NavList:

   

Reply

I wouldn't be too worried about theoretical accuracies differing by 8 arc
seconds. I own both the Astra IIIb and top-end C. Plath's. To compare them,
I've taken comparison Sun sights from shore (since there is too much random
motion on a small boat for good repeatable numbers) and their accuracy is
very comparable. With these tests and under similar conditions, both the
Astra and the C. Plaths give consistent results of less than 1 NM in
absolute error, which to me more than acceptable for all practical
navigation purposes. Though not as nicely made or as finished, the Astra is
a very good value and a bargain for the price. Also, the Astra is lighter
weight, something at least for me that really does help during extended
sights while waiting for clouds to pass or while shooting multiple bodies.

Rod Deyo

----- Original Message -----
From  "Yves Arrouye" 
To: 
Sent: Friday, April 20, 2001 6:41 PM
Subject: Re: Any happy/unhappy Astra IIIB owners here?


> > I own quite a few metal sextants, and my measurements
> > indicate that Tamaya
> > and Plath are more accurate than the Astra.  I have seen used
> > Tamaya Jupiter
> > sextants sell for about the same as an Astra IIIb and I think
> > I would prefer
> > a Jupiter over an Astra given the choice, but you will be
> > quite happy with a
> > new Astra as well.
>
> Celestaire's brochure gives 20" of accuracy for the Astra IIIB against 12"
> for the Jupiter. I wish the Astra IIIB had a bronze arc, if that's the
> secret in the reduction of precision.
>
> I've always wondered: how accurate is a good sextant user? I mean, is 20"
> going to be a limiting factor? That's an error of about 1/3 of a mile
> compared to 1/5 mile for the Tamaya Jupiter, right?
>
> YA
>
> P.S.: Dan, while reading your thread about your sextant accuracy at
> http://www.i-DEADLINK-com/lists/navigation/9903/0042.html you're mentionning Tom
> Metcalf's nav.c. Where can I find that and the relevant litterature? Do I
> need to get back issues of the journal of the institute for navigation?
>
> Another question related to what you wrote there: how's the Davis
artificial
> horizon compared to the practice bubble horizon sold by Celestaire?

   

Reply