The Regulations for Preventing Collisions at Sea were formulated before the invention of radar, and radar has invalidated one of the principles upon which the Rules are based. This principle is that when two vessels are in risk of collision one shall get out of the way, and the other shall stand-on (except in the cases where two vessels are meeting end-on, and where the stand-on vessel finds herself so close that collision cannot be avoided by action of the giving-way vessel alone). This assumes that if one vessel can see another she also can be seen, and this is of course likely to be the case where visual sighting is concerned. From radar observations one cannot know if the other ship has observed you, and it is unlikely that we shall know this with certainty, for radar and other aids may fail. Providing there is sufficient sea-room and not too much traffic, this drawback can usually be overcome by taking early and substantial avoiding action (as recommended in the Annex to the Rules). If one ship makes a manœuvre which cancels the avoiding action taken by the other there is still time for second thoughts; but in crowded waters there may not be so. Even when both vessels are navigated correctly, the imprecision of radar predictions may lead to dangerously close passings.

On the one hand, there is the inevitable reluctance to change Rules that have stood the test of time but I think this reluctance comes mainly from the older officers in their last few years of service, who, very understandably, do not wish to have to learn new Rules and find that their instinctive and almost automatic reaction to any situation gained through years of practical experience has now all to be changed.

On the other hand there is a very strong body of opinion which feels that the old Rules, designed for quite different circumstances and unable by their basic concepts to be suitably amended to meet modern conditions, must be completely re-written—amendment to the existing Rules just will not do.

There are three main reasons why the rules for preventing collisions at sea need revising:

Rule 21 is unsatisfactory. This is particularly the case in encounters between vessels of widely different speeds and manœuvring capabilities when Rule 19 may require an unreasonable manœuvre from the slower and more ponderous craft and Rule 21 at the same time prohibits manœuvre by the more easily handled craft.

If in an encounter the giving-way vessel does not take action in good time, Rule 21 requires that the other vessel must maintain a collision course until the situation becomes so dangerous that action by one vessel is insufficient to prevent collision. For a rule which is intended to prevent collision this seems hardly credible, but in fact Rule 21 does legislate to maintain a risk situation from a time where disengagement might be comparatively easy to a point where it is almost impossible.

It is often suggested that moderate speed in fog should be a function of the performance of the ship in question, but if Rule 21 is to be observed when vessels sight one another, then it ought to be a function of the performance of the vessel required to give way. This of course may not be known until the sighting.

Because it is unnatural to maintain course and speed into a dangerous situation, Rule 21 is frequently disregarded, particularly by navigators of fast and highly manœuvrable craft.

Since the introduction of the present (1960) Regulations for Preventing Collisions at Sea, we at Cardiff have noticed that the actions taken by Masters and senior officers, during simulator exercises, have been bolder and, perhaps, taken somewhat earlier than they were previously. Unfortunately, however, the actions taken by two ships approaching each other often cancel out. This is not always dangerous because the initial actions have generally been taken early enough for further action to be taken but, it does lead to unnecessary delays and frustration. We think, therefore, that it is desirable that any new Regulations should contain a set of rules of action for a vessel detecting another, on a collision course, by radar only.

The transport of cargo is not of itself a navigational subject; it is however the purpose of nearly all marine navigation and a development such as ‘containerization’ which is having such a profound effect on the nature of shipping cannot fail to be of interest to navigators at sea. In this paper, a version of which appears on the U.S. North Atlantic Pilot Chart for May 1969, Mr. Van de Ree of the Ship Analysis Division of the U.S. Navy Oceanographic Office describes the background to the development of unitized cargo handling and transportation, its economic advantages and its significance for the pattern of trade at sea.

In a valuable paper published in July 1960 (Journal, 13, 253) Hanssen and James described the system developed by the U.S. Hydrographic Office (now U.S. Navy Oceanographic Office) for selecting the optimum track for transoceanic crossings by applying long-range predictions of wind, waves and currents to a knowledge of how the routed vessel reacts to these variables. In the present paper the authors, both of the Marine Sciences Department of the U.S. Navy Oceanographic Office, propose a method, based on this earlier work, of using climatic charts on the North Atlantic to avoid regions of high frequency storm conditions and thus improve ship efficiency. Essentially this method is for ships not being routed by a central forecasting office. An earlier version of the paper appeared on the verso of the U.S. North Atlantic Pilot Chart for March 1969.

By means of a Notice to Mariners dated 10 August 1968, and in November of the same year with the collaboration of the Comité Central des Amateurs de France, the French Hydrographic Service conducted an inquiry among the Masters of French ships into the traffic separation schemes in force in the Dover Strait and other areas. The following is the report submitted to the Secretary General to the Marine Marchande. It is reproduced here without its appendices.

This paper describes the four main functions of radar in the Merchant Navy, expresses views on the controversial matter of mode of display and indicates possible solutions to the problem. Mention is also made of the desirability of properly engraving the relative bearing ring and the necessity of being able to take true and relative bearings at one and the same time if required.

It may be useful to outline the progress made in the field of inertial navigation for civil transports made since the last meeting of the Institute held to discuss the subject. After experimental evaluation work, mainly in the U.S.A. but also in this country, the first production equipment made specifically for civil use was the Sperry SGN 10 equipment made for Pan American Airways and first fitted in 1965.

The basic concept of case and cluster rotation in inertial navigation (IN) systems is introduced, and the reduction in the errors caused by changes in gyro and accelero-meter biases is illustrated. The general properties of cluster rotated systems are summarized and it is concluded that, although errors inside the Schuler loops may be drastically reduced by rotation, care must be taken to avoid error sources outside the loops.

This paper describes and attempts to assess the viability of the airborne collision-avoidance system based on time-frequency techniques which is proposed, for use within ground-based control systems, by the Air Transport Association of America.

The rate of growth of air traffic in the London Terminal Area (T.M.A.) is such that the existing airports will be unable to handle it for more than a few years. If a safe and expeditious flow of traffic is to be maintained, even if more airports of the existing type are provided, ways must be found to increase the capacity of individual airports. In any case, it will be necessary to improve the marshalling of traffic between the airports and the air routes to prevent harmful interaction between the various activities. One solution put forward, tacitly assumed that the growth potentials of Heathrow and Gatwick airports were so limited, that a third, and subsequently a fourth, airport of similar design and capacity would be required.

The alternative solution relying on ideas yet to be proved, is more difficult to assess, since possible improvements in technology must be taken into account together with the changes in A.T.C. procedure which their adoption would permit. By 1967, this task had not received the comprehensive study afforded to en-route (Mediator) problems, and no specific operational requirements existed for electronic aids related to this T.M.A. problem.

For this reason, the fairly substantial amount of work which could have a bearing on T.M.A. problems being carried out in various R. & D. establishments and industry could not be directly related to the users' needs.

In his original paper, Turner drew attention to the proliferation of units used to measure the same dimension. Granted the decision to adopt a metric system in this country, there could be no question but that SI was the correct one to adopt. It is not precisely the same as the traditional metric system at present in use on the Continent, but it seemed likely that it would become so, and, as the British Standards Institution pointed out, one change from Imperial to SI was far more logical than a change to traditional metric, followed by a change to SI.

SI avoids all the difficulties mentioned by Turner, but, as B.S.I, state (and Turner indeed infers in his statement that ‘speed (will be measured) in kilometres/hour’), we cannot abandon the hour and the day, which SI would require to be expressed as 86·4 kiloseconds and 31·4496 megaseconds respectively. Angle, too, presents a problem. The radian is quite irreplaceable in some mathematical fields but one cannot express a right angle or a complete revolution as a rational figure in radians. Horscroft revives the metric grade of one-hundredth of a right angle, but, as he points out, this logically demands a new basis for time measurement.

Much is being done to ease the burden on the Master approaching ports, and lane separation is the main thing. It would appear that the next logical step would be to penalize Masters who do not conform to the laid down traffic pattern.

It may be argued that the imposition of a penalty will be adding to the danger of a congested port approach, inasmuch as the Master will be worrying about the consequence of a wrong decision; such worrying may tend to cloud judgment.

However all Masters understand the correct ‘port approach’ technique and that therefore all other vessels will comply with such rules. A case for the imposition of a penalty is shown by the marked reluctance of some Masters to follow the lane patterns. I am speaking from experience when I say that I have seen vessels in the approaches to New York, Delaware River and San Francisco where charts show plainly approach and departure routes, deliberately steaming the wrong way in the laid down routes. It would appear that deliberate flaunting of safety features needs penalization of the person responsible, i.e. the Master.

However, before legislation can be enacted for such a penalty, it will be necessary for legislation to be enacted whereby strict conformance to the laws of approach and departure from a port is law, and not, as at present, recommended. While these routes are only recommended some Masters will still ‘corner cut’.

Schuler himself genially but clearly warned here and there in his 1923 paper that he had not proved his principle, and indicated that the general proof was not within the range of his own limitations, thus inviting his readers to be critical of what amounted to interesting suggestions cheerfully offered. Professor Stratton's commentary (Journal, 21, 507), ‘The Schuler pendulum and inertial navigation’, by its scope, clearness and authenticity, could make effectual the remark that Schuler's calculation of acceleration is not correct except in one and the same great circle and possibly a few other special cases. Schuler jumps to the conclusion that it holds for any spherical motion, thus neglecting much of kinematics. The following standard analysis uses the moving trihedral and the intrinsic equations of ordinary differential geometry. There are many other methods having their own advantages.