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An interesting new term for me, the "Intended track, IT". I had see various 
variants in older (but not old, as they worked with maps, not with traverse 
tables) navigation manuals, pontificating how to plot the courses on the 
chart between the fixes:


1) to plot only DR positions without any improvements for sets and drifts, as 
they are always only guessed, while DR plot is reliable by its internal data 
at least in our times - the gyro course and the speed by a modern log; this 
was the mindset of the Bowditch 1958 I had cited in this thread already; a 
bit sniffy procedure, maybe challenging the fate

2) to plot DR courses corrected by drift angles, as being easier guessed, and 
to take the current data into account only secondarily, e.g. according to the 
point 3)

3) to plot DR and "IT" track (IT allowing for sets and drifts), so as to be 
able to assess the real probable positions along the course roughly and in 
the moment of the turn, to continue both the DR track and IT track from the 
respective turning points and to choose the positions along DR or IT that 
were nearer to dangers; a typical schoolbook procedure

4) to proceed only along IT on the chart, even through the turning points; a venturous procedure


I didn't find any definite and reliable solution of this problem in some 10 
reference manuals I had read - the last resort of the "navigational art", 
isn't it? Yes, thereafter the GPS came up.


Jan Kalivoda

   

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