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.

Reference to a chart of the Thames Estuary will show that the dominant feature of the submarine morphology is the series of elongated banks, of which the Barrow, Sunk and Long Sand are the most important. Between these banks, and with the same north-east to south-west trend, are the navigable channels of the Swin, Barrow and Black Deep (Fig. 1).

The alignment of the channels suggests that they originated as a result of tidal-stream scour of a fairly uniform sheet of fine silt and sand. In each tidal period, streams enter the estuary from the north and flow on the flood in a south-westerly direction parallel to the Essex coast. After about six hours they slacken, turn and flow out of the estuary in the reverse direction. This continuous flood and ebb stream action, with a maximum velocity varying from 2·3 to 2·9 knots depending on whether the tide is neap or spring, has apparently scoured out channels to depths which exceed 10 fathoms in places. If the channels largely arose in this way, the banks represent the modified remnants of the initial surface. These banks are constantly being extended seaward as more riverine silt is emptied into the estuary by the Thames, Medway and the rivers of Essex. The distal end of Long Sand alone has grown almost ½ mile in the past 100 years (see Figs. 1 and 4).

An application of the model to manoeuvre ships based on the range to domain over range rate (RDRR) concept is described. A simulation of a training simulator has been set up on which the target ships manoeuvre by the RDRR model in response to mariner controlled ships. Results of experiments show that the RDRR model manoeuvres targets realistically. The applications are reduced instructor work load and increased simulator reality. The method has the potential for development to manoeuvre ships at sea.

B. A. Colley is now with Plessey Marine, R. G. Curtis is with the Department of Trade and Industry and C. T. Stockel is at Plymouth Polytechnic.

Although meteorology probably has a greater influence on marine and air navigation than any other individual science, many users are not fully aware of the problems of present-day forecasting, nor do they make full use of the services available. This paper is intended to give some idea of the value of observers' reports, the importance of communications, and the problems of present-day forecasting. In particular, attention is drawn to the rapid increase in upper air soundings and the interdependence of surface and upper air observations in predicting the elements for all marine and aeronautical services. Arising from the application of upper air data to surface forecasting, the paper emphasizes the value of applying comprehensive analyses and of marine forecasts prepared by weather centrals ashore; in areas where facilities are not available to the marine user, however, knowledge and experience of single-observer forecasting are still needed.

Anthropologists tell us that over 500000000 years ago the seas swarmed with some type of marine life and that during the Devonian period of 350 0000 000 years ago we could find the first species of monk fish that is now in high demand on the fish market place and sought after in strange hostile waters by European fishermen. The sharks were introduced to the planet at about this time and until this day have had the reputation of being the ocean's most voracious predators.

The total loss statistics for 1979, published in the Casualty Returns of Lloyd's Register of Shipping, provide further evidence of the increasing disparity between the safety records of vessels operating under different flags. Statistics of total losses are likely to be almost completely accurate, especially for ships of over 1000 tons gross, and can be used as the most reliable indication of trends in serious marine casualties. This review of recent total losses will be restricted to trading ships of over 1000 g.r.t.

The title, the gift of Frank George, derives from The Troublesome Voyage of Captain Edward Fenton, E. G. R. Taylor's masterly edition of narratives relating to one of the less successful of Elizabethan adventures. Fenton's voyage of 1582, to China and Cathay, was a total failure. But the tale endures.

Captain Scott went to the pole over the Ross Barrier, up the Beardmore Glacier (Fig. 1) which is about 100 miles long, and then on to the south pole, coming out by the same route. The great Norwegian explorer Amundsen went in from the other side over the shelf, up one of the glaciers and on to the pole. Admiral Byrd flew in and out again in 1929. Apart from these expeditions very little has been done in Antarctica and nearly all of it, apart from the fringe, is untouched.

The collision avoidance of a pair of uniformly moving bodies is considered in three dimensions. The relative motion of the bodies yields an expression relating the time to closest approach, the minimum range, the current range and its rate of change, other variables being unobservable. A Boolean relation is then proposed that is satisfied whenever the minimum range and time to closest approach simultaneously fall below given thresholds. The relation is further studied, in particular with regard to the issue of false and premature alarms. An airborne collision avoidance system is a possible application.

Inertial navigation systems have for many years been mechanised as a cluster of gyros and accelerometers mounted in a servo-controlled gimbal system which isolates the cluster from the motion of the carrying vehicle. Until the spectacular advance in computer technology over the last decade no other mechanization was really feasible, but serious consideration is now being given to strapped-down systems. This paper compares the two mechanizations, outlines some of the advantages of strapped-down systems, and considers some of the contenders for rate-sensing in such systems.

This paper, by the Assistant Chief Electro-dynamic Engineer of the British Aircraft Corporation, was originally presented at the Annual General Technical Meeting of the Guild of Air Pilots and Navigators in September 1976.

This paper discusses a programme being carried out jointly by the British Aircraft Corporation and Hawker Siddeley Aviation into the design of flight decks for civil transport aircraft scheduled to enter service in the 1980s. The flight decks of today have evolved as a result of experience gained since manned flight began; it would be foolhardy to ignore this background and in applying new technology care must be exercised in preserving, as far as possible, conventions and practices which have long been established.

Navsat is a civil satellite-navigation system which was presented by the European Space Agency. It is still at the system definition phase as distinct from the pre-operational stage, but since the original presentation it has been the subject of studies which have included analysis and synthesis of the main parameters.

The underlying principles of the concept as initially described by Rosetti remain unchanged but sufficient progress has now been made to predict the capability of the system in satisfying a number of objectives in the civil fields of navigation, position fixing and survey.

Weather routeing of ships has taken roughly three chronological steps. Originally, seasonal climatological weather charts, bearing little resemblance to actual conditions, gave standard routes. This somewhat passive activity was superseded by the measurement and subsequent forecasting of atmospheric and oceanographic data. Weather routeing became more complex as telex and radio facsimile routeing messages could be regularly transmitted to the ship. This form of routeing is still operational; masters can obtain radio facsimile sea and pressure charts and perform their own routeing, or employ specialist organizations which transmit the relevant routeing advice.

Until 1950 the largest ships of the merchant fleet and the major warships had the same draught, about 12 m. Hydrographic offices concentrated their efforts on those areas likely to contain hazards to such vessels, that is to say the areas extending from the shallow waters to the 20 m contour line. The maximum draught of warships has been stable whereas the draught of merchant vessels increased considerably up to 30 m in recent years. A VLCC may risk grounding after having crossed the 30 m line or even the 40 m line. Nowadays, the part of the continental shelf which is best known is the part in which the largest vessels are unable to operate.

The paper by Captain Cotter on Edward Johnson and the early history of ship's magnetism published in the September Journal sets the scene for the birth, in 1842, of the Compass Department of the Admiralty. Commander Fanning, a former Deputy Director of the Admiralty Compass Observatory, as it later became, here relates its subsequent history. The paper was presented to an Ordinary Meeting of the Institute held in London on 19 December 1979 with Dr J. F. Kemp in the Chair.

This paper traces the fortunes and development of a small department, one of the oldest Admiralty technical departments, from its early struggles with the magnetic compass, through many vicissitudes, economies, defence cuts, wars, intrigues, take-overs and even human frailties. We shall see how technical advances have led to ever more demanding requirements and I hope to show how, by meeting each new challenge, there has emerged the lively, forward-looking organization that today is still responsible for ‘everything that matters’ in navigation equipment, as it was at its inception in 1842.

It is over 10 years since this ill-fated Fastnet Race claimed the lives of fifteen yachtsmen and the total loss of five yachts. A total of twenty-four crews abandoned their yachts and in all, 136 people were saved by being winched into helicopters and taken on board merchant and naval ships as well as other yachts. Some eighteen yachts needed the assistance of lifeboats because they had lost their rudders.

As a result of the loss of the French passenger liner Antilles after grounding on an uncharted rock in the Grenadine Islands in the West Indies, on 8 January 1971, the owners of the ship filed a petition for limitation of or exoneration from liability in the United States District Court for the Southern District of New York. A number of claimants against the owners, chiefly passengers in the ship at the time of loss, entered the limitation proceedings and moved the New York Court to transfer the case to the District of Puerto Rico. After the case had been so transferred, several claimants filed direct action suits against the owners and their insurers; these suits were stayed pending the outcome of the limitation proceedings.