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    Transatlantic on the Royal Clipper and celnav
    From: Gary LaPook
    Date: 2009 Nov 27, 13:44 -0800

    We recently crossed the Atlantic on the Royal Clipper and I recommend it 
    to anyone with an interest in the great windjammers. It's not cheap but 
    a good value considering the number of days you get for your money. We 
    boarded in Lisbon on October 22nd and stopped in Casablanca and Safi, 
    Morocco and at Tenerife, Canary Islands. Then we were ten days at sea 
    and arrived at Barbados on November 7th. She is 437 feet long, has 26 
    square sails on five masts and 16 fore and aft sails. There are five 
    sails on the fore and mizzen, six sails on the main and middle masts, 
    and four sail on the jigger mast. Of the 26 square sails, 24 roller furl 
    inside the yards but two, the main course and the crossjack, use the 
    traditional clew garnets, bunt lines, leach lines, and gaskets for 
    handling the sails and crewman had to go aloft to work these sails. I 
    asked the captain and he said they kept these two so that they could 
    demonstrate the old ways to passengers. Bracing the yards is done with 
    hydrolic brace winches mounted at the base of each mast, two per mast, 
    one pulls in on the braces while the other pays out. Each winch has two 
    braces led to it but onto a drum that has two different diameters. 
    Because of the way the braces are rove, each brace moves up to three of 
    the yards at the same time so that one brace winch, with the two braces 
    led to it, can brace all six yards on one mast. This eliminates the 
    large manpower needed in the olden days when each yard had its own set 
    of two braces.
    
    She is 437 feet long but takes only 220 passengers and the ship and its 
    appointments are more like a yacht than a cruise ship. You can climb the 
    ratlines to what they call the "crows nest" but would traditionally be 
    called the "top" at the level of the main course yard and you get a 
    great view from there. You can also go out on the bowsprit or lay in the 
    net under it and watch and hear the sea rushing by under you. We met 
    many people and most of them had made this voyage many times (some, 
    many, many times) and we are planning to do it again, hopefully next year. W
    
    We were under only sail about half the time and we got up to eleven 
    knots solely with sail power. But when the wind was light, usually at 
    night, they would proceed under power to keep to their schedule. I 
    looked over the stern and could see when the prop was driving the ship 
    and the ship had a different feel when under sail alone, a wonderfully 
    different feel.
    
    The ship published a schedule for each day. On the second day they had 
    "sextant use and the noon sight" on the schedule. I went to the bridge 
    at the scheduled time and found passengers looking through about ten 
    Davis sextants looking at the sun. Not surprisingly they were getting 
    many different readings and I looked through several of the sextants and 
    they all had significant index errors, one of three degrees! I was 
    disappointed that no one was explaining what the readings were used for. 
    That afternoon the schedule said "advanced navigation" so I went to the 
    bridge for that. The second officer was explaining very basic stuff to 
    about a dozen passengers and I looked around and found H.O. 249 on the 
    bookshelf. Someone asked about variation and the second officer pulled 
    out a blue book and said that the changes in variation were listed in 
    that book. From where I was standing the blue book looked like the 
    nautical Almanac and I had never noticed variation information in that 
    book. I innocently asked the second officer if, when doing celestial, he 
    used H.O. 249 or if he used a calculator or programed computer. He asked 
    me what H.O. 249 was. I figured that maybe he knew it by some other name 
    since he came from the Ukraine so I got volume 2 off the bookshelf and 
    showed it to him. He flipped through several of the pages and had that 
    "deer in the headlights look" and it appeared he had never seen the 
    tables before! Even if he was not familiar with this particular set of 
    tables I would expect any navigator to recognize a sight reduction table 
    even if it was not the exact same set of tables that he was used to 
    using.  He then said "no, everything is in the blue book." So much for 
    the level of celnav being practiced today.
    
    I had brought my Tamaya along and planned to take noon sights to gather 
    data for our discussions and to take as many sights as I could to gather 
    data on the accuracy obtainable with celnav (I will write about these 
    things later) so the next day I was on the bridge at noon and took a 
    noon sight. The ships third officer saw me and asked me if I would teach 
    him celnav and I agreed and ended up with about eight other students the 
    next day to take the noon sun. I let them each take a sight as the sun 
    was approaching noon and after it started descending we worked out the 
    latitude the traditional way and it agreed within one NM with the GPS, 
    not bad for first time sextant users. I told them that this was a 
    special case with very simple arithmetic for the solution.
    
    That evening I hit upon a way to introduce the general solution by the 
    St. Hilaire method. I made up a plotting sheet and drew a line showing 
    the latitude line we had determined at 24º 49' North. I then explained 
    that another way we could have done it was to work the standard noon 
    formula from the other end and compute what we would have measured if we 
    had been at 25º North. Then comparing the observed altitude and the 
    computed altitude and knowing the azimuth of the sun was straight south 
    we plotted the LOP and showed that we got the same latitude as before. I 
    then got H.O. 249 and showed that we got the same result using it with 
    an LHA of zero. I then showed them that H.O. 249 would do the 
    computation for the general case. I have never seen it taught this way 
    and I had never thought of it before and I recommend this method to you 
    when you teach celnav.
    
    The next day we had the group shoot the afternoon sun and then we 
    stepped through the entire solution. I had to make up forms for them to 
    use and they weren't perfect so there were many math errors due to the 
    unfamiliarity of dealing with degrees and minutes and keeping them in 
    the correct columns, good forms would have made this easier. We then 
    plotted each of their LOPs on a plotting sheet and compared them with 
    the GPS values.
    
    
    Near the end of the voyage I was talking to the captain and he told me 
    that he does the calculation on a normal calculator and he challenged me 
    to a competition. Later that day I showed up on the bridge with my 
    calculator in my pocket and said I was ready for the competition. He 
    made up a set of values but when he got out his calculator he said it 
    was "kaput" the battery was dead. I worked the problem, so I guess I 
    won. This gave me a great segue to the flat Bygrave. I got it out of my 
    cabin and gave it to the captain as a gift, with some forms, and told 
    him the batteries will not go bad on this one.
    
    http://www.starclippers.com/
    
    
    gl
    
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