NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Beginner
From: Herbert Prinz
Date: 2005 Sep 18, 19:02 -0400
From: Herbert Prinz
Date: 2005 Sep 18, 19:02 -0400
Espen S. Ore wrote: > But it is in certain places along the scale easier to do fine > adjustments one way than another. True. But there is no way telling in advance in which direction the arm slides easier the next time from a given position. Inherent in the simple adjustment mechanism of the Mark 3 (or rather absence thereof) is a physical problem: initial friction at rest is higher than the sliding friction while moving. This creates a tendency to overshoot. The best answer is your own solution: > Actually the most precice measurments are probably when the sextant is > set a > little to high or low (depending on the time) and then kept until the > sun moves up or down to that height. Of course, you don't have this option for establishing the index error. But there you have more time to play until you get it right. Still, once you have managed to _set_ the Mark 3 to the correct angle, be it through presetting it in the way you describe, dexterity, or good luck you can trust the reading regardless which way you set it. That is different from a drum sextant, where the angle to be measured should be set approaching from the same side as when index error was established. Herbert Prinz