernica of 1188 and by Roger Barlow in his A Brief Summe of Geographic of 1540, among other early writers. But with Bristol's rise to fame as a great seaport the name Bristol Channel came to be used and, as early as 1693 we find the name ‘Canal de Bristol’ on a French sea chart by H. Jaillot.

An unknown writer of 1578, whose Discourse was published in John Stow's Survey of London of 1598, in explaining why a site on the Thames instead of one on the Severn was chosen for the metropolitan city, stated that:

‘… the Thames both for the straight course in length and reacheth furthest into the belly of the land, and for the breadth and stillness of the water is most navigable up and down the stream…. The river openeth indifferently upon France and Flaunders, our mightiest neighbours, on whose doings we ought to have a bent eye and special regard…

… For the Prince of this Realm to rest and dwell upon Severn were to be shut up in a cumbersome corner, which openeth but upon Ireland only, a place of much less importance…’

This paper is mainly concerned with the movement of marine traffic in the Upper Bristol Channel, that is the present organization of pilotage services and docking facilities in the area, some of the present difficulties confronting Masters and pilots, and how these difficulties will grow with the increasing size of vessels. This must occur when the Port of Bristol's West Dock opens and would also occur if a new dock were to be constructed at Newport. The conclusion gives outlines of some ideas which have been put forward for providing a segregation and separation of vessels in the area and the possibility of a joint shore-based authority to assist in securing a reasonably safe and economic flow of traffic through the area.

Sir George Deacon, F.R.S., a past president, has recently written a most persuasive case for founding a Chair in Navigation. He mentions Sir Isaac Newton's insistence that Christ's Hospital should teach ‘not only what is necessary to make a mariner skilful in his ordinary road, but also what would assist him to invent new things and practices and to judge what comes before him’. It was in this spirit that a basic analysis of navigation was begun some years ago although it was not expected that Sir Isaac Newton's great conception would be realized. Indeed, the object was only to try to suggest to educators the potential of navigation as a scientific discipline.

Elements of the work dealing with probability and with information theory have already appeared in the Journal and certain ideas have been crystallised into patents taken out by Smiths Industries Limited. Other results are presented here in a condensed form starting with a definition which leads on to a pattern of equipments by using a particular development of dimensions and which highlights the special difficulty of collision avoidance. Linkages between gimballing error, precession and coriolis effect are suggested, and the significance of frames of reference is emphasized, suggesting a unified approach to the trigonometry needed by the navigator. If these crude tools can be tempered by the fire of criticism or replaced by finer cutting edges, the effort will not have been wasted.

The problem of collision avoidance at sea would be an important one even if accidents were rare, but the evidence suggests that they are much more common than one might expect. In the eight years leading up to May 1963 there were 60 collisions in the English Channel area and in the following eight years the number increased to 94. With the development of navigational aids such as radar one might have hoped for a decrease. The suggestion that the increase is quite likely attributable to the possession of radar is ironic indeed. It would appear that having the use of this ‘safety’ equipment allows the mariner to take greater risks, but that the risks which are in fact taken are greater than the equipment allows. We would do better to go back to fog horns alone. Even if over-confidence is not the only factor responsible for the increase in accidents, it does, nevertheless, illustrate the importance of the psychological variable in any man–machine system.

Collisions at sea, however, are not simply due to errors in a man–machine system, It is, of course, the hardware that actually collides, but the cause of the interaction lies in the decisions and indecisions of the two human agents controlling the vessels. It is essentially a social encounter. It is for this reason that the work initiated by Captain Kemp is greatly to be welcomed.

This paper describes the historical background to the Göttingen Professor Tobias Mayer's bid under the terms of the Act 12 Queen Anne, cap. XX (1714) to obtain a reward for having constructed lunar tables of unprecedented accuracy (to about ± ½′) which promised to make both useful and practicable the lunar-distance method of finding longitude at sea. Parliament's decision in 1765 to award £3000 to Mayer's heirs marked the end of an eleven-year period of lively correspondence conducted on the latter's behalf between Professor Johann David Michaelis, Secretary of Hanoverian Affairs in Göttingen, and William Philip Best, one of George III's Privy Secretaries in London. The Nautical Almanac came into existence as a direct consequence of the success of these diplomatic negotiations.

Professor Cortesão sent the following message to the Annual General Meeting of the Institute on 23 October which he had been unable to attend to receive personally his Honorary Membership. An account of the meeting appears at page 111.

The Honorary Membership which the Royal Institute of Navigation bestows upon me, when I have reached the eighty-fourth year of my laborious life, the last forty years of which have been largely dedicated to the study of the history of early cartography and navigation, impresses me deeply and I am very sorry that, due only to my advanced age, I cannot be present at this ceremony to thank you personally for such a great distinction.

I am indebted to Captain Duncan M. Henderson (Journal27, 536) for causing me to seek further than I had done previously to enable me to prove that ‘F’ in old log-books stood for fathoms and not fractions.

I would quote the following authorities who all state definitely that the ‘F’ meant fathoms and that there were usually eight fathoms to a knot, at any rate in the eighteenth and early nineteenth centuries. They are:

The remarks of Mr. Harrison under the above title demand some further comment. One can certainly agree with his substitution of ‘prediction’ for ‘plotting’ but not with his deletion of ‘supposed’. The latter begs the whole question whether the operator will be dangerously deceived and this is far from proven. The latter part of his second paragraph is a generality; there will be many combinations of range and speed in which the result will not be satisfactory.

Mr. Harrison implies, although he does not come right out and say so, that errors arising during ‘classical’ manual plotting are ‘operationally’ acceptable while the errors in automatic plotting are unacceptable. Such a conclusion is illogical if one is willing to concede that any manual plotting procedure can be automated by the use of a digital computer. To examine this assertion in greater detail one may consider the automatic plotter to be made up of a data extraction section and a data processing section.

In Captain F. J. Wylie's article, ‘Maritime radar automatic plotter display philosophy’ in the July 1974 issue of the Journal, he states that the IBM Maritime Application Bridge System (MABS) tracks only six targets for collision assessment purposes. This statement is incomplete and I would like to clarify the impression left with your readers.

The IBM MABS tracks up to 21 targets continuously while performing either automatic or manual acquisition. However, since the MABS also prioritizes targets according to threat potential (based on C.P.A. and T.C.P.A.), only the six most threatening are displayed continuously on the alpha-numeric data display and on the PPI. Should the operator wish to obtain data on the fifteen targets of lower priority he can request them in groups of six, in descending order.

Having read Professor Hugon's informative paper on ‘Navigation in the French merchant navy’ and in particular his remarks regarding the cluttering of the 182 kHz band, I would hazard a guess that he has not listened to the v.h.f. channel 16 band in recent years, when clear of the U.K. and continental areas.

In the open sea well away from land this channel is not often abused, but off the West African coast between about 13° N. and 22° N. the air at night is, more often than not, cluttered with noises like animal and bird calls for long periods on channel 16, and during the day with lengthy chitchat, possibly between foreign fishermen, on this and other channels.

The method here described for finding the position of an observer from horizontal angles to fixed marks, without the use of a station pointer and without the necessity of drawing position circles, was devised by the author and although it may not be original it may be of interest to other navigators.

As a result of the recent marketing of small pocket computers I have found much interest among navigators who would like to use them for working out celestial sights. One computer calculator (the Hewlett-Packard HP-35) in particular appears to be of considerable interest due to its ability to compute trigonometric functions with algebraic logic as well as to store and recall derived intermediate values. Not having been able to find any published work on the use of this type of equipment for the rapid and precise working of sights I have given some thought to the matter and as a result believe the following notes may well be of interest to others.

Some navigators may prefer other methods and other tools, but the Hewlett Packard HP-45 has some fascinating abilities. It might be called the poor man's INS computer, though it does not of course find position. Its only disadvantages are the need for a hood in sunlight and the need for concentration and freedom from distraction. It can be used on the knee for no table is required, and it replaces conversion tables and several other mathematical tables. To a large extent it can replace plotting charts, flight planning charts, Dalton computers, protractors and dividers.

The figure illustrating R. J. Turner's article in the last number (27, 533) was printed without its legend. A short summary of the paper and the illustration and legend follow.

The use and interpretation of a radar display requires a consideration of motion relative to different frames of reference. It is essential for sea or ground stabilization that the correct data is fed to the radar: Fig. 1 illustrates the velocity of the ship relative to different frames of reference and also the quantities measured by different types of log. Ideally, when a radar installation is being planned, the type of log to be installed should be chosen so that the radar can give the information required. With existing installations the type of log fitted should be borne in mind in deciding just what information the display is capable of giving.