Celestial Navigation Baby Steps

We have a sextant on Red Ranger.

I think it might be adjusted properly. The index error appears to be 6.8′. I fiddled around with the mirrors a little and got a single view of the Sun through the various sunshades.

On the way N from Norfolk to Deltaville, I tried some sun sights at about 12:45, through a break in the clouds.

I did the sight reduction calculations. 

And I wasn’t even close.

The math is right. I have correctly solved book problems with the spreadsheet. I have unit test cases to show that it’s right. And the math isn’t all that complex, really.

So, I’m left with operator error. Failing to get the sun’s lower limb on the horizon. Failure to get the image centered. Failure to read the time correctly. Failure to read the instrument angle correctly. 

I have to review the chapters on sextant operations in the Celestial Navigation in the GPS Age book. I also have The Sextant Handbook. Somewhere on the boat.

That will keep me busy for a while.

  © Steven Lott 2016