NavList:

-------------- Original message from Alexandre E Eremenko <eremenko@MATH.PURDUE.EDU>: --------------


> For the first time I had an opportunity to use
> the natural horizon.
> I sailed from Dublin to Kiel, with stops in
> the Scilly Islands, the Isle of White and Helgoland,
> in a 42 feet sailboat, on July 23-August 6.
> Unfortunately, the weather was not good for Cel Nav.
> For several days the Sun was not visible at all,
> on other days I had to use small gaps in the clouds.
> There was no oppornutity for Lunars, and I could make
> only one star observation, in unfavorable conditions.
>
> The first week was a disappointment (from the Cel
> Nav point of view); we sailed downwind with hudge waves,
> and I could only make observations without a scope.
> The results were ver! y bad, but one has to take into account
> that these were my FIRST observations with natural
> horizon.
>
> One general remark on observations without a scope.
> I think, one HAS to use the zero-magnification tube.
> Otherwise, it is hard to make sure that your line
> of sight is parallel to the plane of the arc,
> especially when the boat is shaking violently, and
> its course is not stable.
> This introduces a hudge "colimation error"
> which resulted in errors in position line of several minutes,
> once even 2 degrees, though I am not sure what exactly
> caused such blunder.
>
> In the second week, I achieved a tolerable precision.
> Maybe because of some practice, but more likely,
> because the weather improved.
>
> Here is the statistics of all my observations in the second
> week (August 1-6).
> I used my SNO-T sextant and C! asio watch. Reduction with
> the Almanac and Casio calculator.
> The number in parentheses is the number of observations
> averaged; if there is no number
> in parentheses, this means that only one observation
> was made. The number of minutes
> is the error
> in altitide (using GPS position as AP).
> August 1 Sun, 30 knots wind, waves 2-3 meters,
> course downwind: (5) -0.2'
> August 2 (Sun from a beach, Helgoland)
> (5) +0.5'
> (1) 0.0'
> (2) +0.5'
> (3) +0.5'
> August 4 Sun, good weather (15-17 knots wind, waves less
> than 1 meter): -0.1', -0.1',
> 0.1', -0.5',
> 0.3', -1.2', -0.8', -0.6', (3) -0.3'.
>
> The only star observation was on July 25:
> Venus (4), error -1.4' and Arcturus (1) error +3'.
>
> If anyone is interested, I can post (or send) the full detail
> of each observation.
>
> I a! lso tested my new Bris sextant which I bought at
> Cassens-Plath factory which I visited early in July.
> They said that the one I bought was the last one,
> its production being discontinued.
> I will write a separate message on the Bris sextant.
>
> Alex.