NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Leg 56 Question # 3
From: Lu Abel
Date: 1999 Jul 19, 9:45 PM
From: Lu Abel
Date: 1999 Jul 19, 9:45 PM
At 09:39 PM 7/19/99 EDT, Bill Murdoch wrote: >In a message dated 7/17/99 1:31:35 PM EST, dhhogan@NAV.CNCHOST.COM writes: > >> So you use only the data you can rely on. Time/speed and distance. Which is >why I prefer to DR using a distance log rather than boat speed. > >I agree and do the same, but then why do the USPS and most texts always >multiply time and average speed to get the distance run? I would have >thought it to be better to use the logged distance letting the instrument >find the intergrated product rather than relying on me to guess the average >of the speed readings for an hour. I believe this is an example of the USPS and many of the standard texts either being way behind the times, contemporary, or just not mentioning another way to solve a problem. Way behind - The USPS courses, for example, discuss obtaining speed vs RPM curves for one's boat. Good 1920's practice when electronic knotmeters didn't exist. Maybe actually carried into the 1950s by the Navy. Has anyone on the list actually made such a curve? Contemporary - because most of us have knotmeters Not mentioning - several times I've seen reference to "just trail a Walker log" as a much better way of getting DR distance than 60D=ST, but this technique doesn't seem to have made it into texts and USPS courses. Pragmatically, I wonder how many people still trail Walker logs? I know it's against the spirit of this list, but I feel obliged to point out one can buy several GPS units for the price of a Walker.
