Orientation within orienteering is dependent on the use of two basic strategies; that is, either a compass or Magnetic-North-based strategy, which relies on the use of one set of information; or the use of a map and landmark-based strategy which relies on the use of at least two sets of information. Walsh and found that, when given the choice, young children use the compass-based strategy when following complex potentially disorientating routes.

The efficacy of these two basic orientation strategies was investigated within three different orienteering environments: (1) a familiar known environment; (2) a familiar unknown environment and (3) an unfamiliar unknown environment.

Subjects, age range from 9 to 10·5 years, completed an appropriate orienteering route in each of the environments. Individual mini-cassette recorders and tie-pin microphones were used to record data using a ‘think aloud’ technique as subjects followed their selected routes. Transcripts of the taped data produced a total number of uttered statements for each subject within each environment. A qualitative analysis of these statements identified the following groups of statements expressed as percentages of the total number of statements (as reported by Thorndyke and Stasz): (a) Orientation statements; (b) Relocation or error correction statements; (c) Statements about distractions; (d) Self-efficacy statements.

There was a higher reported use of the compass-based strategy for orientation within the familiar known environment which supported the earlier findings of Walsh and Martland. Although the percentage of compass-based orientation statements was smaller in the familiar unknown and the unfamiliar unknown environments, there was a pattern in the use of orientation strategies within these two environments. Typically, the compass-based orientation strategy was used for initial orientation at the beginning of the route and at the pre-defined control points along the route, whilst the landmark and map-based strategy was used as a means of maintaining and reinforcing orientation within the route. Relocation statements typically reported an awareness of disorientation and were generally followed by attempts to reorientate. Whilst none of the subjects used relocation statements within the familiar known environment, relocation statements were used within the familiar unknown and the unfamiliar unknown environments.

This evidence suggests that both orientation strategies are used in orienteering routes, but that each strategy is used selectively depending on the environment. These findings clearly have implications for the sport of orienteering – particularly the introduction of basic skills to young performers. They support the argument that is essential to introduce the map and compass simultaneously and that relocation and orientation skills should be coached concurrently.

In Captain Wylie's note on ‘Radar as an anti-collision aid: the ultimate essentials in presentation’, masterly definition by an acknowledged expert aptly crowns the discussion which follows Commandant Oudet's paper on ‘Collisions and the Courts’ in the same issue of the Journal. It is interesting and gratifying to find in that discussion a suggestion by E. S. Calvert on manœuvres in close-quarter situations which recalls a similar proposal made by the French Institute at our first joint meeting held in London in 1957. It is that the manœuvre should be a turn of 2x° to starboard if a threat, an echo for example, is perceived x° forward of the port beam. This suggestion passed almost unnoticed at the time although it is mathematically sound if one assumes that the speed of the two vessels is the same.

FOR some 15 years past, Dr. J. C. Beaglehole has been editing the Journals of Captain Cook for the Hakluyt Society. These embrace the three great Pacific voyages, and it is a happy circumstance that the two volumes covering the third voyage, and which complete a series of four massive volumes, have been published by the Cambridge University Press in 1967 in good time for the 200th anniversary, on 26 August this year, of the sailing from Plymouth of Cook in the Endeavour on his first great voyage to the Pacific.

Having loosed the topsails as a signal for sailing and hoisted a Jack at the fore topmast to inform Mr. Banks to come on board on 25 August 1768, Cook sailed in Endeavour next day. The undramatic entry in his journal began—‘At 2 p.m. got under sail and put to sea having on board 94 persons including Officers, Seamen, Gentlemen and their Servants, near 18 months provisions, 10 Carriage guns, 12 Swivels with good store of Ammunition and stores of all kinds’.

Now, with these four volumes, the Hakluyt Society, for the first time, has made available to us the daily entries set down by Cook from that first day of sailing in 1768, throughout the three voyages, until his final entry on 17 January 1779.

There is an urgent need, both at international and national level, for more operational research into marine traffic and the associated collision casualties. At the present time marine traffic research is in its infancy and official analysis of collision is on a national basis with few attempts to correlate the two together and on an international basis. Without this basic information and research on the traffic and accident pattern, it will not be possible to plan effectively to reduce the high cost of collision casualties to ships' operators and to make the necessary improvements in safety over the next decade. This decade will see increasing carriage of dangerous cargoes in bulk, a continual large increase in the number of pleasure boats and the current trend of increasing numbers of merchant ships, fishing and other work-boats will probably continue. Due to this large increase and the trend to mammoth ships, the effective amount of sea space is being rapidly reduced and traffic control is inevitable in some areas.

A continuing study of ship's bridge design and ship control conducted by the Defence Research Board of Canada has recognized that the conventional method of issuing and executing verbal orders contains inherent delay and is a possible source of error in ship control. As a partial solution to this problem, it was proposed that ‘the officer originating decisions to change the course and speed should implement these decisions himself through the direct control of helm and engines on the bridge’ (p. 21). It was further proposed that the direct controls be located on a console positioned at the front of the bridge on the centre-line of the ship.

The conventional location and arrangement of the bridge restricts visibility, however, in areas close to the ship, and this limited visibility from the bridge often causes manœuvring difficulties. In some instances, distances as great as 800 ft. ahead of the bow and 50 ft. abeam are ‘blind areas’. In most cases, areas aft on the centre-line cannot be seen at all. In an attempt to alleviate these problems, bridges have been extended to the sides of ships, or bridge wings provided so that much of the ship's side can be seen by the conning officer. With direct control from the centre-line and the use of a television system, bridge wings could possibly be eliminated, while still providing better close-in vision.

In studying the behaviour of marine traffic in the Strait of Dover observations have been made of vessels contravening the recommendations of the Imco Traffic Separation Scheme. This report, originally published by the National Physical Laboratory (Crown Copyright), considers the risks attached to the courses of these vessels in terms of the number of encounters to be expected and in the light of the recommended routing principles.

In recent years the Regulations for Preventing Collisions at Sea have been the subject of considerable interest to mathematicians. It has been demonstrated that the Rules as they stand are not entirely satisfactory, and this confirms a certain uneasiness which most navigators have in this respect. One of the imperfections in the Rules is that they are not universal: they do not apply in fog, when vessels are not in sight of one another, they do not apply to certain classes of vessel, they are affected by limitations of weather and sea-room, and so on. It does not seem unreasonable that a set of Rules could be devised, based on the mathematical work lately carried out, which would be more rational than the present Rules.

This paper covers the wide area and short range locational technologies that are available for vehicle tracking in particular and mobile user security in general. It also summarises the radio communications services that can deliver information to the user. It considers the use that can be made of these technologies, when combined with procedures for delivering a response, in the security field, notably in relation to personal security, high-value load protection and the after-theft tracking markets.

Self-organising radio systems have been proposed for aeronautical and maritime communication, navigation and surveillance applications. In aviation, the introduction of the VHF Data Link (VDL) Mode 4 is currently being discussed, while the implementation of Automatic Identification Systems (AIS) is planned in the maritime domain. Operating in an autonomous mode, a self-organising radio system employing Time Division Multiple Access (TDMA) does not require a terrestrial infrastructure, such as base stations. The concept of self-organisation is based on the cooperative behaviour of a large number of users sharing a common VHF radio channel. Analyses have shown that uncoordinated stations, so-called hidden users, can cause interference in self-organising radio systems. This paper presents two different approaches to autonomous self-organisation together with the results of investigations of intra-system interference. Such analyses may help to introduce potential improvements to the system performance, which reduce the effect of hidden users in this very promising GNSS-based technology.

The development of augmentation services, such as EGNOs and WAAS, requires careful modelling and simulation before any deployment of equipment takes place. The ideal location of ground stations, and the potential impact of temporary failures of ground equipment, must be assessed in detail, to ensure that proposed service levels of accuracy and integrity are maintained at all times. The correct analysis of these parameters can only be achieved if the various wide area processing models, and their respective error propagation characteristics, are suitably simulated. This paper describes the use of a sophisticated and versatile suite of GNSS analysis tools in recent studies. It describes the incorporation of realistic error budgets for WADGPS and LADGPS corrections, and the potential use of different combinations of GPS, GLONASS, geostationary and other satellites in both GNSS-1 and GNSS-2.

This paper considers the issue of operating aircraft through the North Atlantic's Minimum Navigation Performance Specification (MNPS) airspace. Noting that aircraft constantly strive for reduced fuel burn and uplift, it describes how flight operators and pilots conduct safe, efficient flights through the region. Reference is made to mechanisms of the North Atlantic MNPS airspace in terms of its Organized Track Structure and other routes that exist. These different structures emphasize the level of flexibility available. Flight planning procedures and requirements necessary to obtain oceanic Air Traffic Control (ATC) clearances are mentioned, as is an account of how communication and position reporting procedures operate to apply the Mach Number technique. Other aspects of MNPS operations such as ETOPS operational restrictions, meteorological effects, the employment of Reduced Vertical Separation Minima and planned regional changes aim to provide an overview of the MNPS system's current and future air traffic management.

This paper presents further research on the SNUGL pseudolite-based navigation system presented in this journal in 2003. This system has centimetre-level accuracy, but has an error source arising from right-hand circularly polarized (RHCP) transmissions, unlike outdoor Global Positioning System (GPS). The GPS satellites and pseudolites use RHCP signals, and the polarization affects carrier-phase measurements according to the Line-of-Sight (LOS) vectors from transmitters to receivers. The RHCP error is eliminated by a double differencing process in outdoor GPS, but the error remains in the pseudolite-based system because the LOS vectors from transmitters to a reference and user receivers are different for the close transmitter constellations. This paper shows the RHCP effect on the pseudolite-based navigation system through simulations and experiments. It then shows the RHCP-compensation method improves the measurement and position accuracy by over 10%.

A theoretical analysis of the effects of dual frequency ionosphere propagation correction on GNSS code tracking noise is presented. The effect on tracking noise of using different combinations of the proposed Galileo signals for ionosphere propagation correction is investigated. It is concluded that, for the open or commercial service user, the Galileo signals E2-L1-E1 near to and around GPS L1 should be used to apply ionosphere propagation corrections to the E5 signals. This produces a tracking noise standard deviation about three times larger than that on an E5 signal alone. An ionosphere correction-smoothing algorithm is presented that reduces the tracking noise on the corrected pseudo-range measurements.

Unlike a direct broadcasting satellite navigation system, the transmitting satellite navigation system developed in China uses transponders onboard communication satellites to retransmit navigation signals generated at a ground master station. The transmitting navigation satellite constellation consists of a number of inclined geosynchronous orbit (IGSO) satellites. Considering China's mainland coverage in the northern hemisphere occupies some 62 degrees in longitude, the inclination of the IGSO satellites cannot be too high, or its signals would not be received by the users in the middle and high latitude areas when the IGSO satellite travels over the southern hemisphere. Meanwhile, the latitude of the most southerly station in China mainland that can uplink navigation signals is about 18°N when the IGSO satellite travels to the southern hemisphere. Therefore, there is a need to consider the IGSO inclination to achieve balance between uplinking high-quality navigation signals and covering the high-latitude area. In this work, the navigation performance and availability of the IGSO satellite are examined when navigation signals are uplinked from the stations Lintong and Sanya.

Many problems in navigation can be best viewed and solved as problems in analytical geometry. We only need to understand the geometry of two ‘navigable’ surfaces; the sphere and the ellipsoid of revolution. The ellipsoidal model is generated by revolving an ellipse about its minor axis and this model is used as a global model for the surface of the Earth. The eccentricity of the meridian ellipse is small (≈0·082) so we sometimes refer to this surface as a ‘spheroid’ since the surface is still ‘sphere-like’. The physical Earth is, in fact, referred to as a ‘geoid’ whose surface is that which approximates global mean sea level. The mathematical representation of the geoid is not trivial and the ellipsoid of revolution is an extremely good approximation to it.

This paper compares the differences between the rhumbline courses and distances calculated by three methods: the classical formula, precise formula and by software contained in a typical GPS receiver. It concludes that, while the calculations made by the GPS receiver are generally more accurate than the classical method, navigators must use Tables of Latitude Parts to calculate rhumbline distances accurately.

Conventional cruise control systems fulfil the function of automatic speed control. A desired speed is selected by the driver, and a control system operates on the throttle to maintain this desired speed. When traffic density is moderate or high, the driver is faced with having to adjust the set speed regularly in order to maintain a comfortable distance from preceding vehicles and will frequently have to brake, disengaging the cruise control. Thus conventional cruise control can become a source of irritation when used in moderate or heavy traffic. If a distance sensor is added to a conventional cruise control system, then it is possible to add distance keeping to the basic speed control function. This forms the basis for adaptive cruise control, which can be further improved if a limited authority braking system is incorporated. Use can then be made of both throttle and brake actuators to control the distance and relative velocities between a vehicle and a preceding target vehicle.

When we started surveying Megalithic sites in Britain we used a cloth tape, but after some years it was realized that it was necessary to be more precise and now we use a steel tape for the important sites. Similarly with astronomy; at first we considered it sufficiently accurate to work to ¼° but now we know that it is advisable to work always to within a minute of arc. This is because we have found out that the erectors of the stones sometimes used distant foresights, either artificial or natural, and by using these they could get an accuracy of better than a minute. The method of observing was for the operator to watch the edge of the celestial body grazing a foresight or running down the edge of a hill. He moved sideways until he got exact coincidence and then marked the position. This first came to our attention when we measured up the site at Ballochroy on the west side of Kintyre.

This study of Columbus' navigation is unique because it was written by an historian who is also a trained and experienced professional global (and ocean) navigator, rather than an academic historian with only superficial knowledge of the science of navigation as practiced by Columbus and other early navigators. The study is also unique in that as an American historian author disagrees with his colleagues in the USA who present the “politically correct” view of Columbus as an unskilled entrepreneur who obtained his limited knowledge of navigation as a crew member or passenger on Portuguese voyages, rather than as one of the most skilled and experienced of the cadre of respected Genoese captains and navigators used by kings throughout Europe to perform their maritime enterprises.