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    Re: The Rude Star Finder and teaching stars
    From: Henry Halboth
    Date: 2010 Nov 12, 09:13 -0800

    It would be most difficult to find fault with John Brown’s description of “the highly standardized, exquisitely optimized, even ritualized form of celestial navigation” (as he puts it, exactly) practiced aboard British Merchant Ships in the latter half of the 20th Century – he obviously knows what he is talking about. Generally speaking it certainly is the way it was, regardless of country or service, i.e., Merchant Marine or Navy; perhaps from WW 1 onwards. I would, however, add my oft spoken comment to the effect that “different ships, different long splices”; certainly some ships did more, but then again some did much less, due perhaps largely to the relative sophistication of the Master, as well as the initiative of the individual officers – some were pretty sloppily navigated and kept the salvage companies quite busy.

     

    In supplementation of John’s remarks, I would add my recollections from the late 1930s onward to the effect that that …

     

    1. By the late 1940s, commercial radar began appearing on US Merchant Ships and began to influence navigation. In 1946, I hand the privilege of being shipmates with the first radar set manufactured solely for commercial use, as opposed to previously available military (SO) sets – it was a GE unit with a 6” ppi scope, variable but otherwise fixed range rings, and a surrounding moveable bearing circle. These early commercial sets would usually not remain in operating order for a full voyage unless very conservatively used – continuous operation was out of the question, so their use was generally relegated to special circumstances only. By the late 1950s two (2) sets were being installed to provide redundancy and reliability. Nothing, however, to compare with later modern sets with humongous scopes and auto-plotting features.

     

    2. By the early 1950s, Loran began to appear aboard US Merchant Ships. The first set I sailed with was a surplus military APN-6, an aircraft unit, in which the operator identified and matched individual ground or sky waves on a scope in a step by step process and read off the time difference on the scope. If you didn’t have Loran charts, no problem, tables were provided whereby the time difference could be plotted on a conventional chart as a LOP. All this was quite different from the later multi-station, digital readout sets, which simplified the whole process considerably. The British had their own system, Decca, and between the two systems approaches to US Ports and the Channel were well covered, however coverage worldwide was very sparse or non-existent.

     

    3. In about 1948, the USMS established the first commercial Loran and Radar Operational School at 42 Broadway in NYC, offering a total of 60 hours training, for MM officers, in radar and loran operation, including manual radar plotting for collision avoidance.

     

    4. So long as celestial navigation was practiced on a daily basis as the primary position finding system at sea, the astronomical triangle solution method employed on US Ships, both Merchant Marine and Navy, was largely a matter of individual choice, although LOP methodology was almost universal from the 1920s, or even earlier, forward. HO 211, HO 208, HO 214, Time Sight, Marc St. Hillare, Martelli, Aquino to name but a few, could all produce an acceptable LOP, and were variously used by navigating personnel to this end – only the results counted, not the methodology. US Merchant Marine practice was largely influenced by the Steamboat Inspectors (BMIN), predecessor to the USCG, who, especially at New York, liked to see the Time Sight used on license exams, so many MM officers remained proficient therein as a practical matter; the Navy, on the other hand, usually trained its navigators to use HO 211 (Ageton), with no material difference in the result. Regardless, by the early 1940s, HO 214, by its very simplicity, had replaced most other methods of sight reduction at sea until the advent of HO 249, and even thereafter. Because of the multi-volume bulkiness of HO 214, most conscientious officers maintained proficiency in at least one other method utilizing a more portable form of tabulation. At the USNA and most Merchant Marine Schools with which I am familiar, Dutton was the primary text for instructional purposes with Bowditch used as a supplementary work and for the Tables contained – the training being far more rigorous than anything offered today.

     

    5. I still have two copies of the Rude Star Finder – one purchased about 1943 and labeled  HO 2102-B (Price $1.00) in a reddish brown manila envelope and intended for use with the old format Nautical Almanac, the other of unknown vintage and labeled HO 2102-C/A-N Type 1 (Price unmarked) in a fancier leatherette case and intended for aircraft use with the Air Almanac – they both seem to achieve the same end. A ship’s officer was expected to be proficient in stat identification, at least as far as the navigational stars were concerned, and the primary use for the Rude Star Finder, at least in my experience, was in the pre-computation of altitude and azimuth for early pm/late am observations before/after stars were visible to the naked eye and while a distinct horizon was available. After the advent of HO 249, I put away the Rude Star Finder and pre-computed more accurate, well placed altitudes and azimuths by this publication for the time wanted. There are many star identification methods available, each having its advocates and its detractors – if the Rude Star Finder, or anything similar, works for you, by all means use it..


    Henry

     

     



    --- On Tue, 11/9/10, John Brown <jdb0302---.co.uk> wrote:

    From: John Brown <jdb0302---.co.uk>
    Subject: [NavList] Re: The Rude Star Finder and teaching stars
    To: NavList@fer3.com
    Date: Tuesday, November 9, 2010, 5:51 AM

    Frank Reed wrote:

    "The Rude Star Finder is a good but primitive tool for the task.........It became a traditional component of "apex celestial navigation" (this is the name I use for the highly standardized, exquisitely optimized, and even ritualized form of celestial navigation that was practiced in the latter half of the 20th century, particularly after the year 1958, especially on American and British vessels."

    Here is one recollection of the deep sea navigational routine on board a typical British merchant ship in the early 1960s. Verniers on sextants had given way to micrometers. Chronometers were still powered by springs. The common method of sight reduction involved a longhand solution of the cosine-haversine formulae using 5-figure logs. Towards the end of the decade these methods were cheerfully made redundant by inspection tables such as AP3270/HO249. Various short method tables had been available for some considerable time, but were not popular because of the relatively complicated rules for their use and marginal time savings in computation.

    I joined Royal Mail Lines Limited, of London, as an indentured deck cadet in 1961, promising, amongst other things “not to frequent Taverns or Alehouses, unless upon (my Master’s) business”. The general cargo ships of that long defunct company traded between the UK, mainland Europe, the West Indies, South America and the Pacific coasts of the USA and Canada.

    My first ship had a complement of three deck officers, who kept bridge watches and shared the navigational tasks. The 2nd Mate was responsible to the Master for passage planning and the upkeep of all charts and navigational publications carried on board. Sextants and nautical tables were the personal possessions of each officer and these were stowed on narrow shelves in a chartroom locker. Chronometers and plotting instruments were supplied by the ship, as were the charts, almanacs and sailing directions.

    The day at sea, then as now, was split into six four-hour watches, commencing at midnight with the 2nd mate’s watch. He was relieved at 0400 by the Chief Officer (The Mate), who was in turn relieved by the 3rd Mate at 0800. Zone time was not formally kept on board, the clocks being advanced or retarded as necessary to locate lunchtime roughly in the middle of the day.

    Taking over the watch at midnight, the OOW’s first task was to wind the chronometer, inverting it in its gimbals and giving the key precisely seven half turns. Lest this important task be forgotten, the message “wind chron” was often be found written in soap on the washbasin mirror in the 2nd Mate’s cabin. If the ship was on a great circle track, a new initial course to the destination might be calculated using ABC or Burdwood’s azimuth tables, with the latitude of the destination substituted for declination and the difference in longitude entered in the LHA column. On each night watch, an azimuth of a bright star or planet of fairly low altitude was obtained to determine the errors of the gyro, and the magnetic standard and steering compasses.

    With the coming of dawn on the next watch the navigational tasks stepped up a gear. The OOW calculated the time of civil twilight and the LHA of Aries for that time, setting up 2102-D and selecting five or more moderate altitude stars, well distributed in azimuth. Star sights began as soon as horizon was distinct, with the sextant pre-set to the approximate altitude and aimed on the appropriate bearing relative to the ship’s head, or across a bridge wing gyro repeater. The sequence of sights began with fainter stars in the eastern sky and finished with the brighter stars towards the west. Each sight was timed, by a cadet, if available. He was alerted by the call of “standby” a few seconds before the instant of observation, which was marked by a second call of “stop”. If no timekeeper was available the OOW counted seconds on the short walk from bridge wing to chronometer. A few people were equipped with stopwatches. Sextant altitudes and chronometer times were noted in the navigator’s workbook and sight reduction began, using the Marc St Hilaire method with the cosine-haversine formula for calculated altitude and ABC tables for azimuth. All computation was carried out using the Nautical Almanac and five-figure logs from either Norie’s or Burton’s Nautical Tables. Until the advent of inspection tables the same DR longitude was used for each sight, with the resulting LOPs graphically advanced or retarded to a convenient common time, usually to the nearest hour and some convenient multiple of six minutes. A five star fix, including LOP plotting, generally took about half an hour. With the fix on the passage chart, a mercator sailing calculation provided the distance run and course made good since the previous evening’s fix.

    At sunrise, an amplitude of the sun gave yet another check on the ship’s compasses. Next, when the sun had risen to a reasonable height, observations yielded position lines to be advanced to noon. For the rest of the day estimated positions and running fixes were worked up by calculation, using the traverse table. The intercept and azimuth from a morning sun sight was used to determine the “through” position, or the position closest to the DR through which the LOP passed. The noon DR or EP was then based on the run from this position. The difference between the observed latitude at noon and the DR or EP latitude was then multiplied by the “C” factor (cot az sec Lat) to find the “longitude correction”. The simple but somewhat arcane process is explained in Burton’s Notes to the Tables, sixth edition.

    During the afternoon watch, further position lines were obtained from the sun and perhaps Venus or Jupiter, if available – rarely the moon. In the evening a star fix was obtained using the same process as in the morning, with a similar but reversed sequence of observations, commencing with the brighter and western stars.

    On the homeward passage, in the SW approaches to the English Channel, we cadets manned the Kelvin deep sea sounding machine in search of the 100 fathom contour, marking the edge of the continental shelf with its concentrations of fishing vessels and the prospect of heavier traffic. Once a sounding of 100 fathoms had been found and reported to the bridge, the watches were doubled up, and coastal navigation began in an atmosphere of pleasant homecoming anticipation, known to generations of British seamen as “the channels”.

    How very far away it all seems now.

    John Brown

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