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    Re: Wartime (WW2) navigation
    From: Gary LaPook
    Date: 2010 Feb 01, 11:50 -0800

    Looking at the leg from Curvier Light to WP1 and using the interval of 
    five degrees of longitude for the points approximating the great circle, 
    you get the following information:
    Longitude           Latitude              Distance             Course    
          Cumulative distance 
    180° W              37° 10.0' S         207.5 NM        102.5° T         
    207.5 NM
    175                    37  50.8             241.5                  99.7  
    170                    38  18.3             237.8                  96.7  
    165                    38  33.0             235.5                  93.6  
    160                    38  34.8             234.6                  90.4  
    155                    38  23.8             235.1                  87.3  
    150                    38  00.0             237.0                  84.2  
    Trevor Bell wrote:
    > I agree - this is getting interesting. I acknowledge that the first 
    > waypoint was nowhere near the great circle - that was the intention of 
    > the naval control service routings - to sail off the normal direct 
    > routes but what the calculations have shown is that the total distance 
    > using the different methods varies by only a very small percentage.
    > Having re-read the 1941 inquiry into the Rangitane sinking I can 
    > confirm that the waypoint coordinates I have given are correct but I 
    > realise that there was another error in my previous post: I said that 
    > the NCS told the captain to sail a great circle route between 
    > waypoints. This is wrong - he was told Mercator but the captain said 
    > at the inquiry that he may have sailed great circle. From various 
    > other enquiries I have made I understand that it was virtually 
    > impossible to sail a great circle because of continuous changes in 
    > heading so the great circle was broken up into a series of rhumblines. 
    > If he had sailed an approximated great circle, this makes the position 
    > of sinking (see previous post 11695) much more acceptable at about 
    > 35nm, but still off course.
    > Just to lay another issue to rest - there has been some discussion in 
    > other posts about me using the term 'whole circle' instead of 'great 
    > circle' - sorry about that, it comes from my background as a civil 
    > engineer in which we use the term 'whole circle bearing'.
    > Trevor Bell
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