NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Logs vs Knotmeters
From: Lu Abel
Date: 2008 Mar 29, 17:56 -0700
From: Lu Abel
Date: 2008 Mar 29, 17:56 -0700
In another group I belong to, there's a discussion going on about the accuracy of speed measurements needed for Dead Reckoning (or Ded Reckoning for some purists). Dead Reckoning is really based on distance traveled. So if I measure vessel speed, I have to go through a speed x time = distance calculation. A very long time ago, navigators measured vessel speed (eg, by counting knots pulled through one's fingers from a chip log, hence our term "knots") and then did a speed to time conversion. Somewhere along the line, patent logs (such as the Walker log) were invented and distance was measured directly by trailing the log's spinner. When? And if anyone keeps DR plots any more, what technique is used today? Are electronic paddlewheel knotmeters considered sufficiently accurate to go back to calculating distance from speed? (and at the same time I'll note that electronic knotmeters typically have a log function, so why bother with distance from speed and time calculations?). Thanks Lu Abel --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---