NavList:

   

Reply

Ken,
Thank you for your explanation.
I hope you saw my error correction: the main point of my criticism
of your advertisement was simply wrong: two angles DO define your position
uniquely.

I have one of those Russian globes (with Latin star names);
and I have seen Freiberger globes only in the pictures.
Don't know why they are inferior.

So far I did not find the globe very useful, though I did not try it
as directed: the main purpose according to the manuals is identifying
a single star seen through a hole in the clouds.
Before or after observation of this star.

And of course this bulky thing is not for a small craft.

Alex.

On Wed, 4 Apr 2012, Ken Gebhart wrote:

>
> Alex,
>
> There might not be any demand for this, but the factory made some for
> the Chinese Navy.  They asked if I could sell some, and I was not
> very hopeful. However, we had a space in the catalog at the last
> minute, so just stuck it in. We actually had an order two weeks ago
> from a Prof at a maritime school who wanted to demo it to students.
> It reminds me of the Russian star globe we carried during the cold
> war. It was far greater quality than the East German (Freiberger)
> one.  In eight years of showing it, we sold only one unit (which is
> all we had in stock anyway). Nevertheless, it helped our catalog
> stand out from the others who only carried items that generated x$
> per square inch of space.
>
> Ken
> On Apr 4, 2012, at 4:32 PM, Alexandre E Eremenko wrote:
>
>>
>> Ken,
>> Yes, it looks exactly as the Soviet model, as far as I can judge from
>> those tiny pictures:-)
>> I am still surprized: is there really any substantial demand for this
>> heavy and expensive toy, I mean demand that is not covered by e-Bay?
>> Why else would they make it?
>>
>> You can certainly solve the same problem will all precision needed
>> for practical navigation with a simple plastic station pointer
>> you always had, or with a simple computer program.
>>
>> Besides, there is no place to store this thing in a small boat:-)
>>
>> Alex.
>>
>> On Wed, 4 Apr 2012, Ken Gebhart wrote:
>>
>>>
>>> Alex,
>>>
>>> Yes it is made by the same factory, and possibly is a copy of the
>>> Russian model. Your comment is certainly correct, and we are
>>> replacing "determine the direction" with "identifies".  As for the
>>> two solutions, we didn't want to confuse the reader, or start a new
>>> dialog about the math.  Thanks for your comments.
>>>
>>> Ken
>>> On Apr 4, 2012, at 12:56 PM, Alexandre E Eremenko wrote:
>>>
>>>>
>>>> Indeed!
>>>>
>>>> I am surprized. They do not say who makes them,
>>>> Ken, is it by the Astra factory?
>>>> The construction seems exactly the same as of the Soviet one
>>>> that I have, except that the Soviet one is made entirely of bronze,
>>>> and this one of an aluminium alloy.
>>>> The box is of slightly different construction.
>>>> (Soviet ones on e-bay usually cost a bit less).
>>>>
>>>> There are several imprecise points in the Celestaire description.
>>>>
>>>> a) You do not need to measure the DIRECTIONS (bearings) of 3 objects
>>>> but only TWO HORIZONTAL ANGLES between them. This is done with
>>>> a sextant. (A direction is measured with a compass, and it is
>>>> hard, if not at all impossibe to measure with 1' accuracy).
>>>>
>>>> b) "There is only one solution". There are generally 2 solutions.
>>>> The are usually far apart, if one takes the right objects to
>>>> measure angles between them, and one of the solutions is usually on
>>>> land.
>>>> Geometrically, these solutions are the points of intersection
>>>> of two circles (position lines). Two circles usually intersect at 2
>>>> points.
>>>>
>>>> Alex.
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>> : http://fer3.com/arc/m2.aspx?i=118702
>>>
>>>
>>>
>>
>>
>
>
>
>
>
> : http://fer3.com/arc/m2.aspx?i=118719
>
>
>

   

Reply