bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Observational Errors on the Avoidance of Collision at Sea
Authors: Hollingdale S. H. 
Published: January 2010

At a meeting of the Technical Committee of the Institute held on 9 January 1963 it was suggested that recent theoretical treatments of the collision problem could usefully be extended to include a discussion of the near-miss situation and the effect of observational errors. The basic mathematical relations for near-miss encounters have been set out in this Journal on several occasions, notably by Sadler and Morrell, and in graphical form by Wylie. The recent paper by Parker deals with the effects of both systematic and random errors of radar observations of relative range and bearing.My previous discussion of the collision problem was presented in terms of the idealized situation where two ships are on an actual collision course, in which case the sight line is in the same direction as the relative velocity vector (the relative track). To extend the results to a near-miss situation, one has only to redefine the angle α (see p. 24s of ref. 3) as the angle through which the relative velocity vector rotates when one or both ships manœuvre. I have pointed this out on a previous occasion: ‘The two craft need not be on a collision course; this definition of α applies equally well to a “miss” situation provided that no reference is made to the sight line.
An All-weather Navigational Aid for for the Dover Strait
Authors: Milwright A. L. P. 
Published: January 2010

Whereas almost everyone seems to be agreed that a system of routing ships in the Strait of Dover offers the best solution to reducing the tragic wastage of life and ships that occurs each year in these congested waters, opinions differ on the system of routing that should be adopted.A Working Group sponsored by the British, French and German Institutes of Navigation has considered the problem and their report has been published in the Journal. They recommended that the navigational aids in the area should be revised and that ships should be advised, by means of Sailing Directions and Notices to Mariners &c., to follow the tracks shown in Fig. 1.
Target Tracking by PPI Display or by Automatic Computer
Authors: Gérardin L. 
Published: January 2010

The observation of a radar display by a human operator leads to the establishment of aircraft tracks. These tracks are subsequently used by the controller. More and more often, it is proposed to replace both PPI display and human observer by an automatic computer, either special or general purpose, to perform tracking.In the present paper the basic performances of these two modes of operation are examined, taking into account the psychological and physiological features of human vision and hence the mental association of the viewer. The computer is more precise, but more costly and, when saturated, the drop in performance is abrupt. The number of tracks handled by a human operator is small, but the brain is very versatile and works very well in confused situations, with a slower drop in efficiency than the computer.
The Last Voyage of Sir Clowdisley Shovel
Authors: May W. E. 
Published: January 2010

Much has been written from time to time about the disaster which befell the fleet under Sir Clowdisley Shovel (or Shovell) among the rocks of the Scilly Islands on 22/23 October 1707. Although many writers have discussed the cause of the catastrophe I have come across no one who has examined the D.R. positions of the various vessels involved, and it is these which I propose to consider here.It may be as well to recapitulate the story of the disaster. (At this time, it should be noted, the day at sea was measured from noon to noon and began twelve hours earlier than the civil day. Consequently, the afternoon at sea had a later date to that ashore. Noon positions logged were those at the end of the sea date.)
Marine Radar Automatic Plotter Display Philosophy
Authors: Wylie F. J. 
Published: January 2010

The object of any kind of marine radar plot when ships are in fog is to synthetize as much data on the current traffic situation as affects or will affect the safety of own ship and so to produce a plan picture of the area around the ship and the vessels moving on it, more or less as it would appear to the eye in clear weather. The plot will be expected to show, not only the current position of each ‘target’ vessel, but also the expected forward movement of each and the risk of collision which this involves.The word synthetize is used because it so completely implies the building up of separate elements of information into a whole; in this case, a continually changing whole. The word whole is also worth emphasizing, because only if the situation is so presented can the mariner appreciate the form which its development is taking both between own ship and those target ships which present a direct threat and between target vessels whose mutual evasive manœuvres may indirectly endanger own ship. The needed synthesis cannot be attained unless the predicted future positions of target ships are coordinated in time, so that the relative positions at the future time may be compared with the current relative positions.
Underwater Arctic Navigation
Authors: Cestone Joseph A. , St. George Emery 
Published: January 2010

The objective of this paper is to show that an underwater navigation system can be developed that is technically and economically feasible and of high reliability for long distance under-ice operation. Recent advances in underwater navigation for cruise, exploration and search and rescue operations are considered and applied to the current interest in Arctic waters, where mineral prospecting and oil transportation are potentially important.The paper was read at a meeting of the Institute held in London on 27 February 1974 with F. A. Haworth in the Chair. Mr. Cestone is from the Naval Ships Systems Command of the United States Department of the Navy; Mr. St. George from the Charles Stark Draper Laboratory of the Massachusetts Institute of Technology.
Through the Proper Channels
Authors: Best K. H. 
Published: January 2010

This paper, based on a presidential address given to the British Section, Société des Ingénieurs Civils de France on 11 January 1974, examines the state of sea transport today and proposes a European Maritime Agreement along the lines of the Chicago convention for Civil Air Transport.The following definitions may be agreed.Channels all natural or artificial beds of rivers, estuaries or other bodies of water, or a body of water joining two seas, for example the Channel joining the North Sea with the Atlantic Ocean. The word also means ways of access or communications and methods of conveying nonmaterial things, such as in radio and radar systems.Proper means fit, suitable, efficient and safe; a secondary meaning is correct according to rule and accepted custom.
The Instrumental Ideal
Authors: Bastien A. J. 
Published: January 2010

If astronomical navigation can be made to give its results in as simple a manner and as quickly as do the modern electronic systems, then clearly it can provide an aid whose usefulness will remain undisputed. The aim, then, should be to develop a system of astro-navigation which will give an immediate and continuous reading of, for instance, latitude and longitude; and it seems quite possible at the moment to envisage the nature of such a system. Its realization is perhaps another matter; and this may take time that perhaps the development of other systems will render ill-spent.The ideas put forward in this paper are only concerned with the fundamentals of what, in the writer's opinion, is a possible solution to the problem; they are also not all new.
Heeling and Pitching Error Correction without local Readjustment
Authors: O'Beirne T. H. 
Published: January 2010

This paper first gives a brief account of the deviation theory applicable to magnetic compasses and a unified theoretical treatment of the principal heeling-error and pitching-error effects. Consequences of symmetry in soft-iron correctors are then considered, and a system of six equal soft-iron spheres at equal distances along three mutually perpendicular axes is shown to have no effect at the compass position, any diametral pair thus having a complete negative counterpart in the remaining four.This leads to the deduction of the possibility of a simple form of corrector system in which soft-iron correctors remove those parts of the principal inclination errors which are due to induced magnetism. If the remaining part due to permanent magnetism is assumed to be removed by vertical magnets in the usual manner, the correctors when once adjusted would then require no readjustment on change of locality, in distinction from all known correctors at present in use or in course of manufacture, which require continual readjustment in these conditions.
A New Shore-based Radar Equipment
Authors: Fennessy E. 
Published: January 2010

Presented at a meeting of the Institute held at the Royal Geographical Society on 15 June 1951.Shore-based radar stations to supervise or assist the navigation of ships have now been employed for at least a decade. Such stations were more extensively used during the war than they have been since, principally because there had to be large convoy movements along heavily mined coastlines under conditions when, because of wartime limitations, many of the more conventional navigational aids were not available. The most important wartime development in the use of radar in this direction was undoubtedly the introduction of high power centimetric equipment and the plan position indicator. Since the war the use of shore-based radar to assist navigation of merchant shipping has been extremely limited and the only outstanding installation of this type is the Liverpool Harbour Supervision System, which was brought into service in 1948. This system has now been in operation for three years and has provided a great deal of information and has created a world-wide interest.
A New Wrinkle in Astro-navigation
Authors: de Aquino F. Radler 
Published: January 2010

Over thirty-seven years have passed since the writer published his ‘Wrinkles in Plane Chart Methods’, explaining the value and use of his then new ‘Protractor Diagram’ and ‘Graduated Triangle’ for plotting lines of position on squared paper. A figure showed the simplicity of the solution, overcoming the difficulty of the use of different units for the differences of latitude and longitude.It is now proposed to present a further ‘wrinkle’ to facilitate the use in navigation of six prominent equatorial stars, particularlyMintaka(δ Orionis) which is only 2o′ south of the equator, and practically a fixed star since its annual (precessional) variation in declination is only 2″·67. It is one of the three stars of Orion's belt and its magnitude is 2·5, slightly fainter thanPolaris.
Radar as an Aid to Air Navigation in the Arctic
Authors: Greenaway K. R. 
Published: January 2010

Summary of a paper presented to the Canadian Institute of Navigation at a meeting held in Montreal on 22 September 1950.In 1946 and 1947 a great deal was learned about scope interpretation and the use of search radar as an aid to air navigation in the Canadian Arctic. New techniques, differing from those used during the war, when search radar was considered primarily as an aid to bombing and for pin-pointing, were developed and a great deal of information on interpreting the radar presentation of topography at different seasons was obtained. The use of search radar for navigation in the Arctic is described in this paper, which also gives information on the probable appearance of topographical detail on the display at different times of the year.
Observations of the Green Flash
Authors: Simmons R. E. G. 
Published: January 2010

A Letter published in theJournal(Vol. IV, No. 2, p. 211) from Captain Brett Hilder refers to the use of the phenomenon known as the green flash for obtaining longitude at sea, and an editorial comment on the letter suggests that accurate descriptions of what has actually been observed at different times at sea might be of value to meteorologists. The following notes, though they contain no reference to using the observations for navigational purposes, may be of some interest as they are the result of a great many observations of the phenomenon.Numerous reports on observations of the green flash have been published in meteorological publications where, as a general rule, it is accepted that it is only seen under conditions of extreme visibility and clearness of the atmosphere. From numerous personal observations it has been ascertained that this is in fact not so, and that the green flash can be observed under conditions of extreme cloudiness, haze and humidity so long as the horizon is visible at the time of rising or setting of the heavenly body. Another factor affecting the actual sighting of the green flash is the intensity of light emanated by the body, for the flash is of very weak intensity when compared to the normal brilliance of the body observed.
IV—The Application of Pressure Pattern Flying to Civil Transoceanic Routes
Authors: Pike E. W. 
Published: January 2010

Since the inauguration of the B.O.A.C. Return Ferry Service, the principles of pressure pattern flying have been followed on the North Atlantic as regards flight planning. In co-operation with the forecaster the practice developed of working out a number of flight plans to achieve the shortest possible flight time, and eventually it became possible to select the most favourable route with a reasonable degree of precision.The advent of the radar altimeter furthered development of the pressure position line theory which I believe was first propounded by R.A.E., Farnborough, and has since been elaborately garnished and enthusiastically tested by our American friends during recent years. The words ‘altimetry’ and ‘aerologation’ have been added to our generally common language to cover flight techniques that might perhaps be more simply described as ‘pressure comparison navigation.’
What is the Ideal Air Map?
Authors: Chichester Francis 
Published: January 2010

Why the perfect air map does not exist. Air maps have been struggling for years to reach perfection; most of them fall far short of it for three main reasons:(1) Maps are designed by highly skilled specialists who, however, do not generally know from first hand experience what the practical requirements are. They rely on hearing of these from practical airmen.(2) The better the practical men are at map reading the less able they are to put into words how they set about it and what is required for the ideal air map.(3) Map production is extremely expensive in time, work and materials with the result that map makers are loath to scrap a map once made, if it will ‘do,’ even though they realise it might be improved.
Marine Position Fixing Systems in Use Today
Authors: Hogben H. E. 
Published: January 2010

Before the war the only radio navigational aids in current use by shipping were direction finding systems, operating in the medium frequency band of the radio spectrum.During the war, not only were many new types of position fixing systems evolved, but radar techniques were also developed, thus making available a wide range of new facilities of potential use both to ships of many different categories and to port and harbour authorities for the supervision of marine traffic.
The Reduction of Consol Bearings for Plotting
Authors: Simmons R. E. G. 
Published: January 2010

The use of Consol at long ranges in ships is hampered by the lack of facilities for accurate plotting. Of necessity ocean charts (scale 1:1,000,000 to 1:12,000,000) are used; and on these it is not practicable to plot running fixes, lay off position lines from celestial observations or to compare a succession of cross bearings with any degree of accuracy.When Consol bearings can be plotted on a large scale chart and used in conjunction with other position lines, such as Marcq. St. Hilaire, lines of soundings, m.f./d.f., &c, they are of assistance in defining an observed position; this is especially so in conditions of poor visibility, such as prevail in the approaches to the British Isles and in the North Atlantic.
The Double Altitude Problem: A Historical Note
Authors: May W. E. 
Published: January 2010

The publication of the paper Astro-fix by Computation by Oliver C. Collins in the April number of the Journal serves as a reminder that the observation for the determination of the latitude from two altitudes, usually known as the double altitude problem, is one of some celebrity in the history of navigation.The following notes on the subject may be of some interest although they are far from complete, having been compiled from such books as happened to be readily available, and can only be considered as an introduction to the subject.
Radar and Ice
Authors: Le Page L. S. , Milwright A. L. P. 
Published: January 2010

The need for investigations into the detection of ice by radar became apparent when merchant ships started reporting that ice formations were inconsistent radar targets, and that ships relying upon radar to navigate through ice areas could, in some circumstances, have their safety endangered.Certain investigations, notably those carried out by the U.S. Coast-guard Service and by the Swedish Defence Research Institute, resulted in the publication of a great deal of useful descriptive information but it was not accompanied by measurements of the actual echoing power of ice targets. With the object of carrying the matter further, a special enquiry was made during the 1950 and 1951 North Atlantic ice seasons, when a number of British ships plying North Atlantic routes completed questionnaires in which the sizes and shapes of ice formations were noted together with their radar detection ranges. This enquiry was instituted by the Operational Research Group in the Marine (Navigational Aids) Division of the British Ministry of Transport, which later analysed the data collected and issued a report. There were, however, certain limitations in this investigation. For example, the performance of the radars was not known, because of their inherent differences and the fact that none of the ships carried instruments, such as echo-boxes, for checking performance; further, propagation conditions at the time of making the observations were not established.
A Record of Radar Performance in Ice Conditions
Authors: Perry R. E. 
Published: January 2010

In order to gain first-hand experience of the conditions encountered by the growing number of vessels plying the Hudson Bay route, Mr. R. E. Perry, an engineer of the Decca Radar Company recently made a passage to Port Churchill in the S.S. North Anglia.During the course of this passage a complete radar log was kept by Mr. Perry. This log is noteworthy not only for the many reports of the radar detection of various types of ice but also for the detail and completeness of the information recorded.
Siting a Harbour Radar Equipment
Authors: Lumsden G. J. A. 
Published: January 2010

Captain Lumsden's paper was written for the convention held in Düsseldorf on 16, 17 and 18 May 1961 (Journal, 14, 480). It describes the siting of harbour radar equipment from the point of view of giving warning of approaching ships to the shore authorities, giving navigational assistance to shipping, and port surveillance. In most cases the choice of site for the aerials and displays will have to be a compromise with these three uses of shore radar in mind.The three main elements of a harbour radar are the scanner, which must be sited to survey the area of interest, with the transceiver close by to avoid waveguide losses, and the displays which may be required in a room close to the scanner or in a room distant from it.
A Proposed System to Produce True Motion in Relative Displays
Authors: Manley B. W. 
Published: January 2010

A system is proposed which would be capable of adding information concerning the true motion of objects, to the normal relative display. The method requires the use of two Tenicon storage tubes (ME 1260).The use of marine radar has not eliminated collisions at sea. The reasons for this failure are generally associated with limitations in interpreting the available information, rather than in the equipment itself. One particular problem is the assessment of the time, course and speed of a ship from the information presented on a radar display, which is relative to the observer. It is possible to calculate this information, but the direct presentation of a true course on the display would be advantageous. A solution is to modify the final PPI display so that the centre of the scan, normally fixed at the centre of the cathoderay tube, is displaced continuously at a velocity corresponding to the observer. The true speed and course of a ship can therefore be assessed from the track built up from echoes received during successive scans.
A Norse Bearing-Dial?
Authors: Taylor E. G. , May W. E. , Motzo R. B. , Lethbridge T. C. 
Published: January 2010

In the July number of the Journal Captain C. V. Sølver described the discovery, by the Danish archaeologist Dr. C. L. Vebæk, in Greenland in the summer of 1951, of what was believed to have been part of an early bearing-dial. The object, which was dated by the archaeologists at about the year 1200, was one-half of an oak disk the outer rim of which was carved in such a way as to lead Captain Sølver to the conclusion that the complete disk was divided into thirty-two points or directions. Captain Sølver's paper was illustrated by a photograph of the fragment discovered and of his reconstruction of a similar bearing-dial.Professor Taylor comments below on Captain Sølver's paper, and on the more general question of a Norse bearing-dial which it raised. Comment on the problem invited from a number of members and others is also given.
Practical Navigation over the North Atlantic
Authors: Willis D. C. 
Published: January 2010

This paper, which gives a useful description of the procedures used by one transatlantic operator, was presented in Montreal at a meeting of the Canadian Institute of Navigation held on 7 December 1955. Many of the methods discussed are referred to in the preceding three papers.1. Any discussion of today's long-range navigational practices and problems seems to lead inevitably to pressure-pattern and jet-stream flying. The reason might well be that during recent years the more important practical developments appear to have concerned techniques rather than aids or instruments.
Comparison between two Decca Chains
Authors: Freiesleben H. C. 
Published: January 2010

Summary of a paper presented at a meeting of the Auschuss für Funkortung at Essen on 28 February 1956.In any investigation of the accuracy of Decca fixes it is necessary to distinguish between systematic and random errors. Investigations are generally based on a comparison between a Decca fix and a fix obtained by some other method; because of the high accuracy of Decca the other method must in practice be a terrestrial fix. The investigation can be made by comparing the decometer readings with values calculated for the true position; or the Decca position may be compared directly with the true position. The first way gives the differences of the Decca observations in terms of percentages of a lane, and the second shows immediately the errors of the Decca fix. The second method includes the uncertainty caused by the siting of the Decca stations, that is by the angle of intersection of the Decca hyperbolae. The second method will be of more direct use to practical navigators while on the first will be based considerations of a theoretical and strictly technical nature.