In the eighteenth century nautical charting was a wholly national activity carried out to facilitate the navigation of the nation's own men-of-war and merchantmen. Regarded as what we would today term classified material, the charts were not freely exchanged with other nations for they could aid potential enemies, either in the competitive field of overseas trade or in the strategy of fleet operations. Indeed in the Napoleonic wars marine disasters caused by natural, and often uncharted, hazards were the major cause of casualties on both sides.

In 1972 an atomic time standard based on the fundamental properties of the caesium atom is being substituted for Greenwich Universal Time, based on the rotation of the Earth on its axis, as the ultimate control for international time signals. Greenwich Time and longitude are inseparable, so that any necessary correction to the time signals he receives will be of vital importance to the navigator.

This paper was presented at a meeting of the Institute in London on 27 January 1970 with the Hydrographer of the Navy, Rear-Admiral G. S. Ritchie, C.B., D.S.C., in the Chair. Mr. Humphry Smith, head of the Time Department at the Royal Greenwich Observatory and Chairman of the Directing Board of the Bureau International de l'Heure, reviews the relationship of uniform time systems to the precise astronomical observations that determine the irregularities of the Earth's rotation. He outlines the current proposals for time signals, their correction to Universal Time and the implications for the navigator.

The purpose of this article is twofold: firstly to give readers a general account of the new time-system that will be introduced on 1 January 1972, and secondly to give greater detail in respect of the corrections that a relatively few navigators may need to apply.

The great majority of users will not be (and need not be) aware of any change.

In his paper ‘Time Data and Navigation’ (page 13 of this Number) H. M. Smith has given an excellent background to the change, but that paper was written shortly before the final details were agreed; a little background material is, however, repeated here.

The log-book of the East Indiaman Osterley, 1758–1760 (India Office Library, L/MAR/B.400A), is of considerable interest as Captain Frederick Vincent not only gives the ordinary records of navigation—hourly reading of the log, courses steered; daily northing or southing, easting or westing; meridian distance (departure); difference of longitude (Captain Vincent measures his longitude from the Lizard, except where otherwise stated, but I have converted to longitude from Greenwich throughout); latitudes by account and by observation; variation—but in the remarks column he frequently gives his opinions on the situation of the ship and his reasons for forming them.

Collisions at sea continue to be in the news, many of them, as usual, inexplicable, navigationally as well as radar-wise (a curious phrase in this context). Little is said about radar in the Press because, no doubt, being complicated and technical to the layman, it is not newsworthy like oil pollution or wreck marking. Were the philosophy of its use more generally understood, the equipment might be better matched to the potential value of radar as an aid to collision avoidance.

In a recent article I spoke of the situation now reached in the circulation of traffic at sea as ‘a second spring’. Indeed, after a gloomy winter marked by a sequence of disasters in the Dover Strait it was some comfort to regard them as seed sown in a soil from which new life would not be slow in coming forth. This promise of spring was clear for example in the bold propositions adopted by Imco: ‘To prohibit traffic in the opposite direction on one-way routes’ and ‘to establish a Dover Strait fund’.

In this paper, which was presented at an Institute meeting held in London on 26 May 1971, Captain Brandenburg discusses the problems of port and terminal navigation control in the 1980s and takes up the questions whether such control will be needed and how much control will be appropriate.

This paper is not concerned particularly with problems in Rotterdam, or indeed with any particular ports, but rather with an overall evaluation of probable port developments in the near future, say the 1980s, and with the steps which may be necessary to meet the problems that will arise. In speaking of port and terminal navigation one should distinguish between pilotage, which may be defined as conducting a ship in safety from one manœuvring area to the next, and manœuvre, which is the handling of a ship in confined areas with whatever aids are available. It is well known that the danger and difficulty of manœuvre varies greatly in different areas and this was the subject of an analysis by Captain Wepster, but I shall consider manœuvres common to all terminal areas:

(i) picking up the pilot and lining up into the fairway channel,

(ii) docking and undocking,

(iii) lining up into the fairway channel again,

(iv) dropping the pilot and heading up for destination.

This paper was presented at a joint meeting of the Institute and the R.A.F. Specialist Navigation & G.D. Aero-Systems Course Association in London on 21 April 1971, with Group Captain D. F. H. Grocott, C.B.E., A.F.C., in the Chair. At the meeting the paper was illustrated with many slides which greatly facilitated understanding of some passages. Only a proportion can be reproduced here.

Obviously there are many occasions when the navigator would like to retain a full visual capability at night; this is certainly so in the military context where it may be essential that aircraft operations shall be fully effective under night conditions. It is similarly a truism that the acuity of the human eye, that is the ability to resolve fine detail in the image, decreases as night falls and the illumination level is reduced. Because of this there have been many research programmes over the years to develop sensors to extend the capability of the human eye, and one of the most important developments has been the use of low light television (LLTV) systems as an aid to night vision.

The year 1971 marked the first centenary of the publication of a paper on navigation which appeared in the Proceedings of the Royal Society of London in which the author, Sir William Thomson (later Lord Kelvin) described a new method of determining an astronomical position line. The method was impracticable and was not, therefore, adopted by practical seamen. Nevertheless, its design is ingenious and interesting, and an investigation of its principles adds lustre to the genius of its inventor—reputedly one of the most eminent philosophers of the nineteenth century. Although the method failed in the eyes of the mariners for whom it was intended, Thomson sparked off an interest in short-method tables which has persisted even to the present day.

Listening to Captain Brandenburg's talk on his ideas about the future navaids in Rotterdam (this Journal, 25, 67) I was left with the conviction that even the most ardent opponents of change will at least be better informed having heard it. Although in his introduction he excluded direct reference to Rotterdam, it is well known that the new Auto Com/Radar Data system when introduced there will be a real milestone for historians of port entrance techniques. I would like to think that it will lead us in this country one step closer to the day when we take the option out of progress on our own coasts and waterways and get on with it as they are doing in Rotterdam. There is of course one great difference—in Holland and Germany the Governments and Municipalities are involved, so that the necessary finances are seen in a clearer light.

It is doubtful if at any period in the history of seafaring a greater effort has been made to organize the safe conduct of ships about the seas than that which is being made today, and it is equally doubtful if the need was ever more urgent. At the present time a large amount of thought and work is being put into the task of trying to formulate rules and systems aimed at providing for the safer navigation of vessels at sea. Excellent ideas have been proposed for conduct in traffic, such as those put forward by Dr. Calvert, Admiral García-Frías and many others, which, together with the systems of traffic separation which have been established in areas of heavy shipping concentrations, could bring about a decrease in the present rate of marine casualties.

Commander P. C. H. Clissold, in a contribution to Forum in the April 1971 issue of the Journal, makes a point concerning the collision-avoidance handling of very large single-screw ships. Commander Clissold writes:

‘Because of their unwieldiness an avoiding action must be initiated while still at a considerable distance from the threat, if it is to have any effect. This distance is beyond that at which the eye of the navigator can accurately assess the risk of collision or the need to manœuvre. He must, therefore, depend upon instrumental information for making his decisions; in other words, in clear weather as in thick, he must use his radar and plot continuously if he is not to hazard his ship. If the argument is put forward that this will require two men on watch together and the state of manning does not permit this to be done, the answer is that a change in organization must be made to make it possible.’

In 1970 the Institute formed a Working Party to formulate views on the revision of the collision regulations. Its Interim Report is published in the Journal for October 1970 and two further contributions, by Calvert and García-Frías, were published in a subsequent number (24, 413–20). The Interim Report referred to the value that a manœuvring diagram along the lines originally proposed by Calvert and Hollingdale would have in helping the mariner to assess the effects of collision situations on alterations of course and speed. It has not been possible to secure unanimity about the form of this diagram, but the one illustrated below is based on the contributions of several members and has met with the approval of the majority of the Working Party.

At a first glance, one of the two accompanying diagrams might be taken to represent a three-station Decca or Loran chain, while the other offers familiar instruction on how to interpolate between the lattice lines and plot the fix. In fact, these are illustrations in a German Army handbook entitled An Introduction to Sound Ranging and the Work of the Sound Ranging Section, published in July 1918.

The note by V. L. Bosazza (on page 112) raises a number of interesting points. First it must be noted that there is no indication in Ryder's book that the horizon method, viz. ‘To observe from the cross-trees or other convenient place the angle subtended between the horizon and the enemy's waterline’, was used before it was introduced by Ryder in 1845. Ryder remarked that in not a single man-of-war which he visited before the time of the publication of his book did he find any method in use that would denote satisfactorily the range of a ship at sea; and it was to meet this deficiency that he suggested his horizon method.

The very interesting short note by Cotter in the July issue of the Journal is of importance in the history of survey methods used in charting the harbours of East Africa and the delta of the Zambezi. In my researches into the achievements of the Zambezi Expedition of 1858, I finally found in Francis Owen's book that the vertical angle method had been used in 1820 and also in the voyages of Leven and Barracouta from 1821 to 1823. In 1820 Captain W. F. M. Owen in collaboration with the staff at Woolwich calibrated rockets in order to measure distances at sea.

The number of collisions and groundings and the contact damage suffered by merchant ships every year is considerable, the averages for the years 1965–70 inclusive showing that some 15 per cent of the world's shipping over 500 g.r.t. has been involved annually in such accidents. United Kingdom shipping is no exception, and collisions and groundings alone as reported in Lloyd's Daily Lists during the first four months of 1971 show that ships from some 27 companies were involved, some with more than one incident reported although none had more than three. Collisions, groundings and contact damage are likely to occur if a ship's captain and his bridge watch keeping officers do not have immediately available in a simple form, complete information about their ship and her navigational equipment, and detailed information covering the essential tasks performed on the bridge. Unfortunately however, in a great number of ships, most of this information is not provided in an easily usable form and, as a result, even the most competent of navigators is all too often unnecessarily placed in a difficult and sometimes dangerous situation.

A. White's study of navigational accuracy near Strumble is artificial and draws some wrong conclusions. He seems to assume that it is a crime to be outside the airway. But this airway is isolated, with no mountains near cruising altitude, and no one infringed a neighbouring airway. In a terminal area I am sure accuracy is much higher, because it needs to be. Airway widths vary from one country to another and are unimportant and the boundaries are not evident to pilots, who try to stay not within the arbitrary boundaries but not too far from the centre line. The area just outside the official airway is just as safe and good as the airway, and indeed safer than the centre line where traffic density is highest and only an altitude mistake by controller or pilot is needed to promote a collision—natural dispersion is still safer than extreme accuracy. Crews generally fly only as accurately as necessary, reserving their energy for the most important tasks: the study of Strumble shows adequate accuracy. Incidentally routes and airways should follow the curved path of aircraft instead of the right-angled bends, for instance the standard inbound route to Gatwick: Lydd-Cliff-Mayfield.

When our Norwegian ancestors wished to navigate in the open sea they could find their bearings by the Sun or stars if the sky was not overcast. In foggy weather they used the sólaisteinn or sunstone, ‘a stone with which one could see where the sun was in the heavens’. A knife blade will do equally well as may be seen from Fig. 1. If you place the point of the knife on your thumb nail, as shown in the figure, on a sunny day you can easily see the shadow it casts; turning the blade a little one way or the other the shadow widens, but when the knife edge points towards the sun the shadow is reduced to a narrow line.