A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: Robert VanderPol II
Date: 2017 Mar 20, 15:38 -0700
We agree on the definition of DR.
I think your difinition of EP is a bit more limited than the one I use or that I can find authoritative definitions for. I do not feel that a line of postion is the only way to improve a DR to an EP. Historical knowledge of your own boat's leeway in differing conditions and points of sail/motoring allow you to adjust for leeway. Current predictions are available for many areas without reference to measurement in the here and now. Correlation of soundings with charted depths can also improve on your DR.
Knowlege of your knotmeter's slippage in varying conditions could also contribute to jmproving the DR or EP. I could see arguements that this is part of DR, compensating for mismeasurement by your instruments.
Regardless, your post yesterday implied that I was confusing the DR & EP (or I inferred that you did not know the difffence between the 2, whatever). I did not confuse the 2, I chose EP because that is what I normally would use to start the reduction. If I was not making any estimates of current and/or leeway and had no sounding data then I would use DR. Being prone to sloth it's very likely I would occasionally use the DR or rarely even just an out and out guess on occasion.
Re: S-tables: where to have a look at them?
From: Stan K
Date: 2017 Mar 20, 14:55 -0400