NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Nomograms and emergency navigation
From: James R. Van Zandt
Date: 2007 Oct 15, 07:54 -0400
From: James R. Van Zandt
Date: 2007 Oct 15, 07:54 -0400
I've always had my doubts about the actual practicality of a lifeboat sextant (i.e. that they were intended mostly to impress the passengers) - since CN would also require a cronometer, an almanac, and a calculator or sight reduction tables. If the ship's officers were bringing those to the lifeboat, then why not bring a good sextant too? However, with the sextant alone one could still determine latitude. A few weeks ago, Andrew Nikitin posted some nomograms for altitude correction, with the suggestion they could be attached to the sextant itself. I suggest one additional nomogram, for reduction of a Polaris sighting. I envision a star chart of the polar region, surrounded by a circular scale, with instructions something like this: "Rotate the figure to match the sky, then read the correction from the scale directly under Polaris." I also suggest the offset of Polaris from the north pole in the chart be exaggerated, so the navigator can confirm the sign of the correction for himself. I would also include a worked example. - Jim Van Zandt --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---