NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Why Not To Teach Running Fixes yes
From: Rob M
Date: 2009 Dec 14, 09:13 -0800
From: Rob M
Date: 2009 Dec 14, 09:13 -0800
there is always disparity between the classroom (where this discussion started) and practical application of concepts. the RFIX is taught to get a set of concepts established in a students' head in isolation so they may then be used in situ with other concepts to accurately establish a position (as accurately as possible under the circumstances, which may preclude a real FIX established by simultaneous LOPs). for a time-separated set of navigation LOPs one can establish an RFIX and an EP. Neither are FIXes. seeing the two one can understand the injected estimate of set and drift which may be of interest to the navigator. the plotting of RFIXes also allows a navigator to look back and understand possible errors in previous plotting or challenge assumptions in the estimate of set and drift, etc which are of value. the navigator must remember that the RFIX is not a FIX, nor an EP (even when plotted to equal the position of an EP). the two are different and must be evaluated differently. a FIX is clearly superior to an EP, DR or RFIX, however in the absence of a FIX the RFIX, DR and EP have different values to the navigator. The RFIX and associated concepts, which allow some off the vessel observations to be incorporated into the calculation of position are of greater value to the navigator than just a DR or EP, which are entirely based on assumptions. In complete classroom plotting exercises I regularly teach the plotting of a set of a FIX, then a DR, EP and RFIX an hour later, and then a new FIX an hour further on, and the review the lot forward and back to enable students to see the value in the review and evaluation of the 4 different concepts and how they can each independently inform the navigator. most find this a worthwhile exercise. Rob -- NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com