This paper discusses the necessity and feasibility of the application of Pulse Doppler Radar in vts through analysing the limitations of the non-coherent, single frequency, radar and the advantages of PD radar.

The loss of Admiral Sir Clowdisley Shovel with several ships on the Bishop and Clerks on 23 October 1707, and the subsequent attribution of the disaster by Captain Sir William Jumper of the Lenox, 70 guns, to defective compasses, led to the compiling of reports on these instruments by the Commissioners at Chatham and Portsmouth, by order of the Navy Board. Captain George St. Lo, the Commissioner at Chatham, was at this time about fifty years of age. We first hear of him being appointed a Lieutenant of the Phoenix, 42, in 1678; he was made Post into the Dartmouth, 30, in 1682. With the three years qualifying service necessary before he obtained his first commission he must have had fourteen years almost continuously at sea before his career was cut short by his being severely wounded and taken prisoner when he had to surrender the sorely battered Portsmouth, 46, to superior French force in 1689. While a prisoner of war he took the opportunity to study the dockyard methods of his captors and this, with his reputation for steadfast opposition to all corruption, made him particularly suited to fill the post of commissioner in a dockyard. In 1707 he had already been five years at Chatham, following eight in Plymouth dockyard.

The proposal by A. J. Wright (this Journal, vol. 34, no. 1, p. 142) that banded contour charts should be introduced, appears attractive at first sight. It appears to provide immediately recognizable indication of safe areas for the navigation of those ships whose draught is within certain limits. However, I feel that the system as proposed suffers from some major weaknesses

Allowance for height of tide. Tidal ranges of several metres are by no means uncommon. Failure to make proper allowance for this could result in a wrong assessment by the user of where navigationally safe water lies. Such tidal ranges frequently occur in areas of high-density traffic. Here, the pressures on the mariner are such that the temptation to ‘eye-ball the navigation’ is greatest – yet it is in such areas that positional accuracy based on sound chartwork procedures is vital.

Gyro magnetic compasses are subject to a large number of errors, some of which may be eliminated, or at least greatly reduced, by careful design on the part of the instrument manufacturer and an intelligent operating drill on the part of the user. Table I shows errors under five basic headings, and allots to each error a symbol classifying it as:

(a) The responsibility of the instrument manufacturer (I)

(b) The responsibility of the aircraft manufacturer or its operator (A)

(c) Inadequate knowledge of the geomagnetic structure of the Earth's field (K)

Some sources of error in Table I are marked with an asterisk. It is these which the designers of the compass system described have endeavoured to eliminate.

When the maritime history of the eighteenth century is under discussion it is usual to stress the limitations imposed by the inability of navigators to determine their longitude. It is generally assumed that since the advent of the Davis Quadrant or back-staff the latitude could be observed with considerable accuracy, and that with the compass in a wooden hull and with the more accurate graduation of the log-line as shown by Norwood, the dead reckoning should, over short periods of time, be reasonably reliable.

This paper, which was presented at the Institute Conference on navigation equipment and training standards held in Cardiff on 2–3 April, reviews the recent creation of international safety standards for shipborne electronic navigational aids and the new institutional framework in which these are being generated at IMO, IEC and ISO. It suggests that these safety standards, where they exist, are very similar to those needed by shipowners for efficiency of shipoperation.

The paper which follows, by Moore and Page, was also presented at the Conference, an account of which appears in the Record.

The design of an almanac is a highly technical matter in which principles may have to yield to practical detail. In order that the proposals shall be fully appreciated and fairly discussed the basic principles that have led to the present proposals, and their practical alternatives, will be indicated as briefly and as objectively as possible.

In the Nautical Almanac Office we have much experience in the presentation of astronomical and numerical data; but we are not navigators and we have little experience of the practical use of the Abridged Nautical Almanac. While all criticisms will be welcomed, those relating to practical requirements will therefore be particularly valuable.

The purpose of this paper is to look at the nature of the advances being made in inertial navigation and in navigation displays. In avionics as a whole the advance from one generation of equipment to another can take different forms; sometimes, notably in flight control and instrumentation, the potential of new technologies is exploited almost immediately to provide more advanced operational facilities and systems become more complex. Alternatively, as in the application of solid state electronics to produce equipment for general aviation, the technology is exploited to reduce weight, volume and costs. Inertial navigation exhibits both trends but to a comparatively small degree; the basic system requirement is simple to define and has changed very little, one of the reasons being the particularly demanding nature of the technology and the very long development time scales involved.

In this paper, which was presented to an Ordinary Meeting of the Institute held in London on 22 November 1978, Captain Woodfield, who was for nineteen years master of Royal Research Ships in support of British Antarctic Survey operations, discusses some of the problems of navigating in this ill-charted and ice-ridden area. The presentation was made jointly with Lieutenant Commander P. Le Pla, formerly Navigating Officer of the Ice Patrol Ship HMS Protector whose paper on Antarctic navigation was published in Vol. 31 of the Journal. The President was in the chair.

A Joint Navigation Satellite Committee has been formed to determine the potential for a common satellite system to meet the needs of various agencies. As a potential aid to air traffic, satellites would appear to be most effectively used in cooperation with ground stations at which measurement and computation would be made. Possible user benefits include more effective communications, more reliable and possibly less expensive airborne navigation equipment, reduced diversions and delays, obstacle avoidance capability, more effective emergency warnings, and reduction of communication traffic. For the provider States benefits may include more reliable communications, reduction in number of control centres, improved data collection and distribution capability, reduction in number of facilities, and improved search and rescue capability. A systematic approach to long-range goals is indicated.

The first point to note about the North Atlantic air traffic system is the diurnal pattern of flow. This is strongly tidal, with westbound flow predominant during daylight hours and eastbound flow overnight. There is some traffic which flows against the main stream, particularly during the day, but the strong tendency for one-way traffic results from the difference in local times on opposite sides of the ocean, together with the transit times of flight at current speeds. This means that the general pattern will probably persist, unless and until aircraft speeds change radically.

The introduction of the Mark 10 Decca promised certain advantages over existing types and it was therefore deemed expedient to examine the potentialities of the equipment, its operational accuracy and general suitability for airline operation. The Ministry of Transport and Civil Aviation in conjunction with British European Airways were subsequently involved in two series of tests which began in early 1957 and continued into 1958. These tests were designed to determine the operational suitability of the Mark 10 Decca receiver and, in addition, provide a direct comparison between the performance of Mark 10 and Mark 7 equipment. All the flights were made, by day and night, on B.E.A. routes within the cover of the English chain. Ample opportunity was afforded to study the equipment under typical service conditions.

Mobile satellite communications and navigation are, historically and technically, intertwined. This paper offers a historical perspective on this interrelationship to see if the past provides some guidance to the future.

H.M.S. Challenger is one of Her Majesty's surveying vessels. She is a ship of 1140 tons and carries a complement of 96 officers and men. Built in 1931, she is named after her illustrious predecessor in which the wellknown world oceanographic cruise was made in the years 1872–6. This expedition brought back a great wealth of chemical and physical data, and a huge collection of plants and animals from the oceans. These were checked and analysed and eventually, under the guidance of Sir John Murray, who had been a scientist on board, the results were published in fifty folio volumes known as the Challenger Reports. These reports still form, the starting point for the study of the oceans and marine life.

In the next decade there will be an increasing demand for more accurate self-contained navigation systems due to more stringent air traffic control requirements, particularly with the introduction of the supersonic transport. Although inertial systems have been fairly widely used in military aircraft and missiles, the only self-contained systems in service in civil aircraft are dead reckoning systems based on measuring the aircraft's velocity and heading and drift angle. A big improvement has been effected in the measurement of velocity and drift angle by the introduction of doppler radar. The accuracy achievable with doppler is not matched by the accuracy of existing heading reference systems and the overall accuracy is, at present, inadequate for future requirements.

An inertial navigation system is a possible alternative but its cost will be two to three times that of a doppler heading reference system.

The annual total losses of trading ships as a result of collision and wreck were considered in a previous paper for the purposes of comparing the safety records of different flag groups. Losses up to the year 1979 were included in the tables. In order to assess whether there has been an improvement, the losses for the 5-year period 1980–4 will now be considered and compared with losses in previous years.

This paper was presented at a seminar entitled a European Concerted Approach to Vessel Traffic Services for Safe Navigation – EEC Project COST-301, sponsored jointly by the Institute's Netherlands branch and the Royal Institute of Engineers, Delft University of Technology and the Netherlands Directorate General for Shipping and Maritime Affairs held in Delft on 20 January 1986. It was published under the auspices of the European Environmental Bureau, an independent coalition body of leading environmental organizations in all the European Economic Community countries (with a total membership of over 10 million). The paper, of which the following is a condensed version, seeks to comment on the implications for environmental protection of the various COST-301 research programmes, and to assess the contribution which the findings resulting from them may make to future European coastal state policy and international measures.

Aline De Bièvre is with the European Environmental Bureau and John Kemp is Professor Emeritus at the City of London Polytechnic.

From a weather forecasting viewpoint the situation of the sailing yacht at sea is unique. The yacht is small and entirely dependent on one meteorological element, wind, for its motive power. It is a device where an increase in that power increases the safety factor of speed by a very small margin while at the same time it increases the danger factor to a much larger degree. This is mainly because the increase in wind speed is accompanied by wave building and the latter increases with wind speed, time and, very dangerously, with approach to the shallow water that must often be traversed before safety is gained. It is not only wind speed that puts yachts in danger, but the combination of wind speed and attendant seaway. However seaway is not an element predicted in weather forecasts; it is a branch of seamanship left entirely to the skipper on the spot.