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    John's T-nav diagram
    From: Jeremy C
    Date: 2013 Mar 21, 08:03 -0700

    John's pdf example reminds me of those word problems I had in school. Let me see what I can figure out.

    Givens:
    1) An EP
    2) 2 LOP's of different objects shot at different times
    3) a DR track.

    Conclusions:
    1)A running fix position.
    2) There is a previously unknown current/wind affecting the vessel driving the ship WxN which sets it to the left and slows her down. From this plot I can get an initial set and drift to refine the CMG/SMG so that I can more accurately advance LOP at the next R. Fix if object #2 remains visible. This will give me a greater confidence R. Fix in the future.

    While I am not throwing out any information provided, I am also not making assumptions based on scanty information. I have no data as to range from the objects so any knowledge of my location along LOP2 is derived from the advancement of LOP1. If other data was available such as soundings or ranges, then they would be plugged into the R. Fix as well, and given more weight than the advanced LOP1.

    The issue in this example is that our DR track is off and therefore the advancement of LOP1 is probably off as well. The trouble is that we can't quantify this error with the information we have, so the R. Fix remains a low-confidence position to me, especially given the amount of difference between the R.Fix position and the DR.

    I am not sure how a non-traditional method would bring the DR closer to the R.Fix position with the given information.

    Jeremy
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