This paper considers the effect of receiving a secondary source of information upon ability to acquire and use spatial knowledge (i.e. the formation of a cognitive map). Participants watch videos of three journeys through an unfamiliar area. They then perform tasks measuring ability to integrate the routes into a cognitive map of the area. Subjects viewing the routes whilst hearing route guidance information performed consistently worse than those receiving no guidance. The presence of non-salient information, however, did not impair performance.

Existing studies highlighting differences between gender and age groups regarding spatial ability receive only partial support: the results suggest that ability to drive negates these effects. Female drivers perform as well as, if not better than, their male counterparts, and outperform male non-drivers. This same ‘driving’ effect was also evident in the over-55s group, with both male and female drivers performing significantly better than non-drivers in this age group. The results also show that driving ability enhances ability to cope with and use guidance information, suggesting that systems’ designers should make varying levels of spatial information available for less experienced drivers.

Maps are familiar objects that need little introduction. By strict definition, a map is a diagrammatic representation of the spatial environment – for example, the Earth's surface, the stars or parts thereof. The techniques of map-making, or cartography, are basically concerned with reducing the spatial characteristics of large surface areas to a form that makes them observable. Cartography has been considered as both a science and an art. As an art form and craft tradition with printed maps, cartography traditionally has sought to address aesthetic criteria for human appreciation and visual attractiveness, in addition to considerations of functional utility.

Safe navigation in restricted waters continues to be a perennial concern for ship owners, operators, navigators, and citizens. The Nieuw Amsterdam, a cruise ship which ran aground in Southeast Alaska in August 1994; the Royal Majesty, another cruise ship which ran aground 10 miles east of Nantucket Island in June 1995; and the Regent Star, which caught fire in Prince William Sound, Alaska on 22 July, 1995, are just a few of the recent incidents which remind us of the importance of safe navigation in restricted waters. Clearly, the Braer, the World Prodigy, and the Exxon Valdez provide other examples of the importance of safe navigation in close waters. Fire, collision, allisions and groundings can result if vessels navigating in such waters stray.

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.

This paper and the following paper were presented at a meeting organized by the Institute's Land Navigation Group in October 1995. The meeting was on Loction Technology Applications in Public Transport. Copies of the proceedings can be obtained from the Director (£10 to Members, £15 to Non-Members).

The high seas freedom of navigation, and the lesser rights of transit, archipelagic sea lane and innocent passage applicable in straits used for international navigation, archipelagic sea lanes and the territorial sea respectively, have been said to embrace two notions: ‘one is the right to make progress over the surface of the sea, the other is the duty to make progress only in an orderly way, as to speed, steering, lights and so on – the manner of operation of the right’.

Recent evidence has shown that the effect of a ship moving in shallow water and the resultant squat are not well understood. This paper reviews the general problem of a ship in shallow water and illustrates the corresponding resistance, trim and sinkage at both sub-critical and also at super-critical speeds.

The paper then reviews the various methods of predicting the squat of a ship in shallow water in the sub-critical range, which is applicable to most ships. It is suggested that the simple rule-of-thumb methods are, at best, unreliable and the paper gives examples of empirical methods which have been tested against various sets of data and seem to give more representative answers. A summary of the notation used is given at the end of the paper.

A radar must detect targets before it can display them. Yet manufacturers' data sheets rarely tell us what the products will detect at what range. Many of the bigger radars are Type Approved so we consult the relevant IMO performance standard A 477 (XII). Paraphrasing Section 3.1 of the draft forthcoming revision (NAV 41/6): under normal propagation conditions with the scanner at height of 15 m, in the absence of clutter, the radar is required to give clear indication of an object such as a navigational buoy having a radar cross section area (RCS) of 10 m2 at 2 n.m. and, as examples, coastlines whose ground rises to 60/6 m at ranges of 20/7 n.m., a ship of 5000 tons at any aspect at 7 n.m. and a small vessel 10 m long at 3 n.m.

This helps, but suppose we must pick up a 5 m2 buoy at g km? What happens in clutter? Should we prefer S- or X-band? To answer such questions we use equations which define the performance of surveillance radars, but the textbooks and specialist papers containing them often generalize with aeronautical and defence topics, making life difficult for the nonspecialist.

This paper attempts a concise and self-contained engineering account of all main factors affecting detection of passive and active targets on civil marine and vessel traffic service (VTS) radars. We develop a set of equations for X- and S-band (3 and 10 cm, centred on 9400 and 3000 MHz respectively), suited for spreadsheet calculation.

Sufficient theory is sketched in to indicate where results should be valid. Some simplifications of conventional treatments have been identified.

This short paper discusses briefly the role of the current forms of bus priority used in the United Kingdom and how these strategies are incorporated within our urban traffic control systems.

The philosophy behind the SCOOT (Split, Cycle and Offset Optimization Technique) demand-responsive signal timings program is discussed, and the latest results from the bus priority trials carried out in London by the University of Southampton and London's Traffic Control Systems Unit (TCSU) are appraised. The system installed in London is compared with current dead reckoning vehicle location systems and the major differences highlighted.

The advanced ship's operational control system (ASOCS), as described in this paper, has been developed as an important part of a one man bridge system (OMBS). Systems of this kind are expected to become an essential feature as ship navigational systems develop in the future. This paper systematically analyses the structure and composition of ASOCS and proposes a type of computer network for the system. The functions of ASOCS are analysed with OMBS research particularly in mind.

This paper was presented at a Workshop organized by the Institute in London in October 1995 on the subject of GPS Interference – Is it a Problem? Copies of the Workshop Notes can be obtained from the Director (£50 to Members, £75 Non-members, £10 to students).

This paper is concerned with an investigation into the use of artificial neural networks in the design of fuzzy autopilots for controlling the yaw dynamics of a modern Royal Navy warship model. Results are presented to show the viability of such an approach and that effective designs can be produced.

On 14 September 1494, Christopher Columbus observed a lunar eclipse while at the island of Saona near the eastern tip of Hispaniola. He later recorded in his Libro de las Profecias that, from his timing of the eclipse, he determined his longitude to be ‘five hours and more than one half’west of Cape San Vicente. His actual longitude was three hours and 59 minutes west of Cape San Vicente, so Columbus was off by over an hour and a half, some 23 degrees of longitude.

This year marks the twentieth anniversary of the introduction of Concorde into commercial airline service. The first commercial flights were on 21 January 1976 – British Airways from Heathrow to Bahrain and Air France from Paris to Rio via Dakar. Later in that year commercial flights to Washington/Dulles began on 24 May. Services to New York were delayed until 22 November 1977. The first flight of Concorde was some seven years earlier. The prototype took off out of Toulouse on 2 March 1969 and this was followed by 002 from Filton to Fairford on 9 April. At the time it was anticipated that this was the beginning of an era when supersonic flight would be the normal way to travel long distances. Now, in 1996, Concorde is still the world's only supersonic commercial passenger airliner in airline service. This is an extraordinary achievement. The Boeing SST proved to be too ambitious and the programme was halted in 1971 after the United States Government withdrew support, while the Russian TU 144 was beset with problems. One TU 144 crashed at the Paris Air Show in 1973. The aircraft entered internal airline service in December 1975, flying supersonically between Moscow and Alma-Ata, capital of Kazakhstan, carrying mail and freight, but it did not have the range to operate viable intercontinental passenger serives. Certainly by 1985, if not many years before, the TU 144 was out of service.

About ten years ago this author wrote the software for a suite of navigation programmes which was resident in a small hand-held computer. In the course of this work it became apparent that the standard text books of navigation were perpetuating a flawed method of calculating rhumb lines on the Earth considered as an oblate spheroid. On further investigation it became apparent that these incorrect methods were being used in programming a number of calculator/computers and satellite navigation receivers. Although the discrepancies were not large, it was disquieting to compare the results of the same rhumb line calculations from a number of such devices and find variations of some miles when the output was given, and therefore purported to be accurate, to a tenth of a mile in distance and/or a tenth of a minute of arc in position. The problem has been highlighted in the past and the references at the end of this show that a number of methods have been proposed for the amelioration of this problem. This paper summarizes formulae that the author recommends should be used for accurate solutions. Most of these may be found in standard geodetic text books, such as, but also provided are new formulae and schemes of solution which are suitable for use with computers or tables. The latter also take into account situations when a near-indeterminate solution may arise. Some examples are provided in an appendix which demonstrate the methods. The data for these problems do not refer to actual terrestrial situations but have been selected for illustrative purposes only. Practising ships' navigators will find the methods described in detail in this paper to be directly applicable to their work and also they should find ready acceptance because they are similar to current practice. In none of the references cited at the end of this paper has the practical task of calculating, using either a computer or tabular techniques, been addressed.

On any surface which fulfils the required continuity conditions, the shortest path between two points on the surface is along the are of a geodesic curve. On the surface of a sphere the geodesic curves are the great circles and the shortest path between any two points on this surface is along the arc of a great circle, but on the surface of an ellipsoid of revolution, the geodesic curves are not so easily defined except that the equator of this ellipsoid is a circle and its meridians are ellipses.

Vessel Traffic Services (VTS) advise vessels navigating the waterways, VTS communications provide to the mariner timely, pertinent, and accurate information that would assist in safe manoeuvring of the vessel.

Following several oil spills in 1989, Congress passed The Oil Pollution Act of 1990 (Public Law 101–380). The Act requires the “Secretary to conduct a study…to determine and prioritize the US ports and channels that are in need of new, expanded, or improved vessel traffic service systems.…”

As required by the Act, the US Coast Guard analysed historical vessel casualties and their consequences and projected future vessel casualties and consequences for 23 study zones. The study uses a benefit–cost approach, VTS benefits are defined as the avoided vessel casualties and the associated consequences. The avoided consequences are measured in physical units and are assigned monetary values, VTS costs are defined as the initial federal investment for a state-of-the-art VTS system in each study zone and its annual operating and maintenance costs. Both the benefits and costs are expressed in the 1993 Net Present Value of annual stream over the life cycle at 10 percent basic annual rate. The study recommends VTS design by rank-ordering the zones by net benefit.

In this paper, we use alternative methodologies for offering better assistance in making VTS design decision-making. First, we perform ABC analysis on the zones; that is, we classify them into three groups: The A group deserves a state-of-the-art, full-fledged VTS presence, the B group could use an intermediate level of VTS services, and the c group deserves an elementary level of VTS services, as and if the budget permits. This analysis assumes that VTS services can be offered at various levels with correspondingly changing costs. Secondly, we perform resource allocation analysis; that is, for a given budget and given criterion (e.g. maximize the total benefit), select the optimal zones in which the VTS services should be offered. This analysis, done for various levels of budget, would form a useful decision aid for the VTS design.