Although the Astrograph has never been formally described in print, the basic principles of the instrument are sufficiently well known to require no further elaboration; so also are its limitations. Over many years, numerous proposals (but mainly unpublished) have been made for the extension of the Astrograph to cater for the Sun, Moon, and planets, as well as for a larger number of stars, but none have been really satisfactory. Without such improvements the Astrograph must have a very limited use, and accordingly a further study was made some time ago of its application to the Sun, Moon, and planets. Methods were developed on familiar lines for shifting (and rotating) the star curves for a standard declination to cater for neighbouring declinations, but these introduced complexities that were clearly unacceptable.

This paper is based on a presentation at a seminar on the History of Navigation in the Royal Air Force, held at The Royal Air Force Museum, Hendon, on 21 October 1996. The seminar was organized by the Royal Air Force Historical Society in Association with the Guild of Air Pilots and Air Navigators and the Royal Institute of Navigation. The complete proceedings of the seminar are being published in 1997.

The views expressed in this paper are personal to the author, and not intended to represent official policy of the UK Hydrographic Office.

With the ever increasing use of electronic charts in the small craft sector, this paper is designed to give some background to developments at the United Kingdom Hydrographic Office. Included is a short review of the state of the market, with the author's view of possible future progression. The various formats of data are discussed, with a summary of the legislative background within the commercial market. This discussion is relevant, as it will ultimately shape the future market for small craft users

Inertial navigation techniques have been applied as a means of improving the height information in military aircraft for some time. It is almost certain that the supersonic transport will use inertial techniques for plan navigation and it is interesting to see how far it is worth extending this to include height, and also height rate, information.

It is convenient to start by looking at the fundamental principles of inertial navigation as applied to height measurement; Fig. 1 shows the essential features. There will be an accelerometer measuring vertical acceleration; this must be maintained approximately vertical and can be very conveniently mounted on the main inertial platform. The output of the accelerometer contains a number of unwanted terms for which corrections have to be made. The expressions are well known and are explained in the Appendix.

1. Introduction. By definition a hovercraft or air-cushion vehicle is a vehicle capable of being operated so that its weight is partly or wholly supported by a self-generated cushion of air that is dependent for its effectiveness on the proximity of the surface over which the vehicle operates. Thus from the safety aspect of navigation a hovercraft must be treated as a surface vehicle or craft; for any collision risks involved are proportional to the amount of conventional surface vehicles or craft and static obstructions, in the area of operation. The clearance of minor obstacles less than the hoverheight is practicable; but on present experimental craft with an undersurface clearance of three feet, these clearances are limited to small buoys, waterlogged obstructions and rock outcrops of limited height.

Four steps to Longitude! If we chose, we might interpret the phrase by a sequence of four names: Ptolemy, Charles II, Tobias Mayer and Nevil Maskelyne—the last in 1763. But in fact the steps represent the four marine timepieces made by John Harrison—familiarly known as H1, H2, H3 and H4 of which the last proved its efficacy in 1762. The longitude was found, and by a ‘machine’, just two centuries ago. Now the bi-centenary is being celebrated by a very elegant and informative exhibition at the National Maritime Museum, Greenwich. No navigator should miss it. Even if he thinks scorn of ‘ancient history’ he owes the inventor of the first English chronometer a tribute of respect.

At depths of, generally, between 20 and 250 fathoms in the oceans, sonic and ultrasonic transmissions are frequently scattered by a layer which can be detected on the echo sounding trace, sometimes so strongly as to suggest a sea-bed echo. The cause of this layer, of which the depth has been observed to rise at sunset and sink at sunrise, is not precisely known, though it is generally thought to be biological. Investigations into the deep scattering layer (DSL), as it is called, are being conducted in many countries, principally in the United States, France and Great Britain, and a recent paper by Tchernia has set out the present state of knowledge on the subject.

Traffic separation was first introduced on a voluntary basis in the Dover Strait in September 1967, just over fifteen years ago. Compliance with the IMO provisions relating to traffic separation schemes has been mandatory for all ships during the last five years and for some ships for as much as ten years. It may therefore be appropriate to assess the effectiveness of routing off North West Europe by comparing collision statistics for five-year periods since 1957.

The results given in the following tables apply only to collisions involving trading vessels of over 100 g.r.t. under way and not engaged in any special activities. Collisions in harbours, rivers and congested port approaches where special circumstances apply are not included. The figures quoted for the Dover Strait have been checked against the results obtained by the National Maritime Institute but are based on different criteria, and there may be some discrepancies.

The area covered is the coastal region from the south-western approaches to the Ushant TSS to the approaches to the Elbe including all parts of the English Channel and the Dover Strait, but not including waters off the East Coast of England which are well clear of the traffic separation schemes and deep-water routes.

The numbers of collisions are based almost entirely on Lloyd's Weekly Casualty Reports. Information relating to encounter situations is based on voyage data supplemented wherever possible by information received from additional sources relating to the actual courses steered by each vessel. It is not claimed that the figures constitute a precise record but they should provide a good indication of changes in the incidence of collision off North West Europe.

Astro-navigation cannot be regarded at present as one of the principal aids to air navigation. It suffers, by comparison with radio aids, in that it is slow in use and much more subject to interruption by bad weather. The average navigator needs at least 15 minutes to take and plot a two-star fix with present methods. This is quite a long time in the air, though not prohibitive with present-day aircraft, and in consequence astro-navigation is now used extensively only on long flights over sea or desert where radio aids are lacking.

This is a synopsis of a paper that formed the 1991 Anderson Memorial Lecture. It was presented at a combined meeting of the Bristol Channel and Boscombe Down branches on 21 February 1991

In this paper, which was presented in a fuller version at an Ordinary Meeting of the Institute held in London on 20 December 1963, Mr. Kurz of the United States Maritime Administration and Mr. Bentkowsky and Captain Quinn, both of the Sperry-Piedmont Company, describe a control console for ships which was developed by the Sperry-Piedmont Company under contract from the Maritime Administration. The console, which has its sea trials early this year, comprises five sub-consoles which cater for navigation aids, communications-radar, steering, position plot, and ship condition. The paper enumerates the advantages that might be expected from such an arrangement.

Rule 10 of the new Collision Regulations deals with the conduct of vessels in Imco adopted traffic separation schemes. In this paper, which was presented at a meeting of the Institute in London on 20 April 1977 with Commander R. B. Richardson, R.N. (ret.) in the Chair, Commander Paton, Hydrographic Adviser to the Department of Trade, discusses the traffic situation in the English Channel and Southern North Sea in the light of this Rule with particular emphasis on encounter situations at route junctions and the problems of crossing traffic.

The earliest record of a requirement for ships to carry lights that the author has been able to find is in the Rhodian Laws. These appear to date from about the 3rd or 2nd century B.C., and were certainly incorporated into Roman Law by A.D. 161, although Ashburner suggests that the earliest known copy dates from Byzantine times, A.D. 600–800. The Laws contain a section intended to prevent collisions between vessels under way and vessels at anchor or stopped.

The wide range of interests of members of the Institute, combining as it does all aspects of marine and air navigation from the basic concepts through research, development, design, manufacture and marketing to practical operation, presents a most interesting challenge to the president in his address. This challenge is increased by the knowledge that this address will appear in the twenty-first birthday issue of the Journal in company with articles by eminent members of the Institute on developments in their own fields.

Upper winds over the North Atlantic are strong and their circulation is complex; until aircraft speeds are considerably increased, therefore, the choice of a route which will take the maximum advantage of the wind distribution consistent with safety can make a worthwhile contribution to operating economy. This paper describes some of the methods adopted by Trans-Canada Airline on its North Atlantic route to achieve this end.

In the bicentenary year of the birth of Matthew Flinders at Donington, near Boston in Lincolnshire, it is my privilege to present to Members of three notable British societies some details of the life and work of this great hydrographer.

His surveying and charting impact was made entirely in Australian waters and he is probably better remembered in that country today than he is in his homeland. It is my hope that my discourse, added to the many activities that have been arranged in Britain this year, will do something to rectify this situation. My talk will attempt to tell the brief story of Flinders' 40 years of life and work, beset in his later years by many misfortunes. I will also examine in some detail how Flinders conducted his surveys by taking a few isolated examples, and finally briefly review the results of his labours.

The AN/SSN-6 Navigation Sensor System Interface (NAVSSI) Project is a new system being designed with two primary objectives; to serve as the central distribution computer for navigation data to shipboard combat/weapon systems and to serve as the electronic chart display and information system (ECDIS). The NAVSSI will operate the digital nautical chart (DNC) database being developed by the Defense Mapping Agency (DMA). Our goal is for the digital nautical chart to replace the paper chart as a legal means of ownship navigation plotting. This paper will introduce the project and will primarily explore the use of digital nautical charts for ownship navigation with NAVSSI.

This paper, which was presented at an Ordinary Meeting of the Institute in London on 21 November 1979, with S. Ratcliffe in the Chair, traces the evolution of airborne doppler navigation systems over the past two decades and discusses the treatment of errors introduced when flying over water. Both authors are with Decca Radar Ltd.

The object of this paper is to describe briefly the major developments which have taken place in doppler navigation systems during the past 15 years or so, to indicate the current state of the art and to examine in some detail the behaviour of doppler systems when flying over water. The year 1960 is taken as a starting point since by that time commercial doppler systems were established. A typical general purpose system of that generation (Fig. 1) consisted of the following units:

1. An antenna, probably mechanically stabilized.

2. A transmitter/receiver using either pulse or FMCW modulation.

3. A tracking system.

4. An analog computer.

5. A display of ground-speed and drift-angle.

6. A display of present position.

Ever since the introduction of the Air Almanac and the Astronomical Navigation Tables, requests have been received for information as to the errors that can arise in their use. Estimates of error, for particular combinations, were made on several occasions and, in 1947, the calculation was systematized; but the methods and results were not published. It is now probable that the Sight Reduction Tables for Air Navigation, A.P. 3270 (H.O. 249 in U.S.A.), and possibly the Air Almanac, will increasingly be used for surface navigation and it therefore seems desirable to put on record a precise statement of the errors that can arise through their use. The earlier work has accordingly been modified for the changes in the publications.