bluuebunny/crossref_metadata_2025 huggingface dataset:
A New System of Compass Correction
Authors: Harvey G. N.
Published: January 2010

This paper is concerned with two different problems. The first of these is to correct a magnetic compass so that the essential relationships for zero deviation are maintained even when the ship rolls and pitches. The Harvey-Raynes corrector is described and its advantages are explained. This corrector makes it possible to steady the compass at any time without affecting the accuracy of the existing deviation card.

The second problem considered is the automatic correction of deviation for transmitting magnetic compasses. A system of ‘point-by-point’ correction is developed, based upon the representation of the deviating force by a truncated Fourier series; it is shown that such a truncated series may be represented mathematically in a form immediately suitable for practical application, some such forms being described in detail. It is shown that by means of a small additional device the ‘point-by-point’ type of corrector may be made to correct both variation and deviation, so that for any given part of the Earth the transmitting magnetic compass may be made to point true north.
The Collection of Radar-Meteorological Data
Authors: Hansford R. F.
Published: January 2010

The principles of radar-meteorology have been described by Lieutenant Satow in his paper. This note contributed by the Technical Secretary suggests a system for the collection of data from which a statistical evaluation of one aspect of the subject may be made. Bound copies of this paper with 25 log sheets may be obtained on application to the Institute, price 1s. 6d.—Editor.
An Improved Astrograph
Authors: Sadler D. H.
Published: January 2010

Although the Astrograph has never been formally described in print, the basic principles of the instrument are sufficiently well known to require no further elaboration; so also are its limitations. Over many years, numerous proposals (but mainly unpublished) have been made for the extension of the Astrograph to cater for the Sun, Moon, and planets, as well as for a larger number of stars, but none have been really satisfactory. Without such improvements the Astrograph must have a very limited use, and accordingly a further study was made some time ago of its application to the Sun, Moon, and planets. Methods were developed on familiar lines for shifting (and rotating) the star curves for a standard declination to cater for neighbouring declinations, but these introduced complexities that were clearly unacceptable.
Naval Compasses in 1707
Authors: May W. E.
Published: January 2010

The loss of Admiral Sir Clowdisley Shovel with several ships on the Bishop and Clerks on 23 October 1707, and the subsequent attribution of the disaster by Captain Sir William Jumper of the Lenox, 70 guns, to defective compasses, led to the compiling of reports on these instruments by the Commissioners at Chatham and Portsmouth, by order of the Navy Board. Captain George St. Lo, the Commissioner at Chatham, was at this time about fifty years of age. We first hear of him being appointed a Lieutenant of the Phoenix, 42, in 1678; he was made Post into the Dartmouth, 30, in 1682. With the three years qualifying service necessary before he obtained his first commission he must have had fourteen years almost continuously at sea before his career was cut short by his being severely wounded and taken prisoner when he had to surrender the sorely battered Portsmouth, 46, to superior French force in 1689. While a prisoner of war he took the opportunity to study the dockyard methods of his captors and this, with his reputation for steadfast opposition to all corruption, made him particularly suited to fill the post of commissioner in a dockyard. In 1707 he had already been five years at Chatham, following eight in Plymouth dockyard.
Dead Reckoning Procedures in Air Navigation
Authors: Fry R. H. , Wells P. J.
Published: January 2010

In the early days of air navigation, dead reckoning procedures were inevitably closely allied to those practised at sea, but the rapid development of aviation has considerably reduced these early similarities. To talk generally of D.R. practices is therefore no longer feasible. It is the purpose of this article to outline some of the air procedures and instruments in use, and to give an indication of the reason that lay behind their adoption.
Surface Currents of the Ocean and their effects on Navigation
Authors: Frankcom C. E. N. , Barlow E. W.
Published: January 2010

One of the earliest publications about ocean currents was Dampier's Discourse of Winds, Breezes, Storm Tides and Currents published in about 1700. Dampier wrote his book in 1688 and he says:

By currents I mean a motion of the sea which is different from the tides in several respects—both as to its duration and also as to its course; currents run a day, a week, nay sometimes more one way, then it may be, run another way. In some places they run six months one way and six months another. In some places they run constantly one way and never shift at all.

After some remarkably detailed discussion of currents in the West Indies and off the coast of Africa and in the south seas he says, of the Indian Ocean currents, ‘north of the line the current stays with the monsoon but does not shift altogether so soon, sometimes not for three weeks or more and then never shifts again till the monsoon is settled in the contrary way’. Of the Gulf Stream he says, ‘near the shores on each side of this Gulf there are tides, especially on the Florida shore, and ships may pass which way they please, if they are acquainted’. In conclusion he says, ‘I humbly offer this not as a complete and perfect account but as a rude and imperfect beginning or specimen of what may be done by abler hands hereafter’.
Some Practical Experience of Sea Clutter
Authors: Robb E. M.
Published: January 2010

It is widely known that whilst radar is almost unaffected by the densest fogs, some reduction of its performance must be expected in rain, and sometimes considerable reductions under conditions of very rough sea. Little practical data have been available to the mariner on the extent of reduction which may be expected in rough sea conditions and this short paper will attempt to provide some practical information on the subject.
Anti-collision Manœuvres when using Radar
Authors: Topley Hugh
Published: January 2010

When using radar in thick weather as an anti-collision warning device it is necessary, when planning any manœuvre, to consider the effect of the proposed alteration of own vessel's course and/or speed on the PPI presentation of the target vessel's radar, should she be using it. An alteration of course or speed of own vessel will alter the direction or speed of the apparent motion of the spot on the target vessel's PPI. As the apparent motion on relative plots kept by the two vessels are reciprocal images of each other it is a simple matter to determine, in any particular case, the effect on the target's plot of own vessel's manœuvre by considering the effect on the apparent motion on own vessel's plot.
Closed-Circuit Television as an Aid in Ship Control
Authors: Dean Peter J. , Lewis Ronald E. F. , Morphet R. O.
Published: January 2010

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.
Contour-Based Position Lines
Authors: García-Frías J.
Published: January 2010

Contour charts are of great value ‘providing’, as Hughes says, ‘the navigator with a quick and sure means of comparing the echo sound record he has just made with the variations in contour and so enabling him actually to plot his line of position by soundings’. But it is evident that the most useful method of using contour lines would be if the position lines based on them are plotted in the same way as every position line, i.e. by plotting the intersection of two or more of these lines. The object of this paper is to propose such a method.

It is possible to plot a contour-based position line by means of the sight line to one point of a contour line and its range, because if we draw (Fig. 1) from every point of contour line A, parallels of the same length to the sight line, all points at the other end of contour line define such a position line, which may be called a range-bearing (RB) position line. Better accuracy can be obtained by sextant, using a second sight line to the same or another contour line (Fig. 2), measuring the angle α between them—then we have a position line which may be called a two-range position line. When it is possible to measure the minimum range to a contour, the angular datum can be omitted, using the position line which may be called a mini-range position line.
Navigation of the S.S.T.
Authors: Villiers J.
Published: January 2010

As a general rule the navigational function is aimed at determining the position of the aircraft in order to resolve three types of problem:

(1) To subject the aircraft's flight path to an optimum trajectory calculated before departure or progressively adapted in course of flight to the circumstances encountered.

(2) To choose at each point of the selected flight path the flight system best adapted to the safety and economy of the flight.

(3) Taking into account the presence of other aircraft in the airspace, to know and make known the actual position and the information allowing provision to be made for future positions, so as to permit effective air traffic control.

Departures of the actual from the chosen flight path penalize the flight by a lowering of economy (in flying time or fuel consumption). It does not seem, however, that the problems raised from this point of view by S.S.T. are by nature or in difficulty any different from those which affect conventional aircraft. Taking into account the present-day precision of navigational aids there is every reason to believe that departures of the actual flight path from the optimum flight path will introduce a penalization which it is possible to ignore when compared with the penalization due to the inaccuracy of the knowledge of the elements (winds, temperatures, pressures) which have, in fact, served to determine this optimum flight path.
The Supersonic Aircraft and Air Traffic Control
Authors: Pailhas L.
Published: January 2010

It its early work, the Working Group decided to study amongst other subjects the problems of bringing the S.S.T. into a traffic control system; almost certainly there will be an effect on the flight profile of the S.S.T. and on the requirements for accuracy of the navigation. In the absence of special information on the characteristics and performance of the S.S.T., a study has been made of the trends in A.T.C. handling of terminal area traffic (T.M.A.). The term terminal area has been interpreted in its broader sense, that is to say the region in which present-day transport aircraft and a fortiori supersonic aircraft are not in the cruise phase but are either descending towards the destination airport or climbing from the departure airport. With this definition, the most important terminal areas (those in countries overflown by heavy traffic and in which there is a plenitude of radio navigation aids and control), have in practice the same limitations as the flight information regions in which they find themselves.

If we try to look ahead ten years to the period from 1965 to 1975, it is precisely in this period, in the countries overflown by heavy traffic, that the instruments and systems which have been recently devised and experimentally used to meet the problems of subsonic traffic control will, in fact, become operational. With these points in mind the following notes refer to the possible evolution of traffic control in the future.
Collision and Stranding at Sea
Authors: Deacon D.
Published: January 2010

Having studied marine statistics for a number of years, especially those concerning casualties at sea and in particular collisions between ships, the opening paragraph of the Traffic Separation Working Group's report (this Journal, 19, 4) is, to say the least, lacking confirmatory evidence on two counts.

I refer to the general statements which allege that:

(i) ‘The main risk at sea today arises not as it used to from stranding and shipwreck, but from collision’.

(ii) ‘In the open sea, where nearly 30 per cent of all collisions occur…’

As both include the words ‘at sea’ or ‘open sea’ it is not unreasonable to suppose that they imply freedom to manœuvre under own power unhampered by depth of water or similar navigational restriction.

This being so, and not an irrational definition of the area of concern to the Working Party, what are the facts and how exactly do casualties at sea compare with those in other areas of marine interest throughout the world.

To find the right answer to the global problem is not easy and there are no short cuts, such as for example making a sample analysis in a limited area where traffic density is high, in order to arrive at fairly large numbers which are then used to deduce the statistical probability applicable to all areas.
Radio-astronomy, Radiometry and Infra-red Techniques
Authors: Cade C. M.
Published: January 2010

The year 1932 was one which had no great apparent significance for navigators, and yet it saw the commencement of two new lines of research which today, after an interval of more than a quarter-of-a-century, promise important contributions to the safety of navigators both at sea and in the air.

The two lines of research were superficially quite unrelated, but fundamentally they relied upon the same principle—the detection of radiant energy emitted by objects solely as a result of their temperature. The first of these small beginnings was the discovery by K. G. Jansky that radio waves could be detected from extra-terrestrial sources: the second was the commencement by the U.S. Signal Corps Engineering Laboratories of an intensive study of infra-red devices with the object of obtaining night vision without illumination of the field of view.

From Jansky's discovery has sprung the whole science of radio astronomy, which has revolutionized our ideas about the universe, and brought in its wake, as one practical benefit, the radio sextant. From the work of the U.S. Signal Corps there resulted a number of very useful infra-red components, including the pneumatic detector, better known as the Golay cell.
The Port Arrival and Departure of Ships
Authors: Andrew James
Published: January 2010

In this paper presented on 17 June 1960, with Captain F. J. Wylie, R.N. in the Chair, the Harbour Master of Southampton considers the problem of coordinating shipping movements in a major port. The experience of Southampton is largely drawn upon and a description is given of the communications systems and the use of the harbour radar in that port.
III—The Potential Application of Doppler to Air Navigation
Authors: Williams J. E. D.
Published: January 2010

When motor-cars were first invented, they were sometimes called horseless carriages, so naturally some early automobiles were designed to look (as far as possible) like a horse and carriage without the horse. We may be in danger of making similar errors. Some Doppler Navigators appear designed to perpetuate methods of navigation which doppler itself should help to render obsolete.

Basically, the doppler phenomenon, measured in the aircraft, gives the aircraft's velocity relative to the reflecting terrain as a vector referenced to the aircraft's axes. In other words, angle of attack, drift and ground-speed are measured directly.

The possible application of this information to improved methods of aircraft operation is almost infinite in its variety. The ways of applying, for example, accurately measured angle of attack, to the take-off, approach and landing phases, or to performance analysis, are numerous. Perhaps the most wildly esoteric suggestion for the application of angle of attack information was that aircraft could be weighed in flight by doppler given equivalent air-speed and the lift/drag polar of the aircraft; unfortunately the question of how to obtain a usable accuracy was not precisely explained! Of course, if sufficient accuracy were possible in this application, we could have a rather novel fuel flow-meter since, on all well conducted flights, fuel flow = rate of change of aircraft weight.
Safety and Air Navigation
Authors: Stratton A.
Published: January 2010

With the growth of public air transport, safety in the air is a matter of concern not just to those who design, manufacture and operate aircraft, but to the public at large. After an accident has occurred and an unfortunate chain of events leading to the accident is exposed, it may be easy to say ‘this accident should not have occurred’ or ‘would not have occurred if…’. Publication of annual totals brings forth informed and uninformed comment on the apparent decrease or increase in the accident rate relative to some criteria such as the number of passenger kilometres flown. The objective of this paper is to present a scientific account of the evidence on the relationship between navigation and air accidents and the implications of this evidence for those who are professionally concerned with air navigation. As will become evident, how-ever, there are factors operating which go much deeper than the technical aspects and appear to have their roots in human behaviour, not just of the individual but of organizations and society as a whole.
Navigation in the Use of Helicopters Offshore
Authors: Van der Harten R. J. , Oprel A.
Published: January 2010

This paper, by the Deputy Managing Director and the Director of Operations of KLM Noordzee Helikopters BV., describes the operation of a 24-hour service now available for supplying pilots to ships entering the harbour of Rotterdam and for maintaining communications with North Sea oil rigs, with special reference to the unusual navigational problems involved. The paper, which was illustrated by a colour film, was presented at a meeting of the Institute held in London on 17 April 1974 with Captain V. A. M. Hunt, c.b.e. in the Chair.
II.—The Ergonomic Bridge
Authors: Mackay I. S. S.
Published: January 2010

In considering ships’ bridges, present and future, we must first look at the history of the bridge itself. In the days of sail it was necessary for the helmsman and Master to stand on the poop in order that they could watch the trim of the sails, and for the helmsman to get sufficient purchase on the wheel he had to stand up. With the introduction of steam it was necessary to stand as near as possible to the machinery so that orders could be passed by voice pipe and initially the ‘bridge’ was placed between the two paddle boxes. From here the quartermaster steered the ship and the Master passed orders to the engine-room by voice pipe or mechanical telegraph.
The Effect of Uncertainties on the Collision Problem
Authors: Parker J. B.
Published: January 2010

The theory of the problem of collision at sea has been formulated by many authors and the results of the theory have been used, notably by Morell, Hollingdale and Calvert, to establish practical manoeuvring rules to avoid collision. Any treatment which attempts to take into account the uncertainties in the information available to the navigator is bound to be technically difficult. It is arguable that a theory in which no account has been paid to the possibility of equipment errors is incomplete.
Anti-Collision Rules
Authors: Proctor J. D.
Published: January 2010

In the discussion on the theory and practice of collision avoidance, two areas have been particularly liable to dispute, namely the rules for direction of manoeuvre and for responsibility for manoeuvre. Where two craft meet, some propose a rule of manoeuvre direction fixed by relative bearing, others a flexible rule designed to increase initial miss distance. Some think both craft should manoeuvre (dual responsibility), others only one (single responsibility).
First Round the World: 1519–22
Authors: Taylor E. G. R.
Published: January 2010

In 1518 a Spanish gentleman, just back from the West Indies, addressed a Summary of World Geography to his King. In the Dedication he pointed out that since the Pope's Line, which parted the Portuguese and Spanish spheres, ran through the mouth of the River Amazon, 28°W. of Ferro, all the World beyond 150°E. (i.e. 130°E. of Greenwich) lay open to exploitation by Spain. And according to the World Map of the day the area included Java, Japan, King Solomon's Ophir, and (best of all) the Spice Islands or Moluccas from which the Portuguese were already making fabulous fortunes. This gentleman was not the only person to speak to the young King on this matter. The captains and pilots who had opened up the Spice Islands for Portugal were dissatisfied with the rewards which their own King had given them, and a number of them offered their services and their special and secret knowledge to his rival. Ferdinand Magellan was one of them. From his experience in the Far East he was of the opinion that the Moluccas could be safely approached from the west, by way of the Great Ocean. And it should be emphasized that in suggesting this he had no romantic notions about becoming the first man to circumnavigate the globe. He put forward a business pro position which the Spanish King accepted. Immediately the most thorough preparations were set on foot. They included the making of new charts, new globes, new sea-quadrants and sea-astrolabes, by the best pilots and craftsmen of the day, of whom the most were Portuguese.
The Presentation of Height Information in Aircraft
Authors: Honick K. R. , Stratton A.
Published: January 2010

The problem of presenting barometric height in aircraft altimeters is discussed. The alternative methods of presenting a numerical value are outlined and their characteristics analysed with reference to available comparative evidence providing a quantitative assessment. The properties of various methods of presentation are examined with reference to the varied uses of the altimeter. The conclusions are discussed with relation to the recommendations of the U.K. Altimeter Committee.

It is concluded that no single means of presenting height information will meet all of the roles in which the altimeter is used and that the recommended solution is a combination of a digital counter presentation giving an unambiguous height value combined with a circular scale and pointer rotating once per 1000 ft. providing rate and angular cue information for control purposes. Freedom of choice in presentation can only be achieved by the use of a servo-operated display.
Directional Echo-sounding
Authors: Howson E. A. , Dunn J. R.
Published: January 2010

A description is given of sea trials of two types of narrow-beam echo-sounder developed with a view to obtaining information as regards both the depth and the slope of the seabed. One system involves a two-channel interferometric arrangement, which provides a family of several spaced receiving beams; the other uses an eight-element hydrophone array with electronic sector-scanning of the resultant narrow beam. Photographs of typical displays show that comparable values may be derived for the slope of the seabed beneath the ship for both systems in simple situations. Difficulties in interpretation of the interferometer record with more complex slopes render the use of the electronically-scanned system advisable in such circumstances.
Decca Speed Trials
Authors: Verstelle J. Th.
Published: January 2010

The Decca method of conducting speed trials and its considerable advantages over other methods have been described in this Journal and elsewhere. Decca is nowadays widely and successfully used for acceptance trials (speed, calibration of (Sal) log, turning circles and (crash) stopways) by Royal and Merchant Navy ships of Britain, the Netherlands, France, Denmark, Sweden and probably of other nations.

The results of speed trials of Netherlands Merchant Navy ships are given in the present paper. Those of the equally successful turning circles and stopways are not given here, since their numerical results would be of little interest to the reader; a pictorial representation—among other things allowing for a comparison between various interesting turning habits of different ships—would be more suitable, but would occupy too much space.

Short Description of the Method. Each speed determination consists of 4 to 6 runs, alternatively in opposite directions. In each run 20 photographs of the decometers are taken at 30-second (or, for very high speeds of 30 kt. or more, 15-second) intervals and one single run therefore takes 9½ minutes. Specially calibrated Decca receivers are used to ensure a much higher accuracy than is achieved (and needed) for normal navigational purposes.

With the aid of special, large-scale, Decca charts or special tables, all these decometer readings—80 in 4 runs or 120 in 6 runs—are converted into rectangular coordinates X, Y.
‘Manœuvres to Ensure the Avoidance of Collision’
Authors: Calvert
Published: January 2010

Following the publication of E. S. Calvert's Manœuvres to Ensure the Avoidance of Collision (Journal, 13, 127) a number of people closely concerned with the problem of collision at sea were invited to comment on Mr. Calvert's ideas. This comment was published in Vol. 13, Nos. 3 and 4 (pp. 350–352 and 455–464). Mr. Calvert here replies to some of the criticisms. The paper he refers to as his latest will be published in the October number of the Journal.

to Captain H. D. Harries

Without a more precise definition of ‘open sea’ and ‘crowded waters', I doubt if any figure for the proportion of collisions in each has much meaning. (The same kind of difficulty arises in defining a ‘near miss’.) More precise figures might possibly be obtained by giving the proportion of collisions which occur within so many miles of the mouth of a channel, a channel being defined as an area where local or ‘edge’ rules are in force, or where the traffic is controlled. However, I doubt whether the use which could be made of such statistics would justify the trouble of collecting them. In my latest paper, i.e. the one to be published in the next issue of the Journal, I have given what I believe to be the only possible solution to the crowded-water situation, in so far as rules can provide a solution.
The Accuracy of Predictions from Primary Radar and Secondary Radar
Authors: Marshall F.
Published: January 2010

In conditions of poor visibility it is common practice to plot radar measurements of the range and relative bearing of other ships with respect to own ship and to deduce the relative tracks and passing distances. Radar equipment is available which can to a greater or lesser degree relieve the navigator of the tedium of plotting, and which could be developed into aids of considerable sophistication within the limits set by their cost. However, errors in measurement limit the precision with which relative tracks and passing distances can be computed. An alternative to radar plotting would be a data link between ships to broadcast measurements of course and speed on demand; a radar transponder would transmit the required information in coded form.

This suggestion is highly controversial, but it seems worthwhile to derive the mathematical relationship between errors in the data and the ensuing error in the calculated passing distance and to compare the errors using radar data and transponder data. The value of the comparison is however limited because likely errors in the data are not accurately known. The analysis of the radar plotting method is probably of interest in itself because the deficiencies of the method are derived with some rigour.
Three Classic Collisions
Authors: Fricker F. W.
Published: January 2010

In this paper, based on an article printed on the back of the March 1973 issue of the Pilot Chart of the North Atlantic Ocean, Mr Fricker analyses three collisions that emphasize the necessity for adhering to the concepts of prudence and safety underlying the Rules of the Road; they are no less essential when navigating by radar in reduced visibility. Terms such as ‘right rudder’, readily understood, have not been altered to conform to English Martime parlance.
Manœuvring Large Ships in Shallow Water—II
Authors: Hooft J. P.
Published: January 2010

This paper is a sequel to the author's paper under the same title published in the April issue of the Journal.
Error Synthesis
Authors: Lord R. N.
Published: January 2010

This paper discusses the drawbacks of observational methods of analysing navigational errors and shows the advantages of a synthesizing technique, whereby the effect of any change in the magnitude and distribution of a component error upon the overall resultant error can be evaluated and examined. To this end a computer program has been developed which is capable of accepting both analytical and numerical statistical distributions, representing errors in the components, and combining them to yield the overall effective error. A new error distribution better representative of many navigational error distributions is introduced. The work described is applicable to the investigation of any error which depends upon the interaction of many component errors and is not restricted to the navigation field. An extension of the method to mixed samples is indicated.

The paper describes the final step in the development of a universal computer program aimed at synthesizing navigational errors in order that they can be used in evaluating their effect on any proposed A.T.C. system. The investigation was commenced at the College of Aeronautics in 1963 and has been the subject of several published papers during the interim period.
Some Comments on the Regulations for Preventing Collisions at Sea, 1972
Authors: Wylie F. J.
Published: January 2010

A careful study of Parts A and B of the new Regulations as far as the application of the Steering and Sailing Rules is concerned leaves one disappointed and apprehensive. The first because an opportunity for considerable rationalization has not been fully used and the second because the corner-stone of the edifice of safety which for many years has supported the careful seaman has been knocked out. Apart from these there is a number of ambiguities.

It will be realized at once, of course, that these words are being written by one of the old school who has for several years opposed the more fundamental changes and to whom, since he first went to sea some sixty years ago, the old Rules covered with a minimum of verbiage the infinite variety of maritime circumstances and conditions. Additionally, having studied most of the collisions which have brought shipowners to Court, he has found none in which the Rules were faulted, but a vast majority in which human frailty in the form of misappraisal of the circumstances or conscious disobedience of one or more of the simple Rules had been the cause of disaster.

The corner-stone referred to above was the clear division of responsibility between the two parties to a situation involving collision risk in both the crossing and overtaking encounters.
The Future of the Knot as a Unit of Speed
Authors: White G. J. A. , Stewart O.
Published: January 2010

Stewart very rightly draws attention to the practical value of the knot as a measure of velocity. In so doing he underlines one of the defects of SI: the essential simplicity and uniformity so attractive when considered in abstract becomes rather blurred when put into practice. The knot falls completely foul of SI; neither the unit of length nor that of time is an SI unit. The practical application of both units illustrate the difficulties well.

The choice of a standard set of prefixes to units, each separated by a factor of 1000, is both logical and convenient. One need never write down a number less than unity or greater than 999·999. … If the number is 1000 or more, it is divided by 1000 until it does lie within these limits and the appropriate prefix added to the unit. If it is less than unity, multiplication is substituted for division. For length measurements one starts with the metre and goes up to the kilometre, or down to the millimetre, micrometre and so on. Perhaps the only person whom this does not suit is the astronomer who is likely to prefer the light-year (approximately 10 metres, the index 16 being outside the range of prefixes) or the parsec (2·46 light-years).

The world, however, is not a linear one and difficulties start when one measures areas.
An Anti-collision Indicator
Authors: Mitrofanov O.
Published: January 2010

The problem of collision-avoidance at sea by means of radar is constantly under discussion in maritime circles within the U.S.S.R. This paper, and that of Captain Bukhanovski (Journal, 20, 247,), describe one direction of research that has been actively pursued in the Soviet Union.

The device described was developed by the Central Scientific Research Institute for Water Transport for the Ministry of Merchant Marine and sea trials were carried out in the Black Sea during the summer of 1962. The present paper describes the principles of the device and the performance during trials. It has been prepared for publication in the Journal in collaboration with Captain G. Shoomayko.

Articles on the prototype have appeared in Morskoi Flot (no. 122, 1959, no. 2, 1964), Die Seewarte (Hamburg, October 1961) and Navigation (Paris, July 1962).
A Controlled Azimuth Avoidance Manœuvre
Authors: Lord R. N.
Published: January 2010

The advantages of a standardized avoidance manoeuvre as distinct from a late collision avoidance manoeuvre are discussed with reference to passenger comfort. The general use of plan type displays suggests the possibility of having a standard manoeuvre based upon turning one aircraft on to a new heading.

An analysis of this manœuvre was undertaken in order to obtain data as to the closest permissible approach between pairs of aircraft on various collision courses. Results show that the permissible closure is smallest if the faster of the two aircraft is manœuvred, and that little is gained by changing the heading by more than 30°. The results of this type of analysis can assist also in the programming of the computer in a future automated A.T.C. system.
II—Autolanding and Safety
Authors: Mayes D. J.
Published: January 2010

Before an aircraft is given its Certificate of Airworthiness the aircraft constructor has to satisfy the Air Registration Board that the standards laid down in the British Civil Airworthiness Requirements (B.C.A.R.s) have been met. However, if you go to B.C.A.R. and try and find something under Instrument Approach Criteria, you will be unlucky. This is because the requirements for low weather minima and blind landing operations are still in the form of A.R.B. Technical Notes and working drafts. This state of affairs has come about because of A.R.B.'s reluctance to become bureaucratic and devise arbitrary rules and regulations concerning an operation as new as automatic landing.
Long-range Navigation Techniques for the Supersonic Transport
Authors: Waldman R. H.
Published: January 2010

In this paper, presented by the International Air Navigators Council, and written by its Executive Vice Chairman, the navigation of the S.S.T. is considered from the practising navigator's point of view. Extrapolating from present procedures the conclusion is drawn that navigation system verification should continue to be the responsibility of flight-deck management, that self-contained D.R. systems should be monitored by an externally referenced aid, that raw navigational data should continue to be available to the flight crew and finally that simplicity and reliability in navigation systems should be preferred to finite accuracy.

Consideration of an environment in which operational data and experience are limited to the military is a difficult assignment at the best of times. In order to discuss, with some degree of intelligence, the long-range navigation system considered desirable in the supersonic environment, we have relied mainly on the process of extrapolation using existing data and operational ‘know how’ to formulate practical guidelines.
Navigation and Education
Authors: Anderson E. W.
Published: January 2010

This year, the subject for the Duke of Edinburgh Lecture was chosen by the President and the Council as a result of recommendations made by the Educational Sub-Committee. Although the lecture was to be an individual contribution it was to have the full help and support of the Institute. Without this, the lecture would have been impossible, and therefore it seemed necessary to make acknowledgments at the outset.

Help has been given most freely and generously by many Fellows and Members, and in particular by the President, Professor A. Stratton, by Dr. G. E. R. Deacon, F.R.S., the Chairman of the Educational Sub-Committee, and its members, Captain C. H. Cotter and H. E. Smith, by D. H. Sadler, the Chairman of the Membership and Fellowship Committee, by Captain F. L. Main, a member of the Council, and by M. W. Richey, the Executive Secretary. Further invaluable suggestions came from many sources outside the Institute, notably from Dr. A. Clow of the B.B.C., J. A. Edgar of the Department of Education and Science, Dr. H. F. Huddleston of R.A.E., Farnborough, and Professor S. Sutherland of Sussex University. Finally, a very special word of thanks to B. W. Lucke, Schools Inspector, Liverpool. This paper owes a great deal to his ideas and to his inspiration.
Revised Rules for Preventing Collisions at Sea
Authors: Thompson P. A.
Published: January 2010

In the July number of the Journal there appeared a series of contributions on the revision of the Collision Regulations, preceded by an introductory note which referred to a number of the more important papers on this subject published in the Journal during the last ten years. Partly as a result of this series of contributions, and of a questionnaire recently circulated by the International Chamber of Shipping, Captain Thompson, Master of the S.S. Magara, after discussion with those concerned with the Rules on board his vessel, has drawn up, for general discussion, draft revised Collision Regulations. Naturally they depend heavily on ideas published in the Journal and elsewhere; indeed their particular value is that they take account of many of these ideas and attempt to express them in a practical and seamanlike fashion. Clearly there are loopholes in the draft: it is the work of seamen, not lawyers. What matters at this stage is the intention, which is to provide rules and a code of conduct which are simple, unambiguous and clear. Commander P. C. H. Clissold made some useful comments on the original draft.

Of those who took part in the discussion on the Collision Regulations published in the Journal (22, 285), some favour amending the present rules. and others refraining them completely. There are grounds for thinking that a similar dissension exists among seamen.
Rhumb-line and Great-circle Sailings
Authors: Llewellyn M. R. H.
Published: January 2010

A student of navigation who refers to the standard textbooks will be confronted with a multiplicity of sailings which are said to include plane sailing, parallel sailing, middle or mid-latitude sailing, mean latitude sailing, traverse sailing, short distance sailing using rhumb-line formulae, mercator sailing, great-circle sailing, approximate great-circle sailing, composite sailing and composite greatcircle sailing. To the student it may seem a reasonable assumption that so many differently named sailings are based upon as many different ways of taking a ship from one position to another, which is of course a nonsense.
Sailing Vessels and the Collision Regulations
Authors: Richey Michael
Published: January 2010

It is to be hoped that before the Collision Regulations are revised in any sense that affects the rights and obligations of sailing vessels, people with practical experience of navigation under sail will be consulted. It looks as though their advice will be needed.

One increasingly hears, for example, that under modern conditions steam should no longer be required to give way to sail. ‘It seems quite unreasonable now’—Captain Dickson, for instance, expresses it in the last number of the Journal (22, 448)—‘to expect in most cases that sailing vessels should be required to stand on for power-driven vessels’. But the reason a power-driven vessel is required to give way to sail is not some kind of old world courtesy, but that if there is no wind, the sailing vessel is immobilized: it cannot give way.
Underkeel Clearance
Authors: Dickson A. F.
Published: January 2010

The problem of underkeel clearance is not new; since time immemorial navigators have been concerned to know the minimum depth of water in which they can sail with a ship of given draught. Until quite recently, underkeel clearance requirements were determined almost entirely empirically, and in many cases the rule of thumb values used can be shown to be greater than the requirement of navigational safety would dictate.

In the years since the war the pattern of the oil industry has changed and very large ships are now commonly used to carry crude oil cargoes to a large number of ports around the world. It is obvious that use of these ships, with their deep draughts, has meant that a number of expensive dredging projects have been put in hand to provide adequate access to the ports served. Continuing escalation in size means this will probably continue.
Distribution of Jet Streams at 200 mb. in the Middle East
Authors: Crossley A. F. , Parkinson I. N.
Published: January 2010

1. INTRODUCTION. The distribution of jet streams over the North Atlantic, Europe and the Mediterranean for the two years 1957–8 was described in an earlier paper (Crossley, 1961); the present paper extends the study to the area which is here referred to somewhat loosely as the Middle East —it extends between latitudes 40° N. and 10;° N., and from longitude 30° E. to 90° E. in the north but to only 65° E. in the south (Fig. 1). The aircraft trunk routes intersecting this area include those from the Eastern Mediterranean across Arabia and the Persian Gulf to West Pakistan and north-west India.

The jet streams which affect the Atlantic-European area in the upper troposphere are mostly of the ‘polar’ type with a core in the neighbourhood of 300 mb. so that they can be conveniently located as a rule on the contour charts for 300 mb.; in the Mediterranean region and in the corresponding latitudes of the North Atlantic the westerly subtropical jet stream is also concerned and charts for both 300 and 200 mb.
The Testing of Airborne Inertial Navigation Systems
Authors: Carr J. G. , Scott Leader D.
Published: January 2010

The limitations to the accuracy of an inertial navigator are first of all the inherent accuracy of the inertial components—gyros and accelerometers; secondly the accuracy with which these are controlled, i.e. by power supplies, and electronic circuitry; thirdly the accuracy of the associated navigation computer. All these three can be checked during manufacture and by laboratory testing of components and systems. However, there remains the effect of the aircraft environment on accuracy. It is possible to simulate some of the environment, for example vibration and temperature, in the laboratory, but it is not possible to simulate realistic accelerations, velocities and displacements, and so flight trials form an essential part of the evaluation of an inertial system. Flight trials may be preceded by trials in a land vehicle on grounds of economy, but such trials are of limited value because of the limited velocities and displacements available. In this paper we shall attempt to summarize our experience at R.A.E. and A. & A.E.E. of laboratory, van and flight testing of inertial navigators which has been acquired in joint trials over the past five or six years. During the next twelve months we shall be associated in trials of three further inertial navigators, the Elliott E5, the Sperry SGN 10 and the Ferranti FMP-B, and we shall also describe in this paper some of the techniques which will be used for the first time in these trials. This is not intended to be an exhaustive treatment of system testing, but will be mainly confined to the systems and tests of which we have practical experience.
Inertial Navigation System Testing 1967
Authors: Amacker J. Z.
Published: January 2010

The Central Inertial Guidance Test Facility (C.I.G.T.F.) at Holloman Air Force base, New Mexico, has the responsibility for testing all aircraft inertial navigational systems, aided and unaided, for Department of Defence applications. From 1963 to the present, ten systems have been evaluated. The experience derived from past test programmes has always been valuable to the C.I.G.T.F. engineers in the design of increasingly sophisticated programmes.

This paper retraces some of the experience of the C.I.G.T.F. in its inertial navigation system testing. Test philosophy, objectives and approach are discussed briefly. Flightpath design, radar coverage, range instrumentation, aircraft instrumentation, data reduction and analysis of system performance are then considered. In addition, some mention is made of the test programmes presently being designed, and the technical problems of INS evaluation that the C.I.G.T.F. is now attempting to resolve. Because of the breadth of subject material, ideas are presented mostly at the concept level. Technical details are contained in the references.

The C.I.G.T.F. test method is to fly the test specimen within the coverage of the FPS-16 radars or other instrumentation of the White Sands missile range. An airborne tape recorder records where the system ‘thinks’ it is, along with a range reference time signal (irig-b). Likewise, the FPS-16 radar site records where the radar ‘knows’ the aircraft is, referenced to the same time base. Post-flight data reduction compares the outputs of system and reference at each sample/time, and forms an error plot of the differences in position in each channel. This is the basic error data used to describe system performance.
The Automation of Ships' Navigational Systems
Authors: Ph. Nœtinger
Published: January 2010

It is now two years since a working group set up under the direction of the French Institute of Navigation at the instance of the Secretariat d'Etat á la Marine Marchande delivered a report which was the fruit of a thirteen-months study of the various possibilities of bridge-automation for commercial shipping.

The terms of reference of this study embraced a ship all of whose essential functions were under the control of a central computer, the system, briefly including:

A dead reckoning loop (ship computer dialogue);

A heading speed conversion loop (officer computer dialogue);

An observation calculation loop (officer computer dialogue);

An anti-collision control loop (radar computer dialogue).

Naturally since this was a formal study, the most complete and complex case was examined, and the approximate cost of the data-handling equipment for such a ship was estimated to be of the order of two million francs.