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    Re: Researchers spoof GPS signals to alter superyacht'scourse
    From: Lu Abel
    Date: 2014 Apr 29, 12:06 -0700
    I totally agree.  Except it might not work when objects are 20, even 40, miles away as they were with the Royal Majesty.   Not that the concepts of bow-and-beam bearings or doubling-the-angle-on-the-bow somehow don't work, but rather that (a) angles change slowly at that range and (b) continued visibility of the objects is questionable.

    BTW, many years ago I took a course at Babson College in the Boston suburbs.   During a break I wandered into their library and discovered they have an amazing collection of old maps and charts of New England.  I found one from the early 1900s that covered the coast from Portsmouth Maine to Rockport Massachusetts.   And on the chart was a clear plot of a bow-and-beam effort to determine distance off the coast!  (about 3 miles, not 30)



    From: Peter Smith <NoReply_PeterSmith@fer3.com>
    To: luabel{at}ymail.com
    Sent: Tuesday, April 29, 2014 11:21 AM
    Subject: [NavList] Re: Researchers spoof GPS signals to alter superyacht'scourse


    Hear, hear! for the trusty hockey puck (http://www.celestaire.com/compasses/mini-2000-compass-detail.html). Simple bearings, and 45°/90° bearings for distance-off, are quick and easy. Throw in ranges (where available) and soundings (if you have an echo sounder) and you can do a lot of sanity checking with minimal effort.
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