NavList:

on 9/26/04 11:45 AM, Russell Sher at eastview@MWEB.CO.ZA wrote:

A navigational problem in the Jan/Febr. 2004 edition of Ocean Navigator Magazine (#135) posed a question which involved a navigator shooting the sun to obtain an LOP. Since there is only one LOP there is therefore no fix, but the one of questions asked is ‘What is the Estimated Position?’ I imagine that it is the position plotted on the LOP as being the closest from the DR. Does anyone agree?

Obviously in Coastal navigation, the estimated position is typically the position calculated from Course steered, log reading and taking tidal streams or current into account, but here the context is different.

(You can access the problem at -  www.oceannavigator.com <http://www.oceannavigator.com/>  (look under ‘browse by issue’  - choose jan/feb 2004, select the nav problem )



regards

Russell

Russell,
I agree, but only if the DR is based upon one's best guess of course and speed made over the ground. If course and speed are not equally in contention, then the better known one should weight the EP towards it, and the line going from the DR to the EP may not be exactly perpendicular to the LOP.  This question was discussed to exhaustion a few years ago.  Confusion bore from the fact that even the same edition of Bowditch will have two different definitions of EP, and that air and marine navigation have different customary meanings for DRs and EPs.  It remains an il-defined matter.

Ken Gebhart