In this paper, which was presented at an Institute meeting, held in Britannic House in London on 1 December 1970, the Chief Marine Superintendent of the BP Tanker Company examines the problems of operating large merchant vessels in the Arctic and describes the experience gained from the two voyages of S.S. Manhattan through the North-West Passage. The chair was taken by the President, Rear Admiral G. S. Ritchie, C.B., D.S.C, Hydrographer of the Navy.

Det Norske Veritas is a Norwegian ship classification society with a large classified fleet registered in 94 countries. The paper printed below was presented by Mr Cuming at an Ordinary Meeting of the Institute held in London on 18 May 1983 with Dr J. F. Kemp in the Chair.

Risk analysis is a method of evaluating potential risks which has been used for the past ten years by Det Norske Veritas, in both the shipping and the offshore fields of operations. The method is based on the systematic identification of hazards, the estimation of probability of occurrence and the evaluation of consequences.

A paper by Captain J. F. Kemp under this title was published in the April number of this Journal together with some comments on these proposals. Further contributions to the discussion and a reply from Captain Kemp are printed below.

In the April issue of this Journal Captain Kemp has put forward a carefully considered proposal for making the Rule of the Road more effective. His proposal is well considered because he is aware of the audacity which its careful presentation conceals; he is also careful to suggest a change in the Rules only as a basis for discussion. His suggestion is precise, for it is simply to extend Rule 18 to all encounters, or in other words to require both vessels, when crossing or overtaking, to rotate the line of sight in the normal direction as required in Rule 18.

The ability to map terrain by means of an airborne radar raises many possibilities. Some few years ago it was recognized that a mapping radar which scanned to the side of an aircraft (rather than ahead) might, additionally, have important military potential. The research described here concerns the early operator evaluation of a prototype sidescan equipment which promised, among other things, to permit accurate fix-point navigation at lower flight altitudes.

By recent standards our aircraft was to progress at a fairly gentlemanly rate, somewhat below the speed of sound. Hence the radar map, produced as a moving strip by a rapid photo-development technique, did not threaten to flash past the navigator's eyes at an impossible speed. Nor, in general, did we expect the operator to be provided with anything unsatisfactory in the way of briefing. What is more, the navigator would be able to devote his undivided attention to the radar material whenever a fix-point was due.

Judging from what is written in early Sailing Directions and navigation manuals it would appear that seamen of North-west Europe laid great store in their knowledge of the nature of the bottom in the seas in which they traded. And indeed, even at the present time, mariners are provided (although they may seldom use it) with fairly detailed information about the sea-bed, designedly to assist them in pilotage. A navigator may read, for example, that:

‘The bottom in the Western Approaches appears to consist, mainly of fine or coarse sand, a great deal of broken shell, occasional patches of pebble, gravel, small stones, and, now and then, mud. The sand is mostly white, but in numerous places yellow sand and also black specks are met with…. The greater proportion of yellow sand is found to lie southwards of 49°30′ N and the far larger portion of black specks northwards of that line. This peculiarity is so marked, especially between 9°40′ and 7°30′ W that the mariner running eastwards, and supposing his vessel to be to the southwards of this parallel, should certainly suspect his having been set northwards of his reckoning if the soundings disclose this mixture of black specks to any great extent and with any frequency.’

The regulations governing visual avoidance of collision in the air and the carriage of aircraft lights were originally based on marine practice and extended to include the third dimension in aviation. These regulations were established first by the International Convention for Air Navigation and finally by the International Civil Aviation Organization.

In a recent paper I endeavoured to give a statistical solution of the problem of the separation of aircraft tracks with safety. In it I assumed that the distribution of errors of navigation made by the aircraft was a normal gaussian one; but I added a proviso that the effects of blunders might modify the result. From enquiries of various navigators as to the frequency with which they considered they were likely to make blunders I gathered that with a good navigator an undetected blunder might occur on 1 per cent of occasions and further it seemed reasonable to assume that a blunder might be defined as an error greater than three times the standard error of normal navigation. These assumptions are of course quite arbitrary but they seemed to be suitable to give examples of the effect on track separation; this was done in an unpublished paper. In these examples it was supposed that aircraft flying in the same direction were using two parallel tracks distant L apart and on each track aircraft were flying at fixed intervals but quite independently of the aircraft on the other track.

It was on the river Rhine that radar started its inland waterway career, followed almost immediately by the inland waterways in the Netherlands. In those days the inland waterway fleet was composed of ships owned by a few large companies and ships owned by their skippers.

To the layman navigation may sometimes appear as an old lady whose fads have acquired the sanctity of tradition. In every tradition, however, there is something venerable; and we would be very wrong to laugh at the traditions of the sea, for they are a legacy we have inherited from all our seafaring ancestors since the days of Noah.

The core of this inheritance is the notion of freedom. For centuries the freedom of the seas was absolute and unconditional; all men were free to use the sea, for no man can plant his flag on its restless immensities; and all were free to choose their routes and navigate as they pleased, for encounters at sea were so infrequent that it would be only a most uncommon stroke of ill-luck that produced a collision between two vessels in the vast emptiness of the oceans.

In May 1948 the Radio Technical Commission for Aeronautics, a cooperative association of United States government and industrial air telecommunication agencies, issued a report outlining a comprehensive scheme for the development of air traffic control facilities in U.S.A. for the next fifteen years. This report was prepared by a committee set up by the R.T.C.A., Special Committee 31, and it is generally known as the SC31 Report. It was the result of a study undertaken at the request of the Technical Division of the Air Coordinating Committee, an inter-departmental committee established by the Secretaries of State, War, Navy and Commerce, and directed by the President to examine aviation problems of mutual concern and to develop and recommend integrated policies and actions to be taken for their solution.

At the end of a conference held in London in June 1957 to discuss the avoidance of collision at sea and in the air, it was recommended that the three sponsoring bodies (the British and French Institutes of Navigation and the Ausschuss für Funkortung) should set up a representative Working Group to study the desirability of amending the Collision Regulations to take into account the use of radar.

The Group, which was formed in January 1958, was composed of the following members, not all of whom were able to attend every meeting: Commander P. C. H. Clissold (School of Navigation, University of Southampton), Captain W. H. Coombs (Honourable Company of Master Mariners, Barrister at Law), Captain R. Dublineau (Compagnie Générale Transatlantique), Captain P. Dupuy (Compagnie des Chargeurs Réunis), Captain H. Giessler (Ausschuss für Funkortung), Captain H. D. Harries (Regierungedirektor beim Bundesminister für Verkehr), Vice-Admiral K. Hoffman (Bundesverkehrsministerium), Professor P. Hugon (Professor Général d'Hydrographic, Rear Admiral, Ret.), Captain E. H. Ketels (Verband Deutscher Radar), Captain Le Bihan (Compagnie des Messageries Maritimes), Captain G. Lohmnitz (Norddeutscher Lloyd, Bremen), Captain P. Marchand (Ocean Weather Ship Service), Dr. F. W. Marienfeld (Bundesverkehrsministerium), Captain D. G. Tait (Honourable Company of Master Mariners), President Dr. R. Vogler (Bundesoberseeamt, Hamburg), Captain F. J. Wylie, R.N. (Director, Radio Advisory Service), Captain C. J. Wynne-Edwards, R.N. (Director, Compass Department, Admiralty Compass Observatory). The members of the Group served only in a personal capacity.

Introducing the notion of a pseudoloxodrome, we generalise a single-heading navigation to conformally flat Riemannian manifolds, under the action of a perturbing vector field (wind, current) of arbitrary force. The findings are applied to time-optimal navigation with the use of the Euler–Lagrange equations. We refer to the Zermelo navigation problem admitting space and time dependence of both a perturbation and a ship's speed. The necessary conditions for single-heading time-optimal navigation are obtained and the pseudoloxodromes of minimum and maximum time are discussed. Furthermore, we describe winds which yield the pseudoloxodromic and loxodromic time extremals. Our research is also illustrated with the examples in dimension two emphasising the single-heading solutions among the time-optimal trajectories in the presence of some space-dependent winds.

Spherical trigonometry formulae are widely adopted to solve various navigation problems. However, these formulae only express the relationships between the sides and angles of a single spherical triangle. In fact, many problems may involve different types of spherical shapes. If we can develop the different formulae for specific spherical shapes, it will help us solve these problems directly. Thus, we propose two types of formulae for combined spherical triangles. The first set are the formulae of the divided spherical triangle, and the second set are the formulae of the spherical quadrilateral. By applying the formulae of the divided spherical triangle, waypoints on a great circle track can be obtained directly without finding the initial great circle course angle in advance. By applying the formulae of the spherical quadrilateral, the astronomical vessel position can be yielded directly from two celestial bodies, and the calculation process concept is easier to comprehend. The formulae we propose can not only be directly used to solve corresponding problems, but also expand the spherical trigonometry research field.

We investigated the contribution of visual imagination to the cognitive mapping of a building when initial exploration was simulated either visually by using a passive video walk-through, or mentally by using verbal guidance. Building layout had repeating elements with either rotational or mirror symmetry. Cognitive mapping of the virtual building, determined using questionnaires and map drawings, was present following verbal guidance but inferior to that following video guidance. Mapping was not affected by the building's structural symmetry. However, notably, it correlated with small-scale mental rotation scores for both video and verbal guidance conditions. There was no difference between males and females. A common factor that may have influenced cognitive mapping was the availability of visual information about the relationships of the building elements, either directly perceived (during the video walk-through) or imagined (during the verbal walk-through and/or during recall). Differences in visual imagination, particularly mental rotation, may thus account for some of the individual variance in cognitive mapping of complex built environments, which is relevant to how designers provide navigation-relevant information.