The need for measures to guide shipping in congested waters to reduce collision risk has received a very considerable amount of attention over the past few years. The Safety of Life at Sea Conference in 1960 recognized the danger of collision in congested areas and required ship owners to formulate ways whereby some measure of control of traffic could be introduced with a view to reducing collision risks. Shell Tankers accept this responsibility and are, therefore, anxious to make some contribution towards the solution of the problem.

Many valuable papers on the subject have been published in professional journals recently. Most of the authors have emphasized the difficulties in which Masters are placed when called to navigate their ships through heavy traffic in reduced visibility, and Calvert in his study of the collision-avoidance problem reached a first conclusion that whatever might be done to improve anti-collision manœuvring, there was an urgent need for regulation of traffic in areas of congestion.

The recent developments at the Gironde-estuary have aroused great interest and, particularly in ports where radar installations covering the approaches are in operation today, the question arises whether the adoption of some such scheme would be feasible and advantageous.

Considerable experience with shore—based radar assistance had been gained over the years, but so far information only has been supplied and never advice. It was reasoned that only the men on the spot—master and pilot on the bridge—can decide what is to be done; advice from the shore, given without proper knowledge of what goes on on board, has been looked upon as dangerous.

At a meeting of the Technical Committee of the Institute held on 9 January 1963 it was suggested that recent theoretical treatments of the collision problem could usefully be extended to include a discussion of the near-miss situation and the effect of observational errors. The basic mathematical relations for near-miss encounters have been set out in this Journal on several occasions, notably by Sadler and Morrell, and in graphical form by Wylie. The recent paper by Parker deals with the effects of both systematic and random errors of radar observations of relative range and bearing.

My previous discussion of the collision problem was presented in terms of the idealized situation where two ships are on an actual collision course, in which case the sight line is in the same direction as the relative velocity vector (the relative track). To extend the results to a near-miss situation, one has only to redefine the angle α (see p. 24s of ref. 3) as the angle through which the relative velocity vector rotates when one or both ships manœuvre. I have pointed this out on a previous occasion: ‘The two craft need not be on a collision course; this definition of α applies equally well to a “miss” situation provided that no reference is made to the sight line.

The aim of the Duke of Edinburgh's Lectures is ‘to extend the horizons of navigational interest’. I have been able to interpret this literally, for if you extend these horizons far enough, what do you arrive at but the subject of this lecture, the shape of the Earth? It is a subject which has been revolutionized in the past five years by analysis of the orbits of artificial satellites: the two years from 1958 to 1960 saw more progress than the previous 200 years, and since 1960 the pace of progress has shown no sign of slackening.

Through the interest of Mr. S. M. Burton, I have recently seen for the first time the comprehensive proposals for ‘astrofix tables’, compiled by Gilbert F. Cunningham, B.A., Ph.D. (then Staff Navigator, R.A.F.V.R.) and submitted to the Empire Air Navigation School at Shawbury in May 1945. Dr. Cunningham, a member of the Institute since 1948, is no longer actively engaged in the field of navigation, and he has therefore agreed to allow me to describe in the Journal those features of these proposals that are both new and interesting

The problem of introducing any system of routing at sea is how to achieve effective control at an international level without drawing up hard and fast rules or imposing restrictions that might well, in view of the impossibility of policing vast ocean areas, prove nugatory. We hold that it is better to replace the rigidity of the prescribed route (the only relevant example, and that inconclusive, is the North Atlantic Track Agreement) by the much more fluid notion of the ‘recommended and protected route’, for which we have adopted the name ‘naviroutes’.

The consideration of the effect of observational errors on the problem of manoeuvring ships at sea has, surprisingly enough, only recently become the object of attention by contributors to this Journal, though the basic background was provided many years ago by Sadler. The discussion at the Technical Committee of the Institute emphasized the importance of a statistical treatment of the problem and this led first to a brief note by myself in which systematic and random errors in range and bearing were discussed, and later to a full survey by Hollingdale in which it was shown that the total time to the instant of closest approach should be divided between observing time and manoeuvring time. An article by Proctor, though rather out of the main stream of the ideas pursued by the above mentioned contributors, breaks new ground in the sense that comparisons are made between different types of manœuvre on a probabilistic basis.

The problems posed by the ever increasing size of tankers are not those of ‘bigness’ alone, or even at all. Southampton has been accustomed to the world's largest ships since the turn of the century; such as instanced by the Aquitania of 43,000 tons gross of pre-1914, the Majestic, 53,000, Normandie, 73,000 and Queen Mary of 83,000 between the wars, and since, the Queen Elizabeth, 85,000 and more recently France, the longest ship in the world, at 1043 ft. All these ships, however, are quadruple screwed, and for that matter there is not a cargo or passenger ship of more than 14,000 tons gross coming to the port which is not at least twin-screw. It had always been supposed that there was a limit to the size of ship which could be safely manœuvred with a single screw in confined spaces. The advent of the single-screw mammoth tanker, turbine engined, has put a new angle on this problem, but pilots generally are not at all sure that this is in the best interests of safety.

In the discussion which followed the Institute's proposal on routing, Captain Oudet proposed that the collision problem should be investigated in other areas where the risk was known to be high. This paper discusses the origin of NEMEDRI routes and the collision problem on specific NEMEDRI routes in the North Sea.

The origin of NEMEDRI (Northern European and Mediterranean Routing Instructions) routes is a matter of history and necessity, some understanding of which is necessary in any analysis of present problems, NEMEDRI routes are those swept routes through declared danger areas due to mining in World War II in North European waters, the Mediterranean and Black Sea. These routes take their name from the NEMEDRI publication issued to mariners giving the relevant hydrographic information for these particular areas. The swept routes and declared danger areas in many other areas, such as the remote Kerguelen Islands, Tonga or off Korea, have no such special publication and are notified in Notices to Mariners. The present navigational significance of the NEMEDRI routes is that they carry a very substantial amount of the world seaborne trade.

Much attention has been given in the past to the need for aligning navigational systems in the horizontal and the vertical planes. The alignment problem has, in the main, been that of aligning inertial navigators or gyro platforms, but the problem also affects all navigation and attack equipment.

In the past insufficient consideration has been given to the alignment of navigational sub-systems (including missile guidance systems) to the aircraft on which they are carried. The Experimental Navigation Division of the Aeroplane and Armament Experimental Establishment is investigating current methods of aligning equipments to aircraft with a view to improving them and recommending a future policy for the overall alignment of navigation and weapon systems, for service and civil aircraft.

The shortest route from the Great Lakes and St. Lawrence River to Europe passes through the Strait of Belle Isle. The alternative routes pass through the Cabot Strait and are between 100 and 400 miles longer according to the European port of destination. The Strait of Belle Isle is, however, normally closed to navigation from the end of December until the middle of July due to the presence of pack ice and icebergs.

Air reconnaissance patrols flown over the Labrador, Belle Isle and East Newfoundland areas seem to indicate that, for the past few years at least, ice conditions have not been so severe as to hamper navigation throughout the normal period of closure. Consolidated ice is only present from the third week of January to mid-February and clears in mid-April to mid-May; only icebergs present a problem in May and June. It is hoped t o show that with proper air reconnaisance at the beginning and end of the ice season, navigation through the Strait could be extended to eight or nine months of the year, or even longer, instead of the present short season of only 5½ months.

The following discussion took place at a Technical Session of the Institute held in London on 24 May 1963, with the Chairman of the Technical Committee, Wing Commander E. W. Anderson in the Chair. Opening the discussion, the CHAIRMAN suggested that the problem might first be examined from the point of view of (a) a tactical solution and (b) a strategic solution.

It is not the purpose of this paper to enter too deeply into the controversy between heading reference systems (combined with a velocity sensor) and full inertial systems. Rather it is intended to indicate what may be achieved at the present time, and in the next few years, using a heading reference system combined with a velocity sensor such as doppler radar. In conclusion the performance, weight, size, cost and reliability of such systems will be compared with similar figures for a full inertial system in the hope of stimulating thought and discussion as to what is the correct choice of system as well as to what the user may be able to afford.

In the early part of the last decade the most widely used heading reference was the gyro-magnetic compass—a flux-valve being used to give good long-term heading accuracy whilst short-term variations are smoothed out by the integrating action of a' directional gyroscope. The directional gyroscope was in fact slaved to the magnetic reference. Accuracies of 1°·0 (r.m.s.) are typically achieved by such a system, although higher accuracies are sometimes claimed under certain specified conditions.

There are two approaches to the study of errors in astronomical observations at sea. One is to collect as much information as one can from practising navigators; the other, described here, is to carry out controlled experiments with the object of breaking down the various causes of error, a virtually impossible task if the first approach is adopted. In both cases a large mass of data must be carefully studied and analysed, and this is particularly important where one aims to resolve the errors into separate components (those due to dip uncertainties, horizon, body, degree of twilight, and sea state).

The Great Lakes of North America, four of which form the border-line between the United States and the Dominion of Canada, increase in size from east to west, Lake Ontario being the smallest but still 180 statute miles in length. Lake Erie is the shallowest, with an east to west extent of 236 statute miles. Lake Huron has a maximum length of 247 statute miles from south to north. Lake Michigan is the only one of the lakes entirely within the confines of the United States, extending 321 statute miles from north to south. The largest and deepest of the group is Lake Superior, where the principal sailing course from Sault Ste. Marie to Duluth is 383 statute miles.

The structural changes in shipping since the war and the trend towards super-tankers, large bulk carriers and fast freighters is unmistakable. Fast ships are expensive and it is natural that the large investment in these ships should be balanced by increasing the number of voyages and reducing the time spent in port. In this connection radar provides a welcome aid towards faster voyages, for even in foggy weather ships equipped with radar can reach their destinations earlier.

For some time there has been an interest in nautical circles in the effect of temperature-differences between air and sea on the dip of the horizon. In about 1900, from his observations on board K.K.S. Pola, Koss established a relationship between the dip and the temperature-difference between air and sea, and an attempt was made, without much success, to produce corrections based on this relationship. New observations seemed only to add new uncertainties. A recent comprehensive review of the subject draws the conclusion that for practical purposes it is impossible to calculate the dip from measured temperatures by means of theoretical or empirical formulas. Indeed it is not possible to calculate the dip from simple measurements of temperatures at a given point to within o′·1 or o′·2. Horizontal irregularities, especially of thermal stratification and of wave height, always cause deviations of the dip from its calculated value. Nevertheless it is sound practice to correct the mean dip for temperature differences between air and sea. An analysis of observations where there are large temperature-differences—i.e. cases where the correction becomes noticeable—shows that the dip is greater or smaller than normal if the air is, respectively, cooler or warmer than the water. Out of 179 observations made by the Institute of Geophysics at Hamburg University with temperature-differences between air and sea greater than 2°C, not a single observation did not obey this rule.

In this paper, which was presented in a fuller version at an Ordinary Meeting of the Institute held in London on 20 December 1963, Mr. Kurz of the United States Maritime Administration and Mr. Bentkowsky and Captain Quinn, both of the Sperry-Piedmont Company, describe a control console for ships which was developed by the Sperry-Piedmont Company under contract from the Maritime Administration. The console, which has its sea trials early this year, comprises five sub-consoles which cater for navigation aids, communications-radar, steering, position plot, and ship condition. The paper enumerates the advantages that might be expected from such an arrangement.

During 1960 the French civil and military authorities decided to coordinate their efforts and to step up the programme of research and practical tests on landing in poor visibility. They felt that they could best contribute to the development of air transport in this vital field by adding their own vigorous and intensive efforts to the considerable body of work already undertaken by other countries. Numerous automatic landings had already been made in the U.S.A., and the British Blind Landing Experimental Unit had made several thousand. Yet, in spite of the results obtained, many problems still remained unsolved and many questions unanswered. There was evidently still room for much more practical work and theoretical research.