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.

With the generous permission of Smiths Industries research is now being undertaken within the Department of Maritime Studies at the University of Wales Institute of Science and Technology, under the supervision of Captain C. H. Cotter. This has led to a study of information theory and its interesting links with entropy; information, as a result of work done, reduces randomness and introduces orderliness just as, in another context, housework reduces random dust and introduces cleanliness.

In October this year an international conference on the revision of the International Regulations for Preventing Collisions at Sea will be held in London. A working party appointed by the Maritime Safety Committee of Imco, under the chairmanship of Captain A. C. Manson of the Department of Trade and Industry, has drawn up proposals for the revision of the present regulations. Captain Manson described these proposals to an open session of the Technical Committee held in London on 17 May 1972 with Captain D. A. G. Dickens, an Elder Brother of Trinity House, in the Chair. Introducing the subject the Chairman said that the Institute, through its Journal, the discussions it had promoted on previous occasions, and through the working party set up in 1970, had taken a significant part in forming opinion on the issues involved. In particular perhaps it had ventilated the suggestions that collision avoidance might better be based on positive manœuvring instructions rather than by simply apportioning responsibility. The long-term influence of these suggestions may well be considerable even though they might not in the event be reflected in the Rules now being proposed.

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 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!

Modern marine navigation is experiencing a more drastic change than ever before; automated systems are being introduced extensively in various parts of ships at various levels, inertial navigation systems are on the verge of introduction, the Navy Navigation Satellite system is now open for civilian use, and parallel with these developments modern data processing systems armed with electronic computers are being used at sea. In the processing of data, the application of modern statistical methods such as Kalman filtering should be noted.

At the tripartite conference held in Eastbourne in May 1964 by this Institute, the French Institute of Navigation and the Deutsche Gesellshaft fur Ortung und Navigation, it was agreed to set up a representative working group to study the environment and its influence on the navigation systems to be chosen for supersonic transport aircraft, and to clarify the governing parameters. The early work of the group was necessarily hampered and delayed by a lack of reliable data on the probable performance of S.S.T. aircraft and on their manoeuvring capabilities and limitations. Flight trials with Concorde may suggest some modification of figures given in this paper.

The group has now completed its work and a report will be published by the Deutsche Gesellshaft für Ortung und Navigation. In addition to the two sections on meteorological factors and air traffic control, which appear to be of more general interest to readers and are included in an abridged form in this issue of the Journal, the complete report also covers the probable performance characteristics of S.S.T. aircraft and a review of available navigation systems. The temperature frequencies discussed in section 4 are illustrated in a paper by Wehry published in July 1968 (Journal, 21, 277) and will be reproduced in the final report. The Chairman of the group was Dr. Karl Karwath.

When geophysical measurements are made from the air, it is important to know the position of the aircraft. The position at any time is usually known from a combination of position-fixing and dead-reckoning systems. In-flight optimization of this combination is a well-studied subject. When post-flight track plotting is required for geophysical survey, use can be made of both the initial and terminal position fixes to correct the dead-reckoning track and hence improve on the in-flight version. This technique is applied to compute the track of aircraft conducting ice thickness measurements in the Antarctic, and the effect of certain errors is evaluated. The algebraic results are equally applicable in parts of the world where better navigational aids are available. A relation is derived between the track plotting errors and die errors in the geophysical measurement such that the precision of one is not degraded by errors in the other.

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.

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.

Two of the proposed airborne collision-avoidance devices at present under discussion are the A.T.A. time-frequency system and a later proposal termed SECANT. The present paper attempts to discuss the geometry of the escape manœuvres associated with the use of one or other of these devices; the electronic problems involved in these ingenious but intricate devices will here be largely ignored, and discussion will be confined to the problems facing two conventional aircraft in an encounter at an appreciable altitude.

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.

Increasing traffic movements, size of aircraft and congestion of large buildings around modern civil airports, particularly those involved in major international operations, together with the predicted operation of STOL and VTOL types of aircraft, have led to an intensive review of the future needs for new approach and landing aids.

This paper was presented at an Institute meeting held in London on 15 December 1971, with Mr. H. E. Smith, Chairman of the Technical Committee, in the Chair. Mr. Wood, who is the United Kingdom member of the I.C.A.O. All Weather Operations Panel, reviews the whole situation broadly, with emphasis on operational requirements, present and future possibilities of the v.h.f./u.h.f. ILS guidance system and the effort, both national and international, to establish a new approach and landing guidance system which will satisfy future requirements.

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.

‘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.’

A symposium on The Application of Computers to Ship Operations was held at the Department of Navigation, Liverpool Polytechnic, on 1, 2 and 3 March 1971.

The symposium was introduced by the Head of the Department, Captain F. L. Main, who briefly reviewed the revolution in world shipping over the past twenty years involving great increases in tonnage, speed of vessels and traffic congestion, accompanied by a progressive reduction in manning scales. This had been made possible by automation and one of its logical consequences was the use of computers both at sea and in port administration. The aim of the symposium was to explore the potential of the digital computer in these fields, to define its possible limitations and to emphasize the need of adequate training for the personnel involved.

Of the nine papers presented, four more directly concerned with the application of computers to navigational systems are printed below. Other papers dealt with the application of computers to cargo handling, ships' accountancy and port administration with particular reference to the recent experience of the Mersey Docks and Harbour Board. Captain Holder and Captain Jones are both in the Marine Operations Research Unit at the Liverpool Polytechnic.