Presidential Addresses over the years have covered a variety of subjects, mainly scientific and generally devoted to navigation. Being neither a scientist nor, strictly speaking, a navigator, I have chosen the work of the Institute as the subject of my Address. Today, the Institute celebrates its twenty-first anniversary and we can suitably reflect on its growth and achievements. We are immensely proud of the fact that Your Royal Highness consented, as long ago as 1952, to become our Patron. We are always honoured and delighted that you have been able to attend so many of our Annual General Meetings and to take the Chair. You inspire us, Sir, to keep in full view the objects of the Institute, which were laid down in 1947 and which are:

‘To unite in one scientific society those interested in navigation’ and ‘To advance the science and practice of navigation and its associated sciences’.

In ‘A Modern View of Lunar Distances’ (Journal, 19, 131) H.M. Nautical Almanac Office has already covered most of the technical aspects of the method of lunar distances which the Almanac made practicable; in ‘The Foundation and Early Development of the Nautical Almanac’ (Journal, 18, 391), Dr. E. G. Forbes has given a scholarly, fully documented, account of the early history of the Almanac; and Mr. Sadler himself has written many articles on various aspects of the bicentenary. This general account, which necessarily must duplicate parts of these articles, is directed as far as practicable to those aspects that are likely to be of greatest interest to members of the Institute not technically concerned with astronomical navigation. The paper was presented, in an abridged version, at the Annual General Meeting on 25 October 1967.

The economic development of archipelagic territories is intimately linked with shipping. In the archipelagoes of the Pacific small vessels connect many islands with one or two port towns. These towns are entrepôts for cargoes of consumer goods, petroleum and timber, and they are transhipment points for copra and fresh produce coming in from the island hinterlands. Towns, such as Suva, Lautoka, Apia, Nuku'alofa, also serve as local markets and educational, social and medical centres for the people of the outer islands.

In Fiji there are about 90 inhabited islands outside Viti Levu. The villages and estates in the outer islands all focus in some way on the port of Suva. There are many economic and social problems in the islands and these are made more acute by high freight rates and the unreliability of some services. But most of the shipping operators would be hard put to reduce freight rates or to improve the quality of their ships and services. One reason for this is the burden of marine accidents.

Some forty years ago, in the early days of automatic steering, autopilots were looked upon as a mere addition to the gyro-compass equipment. It was a black box, which was said to be able to reduce fuel consumption. It was also a gadget that amused passengers. The original introduction of the autopilot was based on these two aspects and its application was consequently confined to a small number of large passenger vessels.

Yet the name autopilot clearly indicates the possibility of automating an important element of the ship's routine, the steering. However, at this stage shipping in general was not ready for this aspect. The cost of labour on board played a less important part then than it does today. It took another twenty years before it became clear that it was precisely the labour-saving capacity of the auto- or gyro-pilot which would play such an important role in the rationalization of the ship's manpower requirements.

This paper describes a series of data handling systems, termed MARIDAS, which would cater for various maritime problems and situations. Eleven specifications have been prepared, of which three, those for hydrographic work, harbour and pilotage, and merchant ships, are reproduced as Annexes here. A version of the paper has appeared in naval publications with restricted circulation.

In the past decade various navies have introduced electronic data processing to ease the strain on ship captains and their officers in order to increase their efficiency. The need is urgent as the quantity of information now available from the many sensors has grown so remarkably, and the speeds of aircraft and targets have increased to such an extent, that human reaction and ability is fully extended. However, the thought processes in all the operations which have to be performed have remained the same. These processes are largely related to the solution of trigonometrical or triangulation problems: Spherical, for astronomical or satellite navigation; Plane, using distances and angles for geographical or relative position problems and speeds and angles for relative velocity problems, avoidance of collision and intercept.

It is not often that a drama of the sea provides the main story in the news, and it is still more unusual for such an occurrence to continue to occupy the headlines; but the Torrey Canyon disaster was unique in having done this for a whole month and more. Day after day, there was a slow and inexorable increase in the area affected by the catastrophe and in its duration: while such protective measures as could be improvised could seldom do more than repair damage that it was impossible to prevent.

An area navigation capability can be of considerable benefit to users as well as providers of ground facilities. A.T.C. radar terminal service and area navigation utilizing cockpit pictorial displays are complementary from a total system viewpoint. Pictorial displays, coupled with digital computers capable of storing navigation information, will greatly reduce pilot workload. Optimum usage of A.T.C. radar service and cockpit navigation will provide maximum redundancy at least total cost and reduce controller workload.

Pictorial computer procedures will have many applications of benefit to high density terminal areas, such as (1) departure paths from a satellite airport, (2) descent paths from high altitude to a terminal area, (3) missed approach patterns, (4) approaches to satellite airports, (5) simplified holding procedures, and (6) discrete paths for descent corridors. Procedures are expected to be developed as a result of a full-scale Federal Aviation Administration operational programme for selected en-route and terminal areas permitting use of area navigation facilities, using F.A.A., airline and general aviation aircraft in a live A.T.C. environment.

The practical feasibility of blind take-off, landing and rolling to a stop has been adequately demonstrated, and both ground and airborne facilities are now being provided which will permit its progressive implementation operationally. Thus, one of the major questions remaining to be answered is the extent to which supporting airfield facilities are required to be improved in order to match the landing capability.

The present paper represents a contribution to discussion of the problems involved in ensuring that airport ground movements of both aircraft and vehicles can continue efficiently, and of the various measures which can be taken to minimize these problems. The conclusions drawn represent the opinions of the Blind Landing Experimental Unit, based upon the limited information which so far is available on this topic, and thus do not necessarily reflect firm U.K. policy since this must involve further study and investigation.

Delays in the terminal area lead to increases in the operating cost of the aircraft involved. We assess these costs as one criterion of the effectiveness of the air traffic system in the terminal area, and to give a measure of the desirable expenditure on methods of reducing delay (e.g. improved radar, additional runways or even an extra airport). This note discusses methods of assessing the cost penalty of delays exclusively to the airline operator and gives examples for three types of aircraft, a short-range subsonic jet, a long-range subsonic jet and a supersonic transport.

Terminal area delays occur essentially because aircraft apply for use of the runway, either for take-off or landing, in a random fashion and because the acceptance rate of the runway is limited by the need to maintain safe separation between aircraft on and in the vicinity of the runway. Such delays involve penalty to the aircraft operator in terms of extra time and fuel consumed and hence of extra operating cost.

Since government and industry have officially accepted the introduction of the International System (S.I.) Units for all forms of measurement it is relevant to examine the implications of this for marine navigation.

The present situation. Marine navigation is no different from many other fields in that a proliferation of units is used to measure the same dimension and, moreover, these units have no systematic relationship to each other. In this respect length is the worst offender: we measure heights in feet, depths of water in fathoms, distances in cables or nautical miles and moreover these nautical miles may be British standard, International standard or those precisely determined by latitude.

I Was interested to see Mr. Pepper's note in the July issue of the Journal. The intriguing question of Hariot's unexplained approach to a problem that appears to require a knowledge of the integral calculus and exponential functions had attracted my attention when Taylor and Sadler published their paper in 1953. In 1956 a note by me on this subject was published, with a comment by Mr. Sadler, which offers much the same explanation. I, too, was unaware that there was any evidence of Hariot's familiarity with the conformal property of the stereographic projection.

An interesting, easy and useful method of finding the observer's distance from a ship, buoy or isolated lighthouse, the height of which is unknown, is by measuring the angle between its waterline and the horizon. To this is added the angle of dip for the height of eye.

From the figure it can be seen that the angle so obtained is equal to the angle at the object between the observer's height of eye and his own waterline.

Douglas Lindsay's article in the Journal (20, 249) raises numerous interesting points and I agree with much of what he says, but he has orientated himself so strongly towards the problem of the big ship that he has recommended a change that would bring complete confusion at the smaller end of the scale.

The most useful points Mr. Lindsay raises are the need for increased ranges for ships' navigation lights, coupled with the dangers of extraneous lights. Both these points apply in their own way to small vessels. However, I disagree with Mr. Lindsay's article where he refers to the meaning of a single white light. He starts his argument by saying:

I Have been following the articles on this subject in the Journal 1 with some interest and hope that the personal views of one comparatively junior officer may be of some interest.

It is implicit in all these articles that, except in the close-quarter situation which the Rules are surely designed to prevent, the sound signals are unsatisfactory. What is not stated in so many words is that, international conferences notwithstanding, Rule 28 (a) is more observed in the breach than otherwise. I cannot of course be sure, but I suspect that this has been so since electric navigation lights superseded oil in general use, thus increasing the recognition range and allowing avoiding action to be taken at greater distances. There is also the natural human, if not legally commendable, desire to let sleeping captains lie.

In the paper which he read on 19 April 1967, Captain Dickson described in some detail the investigations which have been carried out to determine the underkeel clearance which should be allowed in any given circumstance. These investigations have concentrated on the vertical movement of a tanker under different conditions, particularly in determining squat and the effect of wave motion. However, another factor in the underkeel clearance equation is the charted depth and this also is affected by ship movement, in this case the movement of the surveying vessel which obtained the soundings. In the following note the probable effect of this movement is discussed and suggestions made by which the effect might be reduced.

I would like to comment on the change in underkeel clearance due to the motion of a ship in a seaway (A. F. Dickson, this Journal, 20, 363).

Captain Dickson, in his conclusions, states that known techniques do not allow underkeel clearance to be calculated when ship motion is present. In fact there are a number of reliable ways of calculating the motions of a ship in waves (for example References (1) and (2), which treat the case of pitch and heave) which may help in this problem. These methods usually assume the ship is in deep water and is heading directly into the waves which are further assumed to be long-crested; but I believe it may also be possible to make reliable calculations for shallow-water effects and for waves which are, in reality, short-crested.

We would like to reply to some of the comments and all the criticisms made on our suggested amendments and additions to the existing (1960) Regulations for Preventing Collisions at Sea, which have appeared in this Journal(20, 103, 340).

to Captain G. Swallow, R.N.

Upon reflection we agree to some extent with the comment on our suggested re-wording of section 16 (b). However, for the very reasons he has pointed out, with reference to certain court cases, we feel that the mariner must be made absolutely certain about his position in law with regard to this section. This section, as it stands, can be very misleading in that it gives the mariner in charge of a power-driven vessel the impression that he need not always stop his engines if he hears a fog signal forward of his beam from another vessel, which has not been sighted. Yet in all the court rulings that we have seen, concerning the interpretation of this section, there is not one case where a mariner has been excused from failing to stop his engines on the grounds of the ‘apparent’ escape clauses, i.e. because of ascertainment of position and/or practicability.