NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: FW: Re: Chronometer Suggestions
From: Peter Fogg
Date: 2009 Jan 10, 19:03 +1100
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From: Peter Fogg
Date: 2009 Jan 10, 19:03 +1100
On Sat, Jan 10, 2009 at 18:31, <glapook@pacbell.net> wrote:
Hmm. The assumption that the purpose of position finding is to avoid danger may obscure a more important reason for the activity. I propose that the main reason for deriving a position, particularly when well away from land, is to find out in what direction the destination lies. Depending on how far away that destination (or waypoint) may be, an hour's worth of time error could make a great deal of difference to the correct heading. And if the error was consistent, which it presumably would be, could lead to the poor sailor becoming altogether lost.
Tell us you're pulling our leg, Gary ...
And here is the simple answer. If, where he is sailing, he can
tolerate a one minute of longitude error all he needs is a watch that
is accurate within 4 seconds. If sailing in the middle of the ocean
more than fifteen degrees of longitude away from any danger you can
use a watch with a one hour error.
Hmm. The assumption that the purpose of position finding is to avoid danger may obscure a more important reason for the activity. I propose that the main reason for deriving a position, particularly when well away from land, is to find out in what direction the destination lies. Depending on how far away that destination (or waypoint) may be, an hour's worth of time error could make a great deal of difference to the correct heading. And if the error was consistent, which it presumably would be, could lead to the poor sailor becoming altogether lost.
Tell us you're pulling our leg, Gary ...
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