This paper formed the 1990 Anderson Memorial Lecture and was presented to the Bristol Channel Branch on 22 February. In developing his theme, George King concentrated very much on the characters of the navigators concerned with six extraordinary exploits, but without losing sight of the navigation itself. The following version is necessarily much abridged and the editor has reluctantly omitted the detail of fascinating accounts of the expedition commissioned by Thomas Jefferson to explore the American West, the epic open boat voyage by Ernest Shackleton in the Antarctic in 1916, the first solo air crossing of the Atlantic by Charles Lindbergh in 1927, and the spectacularly successful Apollo 11 mission in 1969. The full text of George King's meticulously researched and brilliantly written paper is available to members from the Institute, price £3.

This paper, by the Deputy Operations Manager of the Marine Department of Hunting Surveys Limited, was presented on 15 November 1979 at a meeting of the Solent Branch of the Institute held at the College of Nautical Studies, Warsash. It deals with the operation of semi-submersible laybarges based on experience in the northern North Sea from 1975 to 1979. It covers, from the survey contractor's point of view, the different phases of operation from the time the oil company selects the route until the line is laid and surveyed on the seabed. Some aspects of the work described would not normally be associated with surveying or navigation but have been carried out by survey teams in laybarges.

A new system of electronic scanning is described in which the narrow receiving beam of an acoustic echo-ranging equipment (i.e. asdic) is swept over a wide sector at a very high speed. Since the transmitted pulse covers the whole sector, and the scanning is done at least once per pulse duration, an effectively instantaneous search of the sector is made without any loss of information. The results of trials at sea are shown and possible applications to surveying and navigation are briefly discussed.

The use of underwater acoustic echo-ranging systems in the form of echo-sounders (as fitted on most ships nowadays) and asdics (as used, for example, for submarine detection during the war and now applied to whale-finding and fish-finding) is well-known.1 These existing systems use a single beam of acoustic energy, the pulse being transmitted by a transducer (or loudspeaker), and received, after reflection from the sea-bottom or whale or other object, by the same or a different transducer (this time used as a microphone). The time difference between transmitted and received pulses measures the range of the bottom or object, and is recorded on a chart by a stylus moving at a speed equal to the velocity of sound in water multiplied by the ratio of the width of the chart to twice the maximum range of detection. The transmission of the pulse marks the left-hand edge of the paper, and any echo received causes a mark at a point in the stylus sweep corresponding to the range of the object causing the echo. The paper is meanwhile moving at right angles to the stylus sweep, so that the next pulse transmission marks on a line adjacent to the previous one.

For a long time it has been accepted as fact that at least certain animals, such as birds and honey bees, have an in-built sense of orientation which enables them to find their way home. Less well-known examples occur among the molluscs and amphibians.

In 1972 an atomic time standard based on the fundamental properties of the caesium atom is being substituted for Greenwich Universal Time, based on the rotation of the Earth on its axis, as the ultimate control for international time signals. Greenwich Time and longitude are inseparable, so that any necessary correction to the time signals he receives will be of vital importance to the navigator.

This paper was presented at a meeting of the Institute in London on 27 January 1970 with the Hydrographer of the Navy, Rear-Admiral G. S. Ritchie, C.B., D.S.C., in the Chair. Mr. Humphry Smith, head of the Time Department at the Royal Greenwich Observatory and Chairman of the Directing Board of the Bureau International de l'Heure, reviews the relationship of uniform time systems to the precise astronomical observations that determine the irregularities of the Earth's rotation. He outlines the current proposals for time signals, their correction to Universal Time and the implications for the navigator.

A better understanding of passenger movement in multi-modal transit situations is the major aim of this study. By using a novel Cooperative Positioning (CP) approach, algorithms can be generated which considerably increase the accuracy of person tracking. Smooth transit at stations is enabled, thus the total waiting time for routing at the traffic interchange is reduced. A Location-Based Services (LBS) user is guided by the service and located with the assistance of the whole user group. In addition to the technological developments, the acceptance and end-user needs are considered. End-users of such a service have the right to withdraw their consent for transferring location-based and other personal data at any time. They also receive clear and comprehensive information about when and why they reveal their personal data and location and its further use. In this paper, the concept is introduced followed by a comprehensive discussion of the suitable CP localisation techniques as well as an implementation strategy. Furthermore, ethical and usability aspects are discussed to ensure user-friendly results.

In this paper, the well-known multiplicative extended Kalman filter (MEKF) is re-investigated for attitude estimation using vector observations. From the Lie group theory, it is shown that the attitude estimation model is group-affine and its error state model should be trajectory-independent. Moreover, with such a trajectory-independent error state model, the linear Kalman filter is still effective for large initialisation errors. However, the measurement model of the traditional MEKF is dependent on the attitude prediction, which is therefore trajectory-dependent. This is also the main reason why the performance of traditional MEKF is degraded for large initialisation errors. Through substitution of the attitude prediction related term with vector observations in the body frame, a trajectory-independent measurement model is derived for MEKF. Meanwhile, MEKFs with reference attitude error definition and with global state formulating on special Euclidean group have also been studied, with the main focus on derivation of the trajectory-independent measurement models. Extensive Monte Carlo simulations of spacecraft attitude estimation implementations demonstrate that the performance of MEKFs can be much improved with trajectory-independent measurement models.

As no internationally agreed-upon method for determining safe speed values currently exists, collecting vast amounts of information on conventional ship behaviour could be used to train autonomous ship intelligence in determining safe speeds in different conditions. This requires speed data collected from conventional ships to resemble what can be described as safe speeds. To test this, the Automatic Identification System (AIS) and environmental data – namely visibility, mean wind speed and significant wave height – were collected and merged for two study areas in Norway in the period between 27 March 2014 and 1 January 2021. Regression analyses based on 47,490 unique vessel transits were conducted and supplemented by two graphical methods for revealing relationships between variables. Contrary to the contemporary understanding of safe speed, reduced visibility did not lead to significantly reduced transit speeds. Wind and waves caused a reduction in speed in the open ocean, but not in coastal waters. Transit speeds were lower in coastal waters than in the open ocean.

As every schoolboy learns, a point has position but no size, and a line has length but no breadth. Nevertheless, to a navigator concerned with fixing his ship, points and lines are represented on his chart as fine pencil marks.

The manner of representing the results of observations as pencil ‘points’ or ‘lines’, has undoubtedly led to the belief that a ship's position must be represented as lying at a point on a position line which is drawn on a chart. Nothing short of perfection in position lines is ever expected by most practical navigators, and two position lines crossing at a point are usually regarded by seamen as yielding a perfect position: and if three position lines meet at a point! … there is seldom even the slightest doubt in the mariner's mind about the reliability of such a fix. On the other hand, three position lines which do not meet at a point are usually regarded as being something not quite respectable.

This study introduces a new real-time kinematic (RTK) positioning method which is suitable for baselines of different lengths. The method merges carrier-phase wide-lane, and ionosphere-free observation combinations (LWLC) instead of using pseudo-range, and carrier-phase ionosphere-free combination (PCLC), or single-frequency pseudo-range and phase combination (P1L1). In a first step, the double-differenced wide-lane ambiguities were calculated and fixed using the pseudo-range and carrier-phase wide-lane combination observations. Once the double-differenced wide-lane integer ambiguities were known, the wide-lane combined observations were regarded as accurate pseudo-range observations. Subsequently, the carrier-phase wide-lane, and ionosphere-free combined observations were used to fix the double-differenced carrier-phase integer ambiguities, achieving the final RTK positioning. The RTK positioning analysis was performed for short, medium, and long baselines, using the P1L1, PCLC, and LWLC methods, respectively. For a short baseline, the LWLC method demonstrated positioning accuracy similar to the P1L1 method, and performed better than the PCLC method. For medium and long baselines, the positioning accuracy of the LWLC method was slightly higher than those of the PCLC and P1L1 methods. In conclusion, the LWLC method provided high-precision RTK positioning results for baselines with different lengths, as it used high-precision carrier-phase observations with fixed ambiguities instead of low-precision pseudo-range observations.

Professor Kemp1 has revisited the circumstances in which the Princess Alice crossed ahead of, and was run down by, the oncoming Bywell Castle in 1878. This note focuses on the seamanship of the manoeuvre made by the Bywell Castle in the agony of the moment before collision. This manoeuvre was judged to be wrong at the time. The note concludes by considering how this manoeuvre would be judged today in the light of the seamanship required by Rule 17 of Colregs 1972 and draws attention to proposals made by Captain Phillip Colomb to the Thames Traffic Committee in 1879.

Accurate navigation systems are required for future pinpoint Mars landing missions. A radio ranging augmented Inertial Measurement Unit (IMU) integrated navigation system concept is considered for the Mars entry navigation. The uncertain system parameters associated with the Three Degree-Of-Freedom (3-DOF) dynamic model, and the measurement systematic errors are considered. In order to improve entry navigation accuracy, this paper presents the Multiple Model Adaptive Rank Estimation (MMARE) filter of radio beacons/IMU integrated navigation system. 3-DOF simulation results show that the performances of the proposed navigation filter method, 70·39 m estimated altitude error and 15·74 m/s estimated velocity error, fulfill the need of future pinpoint Mars landing missions.

Piloting in the Panama Canal is exceptional as, due to its importance, the functions of the captains of vessels are taken over by pilots. Hence, prior to inauguration of the expanded canal, a limited number of pilots experienced on the existing canal were certified for the transit of Neopanamax vessels by means of planned and innovative individual learning. After this organisational training through operative training, with the implementation of the expanded canal in June 2016, the routine training started. Hence the learning curve in the performance of these manoeuvres will represent the growing skill acquired by both the pilots and the organisation. Given that the learning effect is measurable, this paper has the dual objective of determining two curve models: the organisation operative learning curve model and the routine learning curve model for pilots performing transit manoeuvres in the expanded Panama Canal waterways and the Cocolí and Agua Clara locks. Manoeuvre times in locks and transit in the whole of the canal were followed up continuously in the first 42 months of operation.

Bridge design has undergone changes in the last few decades resulting in increased awareness of the need for safety while maintaining the minimum of personnel. The concept of the one-person bridge has been studied fairly extensively with respect to military and large merchant vessels, but much of this work has been ignored by those designing for smaller ships, particularly fishing vessels. This paper derives principles for positioning the electronic fishing aids of ‘single ticket’ fishing vessels while applying, where applicable practically, the ergonomic principles developed from the wider community. The paper then applies the principles to the wheelhouses of two fishing vessels and suggests modifications for greater compliance. A conceptual wheelhouse design is given that satisfies all the principles while including the usual suite of electronic aids typically carried by such fishing vessels.

The benefits of Global Navigation Satellite Systems (GNSS) and in particular GPS have been demonstrated worldwide, and continue to accrue in the form of new applications. Today, some mission critical applications (largely driven by safety) mostly in aviation and to a lesser extent maritime, rely on a number of techniques for the provision of integrity monitoring services. However, for many applications such as those associated with the emergency services, road user charging and personal navigation devices, no such monitoring exists and service validation is limited due to technical and cost constraints. The problem is exacerbated by a recent increase in more challenging problems, particularly in the security industry, in which jamming devices have been used to disrupt the use of GPS. This paper presents a new approach for a cost effective local solution to the problems above, at the individual user level, by providing the user with information on Quality of Service (QoS). The approach is based on the deployment of a single or network of probes supported by an existing regional network. The probes communicate with a central server and are designed to detect localised events whilst the regional network isolates space segment anomalies. The latter is addressed in detail in this paper in terms of design methodology and performance, using the Ordnance Survey's UK GNSS network.

The accuracy of speed prediction error to the next waypoint is a key factor in maintaining longitudinal separation on oceanic routes. This estimation is often used by air traffic control to estimate the future position of aircraft, and the estimation errors result in potential separation infringement. While most aircraft can calculate the estimated time at each future waypoint using the onboard Flight Management System, the factors affecting the inaccuracy of the estimation require more clarification. This paper investigates the accuracy of the speed prediction error on oceanic routes and examines the main factor of error using airline flight data. The results show that wind prediction error is a main source of speed prediction error, and significant differences of the speed prediction error among airlines and aircraft types were observed.

A large interest in developing commercial Location-Based Services (LBS) and the necessity of implementing emergency call services, have led to the intensive development of techniques for mobile users' localisation. In this paper, a Public Land Mobile Networks (PLMN) -based technique for initial position determination is proposed as an alternative to satellite-based methods in environments with obstructed satellite signals. Two positioning models, based on handset available Received Signal Strength (RSS) measurements from Global System for Mobile Communications (GSM) base stations and the use of Support Vector Machine (SVM) algorithms, are proposed. Performances of proposed models are verified using field measurements, collected in a suburban environment. Models are analysed in terms of positioning accuracy, complexity and latency, and compared to some other promising PLMN-based techniques. Using proposed SVM-based positioning models a median error of 4·3 m–6·2 m and latency of less than a second can be achieved.

Farmers are having to gather increasing amounts of data on their soils and crops. Precision agriculture – the targeting of inputs such as fertilizers and herbicides according to locally determined (‘metre-by-metre’) requirements – is based on a knowledge of the spatial variation of soil and crop parameters across a field. The data has to be spatially located and GPS is an effective way of doing this. A backpack data logging system with GPS position tagging is described which has been designed to aid a fanner in the manual collection of data.

Increasing lunar exploration activities are giving rise to higher demands for a navigation constellation system in cislunar space. A novel constellation of solar sails around the Sun-Earth Artificial Lagrangian Points (ALPs) is proposed for cislunar navigation in this paper, which benefits from the numberless and out-of-plane advantages of ALPs compared with the classical Lagrangian points. To relieve the technical pressure on sail equipment, a two-layer optimisation strategy including the navigation constellation architecture and trajectory design is developed to reduce the desired lightness number of the sail's motion. The constellation architecture is constructed in the shape of a regular tetrahedron, whose size and orientation are derived from the realisable lightness number at the ALPs. The powerful Hamiltonian structure-preserving controller and differential evolution algorithm are adopted to propagate the bounded quasi-periodic trajectory with minimum lightness number variation. With the premise of the sail's high feasibility in the mechanism, the numerical navigation simulations for a typical trans-lunar weak stability boundary trajectory indicate that the proposed navigation constellation has a low geometric dilution of precision factor and a good navigation performance.