This account of a recent simulator experiment at the City of London Polytechnic on encounter reaction times at sea will also be published as an internal National Maritime Institute report.

Two ships are said to have an encounter when they pass within a certain distance of one another, say half a mile. The encounter rate bears a relation to the collision rate in a given area of sea and consequently it is desirable to minimize the encounter rate. The effect of routing in sea areas with a high density of shipping has been to reduce the total number of encounters but to increase the number of overtakings. Thus the introduction of a routing scheme greatly increases the proportion of overtaking encounters in the main lanes. For example, the routing scheme in the Dover Strait (with I per cent of through rogues) has increased the proportion of potential overtaking encounters from 27 to 95 per cent.

Rule 10 of the new Collision Regulations deals with the conduct of vessels in Imco adopted traffic separation schemes. In this paper, which was presented at a meeting of the Institute in London on 20 April 1977 with Commander R. B. Richardson, R.N. (ret.) in the Chair, Commander Paton, Hydrographic Adviser to the Department of Trade, discusses the traffic situation in the English Channel and Southern North Sea in the light of this Rule with particular emphasis on encounter situations at route junctions and the problems of crossing traffic.

As on previous occasions this Institute meeting was held to discuss different aspects of the Admiralty Chart as described by the Hydrographer of the Navy and his assistants. Earlier meetings had led to the formation of a Chart Users’ Panel, drawn largely from the Merchant Navy, and members of the panel were present on this occasion. The meeting described below, the fifth of this series, was held in London on 15 March 1978 with the Hydrographer, Rear Admiral D. W. Haslam, O.B.E., in the Chair.

Concorde has now been operating on routes both east and west of Europe for over a year and has become an accepted part of the international air transport scene. This paper examines these operations in the light of experience, with emphasis on navigation and operational planning. Of special interest is the way in which the triple inertial navigation system on the aircraft has been used to ensure accurate and reliable track keeping on complex routes. Concorde routes are constrained as much by political as by operational considerations and long term planning was necessary to obtain route profiles which gave the shortest distances and optimum acceleration/deceleration points.

A recently completed preliminary long-term study of air traffic control systems in Europe1 suggests that traffic density is likely at least to double before the end of the century. The study also concludes that, apart from the problem of airport capacity, which was not considered, the existing ATC systems in Europe will not be able to cope with such an increase in traffic. There is therefore a need to consider methods of increasing the capacity of the European ATC system or providing a new system and, in view of the time required to effect significant changes to such systems, the task is becoming urgent.

Assumingthere is to be no deterioration insafety, theprime requirements for any proposed changes are economy and flexibility. Apart from its obvious intrinsic value, economy is necessary because there is an increasing trend towards recovering the total cost of ATC from the user. Higher charges are therefore likely to stultify the growth in air transport and an underlying assumption is that this would be undesirable. Flexibility is required because traffic forecasts so far into the future are likely to be in error and the system design must allow for this because there is likely to be some economic penalty if the forecast proves to be either too high or too low.

The new-look Admiralty chart is no longer novel; the first metric chart was in fact published ten years ago and there are now over 700 metric charts in our standard series, representing over 20 per cent of the total currently in publication. Their impact is disproportionate to their numbers however, since many metric charts figure among those most used, and there is now about a one-in-three chance that any Admiralty chart being employed is a metric one. Popular charts tend to be much-corrected charts and in fact a third of the new editions and a third of the paste-on blocks that we issued last year were to metric charts. Moreover, we now publish a hundred new charts a year and hope that this figure will be maintained.

When radar was first introduced to the merchant fleets of the world, many people felt that a practical solution to the collision avoidance problem had been found. However, a review of worldwide collision statistics of the past 20 years indicates that, in spite of the expanded use of radar, the over-all collision rate remains alarmingly high. Because of radar's less than perfect record for preventing ship collisions, development of various types of collision avoidance systems has taken place. The implied promise in this development is that the computer-aided radar will provide a lasting answer to the collision avoidance problem.

The Royal Navy employs naval architects to design its ships and a number of establishments exist to advise the Director General, Ships, on various specialist subjects connected with warship design. The Admiralty Experiment Works at Haslar, near Gosport, (AEW) which was founded in 1872 by the father of modern naval architecture hydrodynamics, William Froude, advises the Director General on all aspects connected with hydrodynamics. Froude's activities and those of his son R. E. Froude, who succeeded him as Superintendent, covered a wide field but the study of resistance and propulsion in calm water occupied most of their energies. William Froude was indeed responsible for the first real understanding of the mechanism of ship resistance and was able to demonstrate that the resistance of a ship could be accurately predicted from model experiment results.

Collision avoidance radars formed the subject of an Institute meeting held in London in October 1975 (this Journal, 29, 232). The subject has been given a sharper edge by President Carter's message to the U.S. Congress on 18 March 1977 which proposed, amongst other regulations, that all oil tankers over 20,000 dead weight tons which call at American ports, should carry ‘back-up radar systems including collision avoidance equipment’. The issues are highly contentious and the Institute has published a great deal on either side as the debate has grown. The papers which follow describe a research project carried out at the Department of Maritime Studies at Liverpool Polytechnic for Shell International Marine. They were presented at an Institute meeting held at Shell Centre on 17 November 1977 with Captain Ralph Maybourn in the Chair.

J. A. Butt, Head of the Communications and Navigation Department at Shell International Marine, first looks at the investigation from the shipowner's point of view. Captain K. D. Jones, an Extra Master, and Director of Research in Maritime Studies at Liverpool Polytechnic, then discusses the scope of the project and describes the range of experience undertaken. C. G. Rowsell, seconded from Shell Tankers U.K. Fleet to the Operational Services Department, Shell International Marine, finally, gives a detailed account of the investigation and its results. The discussion was opened by Captain A. Wepster, Director, Navigation Research Centre, Netherlands Maritime Institute, and Captain F. J. Wylie, provides a written commentary.

In the January 1977 issue of this Journal an article ‘The new buoyage system’ by the Hydrographer of the Navy was one of the many steps taken during the past two years to explain to chart users what IALA System A is all about. Newspapers, magazines, schools of navigation, yachting clubs and commercial printers have all helped to spread the gospel. There are on the market a variety of booklets, wall charts, plastic models, cassette teaching aids and films. The new symbols used to portray the details on the charts can be found in Navigation Publication NP735, available from Admiralty chart agents.

A model is developed for conflicts between ships at route intersections. Quantitative measures are presented for conflict intensity and duration and for intersection capacity. These measures are shown to be related to the geometry of the intersection and to the statistics of the incident flows. An optimum intersection angle is found.

This note on the distribution pattern of some Omega observations is based on a study of the phase differences observed at the Faculty of Fisheries at Hokkaido University (41° 48·4′N., 140° 43·3′E.). The A—D pair was investigated continuously, at half-hourly intervals, from i February 1974 to 31 January 1976, the A—C and C—D pairs from 1 January 1975 t o 31 December 197J and the A—H and D—H pairs from 1 January 1976 to 31 December 1976.

It is seven years since the Hydrographic Department published charts for yachtsmen only. Our policy since then, dictated by the pressure on our resources, has been to suit Admiralty charts and publications as far as possible to the needs of all sorts of user; but we hope that we will be able in a few years to re-enter the field of yachtsmen's publications. It is interesting to see how other hydrographic offices have tackled the problem. In April 1977 members of the International Hydrographic Organization discussed special charts for small craft use; a summary of the prepared statements appeared in the International Hydrographic Bulletin in September. The charts concerned are mainly large-scale inshore ones rather than passage charts.

The number of ships in the world's fleet increases each year, and at an increasing rate. In 1975, 2530 new steam and motor ships went to sea, compared with 1006 in 1965 and 134 in 1955. The tonnage increase is even more startling. Lloyd's Register of Shipping quotes the 1975 total world tonnage of vessels of 100 gross tons and upwards as 342,162,000 tons, an increase of about 10 per cent over the previous year and double the figure recorded in 1966. These larger ships are less manoeuvrable and more difficult to stop. They are also restricted in where they can go in safety and thus constitute a considerable collision and stranding hazard. The growth is most apparent in tankers, ore carriers and OBOs (oil, bulk or ore carriers). The French Shell tanker Batilus (550,000 tons) quoted as having a 72 ft draught is operating close to home and recently discharged 170,000 tons of crude oil at le Havre before continuing her passage to Rotterdam. In January 1977 the Chairman of Globtik Tankers ordered three nuclear powered oil tankers for delivery in 1985, 1986 and 1987. Their size is quoted as 600,000 tons, and their speed as well over 20 knots. The Globtik Tokyo is already at sea—469,470 tons deadweight, 1243 feet long, 203 feet beam and 92 ft draught! She sails under the British flag, and trades between Japan and the Persian Gulf. The U.K. has now nine ships of over 140,000 tons gross (275,000 tons deadweight) out of a world total of 59 and the world total of ships over 100,000 tons gross was 479 at the last count.

The 1967 Conference of the International Hydrographic Organization (IHO) set up a six-nation Commission to obtain an agreed specification for a series of small-scale international charts, with a view to sharing production among a number of hydrographic offices on a regional basis. The intention was that any office could reprint any or all of the sheets, and make modifications for language or to obtain conformity with its own national series.

Studies have already been published on the probability of collision at sea, the effect of darkness and reduced visibility on the probability of collision, and on the distribution of collisions in particular areas. Only Minorsky and Comstock appear to have studied the extent of the resulting damage and sufficient data are not available for detailed analysis.

The establishment and operation of any traffic management system calls for a considerable outlay, so that an objective estimate of the extent of collision losses is often required. Such a cost/benefit survey was carried out by the Japan Transport Economics Research Centre on the assumption that a traffic management system can greatly reduce the incidence of collisions involving vessels of over 3000 g.r.t. Since half the aggregate loss is shown to relate to these large vessels (and considering their increasing capital value), an expenditure of ten billion yen or more (£20 million) over a period of ten years would appear to be cost effective if its primary purpose were to avert accidents to large vessels.

Commander R. A. G. Nesbitt, Superintendent of Notices to Mariners, described a number of proposed future changes in the style and format of Admiralty Notices to Mariners, illustrating his remarks with a series of Vugraph projections of the relevant pages.

Ample information is available on the growth-process of the International Regulations for Preventing Collisions at Sea 1972. However, after having been set to words little has been published in the Netherlands to assist the ‘men on the bridge’ in the practical use of these Rules of the Road. In the Netherlands—as elsewhere—seafarers have attended courses which dealt with the use and interpretation ol the revised Rules. Little is known of deliberations and consultations between national and international Institutions and consequently it must be feared that mariners have not been uniformly advised.

AN interesting account of the deliberations leading to the international acceptance of the new buoyage system (Iala Buoyage System ‘A’), the first phase of which came into effect last year and which was described by the Hydrographer of the Navy in the January 1977 issue of this Journal, formed the subject of one of the papers presented at the International Hydrographic Conference in Monaco in April. The author, Captain J. E. Bury, who is a senior Elder Brother of Trinity House, has for some years been Chairman of the Iala sub-committee which formulated the new system.