AP in the east.

[wannathermal]

I'm in the Western & Northern hemisphere and haven't had any experience in working an Eastern longitude problem.

Wannathermal, could you give us an example for better clarification?  Ap only is used when the LOP plot is done.  DR longitude is your estimated position.

Thanks,

Carlos




Carlos

Well since for me the object of the exercise is to, using the Nautical Almanac and HO249 or 229)  find my position (or for my students to plot the boats actual position) underway Ap is an important component of their site reductions, probably the most important component, get it wrong and your fixes won't work although everything looks good.

So, on Feb 18, 2018 @ 135730 UT 
DR N39°33' E 18°05'course 041T @ 7.5kn (our actual position, approaching the heel of Italy in near gale condition ) 
GHA 25°54' 
So the LHA is 43°59' rounded up to 44°
Assumed Longitude is 18°06' ( longitude integral degree plus 60'-GHA minutes for the minutes)
Assumed Latitude is 39°

My LOP, see attached, went right through my DR and an afternoon running fix was within 2 miles. 

I hope this explains my concern with the instructions.

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I'm in the Western & Northern hemisphere and haven't had any experience in working an Eastern longitude problem.

Wannathermal, could you give us an example for better clarification?  Ap only is used when the LOP plot is done.  DR longitude is your estimated position.

Thanks,

Carlos




Carlos

Well since for me the object of the exercise is to, using the Nautical Almanac and HO249 or 229)  find my position (or for my students to plot the boats actual position) underway Ap is an important component of their site reductions, probably the most important component, get it wrong and your fixes won't work although everything looks good.

So, on Feb 18, 2018 @ 135730 UT 
DR N39°33' E 18°05'course 041T @ 7.5kn (our actual position, approaching the heel of Italy in near gale condition ) 
GHA 25°54' 
So the LHA is 43°59' rounded up to 44°
Assumed Longitude is 18°06' ( longitude integral degree plus 60'-GHA minutes for the minutes)
Assumed Latitude is 39°

My LOP, see attached, went right through my DR and an afternoon running fix was within 2 miles. 

I hope this explains my concern with the instructions.

I need to add;

DR is our Estimated position derived from our last fix using speed and course, this can also be our EP.
Ap is the Assumed Longitude and Assumed Latitude used to plot the intercept.
Ap is the assumed position