NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
DR
From: Millard Kirk
Date: 1999 Feb 22, 01:06 EST
From: Millard Kirk
Date: 1999 Feb 22, 01:06 EST
Silicon Sea, On Leg 46 of the Silicon Sea cruise I made an assumption on one of the problems and then went back and change the answer after re-reading the question. Well it looks as if I have done it again on Leg 47. The use of calculator and computer makes working navigation problems easy, but sometime we tend to forget the basic definitions. Problem: 2) What is the DR at 1930ZT? I must admit that these problem have been a great learning experience for me. If one uses the current to get the DR is it really DR or estimate position (EP). Bowditch - Dead reckoning (DR) determines position by advancing a known position for courses and distances. A position so determined is called a dead reckoning (DR) position. It is generally accepted that only course and speed determine the DR position. Correcting DR position for Leeway, current effects and steering error results in an estimated position (EP) Minor point - I am not getting picky in problem 2. It's just that I used my Celesticomp V to do these problems. It started me to thinking how it works, since I have not used it for several months I have to review and understand the working of it. I started with the "Plan" which gives me "Rhumb Line Dist.", "Rhumb Line True Course" and if you plug in the VAR and DEV you get the "Magnetic Course or Compass Course (CS)" To get DR on the Celesticomp V it asks for Departure Lat & Lon, Steered, Speed, Var&Dev and Turn Point time. I guess the "Steered" always did drive me little crazy in the DR program because there is a program that is called STEER/CUR which give one the Course to Steer if one has Desired Course (TC) Var&Dev, Log Speed, Current Dir, and Current Velocity. So if I use the "Steered" Compass course from the STEER/CUR in my DR program I actually get EP not DR. Going back an looking up what DR means has helped me straighten out the difference between DR and EP, and my Celesticomp V. I guess one should use all the information he has arrive at the DR-EP. Still............... Learning the Hard Way!! Millard Kirk KB8YQO | mailto:mkirk@XXX.XXX 116 Lewis Ave | Homepage- http://webpages.marshall.edu/~mkirk/ Barboursville, WV | A West Virginia Blue Water Sailor 25504 | Phone: (304) 736-6544 First United Methodist Church, Barboursville, WV Homepage http://www.gbgm-umc.org/bfumcwv/ =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-= =-= TO UNSUBSCRIBE, send this message to majordomo@XXX.XXX: =-= =-= navigation =-= =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=