by Dave Gittins
If I doubted my reckoning after a long time at sea I verified it by reading the clock aloft made by the Great Architect, and it was right.
Captain Joshua Slocum, navigating by Lunar Distances. Sailing Alone Around the World.
The navigational skills required of the officers of Titanic's time never cease to amaze. Today, the navigator has the benefit of the Global Positioning System, whose numerous satellites provide extremely precise positions at all hours. GPS receivers are seen in the tiniest pleasure craft and are often used merely to record favourite fishing spots. Should the GPS fail, many amateurs would be reduced to eyeball navigation. More professional navigators retain sufficient knowledge of celestial navigation to get by without electronic aids. Precomputed tables, such as HO249, remove the need for so much as an electronic calculator. Given a few books, notably the Nautical Almanac, plus an accurate timepiece, the expert navigator can bring the ship safely home unaided.
In the days of Titanic, the navigator's life was more complex. In this article, only the navigational aspects of an officer's training will be considered. Far more was required of the would-be officer than navigational skill, such as knowing how to safely stow various cargos and what to do when members of the crew were thrown into a foreign jail for 'drunk and disorderly'. Such subjects were generally orally examined and are here passed over. It was the navigational knowledge that really tested the tyros and had them toiling over textbooks in 'cram schools'.
In Britain, four certificates were granted. In order, they were Second Mate, First Mate, Master and Extra Master. By 1912, it was possible to earn certificates in steam only. Major shipping lines were not entirely happy with this and required their officers to hold certificates in both sail and steam. It was believed experience in sail imparted great sensitivity to the antics of wind and waves. All Titanic's officers held such certificates. The Extra Masters were Captain Smith, Chief Officer Wilde, First Officer Murdoch, Second Officer Lightoller and Fourth Officer Boxhall. Third Officer Pitman, Fifth Officer Lowe and Sixth Officer Moody held Master's certificates. Freighters required lower qualifications. On Californian, Captain Lord was an Extra Master, Chief Officer Stewart was a Master, Second Mate Stone held a First Mate's certificate and Third Mate Groves held a Second Mate's certificate. (There are some discrepancies in the titles of Californian's officers. I give them as given by Captain Lord).
It should be understood that, like a modern university degree, the certificates did not guarantee promotion, or even employment. It was quite normal for officers to serve in positions below those for which they were qualified. Many Extra Masters never attained command.
In Britain, examinations were conducted by the Marine Department of the Board of Trade. The important point about the navigational methods used is that they were intended to provide the utmost precision. Therefore, all calculations made use of spherical trigonometry, that arcane world in which triangles may contain angles totalling more than 180°. The navigator had to be familiar with all the trigonometrical functions of angles. To make calculations involving these functions, it was necessary to employ their logarithms. Six figure logarithms were used. To add to the fun, angles were often measured in hours, minutes and seconds, rather than in degrees. Thus, in a calculation of longitude, the final result was found by converting hours, minutes and seconds of time to degrees and minutes of longitude. British navigators usually obtained logarithms and trigonometric functions from the venerable Norie's Nautical Tables, which is still published, though without some of the tables used in 1912.
A fully worked example of a longitude sight will be seen in the Navigational Appendix of Titanic: Monument and Warning.
The lowest certificate required knowledge of the fundamentals of navigation. This extended to checking the compass by observations of the sun and the determination of latitude and longitude by solar observations only. At a pinch, a qualified Second Mate could bring a ship safely home in the absence of better-qualified officers, given some sun sights.
The second certificate introduced navigation by the stars. This included calculating in advance the position of useful stars, so the navigator's sextant could be pre-set to their altitude, ready for observations. A useful skill was the ability to take a quick sight of an unidentified star, seen through a break in clouds, before identifying the star and calculating a position line.
To gain the certificate needed to command, the candidate had to know how to navigate by the planets and the moon. These bodies introduce extra corrections. Latitude by Polaris, using a complex method involving logarithms, was required, together with advanced knowledge of the compass and its errors.
It will be noticed that no mention has so far been made of great circle sailing, which was so important to ocean-going ships. Masters and Mates were only capable of navigating a great circle course if it had been worked out in advance.
This was the province of the Extra Master. This learned mariner was required to solve problems of considerable complexity, using spherical trigonometry. An examination question might ask the candidate to determine the great circle course from a point on the Kamchatka Peninsula, in Russia, to Cape Horn, listing all the turning points on the course and the courses to be steered between them, assuming the course is changed every 10° of longitude. This calculation occupies two large pages.
The Extra Master was required to know how to find a position by Sumner's position lines. (See Wikipedia or a nautical textbook). Spherical trigonometry was required, rather than the short methods later used. Although Sumner's method had been in use for many years, some navigators regarded it as inferior to the Board of Trade's approved methods, as it required drawing on a plotting chart to obtain a position. The Board of Trade methods gave latitude and longitude without plotting.
Some of the Extra Master's skills savour of party tricks. For instance, it is possible to determine latitude and longitude simultaneously in daylight by observing the sun and Venus. The altitude of Venus can be pre-calculated and the sextant set accordingly. The sun can then be observed at noon for latitude and Venus gives longitude, when sufficiently far from the sun. Perhaps such observations impressed the junior officers.
The Extra Master was able to construct Mercator charts from scratch, allowing for the changing length of a degree of longitude between the equator and the poles, and the slight oblateness of the earth's sphere, which affects the length of a minute of latitude.
An important feature of the Extra Master's examination was that the candidate was expected to demonstrate an understanding of the methods. At the lower levels, a certain amount of rote learning, without deep understanding, could suffice. The would-be Extra Master was required to write essays on such topics as tropical revolving storms and to explain the reasoning behind the celestial navigation. Plenty of diagrams were required and neat and methodical work was expected. This is partly why the examination occupied 26 hours, spread over five days. The examination papers were marked progressively and after a final oral examination the candidate was immediately informed of his fate. A successful candidate was given a 'blue paper', which served as a temporary certificate, pending the issue of an elaborate certificate, signed by the senior officials of the Marine Department of the Board of Trade.
It was not uncommon for capable officers to fail the Extra Master examination at the first attempt. A few arithmetical errors would suffice to send a candidate back to his textbooks. Edward Smith, later master of Titanic, suffered this fate, but soon passed at a second attempt. Quicker success was enjoyed by Stanley Lord, of Californian and James Bisset, of Queen Mary.
A curious fact is that until 1906 the Extra Master was required to be able to find the longitude using the long-obsolete Lunar Distances method. In this method, familiar to Captain James Cook, Greenwich Mean Time was found without a chronometer
by observing the moon's angular distance from certain stars, or from the sun, and referring to tables prepared at Greenwich Observatory. This formed a starting point for calculating the local time and hence the longitude. The results were rough, but in the absence of chronometers they were all that could be had. Titanic's older officers, such as Captain Smith and Chief Officer Wilde, had learned this method, but it's most unlikely they ever used it. When the requirement was dropped, it was replaced by a course in naval architecture.
In the hands of skilled officers, the Board of Trade's approved methods were remarkably effective, given good conditions for observations. The lengths of voyages by the crack liners between Britain and New York were frequently within a few miles of the theoretical distance, showing how closely the course was followed. The standard on freighters was rather lower, as they carried fewer highly qualified officers willing to perform complex calculations to an unnecessarily high accuracy.
No dates are given for these books, which were re-printed over many years during the late 19th and early 20th centuries. They are all British and are based on the Board of Trade examinations.
Captain L F Hansen. Trigonometry and Navigation. (Deals only with Extra Master).
Captain S T S Lecky. Wrinkles in Practical Navigation. (Reprinted over many years and hugely popular. It even manages to amuse).
Nicholl's Guide to the Board of Trade Examinations. (Covers only up to Master).