Before the war it would have been comparatively easy for anyone interested to quote the names of all the really large ships afloat, if not some of their vital statistics. To do so today would require a considerable feat of memory as the number of vessels in the 50,000 ton and upwards class has reached almost 200 with, in recent years, a growing emphasis on those of over 100,000 tons. In the last few years no less than 51 of these monsters of over 100,000 tons have appeared at sea representing about 1/10th of the total world tonnage completed during that period. There are several 326,000 tonners ploughing the seas; 350–375,000 tonners are on the slips, with 750,000 tonners on the drawing boards and the possibility of topping the 1 million mark in the future.

Because tankers are increasing in size some thought has lately been given to reducing the underkeel clearance in order to make more economic use of available water. But the problem is being stated in unnecessarily narrow terms by placing too much emphasis on tanker draught. A lot more cargo is still being carried in moderate tonnage vessels, which would show a sizeable economic benefit from a reduction in their under-keel clearance in many areas where tankers would not venture.

Dr. David Lewis has contributed two earlier papers to the Journal on Polynesian navigation: ‘Ara Moana’ in 1964, a theoretical examination of navigation methods, and ‘An experiment in Polynesian navigation’ in 1966, an account of his own voyage in the catamaran Rehu-Moana from Tahiti to New Zealand. The present paper presents the result of further research which included voyages between the islands with Polynesian navigators. A version of this paper, which was presented at the Annual General Meeting of the Australian Institute of Navigation in Sydney on 10 and 11 October 1969, has been published in Navigation (Sydney).

The Collision Regulations are due for revision by Imco in 1972 and already governments and other agencies are formulating proposals for consideration by its Maritime Safety Committee. The Institute's working party on the subject, which was formed initially to try to lessen the area of disagreement between people who had put forward positive proposals over the last few years, has now formed a cohesive view and formulated a set of recommendations. These are given in the interim report which follows. In the normal course of events things would have been allowed to run their course and the final report published only after further meetings of the working party which has still to reach firm conclusions on a number of points (for example on the precise form of the manœuvring diagram referred to at the end of Section 2 and in proposition (14), and on the whole question of lights). However, time is short and it seems probable that if the views of the working party are to have any effect on the deliberations of Imco, they must be made known straight away. The report (of which M. W. Richey is the author), therefore, which embodies the whole area of agreement between the members of the working party, is published here in interim form.

Dr. Calvert has expressed some unease from his own point of view about propositions (1) to (19) and it is hoped in the final report to publish an appendix by him suggesting a totally new approach to the whole problem of collision avoidance by manœuvre. It is hoped also to publish an appendix by Admiral García Frías describing the system he proposes. Both these contributions are perhaps likely to be of long-term rather than immediate significance.

The equipment fitted in Queen Elizabeth II was supplied by Aerospace through the International Marine Company. It consists of three units: an aerial, a two-channel receiver and a data processor. The receiver and data processor are housed in a single rack, the print-out machine stands beside the rack on its own pedestal. The aerial reposes on the truck; how-ever, as a result of experiments carried out on board, we are convinced that satisfactory reception of signals is obtained with the aerial sited directly on to the wheelhouse top. The rack and pedestal are located in a corner of the chartroom. Since fitting (Dec. 1968) the receiver has operated continuously, though we must own up to an occasional spot of bother with the processor. Nevertheless the vessel has only on one occasion entered port with the equipment out of use.

Geophysical exploration involves the measurement, at the surface of the Earth, of physical quantities which will provide information about the structural configuration of the Earth's crust. Geophysical surveys are made for petroleum and mining companies to discover subsurface structures favourable to the accumulation of minerals of economic significance.

When geophysical exploration was extended to sea, pinpoint marine navigation became a requirement so that the prospector could return to the exact site of the geophysical anomaly. At first, operations were so near the shore that position determination was no problem. Visual observations were quite adequate. As operations pushed farther from land, high-accuracy electronic systems were pressed into service. Such names as Decca, Lorac, Raydist, and Shoran are familiar in the oil industry. But when operations extended beyond the range of precision radio systems and into areas where they were neither available nor could readily be made available because of hostile terrain, natives, or politicians, or where adequate surveys of shore transmitting stations were impractical, other means of navigation were needed. Navigation satellites, used in conjunction with other navigation equipment, fulfil this need.

While the position fixing techniques employed in offshore drilling and exploration are in many ways similar to those used by the shipping industry—and, indeed, many systems are available to both—there are, nevertheless, several important differences. Accuracy and repeatability are two, in particular, which stand out. It is difficult to state in precise terms what accuracy is acceptable in an offshore survey because the customer is often obliged to accept the best of what he is offered but something of the order of 100 metres is likely to be the target. This is very much better than is required by the average ship out of sight of land or, for that matter, is obtainable in many cases with the instruments available. Repeatability means little to most navigators who rarely have any requirement to return exactly to any position denned in the past. The surveyor, on the other hand, has a continuing need to do this, running lines across his survey grid for check purposes, or at a later date when carrying out another survey or positioning a drilling rig.

Following an invitation by N.A.S.A., the Bundesrepublik Deutschland carried out an experiment with the U.S. satellite ATS-3 (Applications Technology Satellite). The satellite is synchronous, or stationary with respect to the Earth's surface, at an altitude of about 35,800 km. above the equator.

The object of the experiment was to determine the system parameters for a navigation satellite system. This included investigation of the bandwidth of the ultra short-wave band used, and testing speech and data transmission between ships and the mainland, as well as carrying out determinations of baselines. The results are published in Research Report FB69—37 of the Bundesministerium für Bildung und Wissenschaft. The experiments were carried out during two expeditions of the German research ship Meteor, under the direction of the Deutsche Hydrographische Institut. The expeditions were to the west African coast in the spring of 1968, and in the summer to the Faroe Islands. In the fall of 1968 investigations were completed by measurements from a mainland station which was installed on the institute building of the Deutsche Forschungs- und Versuchsanstalt. This paper describes only the position experiment.

The problem of the autonomous determination of the position of a moving object (inertial navigation) on the Earth is solved by gyros, accelerometers, integrators and a computer. We will indicate three possible schemes of inertial navigation.

The coverage of this paper, which was presented at an Ordinary Meeting of the Institute held in London on 18 March 1970, includes:

(1) A brief review of current aircraft flight control systems.

(2) A discussion of the benefits to be gained in terms of manual handling and full automatic pilot modes, in using feedback control techniques in the primary flight controls (Manœuvre Demand Control).

(3) A description of the work done on Manœuvre Demand Control at the Royal Aircraft Establishment, Farnborough, in the Avro 707C aircraft and in the Hunter Mk. 12 aircraft.

The introduction by an airline of a new aircraft type into passenger service, the inclusion of a new route in a world-wide network, or the adoption of new cruising flight levels, are preceded by extensive route analyses and flight planning studies. The known or expected performance characteristics of the aircraft are matched against statistics of wind velocity and ambient temperature, in order to derive estimates of sector times, fuel requirements and payload capacities. This paper refers to some of the sources of the meteorological data hitherto employed for this purpose and presents the results of a recent airline study of environmental conditions at Concorde cruising levels on a selection of routes.

The note by J. W. Crosbie prompts the writer to the following comments. Lecky's Tables2 do not cover vertical angles below the geometrical horizon (zenith distance =90°), or, indeed, angles of less than 10’ above it. Crosbie's method, also, does not cater for angles below the geometrical horizon, though it could be adapted to do so. His extraordinary evolutions with the traverse tables, undertaken to avoid solving a quadratic equation by orthodox methods, are fascinating. Surely, a slide rule, with which the equation could be solved in a few seconds, is available in today's chartroom.

If Turner is right that ‘the underlying theory of the traditional approach (to rhumb-line sailing) is obscure’ and that there is a ‘lack of ready availability of a table of distances of parallels of latitude from the equator, it is certainly not the fault of this Journal which precisely 20 years earlier published a paper which gave:

1. The correct mathematical theory of rhumb-line sailing on an oblate spheroid.

2. The name ‘meridional distance’ to what Turner now calls the L(φ) function.

3. A table to reduce latitude to meridional distance.

4. A rule of thumb procedure to calculate rhumb-line distances correctly with no more labour than that which has always been used to do it wrongly.

5. A method (with table) for use on the spheroid when the track angle is nearly 90° and the method Turner discusses is impracticable.

6. A survey of methods and tables then current.

Although Admiral Ritchie does not agree, I still think that some significance does attach to the difference between the British Standard Nautical Mile and the International Mile. It is a matter of definition and is of vital importance to the young student beginning to study navigation. Unless basic definitions are clear and unambiguous continual difficulty arises which obscures practical considerations of the reliability of measurements that are made. Moreover, it is extremely unfortunate that the length of a minute of arc of a meridian was ever given the label ‘mile’—a standard of measurement of distance, or that anyone should ever have suggested measuring distance with a unit of variable length. The confusion that has been caused in the minds of student navigators over the years is enormous and the opportunity now exists for this source of confusion to be removed.

The Trinity House and Honourable Company of Master Mariners would, of course, have much preferred to comment on Commandant Oudet's latest article in the same edition as the article appeared (Journal, 23, 371). However, as we could only be afforded a weekend in which to give a considered reply this was clearly impossible, bearing in mind the grave and far-reaching issues involved.