This paper, which was presented at an Ordinary Meeting of the Institute held in London on 20 November, 1964, presents the results of a study on the interrelation of cruise fuel consumption, temperature and track selection in supersonic transport operations on the New York–London/Paris route. The range of temperature variations at S.S.T. altitudes over the North Atlantic for 26 months is illustrated and from this data period 24 cases are chosen to reflect extreme departures from standard and to give a seasonal distribution of such variation. The results of the application of a computerized nasa programme to these 24 cases to determine whether diversion from the great circle is warranted, in terms of economy of cruise fuel consumption due to existing temperature gradients over the area, are then discussed and illustrated.

The results of a general solution, taking into account all these considerations, applied to an additional 117 cases are also discussed and illustrated. Finally the influence of climb fuel consumption upon cruise fuel consumption and data requirements for temperature forecasts in climb and cruise are discussed.

Every collision situation implies the existence of a sector within which any course steered will lead to a dangerously close approach and a sector within which the danger of collision will be avoided. The definition of these sectors may be said to constitute the structural aspect of the collision problem. The appropriate manœuvre in a given situation constitutes the operational aspect. The structural aspect is fundamental to the problem itself, the operational aspect offers possible solutions. The Steering and Sailing Rules involve the structural aspect because this is the only basis for legal rules.

In proposing a Sector Rule for use with radar in conditions of bad visibility, it is intended to establish a structural basis for legislation. In its most general terms, the Sector Rule is based on the principle that if the radar echo of another ship is always at an angle to one's own course determined by the speeds of the two vessels, their distance apart and the safe passing distance, then one's course lies within the safe sector for collision avoidance.

In this paper, which is a revised and up-dated version of an article which appeared on the back of the United States Pilot Chart of the North Pacific Ocean for May 1964, Mr. Fricker, a member of the Maritime Safety Division of the United States Naval Oceanographic Office, first of all analyses world-wide statistics of collision at sea on a geographical basis. He highlights the results of an investigation conducted by the U.S. Coast Guard into the conditions surrounding marine collisions; taking into account the results of this enquiry the author then goes into the common causes of collision. The paper then reviews the whole subject of radar and collision and the interpretation of the Collision Regulations in relation to the use of that aid. Certain collision counter-measures such as particular radar displays, improved lights and sound signals, bridge to bridge communication, &c. are then discussed.

Since January 1962, waves have been recorded by a shipborne wave recorder (Tucker, 1956) on the Sevenstones light-vessel which is stationed about 20 miles south-west of Land's End in about 200 ft. of water. Records were taken at three-hourly intervals and were mostly of 12 minutes’ duration. The analysis presented here is based on 2920 records taken in the first year of operation; the method of analysis which has been used is that described by Tucker (1961). This gives for each record:

(a) H1 = The sum of the distances of the highest crest and the lowest trough from the mean water level.

(b) Tz = The mean zero-crossing period.

(c) Tc = The mean crest period.

Radar was introduced as a navigational aid at the end of the last war. In spite of its introduction collisions soon began to occur again and even to increase in frequency with the increase in the number of radar sets in use. Evidence accumulated, and its examination and correlation revealed a systematic pattern of accident. This led gradually to the formulation of a code, officially promulgated in 1960 by the International Conference on Safety of Life at Sea.

It may be surprising that so long should have elapsed and so many accidents occurred before this was achieved, but the fact remains and should never be forgotten: even more so as things are still continuing the same way. Collisions still take place, and though it is difficult to determine the exact nature of the general trend, it certainly shows no sign of producing the spectacular drop we all hope for. Recently Captain Weekes, in this Journal, regretted the complete ignorance among the majority of seamen of papers and discussions on collision risks and the means of avoiding them, and hoped that steps would be taken to make them more widely known.

It is never easy to convert theory into practice.

This article is based on a series of circulars compiled for and issued to shipowners and their ships. In the October number of this Journal, Captain Wylie dealt with the limitations of true-motion displays at slow speeds and of plotting when courses and speeds are varying. The present article groups relevant extracts from court cases and enquiries under the various points in the Collision Regulations. (Dates given refer to the court hearings.) Subsequently it discusses certain manoeuvres and radar practices and their effects on collision hazards.

The purpose of this paper is to discuss en-route separation criteria applicable to the supersonic transport. Separation standards are described; equations are given and analysed which show the factors influencing separation; finally, suggestions are made for a supersonic transport air traffic control system for the North Atlantic. The discussion is concerned with longitudinal and lateral en-route separation in a non-radar environment, as opposed to radar separation in the terminal areas. The terminal problems are so complex as to require separate consideration and have been investigated by other authors. An appendix on the derivation of equations expressing statistical parameters of errors and estimated aircraft separation has here been omitted.

Much is written about the use and misuse of radar, but little has been said of what the mariner really needs to help him in his use of radar as an aid to avoiding collision in fog. In considering this, one must have particularly in mind the bridge on which the radar observer is also the watch officer and navigator.

It is generally accepted that he needs to be sure which targets are potential hazards and this must include those with whom the collision risk will be increased by alterations of his own course and/or speed, made to avoid others or in the course of navigation. In the commonly encountered multi-ship situation, there will, therefore, be several ships, maybe six or eight, about which detailed and up-to-date information is highly desirable.

This detailed information is of two kinds, relative to own ship and true. The relative data gives the degree of risk of collision of each target, in terms of the C.P.A., or closest distance of approach on present courses and speeds, and the time interval before this position would be reached. As a means of assessing priorities, the time is just as important as the distance. The bearing of the C.P.A. is less important, except in so far as it indicates on which side the other ship would pass.

The true information required comprises the courses and speeds of the other ships for which the degree of risk is significant.

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

Latitude by meridian altitude is one of the commonest position lines used in the Merchant Navy today, and the traditional method of obtaining it is to observe the Sun until it reaches maximum altitude, at which point it is said to dip. With the advent of power-driven vessels, however, this method became liable to an error of 5 minutes of arc, and as faster surface craft are developed it is reasonable to assume that the error could be even greater. This is because the rate of change of altitude of a body is related to the observer's speed over the Earth so that the body will dip either before or after meridian passage depending on whether the observer is moving towards or away from the geographical position of the Sun.

D. H. Lewis, in his article ‘Ara Moana: Stars of the Sea Road’ in the July 1964 issue of the Journal of the Institute of Navigation (pp. 278–88), speculates on how the Polynesians could have navigated to known distant destinations, but does not explain how the knowledge of die distant destinations on which he relies for his theories was gained by the supposed navigators. Before anybody can navigate to somewhere, someone must first have gone there and come back. Lewis does not tell us how the Polynesians gained their knowledge of the existence, location and size of New Zealand and Hawaii, and of the currents on these courses, on their outward voyages of discovery, and then used this knowledge to get home again. His statement that ‘it seems probable that the Polynesians steered by horizon stars until the zenith star showed that they had reached the right latitude, and then turned east or west’, obviously has no application to voyages of discovery which by definition were made without prior knowledge of the existence, latitude or size of the objectives. The alternative supposition that the discoverers were able to keep account of their courses from bearings on stars which were reputedly aligned with the destinations and the home islands overlooks the fact that such star bearings gave no clue whatever to longitudinal displacement. There was no practicable method whereby the discoverers could have known the longitudinal relationships of their discoveries and their home islands.

I have read with interest Colin Jack-Hinton's article ‘The Use of Apparent Consistency in Errors of Latitude in the Identification of 16th and 17th Century Pacific Islands Discoveries’ in the July 1964 issue of the Journal of the Institute of Navigation (pp. 311–13). Jack-Hinton takes as his main target the two instances in my book The Discovery of the Pacific Islands in which I used persistent or steady southerly error as an aid to or basis for differentiations between atolls situated north and south of each other, namely Mendaña's Los Bajos de la Candellaria in reference to Roncador Reef and Ontong Java, and the first atoll seen by Le Maire after leaving the Home Islands in relation to Ontong Java and Nukumanu.

The whole question of Polynesian navigation is highly controversial. Dr. David Lewis's paper ‘Ara Moana: Stars of the Sea Road’, in the July issue of this journal, prompts me relate the story of Kau Moala in somewhat greater detail and to assess his achievements and motives, largely from his own account of his voyages.

Kau Moala was a Tongan Chief renowned for his epic feat of navigation which probably took place in the years just before 1800. The details come to us from a young English castaway named William Mariner, who spent several years in Tonga and knew Kau Moala personally. When Mariner got back to England his experiences were compiled by J. Martin and published by John Murray, London, in 1817. The work is generally known as ‘Mariner's Tonga’, the full title being An Account of the Natives of the Tonga Islands. The story of Kau Moala's famous Odyssey is given on pages 307–322 of volume I of the second edition, published in 1818. Mariner gives the Chief's name as Cow Mooaly.

The story starts with Kau Moala going from Tonga to Fiji to engage in some warlike adventures to enhance his prestige, as many another Tongan Chief had done before, and as several did later. After two years of fun and mischief he decided to return home, and set out in his large double canoe.