In September 1931 Sir Hubert Wilkins and Harald Sverdrup made the first attempt to explore the Arctic Ocean by submarine in Wilkins's Nautilus. The Nautilus was the ex-Navy submarine O-12 modified with topside runners to slide against the underside of the sea ice. Seventeen years later the US Navy developed the sonar system necessary for safely piloting a diesel-battery submarine underneath the ice pack and began exploration of ice covered areas.

In 1957, with the nuclear-powered Nautilus, the US Navy began exploration far into the Arctic Ocean. Problems were found concerning determination of ship's position, ice avoidance manoeuvres, and surfacing up through ice. Sonar and inertial navigation equipments and operating techniques were developed to solve these problems. Submarines have since sailed to all parts of the Arctic Ocean during all seasons — more than twenty explorations since 1957. The history, problems and interrelationships of the many explorations are described.

Dr Lyon's paper was presented at a colloquium on the conquest of the North Pole held in Paris, 7–1 1 November 1983, and organized by the Centre d'Etudes Arctiques by whose permission it is here published. (Throughout the paper miles means nautical miles.)

This paper, with Dr Lyon's was presented in Paris in November 1983 at an international colloquium organized by the Centre d'Etudes Arctiques of the Centre National de la Recherche Scientifique, by whose kind permission they are here reproduced. The theme of the conference, at which some 35 papers were presented, was the Conquest of the North Pole; the subjects covered included both the history of Arctic exploration and contemporary problems and the future of polar transport, sea and air. Mr Kerr is Director of the Canadian Hydrographic Service's Atlantic Region; both he and his co-author are at the Bedford Institute of Oceanography in Dartmouth.

In the course of a summary of established views about the still unknown origins of portolan charts (this Journal, 36, 124, 1983) the hypothesis was advanced that they originated as a result of the maritime interests of Frederick II of Hohenstaufen. It should perhaps be made clear straight away that this is no mere attempt by a German author to further German pretensions in this matter. In fact, of course, Frederick II (1194–1250) was the last emperor of the Holy Roman Empire and, according to the excellent biography by Kantorowicz, felt himself more and more the spokesman for cosmopolitan thought as his years advanced. He spent his youth in Sicily and was known as ‘The Sicilian’, and learned to speak German only during the third decade of his life during his first visit to Germany; by then he was fluent in half a dozen other languages. Sicily of course, where he spent most of his life, meant not simply the island but the kingdom of the two Sicilies which, since the Norse conquests, comprised extensive parts of southern Italy and notably Apulia, where Frederick had his court at Foggia. His dominions bordered papal territory, which accounts for the hostility to him of several popes.

Navsat is a civil satellite-navigation system which was presented by the European Space Agency. It is still at the system definition phase as distinct from the pre-operational stage, but since the original presentation it has been the subject of studies which have included analysis and synthesis of the main parameters.

The underlying principles of the concept as initially described by Rosetti remain unchanged but sufficient progress has now been made to predict the capability of the system in satisfying a number of objectives in the civil fields of navigation, position fixing and survey.

A mathematical collision risk model can be used for evaluating air traffic control (ATC) separation standards. As one of the parameters required for calculating the expected number of collisions by this model, the probability of overlap in the vertical dimension based on height-keeping errors of aircraft must be estimated.

However, there are few examples of empirical data on height-keeping errors because data collection is expensive and time-consuming. In order to collect these data, the author et al. started data collection using a newly developed simple height-finding radar, the navigation accuracy measurement system (NAMS) which has been installed under a trunk airway in Japan.

In this review of the evolution of displays and controls in military and civil fixed-wing aircraft, the author traces the development of flight instruments, largely in this country, from their rudimentary beginning before the first World War to the present high degree of automation and suggests certain pitfalls from the pilot's point of view in high-technology solutions.

The Wright Brothers' aeroplane flew with only a stopwatch, a tachometer to measure engine speed, and an anemometer, all for measuring performance; the pilot had no instrumentation to help him fly the aircraft. There was little change up to the beginning of the first world war in 1914. The cockpit hardly existed as such: controls varied in design; some were levers, and often there was a wheel which, in the early days, controlled wing warping to change the lift of each wing to allow the aircraft to bank.

In a previous paper a model was outlined for an encounter between two vessels using the ‘range to domain over range rate’ (RDRR) criterion. This paper shows how the model has been developed to simulate traffic flow and collision avoidance through the main south-west bound lane of the Dover Strait traffic separation scheme. B. A. Colley and C. T. Stockel are at Plymouth Polytechnic, R. G. Curtis with the Department of Trade and Industry. The paper was presented at an ordinary meeting held in London on 16 November 1983.

Since drilling for oil and gas began in the North Sea in the mid 1960s, the possibility of merchant ships colliding with offshore platforms or rigs, has been of concern to both government and operators. There are nearly 100 fixed and floating installations in the UK sector of the North Sea; they vary in size, location and type of construction, but in all cases, collision would pose serious risks to life, pollution and loss of production. Some platforms are near busy shipping lanes and some have several hundred personnel on them at certain times.

The purpose of this paper, which was presented at a joint meeting held in London with the Nautical Institute on 1 December 1983, is to give an account of the development of Dynamic Positioning from its inception to the present day, a simple description of the principles on which it works, and makes some predictions about its future.

Dynamic Positioning (DP) has been defined in various ways. For the purpose of this paper it will be denned as ‘The ability to hold a vessel in its desired position automatically without the use of physical restraints.’ Physical restraints are ropes, cables, anchors or any other items which connect the vessel to the bottom or to a fixed structure, be it an offshore installation or quay. The word ‘automatically’ means that manoeuvring control must be achieved without manual input.

Lewison gave a brief outline in modelling of marine traffic flow and gave four possible definitions of the ship to ship encounter as well as developing his own optimal criteria. Barratt has been working on the concept of an encounter for several years and has developed the postulates given by Stratton in a presidential address to the Royal Institute of Navigation in 1971. It is interesting to note that Lewison1 distinguished between a ‘ship domain’, which is the area around a vessel that it is observed to keep free of other traffic and is estimated in terms of the actual density of shipping observed to occur around a vessel, and an ‘encounter area’, which is a radius traced out around a ship in the different directions from which threats may come and is the desired area which the vessel should try to keep clear. The nicety of the ‘encounter area’ is that it is generated in terms of mathematical models and in quantitative terms, and can be reasonably easily established; but it totally ignores any human element or navigators' preferences, whereas the ship domain takes both these factors into account and can only be established after long observation of actual traffic behaviour.

The fisherman's task in navigating his craft are threefold:

(i) to guide his craft safely and by the most direct route between his terminal ports and the fishing grounds;

(ii) to shoot, tow and haul his fishing gear in such a manner as to prevent it being damaged or becoming fast to any obstruction on the seabed;

(iii) to search for aggregations of commercial fish species and by lures, snares and the use of towed nets to capture viable quantities of the fish located.

The navigation to and from the fishing ground poses the same problems as for other marine craft, but once on the grounds, using towed or encircling nets, the position of the nets, not only horizontally but also in the vertical plane, are as much his concern as is the position of the parent vessel. Most fishing grounds are situated where there are irregularities in the seabed topography or where oceanographical factors provide a rich feeding area for a range of fish species. Alternatively many fish species carry out an annual migratory journey to their spawning areas or towards more favourable environmental conditions, their shoaling behaviour at this time making them particularly susceptible to mass capture.

Vessel damage incurred by ships manoeuvring in restricted waters and during berthing operations has identified a need for a precise navigation system that would give a master positional information of a high degree of accuracy in a simple visual manner. Such a system would improve operations in marginal weather conditions and decrease turn-around time for the regular port user.

Drawing upon its offshore survey and positioning experience, Wimpol Ltd has developed a precise vessel positioning system which meets a demanding specification with regard to accuracy, reliability and simplicity of operation.

An article entitled ‘Defining the Close-Quarters Situation at Sea’ in this Journal (36, 454, September 1983), described how certain manoeuvres made by ships could safeguard against close-quarters situations developing at sea and, when circumstances demanded, these manoeuvres could ensure compliance with Rule 19(e) of the Collision Regulations.

Basically it was suggested that engines should be stopped when the distance between two such approaching vessels was N nautical miles, which was pre-calculated. If that action appeared insufficient, full astern power should be applied after an interval of Δt minutes had elapsed or, at the latest, when the separation distance between the two vessels was not less than Ab(SP) nautical miles.

In Gerald Forty's paper published in Vol. 36, September 1983, line 36 on p. 325 should read: ‘When using the lower limb with a shade…’