This paper presents the preliminary study of a stratospheric segment within a satellite navigation system of present and future generation (GPS and Galileo) implemented by means of High Altitude and Very long Endurance (HAVE) platforms. The paper discusses a possible scenario in which the main features of the HAVE platform are exploited to define an innovative Aerial-Based Augmentation System (ABAS) for the provision of differential services. This particular local segment improves the provision of a differential navigation service. It is suited to the broadcasting of differential corrections in critical areas such as mountainous and sea regions where, to guarantee wide coverage, a large number of terrestrial reference stations would otherwise be required. The study includes a description of the proposed DGPS augmentation system, and a discussion of the system architecture and expected performance.

Collision avoidance (COLAV) is a prerequisite for the navigation safety of unmanned surface vehicles (USVs). Since USVs have to avoid obstacles clearly and timely, i.e. the COLAV should be agile, the COLAV algorithm should have low computation complexity and make efficient COLAV decisions. However, balancing between the computation complexity and the COLAV decision optimality is still intractable at present. This paper innovatively proposes a COLAV algorithm for USVs by combining the velocity obstacle method with the predictive model method, named the collision shielded model predictive control (CS-MPC) algorithm, such that the agility of USVs COLAV is improved. The runtime of the proposed COLAV algorithm is shortened by shielding the dangerous parts of the search space of the COLAV decisions, and the COLAV decision is efficient with the aid of the accurately predicted motion trajectory by the motion mathematical model of USVs. As such, the USV can safely navigate in complex water areas where multiple vessels and obstacles exist. A series of simulations on a yacht in different kinds of encounter situations were carried out to verify the effectiveness and the agility of the proposed CS-MPC COLAV algorithm.

There has recently been some discussion in the Journal1 as to the meaning of the word ‘dyoll’ when it appears in English ship inventories of the years 1410–12, which have been partially published, by Nicolas2 and Sir Alan Moore.3 Nicolas quotes from the Accounts and Inventories of John Starlyng, Clerk of the King's Ships to Henry IV, but he mistakenly dates these documents 1338, which date has been corrected by Moore to 1410–12.

Summary

Examples have been given of certain words which seem to be used correctly by navigators where there is any chance of ambiguity. It is suggested that, if these and other terms can be formally denned and agreed by the Institutes of Navigation, bad language will gradually die out and confusion in navigation terminology will be reduced to a minimum. A similar exercise might also be undertaken with regard to abbreviations.

It may be that the British Institute of Navigation working with other English-speaking Institutes of Navigation could make a start by defining certain words in the hope that they will gradually come to be used with a specific meaning. The alternative is a continuation of the present chaos whereby an official body such as the Airlines Electronics Engineering Committee can decide that ‘course’ and ‘track’ have the same meaning and therefore that a direction is a line.

This note is published with the kind permission of Mr. K. Fearnside, Technical Director of Smiths Aviation Division, but is not intended to represent Company views. Mr. M. W. Richey's advice and help is gratefully acknowledged.

In many critical areas today navigation is more concerned with maintaining the flow of traffic than with finding the way. In his Presidential Address, which was presented at the Annual General Meeting of the Institute in London on 14 October 1970, Mr. Stratton discusses some of the characteristics of sea and air traffic systems and how they interact with the costs and benefits to the community as a whole.

In my previous address I concentrated on the way in which new scientific principles have been applied to determining the basic quantities of position, course and speed as inputs to the navigation process and with some of the technological problems encountered. The science and technology of navigation, however, are but the means by which navigation fulfils an operational task which itself is directed at the safe and expeditious movement of passengers and goods or to some military ends. In this address I will concentrate on some of the current and future operational tasks for navigation on the sea and in the air in fulfilment of the commercial need to transport goods and passengers and of the personal use of the vehicle for transport and leisure.

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.

At the end of February 1971 an exploratory survey of marine traffic on the English side of the Dover Strait was organized and conducted by the National Physical Laboratory of the Department of Trade and Industry. The aim of this first short-term study was to examine possible methods for the long term, and the basic radar ship count was carried out by Decca Radar on behalf of the N.P.L. This trial took place over 72 hours between 12.00 hours on Friday, 26 February and 12.00 hours on Monday, 1 March 1971, all times G.M.T.; it showed that further flow data in other areas of the Strait would be of value and Decca Radar decided to gather additional limited data on traffic flow. The most urgent appeared to be at the narrowest part of the Strait between Cap Gris Nez and Folkestone where the Greek M.V. Niki sank off the Varne during the trial at 20.00 G.M.T. on Saturday, 27 February.

It is probable that Congress will require oceangoing ships in US ports to use Differential GPS (DGPS) and electronic charts once DGPS is available on all coasts of the US, which is currently scheduled for completion by the end of 1996. The type of electronic chart currently envisaged, the Electronic Chart Display and Information System (ECDIS) under development by the IMO & IHO, is unsuitable for those ports which are entered through long dredged channels – a category that includes Houston, Gramercy and New Orleans, the three ports which handled the most foreign tonnage in 1991. A different type of electronic chart has been in daily use in such channels, with microwave positioning, since 1984; the combination of DGPS with such a software package has been called an Electronic Navigation System (ENS) and differs from ECDIS in that the ENS is designed to supplement the published chart, not replace it. The paper suggests that the utility of ECDIS would be enhanced if its specifications were modified to allow the entry of the data files used by the ENS, thus giving ECDIS a similar capability for blind navigation in confined waters. Standardization of the current data format would also permit alternative versions of ENS to be developed.

The US Coast Guard has a project to provide a differential global positioning system service for harbour and harbour approach (HHA) areas of the coastal United States. The Great Lakes, Puerto Rico and most of Alaska and Hawaii will also be covered by the service. The Coast Guard's DGPS system will fulfil the 8–20 metre navigation accuracy requirement for HHA with an availability of up to 999 percent. The Coast Guard intends to provide this service to the general public and other government agencies, as well as use the system for its own missions. This capability is expected to enhance maritime safety in keeping with the National Transportation Policy by providing an all-weather radionavigation service to supplement existing radar and visual techniques, as well as a highly accurate position sensor for future electronic chart displays. This paper describes the Coast Guard's programme. Background and historical information on the development of pseudorange differential GPS is presented first, followed by a description of currently available technology. Various aspects of the Coast Guard's plan for implementing DGPS are then described, concluding with a rough project time line and a statement concerning Federal DGPS policy.

This paper deals with the facilities for landlall that can be provided by lighted aids to navigation. The relationship between the navigational errors of ships approaching from the open sea and the performance to be selected for a landfall light is worked out. The probabilities of a successful landfall in various circumstances are then analysed. Finally the limitations of light as the sole aid to navigation in the process of making a landfall are discussed. Rear Admiral van Hooff was for long head of the Netherlands Pilotage and Lighthouse Service; Ir. Sirks is technical director of the Netherlands Lighthouse Service.

The term marine pilot is applied to the man with local knowledge who acts as a guide to mariners in his own specific and limited district, but it is difficult to confine the work of a pilot to anything so specific. Over eight centuries Cinque Ports' pilots have conducted snipping from the Dungeness-Dover sector of the English Channel both into the Cinque Ports and into the ports of the Thames. They have also taken ships to the more northerly waters of the British Isles and were often asked to pilot ships along the European coast as far as the Baltic. They do this today and for the purposes of this paper they are pilots who work in a defined district but who are not necessarily confined to that district.

This paper was originally published in Vol. 34 of the Journal (p. 286). In its reprinted form, it has been reduced in length by Robin Payne. It is followed by comments from Stuart Quarrie.

Captain Illingworth's paper was read to an Ordinary Meeting of the Institute held at the Royal Geographical Society on 17 March 1950. Introducing the speaker, the chairman, Captain G. C. Saul, said that Captain Illingworth's name was familiar to anyone who had had any connection with ocean racing, and to most people who were interested in sailing. He was Commodore of the Royal Ocean Racing Club (RORC) and of the Royal Naval Sailing Association, and was a member of the Council of the Yacht Racing Association.

He had had many years' experience of long distance racing and had won his first championship in 1929. In 194; he had won the Sydney—Hobart race in Rani and in 1947 won the Fastnet and the Channel Race in Myth of Malham (Fig. 1). In 1948 he took part in the Bermuda race in Myth of Malham and then sailed back across the Atlantic to compete in the Santander and Belle He races. In the latter race he beat the whole ocean racing fleet boat for boat. In 1949 he again won the Fastnet Cup and also won the points championship over the whole season.

The International Maritime Consultative Organization (now IMO) carriage requirement for ARPA began to take effect in 1984 and became progressively mandatory worldwide; prior to this, for certain classes of vessels trading to the USA, a national requirement was introduced in 1982. These radar plotting aids perhaps constituted the first widespread use of computing power aboard merchant vessels. In implementation, even the early ARPAS were much more than the mere plotting aid which their name suggests. Sophisticated processing gave the navigator a system which offered significant assistance in scenario analysis, with the well known ability to display graphically the effect of a trial manoeuvre being the most active element of the system.

This paper examines the problem of those ship collisions which are associated with infringements of the International Regulations for Preventing Collisions at Sea. Experimental evidence indicates that there are classes of encounters which lead to indecision and uncertainty on the part of ship's officers. It is suggested that the identification of these classes of encounters is the first step towards eliminating the difficulties associated with them.

It is a well-known fact that humans are subject to circadian alterations caused by the action of sunlight. This strongly affects their behaviour and skill, making them change their level of alertness from high at daytime to low at night-time. Taking into account this biological feature, and considering that commercial shipping is one of the oldest round-the-clock activities, raises the question whether bridge watchkeepers can carry out their tasks on night shifts with the same level of alertness as on day shifts. Furthermore, night bridge watchkeeping has to be performed in darkness or very dim light to improve the visual capacity of lookouts. A sample of vessel collisions was analysed and it was find out that this kind of accident tends to be more frequent and more serious during the darkness period of the solar day.

Oceanus is a hardware and software platform designed and developed to provide useful information to the crew of a racing yacht. The key features of the proposed solution are its reliability, the possibility to extend and customise it, and its context-awareness, which simplifies its usage in an intelligent way. The target users of the system are both beginners who want a navigation aid, but cannot afford the expensive and often overly complicated commercial systems available on the market, and more experienced sailors who can benefit from an open and customisable instrument to study and fine-tune the setup and performance of their sailing boats. Furthermore, Oceanus strives to be as much as possible a low-cost architecture, both in software and hardware requirements.

Every sailor, at the back of his or her mind, is aware that the nearest land is likely to be directly beneath the ship's keel and he or she is interested to know just how near. For over two thousand years, mariners measured depth of water by using a sounding rod in shallow areas and the lead and line in deeper water. This paper considers how, during the “Dark Ages”, sailors in the North Sea might have navigated, including the use of sounding rods and lead lines for way-finding during a time when no other navigational instruments were available. Because of the lack of contemporary records the authors firstly consider the use of depth finding in earlier and later times to shed light on how the early North Sea sailors might have operated. The latter part of this paper takes account of the earlier discussion, together with some records of North Sea voyaging, to suggest how “Dark Age” sailors might have used sounding rods, the lead and line, and other techniques to navigate around and across the North Sea.

People with physical disabilities often face many challenges due to the non-compliance of public buildings to accessibility standards. Hence, it is necessary to provide them with relevant information about the quality of access associated with the environment they plan to visit. In this paper, we propose ‘AccessVOR’ (Accessibility assessment based on VORonoï Diagram), a novel approach that aims to automatically generate an indoor navigation network and to assess its accessibility for people moving with wheelchairs based on the American with Disabilities Act Accessibility Guidelines (ADAAG). A semantically enriched spatial database is developed based on ADAAG and the Indoor Geography Markup Language (IndoorGML) standard. A Three-Dimensional (3D) navigation-graph is then generated from the various components of an indoor environment using a Voronoï Diagram. The semantics of ADAAG allow assessing the accessibility of each segment of this navigation graph. Next, a navigation cost is allocated to this graph based on the accessibility of each segment of the network graph for navigation purposes.

This study attempts to offer the first ever analysis of Austrian aviation cartography from its origins in 1908 to 1938. The thematic focus is on Austria's contribution to the debate on the standardisation of aeronautical charts on an international scale, on the continuities and changes characterising the aeronautical charts produced in Austria, and on a comparison of these maps with similar ones from other countries. The paper aims to expound on the thesis that, while the theoretical basis for aeronautical charts had principally been in place internationally and in Austria during the 1910s, there had been almost no practical follow-up on this know-how in Austria between 1915 and 1922. After 1923 novel aeronautical charts were produced, but the Austrian output sometimes fell below international standards regarding both quantity and, in part, also quality. The international agreed rules were interpreted in keeping with Austria's own requirements. It appears, however, that this development was not limited to Austria, as the new rules took hold in other countries somewhat belatedly as well.

Connected and Autonomous Vehicles (CAVs) have been researched extensively for solving traffic issues and for realising the concept of an intelligent transport system. A well-developed positioning system is critical for CAVs to achieve these aims. The system should provide high accuracy, mobility, continuity, flexibility and scalability. However, high-performance equipment is too expensive for the commercial use of CAVs; therefore, the use of a low-cost Global Navigation Satellite System (GNSS) receiver to achieve real-time, high-accuracy and ubiquitous positioning performance will be a future trend. This research used RTKLIB software to develop a low-cost GNSS receiver positioning system and assessed the developed positioning system according to the requirements of CAV applications. Kinematic tests were conducted to evaluate the positioning performance of the low-cost receiver in a CAV driving environment based on the accuracy requirements of CAVs. The results showed that the low-cost receiver satisfied the “Where in Lane” accuracy level (0·5 m) and achieved a similar positioning performance in rural, interurban, urban and motorway areas.