We spotted Pelican Pete lying under his boat sloshing on a coat of bottom 
paint.  It is a coincidence that we just gave up trying to use his 
NavPak Android/Kindle app for celestial navigation,
so we decided to ask if he could help.

“Pelican Pete, can you suggest a simple exercise to get some meaningful 
numbers on the screen?”

“I'll try”, Pete replied.

The Almanac function in NavPak gives pre-computed Altitudes and Azimuths 
so we can use it to make up hypothetical sights to solve and plot.
After we plot 2 or more sights we can get a fix.

Start by going to the Almanac panel and tap the button:  GMT Time [Edit] 

This takes you to the GMT Time panel.  Tap the button:  [Set to Clock],
then tap [SAVE] to return to the Almanac panel.  In this panel,
tap the button: [Calc].  This calculates all the planetary positions based
on the GMT.  

Use the up and down arrow keys to see the Almanac list.
Notice that when you scroll through the list, the altitude (Alt)
will be blue or yellow.  Blue is below the horizon, and yellow is above
 the horizon.  For our example, scroll till you get to a body with a yellow
Alt.  Make a note of the nearest whole degree of Alt.  We then use this as
an example Hs that we can enter into the next panel.  

Tap the button: [SR ->].  This takes us to the Sight Reduction panel. 
 All the info from the Almanac panel is transferred here to the Sight
Reduction panel.  All you have to do is enter your Hs here.
Tap the button: [Calc].  The resulting Intercept (Int') should be less
than 30 miles if you used reasonable care estimating the Alt and entering the Hs.

Now tap the [SAVE] button to save the sight, and then tap the [Plot] button
 and you should see a Line of Position (LOP) on the Plotting Sheet.


Pelican Pete!  You're making a mess!

“Oh, do you mean with the paint or the explanation of the sample?”, Pete asked.

I blurted out: “Both!”

“I haven't finished either yet, You just cut me off”, Pete replied.

To make the sample complete, we should plot another sight so we can get a fix.

Each sight will have a unique time, so go back to the GMT Time panel and enter a 
new time.  Then go back to the Almanac panel, tap [CALC] and use the up and down 
arrows to select another body with a yellow Alt, indicating that it is above the 
horizon.

Estimate the nearest whole degree of the Alt, then go to the Sight Reduction
panel using the button: [SR->].  Enter the Alt as the HS, then tap the button:
[Calc] and check the Int.  Tap the [SAVE] button and then tap on the button: 
[Plot] and you should now see 2 LOPs.

If the Intercepts (Int') were not too big then the LOPs should intersect.
Where they intersect a white cross will be shown with the latitude and longitude.
This is our fix.

“You didn't say anything about the Assumed Position (AP) or Dip. Now I'm totally
confused.”

For the purpose of the example, if we use the same AP in the Almanac that we use
 for plotting then it should line up.  To simplify things, we are estimating whole
degrees, so the Dip will not make much difference.

To be continued...