NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: "Improved" sextants
From: Lu Abel
Date: 2006 Jul 3, 20:15 -0500
The problem is to define what kind of "improvements" are allowed in our
sextant that "just kept on undergoing improvements."
Let's start with a couple of examples of past "improvements" allowed by
new technologies:
Aluminum has replaced brass as the material of choice for sextants,
making them lighter and easier to handle. Cheap, pure aluminum required
tremendous progress in metallurgy and in the technology of aluminum
refining. Perhaps 3/4 of a century ago someone looking for "improved"
sextants would have demanded they remain made of brass, though.
If we were having this discussion roughly 1-1/2 centuries ago, would
someone looking for an "improved" sextant have forbidden a switch from
verniers to drums, even though the entire history of sextants is marked
by ever-improving high-precision manufacturing and at some point this
allowed a switch from verniers to drums?
The reason I bring this up is that we live in an age of incredible
progress in electronics. But traditionalists seem to eschew the devil
of electronics, so is it excluded from technologies allowed to "improve"
sextants?
If not, the following would be trivially simple:
1. Electronic readout of sights (no more staring at verniers, just a big
LCD display). By the way, the mechanism needed for an electronic
readout could trivially eliminate the bother of Index Error.
2. Electronic image stabilization. Rock-steady bodies and horizons
even on the smallest, bounciest vessel.
3. In fact, no traditional arm on the sextant -- just two images (one of
the horizon, one of the sky). Twiddle a knob controlling the latter and
the image is brought down to the horizon.
4. Automatic height-of-eye calculation. No, not from GPS (way too
inaccurate) but either through ultrasonic ranging down to the ocean, or
through an electronic barometer that's lowered to the ocean's surface
and then brought up to the sextant.
5. Throw in a little bit of electronic knowledge about the body sighted,
and with this and the above we go straight away from ho to Hs, no
tedious tables, no mistakes (hmmm, do I add or subtract HP? Is
"off-the-arm" IE added to or subtracted from ho?
5. Last but not least, built-in logging and reduction of sights. A
microprocessor of far less power than is required by GPS could keep
accurate time, log sights at the press of a button (bring body down,
press trigger, ho and time automatically logged) and finally using a
built-in NA, reduced.
Now let's get even more radical (if the above aren't):
Some satellites use "celestial" to keep themselves correctly oriented.
Could such star-tracking mechanisms be adapted to the "improved sextant?"
In fact (although it pains my heart), is a human sight-taker necessary
with a 21st-century sextant??? Or is it better off with an image
processing system? A built-in electronic almanac would know all
available bodies at any point in time, an automated image finder would
try to find them, for each that was visible it would bring them down to
an automatically found horizon (heck, let's use a laser gyro and not
even need to see the horizon, we need to see it only to get a precise
sense of vertical and horizontal and a laser gyro could do that
instead), and last but not least, each body would be automatically
captured and reduced.
Meanwhile, we all sit and fiddle with our GPS sets because robo-sextant
is doing it all for us.
Just some thoughts -- and my apologies to all the wonderful people on
this list, many of who are probably very, very ill at this point...
Lu Abel
Robert Eno wrote:
> Interesting idea.
>
> Let's say GPS was never invented, nor any other kind of external electronic
> system. What would the modern sextant have looked like had it just kept on
> undergoing improvements?
>
> Whatever happened to the "Sextants of Tomorrow" as described in Bruce
> Bauer's "Sextant Handbook"?
>
> Robert
>
>
>
>>Seriously...it might interest an engineering class to take on the project
>>of
>>redesigning a sextant for ultimate accuracy using modern materials and
>>techniques, as a project, with no further goal. Whether that could then be
>>transformed into something more....An interesting project anyway.
>>
>>
>>
>
>
> >
>
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
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From: Lu Abel
Date: 2006 Jul 3, 20:15 -0500
The problem is to define what kind of "improvements" are allowed in our
sextant that "just kept on undergoing improvements."
Let's start with a couple of examples of past "improvements" allowed by
new technologies:
Aluminum has replaced brass as the material of choice for sextants,
making them lighter and easier to handle. Cheap, pure aluminum required
tremendous progress in metallurgy and in the technology of aluminum
refining. Perhaps 3/4 of a century ago someone looking for "improved"
sextants would have demanded they remain made of brass, though.
If we were having this discussion roughly 1-1/2 centuries ago, would
someone looking for an "improved" sextant have forbidden a switch from
verniers to drums, even though the entire history of sextants is marked
by ever-improving high-precision manufacturing and at some point this
allowed a switch from verniers to drums?
The reason I bring this up is that we live in an age of incredible
progress in electronics. But traditionalists seem to eschew the devil
of electronics, so is it excluded from technologies allowed to "improve"
sextants?
If not, the following would be trivially simple:
1. Electronic readout of sights (no more staring at verniers, just a big
LCD display). By the way, the mechanism needed for an electronic
readout could trivially eliminate the bother of Index Error.
2. Electronic image stabilization. Rock-steady bodies and horizons
even on the smallest, bounciest vessel.
3. In fact, no traditional arm on the sextant -- just two images (one of
the horizon, one of the sky). Twiddle a knob controlling the latter and
the image is brought down to the horizon.
4. Automatic height-of-eye calculation. No, not from GPS (way too
inaccurate) but either through ultrasonic ranging down to the ocean, or
through an electronic barometer that's lowered to the ocean's surface
and then brought up to the sextant.
5. Throw in a little bit of electronic knowledge about the body sighted,
and with this and the above we go straight away from ho to Hs, no
tedious tables, no mistakes (hmmm, do I add or subtract HP? Is
"off-the-arm" IE added to or subtracted from ho?
5. Last but not least, built-in logging and reduction of sights. A
microprocessor of far less power than is required by GPS could keep
accurate time, log sights at the press of a button (bring body down,
press trigger, ho and time automatically logged) and finally using a
built-in NA, reduced.
Now let's get even more radical (if the above aren't):
Some satellites use "celestial" to keep themselves correctly oriented.
Could such star-tracking mechanisms be adapted to the "improved sextant?"
In fact (although it pains my heart), is a human sight-taker necessary
with a 21st-century sextant??? Or is it better off with an image
processing system? A built-in electronic almanac would know all
available bodies at any point in time, an automated image finder would
try to find them, for each that was visible it would bring them down to
an automatically found horizon (heck, let's use a laser gyro and not
even need to see the horizon, we need to see it only to get a precise
sense of vertical and horizontal and a laser gyro could do that
instead), and last but not least, each body would be automatically
captured and reduced.
Meanwhile, we all sit and fiddle with our GPS sets because robo-sextant
is doing it all for us.
Just some thoughts -- and my apologies to all the wonderful people on
this list, many of who are probably very, very ill at this point...
Lu Abel
Robert Eno wrote:
> Interesting idea.
>
> Let's say GPS was never invented, nor any other kind of external electronic
> system. What would the modern sextant have looked like had it just kept on
> undergoing improvements?
>
> Whatever happened to the "Sextants of Tomorrow" as described in Bruce
> Bauer's "Sextant Handbook"?
>
> Robert
>
>
>
>>Seriously...it might interest an engineering class to take on the project
>>of
>>redesigning a sextant for ultimate accuracy using modern materials and
>>techniques, as a project, with no further goal. Whether that could then be
>>transformed into something more....An interesting project anyway.
>>
>>
>>
>
>
> >
>
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
