| Author |
Message |
Peter McLelland
Guest
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 Posted:
Fri Nov 18, 2005 5:08 pm Post subject:
Re: Wanted: Quality Sextant |
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"News f2s" <jimb@seesignature.f2s.com> wrote in message
news:dlk872$rfi$1@news.freedom2surf.net...
| Quote: |
"otnmbrd" <otnmbrd@earthlink.net> wrote in message
news:RA8ff.1874$jI5.1667@newsread1.news.pas.earthlink.net...
Sounds like you're talking about Loran A, not "C"..... two
different animals. <snips> > LOL sounds like you're
talking about the old WW2 sets
Exactly. Murmansk convoys. I'm not even sure it was Loran since it
was so secret it didn't have a name at the time. It was a radio
phase difference measuring system. You had to tune in, then fiddle
with oscillograph cursors to measure phase differences.
|
Sounds like one of the early LORAN boxes, I was still using one in the 70s,
not that accurate by today's standards, but if all you had after 48 hours
deep it was marvelous.
| Quote: |
For those making long trans- ocean passages, the ability to use
a sextant is still good insurance.
Certainly feasible, especially in trade wind latitudes. And fun,
if you're getting bored. And good for one's self esteem -
exercising an archaic skill. I guess you'd not agree with my use
of the word 'archaic' here.
|
Considering the ammount of time GPS has been available 'archaic' is perhaps
not the description I would give it.
| Quote: |
Insurance? Yes, I'd go along with that. 'Good' insurance? That
implies value for money - or value for effort in this case. That's
maybe where we differ. The effort of sextant position lines is
high compared to having a second GPS aboard - spare batteries and
all. And GPS hasn't gone off air yet for more than one day in its
many years of operation, so its not going to go missing during my
next voyage.
In general terms it is not so much the availability of the satellites that |
concerns me but the availability of the receiver. I have had one of my sets
refuse to 'lock in' despite having satellites in view and in the open sea.
Accidents happen and having a manual back up would seem to make sense on
longer passages.
Peter |
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Gordon
Guest
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| Posted:
Sat Nov 19, 2005 12:19 am Post subject:
Re: Wanted: Quality Sextant |
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"Armond Perretta" <newsgroupreader@REMOVEcomcast.net> wrote in message
news:OpqdnYzrYNfEUODeRVn-vg@comcast.com...
| Quote: | [trimmed to r.b.c]
Gordon wrote:
Regarding sextants: An idea!
A simple solar powered calculator now costs less than $10. An
angular measuring device (precision potentiometer), a few bucks.
Why not marry it altogether to create a sextant that automatically
figures lat and long as soon as you push a button telling it you just
shot the sun, or moon, or Polaris.
If it stored the readings, it could even average out over time for
more accuracy.
Is this farfetched? ..
Yes. A single reading, or an averaged set of readings on the same body,
does not "automatically figure lat and long." A single reading yields a
line of position.
In any case you are late to the table since attachments like this were
available at least 15 years ago.
--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://home.comcast.net/~kerrydeare
|
Where? I searched on sextant attachments but came up dry.
G |
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rhys
Guest
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| Posted:
Sat Nov 19, 2005 1:08 am Post subject:
Re: Wanted: Quality Sextant |
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On Thu, 17 Nov 2005 23:55:31 GMT, Gary <plumperNOSPAM@shaw.ca> wrote:
| Quote: | Gordon wrote:
Regarding sextants: An idea!
A simple solar powered calculator now costs less than $10. An angular
measuring device (precision potentiometer), a few bucks.
Why not marry it altogether to create a sextant that automatically
figures lat and long as soon as you push a button telling it you just shot
the sun, or moon, or Polaris.
If it stored the readings, it could even average out over time for more
accuracy.
Is this farfetched? Sounds relatively simple to me.
Would make a simple backup for GPS and a simple plastic unit shouldn't be
too expensive.
Gordon
You could even put a GPS in it so you wouldn't have to enter a dead
reckoning position or take the time. Wow! Great idea.
Gaz
|
Yes, I use GPS, and yes, I'm learning the sextant. Why? Keeps the hand
steady, and the brain sharp, and it's a safe redundancy.
But the main reason? The U.S. military can turn off GPS for whatever
reason it deems necessary. Like parts of the Internet (see "top level
domain registries"), it's American property.
Which is fine. They own it. But not, the last time I checked, the
stars or the moon or the sun, all of which I can use with a sextant
and a bit of math to find myself and my boat on the waters.
R. |
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Brian Whatcott
Guest
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| Posted:
Sat Nov 19, 2005 4:10 am Post subject:
Re: Wanted: Quality Sextant |
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On Fri, 18 Nov 2005 17:29:40 +0200, Tapio Sokura <oh2kku@iki.fi>
wrote:
| Quote: | Gary wrote:
Meanwhile, you could buld one:
http://www.tecepe.com.br/nav/CDSextantProject.htm
I built one of those last summer. With four shots of the moon using an
artificial horizon I got to within 5 nm of my actual position. The LOPs
all met at roughly the same place on a plotting sheet and the "error
polygon" was in diameter a lot smaller than the actual error. So I might
have made some systematic errors while doing the calculations, should
redo the stuff some day..
Tapio
|
I copied your URL to an instrument list and a sextant list.
Thanks
Brian Whatcott Altus OK |
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Armond Perretta
Guest
|
| Posted:
Sat Nov 19, 2005 5:08 pm Post subject:
Re: Wanted: Quality Sextant |
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[trimmed to r.b.c]
Gordon wrote:
| Quote: | "Armond Perretta" <newsgroupreader@REMOVEcomcast.net> wrote ...
Gordon wrote:
....
Is this farfetched? ..
...
... you are late to the table since attachments like this
were available at least 15 years ago.
Where? I searched on sextant attachments but came up dry.
|
You will have to wade through back issues of Practical Sailor. The article
included photos and details of construction. BTW, we are talking here about
an item that is quite complicated and rather delicate, so it is doubtful
that using it other than on an aircraft carrier will be practical.
If you try the PS web site you will find that the search does not extend
back far enough, so you must look by hand. I have every issue of PS from
Jan 1980 to the present, but unless you want to give my your credit card
number (_and_ PIN) I don't think I'm going to go too much farther with
this.
--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://home.comcast.net/~kerrydeare |
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Tapio Sokura
Guest
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| Posted:
Mon Nov 21, 2005 9:08 am Post subject:
Re: Wanted: Quality Sextant |
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Gary wrote:
| Quote: | Tapio Sokura wrote:
I built one of those last summer. With four shots of the moon using an
artificial horizon I got to within 5 nm of my actual position. The
Very nice. Did you make the artificial horizon too? I understand that
you can use a pan of cooking oil and divide the observed angle between
the body and it's reflection in half for a makeshift artificial horizon.
|
I just used a large flat saucer filled with water. And a windless
night.. something more viscous than water would definately work better
when wind is involved. There are a few pics at
http://www.oh2kku.ham.fi/pics/cd-sekstantti/ of my version and a scan of
the plotting sheet I used. The sun shades are slide frames fitted with
BAADER AstroSolar safety film.
Tapio |
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Jeremy Parker
Guest
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| Posted:
Mon Nov 21, 2005 9:23 pm Post subject:
Re: Wanted: Quality Sextant |
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"News f2s" <jimb@seesignature.f2s.com> wrote in message
news:dlk872$rfi$1@news.freedom2surf.net...
| Quote: |
"otnmbrd" <otnmbrd@earthlink.net> wrote in message
news:RA8ff.1874$jI5.1667@newsread1.news.pas.earthlink.net...
Sounds like you're talking about Loran A, not "C"..... two
different animals. <snips> > LOL sounds like you're
talking about the old WW2 sets
Exactly. Murmansk convoys. I'm not even sure it was Loran since it
was so secret it didn't have a name at the time. It was a radio
phase difference measuring system. You had to tune in, then fiddle
with oscillograph cursors to measure phase differences.
|
Could it have been the British "Decca Navigator" system, or some
ancestor of it? As I recall - and it's about all I recall, after not
thinking of it for more than forty years - it used CW signals, not
pulses like loran
Jeremy Parker |
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Martin Potter
Guest
|
| Posted:
Tue Nov 22, 2005 8:30 am Post subject:
Re: Wanted: Quality Sextant |
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"News f2s" (jimb@seesignature.f2s.com) writes:
| Quote: |
Exactly. Murmansk convoys. I'm not even sure it was Loran since it
was so secret it didn't have a name at the time. It was a radio
phase difference measuring system. You had to tune in, then fiddle
with oscillograph cursors to measure phase differences.
|
An early version of Decca Navigator perhaps? LORAN worked on time
differences, DECCA on phase differences.
.... Martin VE3OAT |
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krj
Guest
|
| Posted:
Wed Nov 23, 2005 1:08 am Post subject:
Re: Wanted: Quality Sextant |
|
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rhys wrote:
| Quote: | On Mon, 21 Nov 2005 15:23:43 -0000, "Jeremy Parker"
JeremyParker@compuserve.com> wrote:
"News f2s" <jimb@seesignature.f2s.com> wrote in message
news:dlk872$rfi$1@news.freedom2surf.net...
"otnmbrd" <otnmbrd@earthlink.net> wrote in message
news:RA8ff.1874$jI5.1667@newsread1.news.pas.earthlink.net...
Sounds like you're talking about Loran A, not "C"..... two
different animals. <snips> > LOL sounds like you're
talking about the old WW2 sets
Exactly. Murmansk convoys. I'm not even sure it was Loran since it
was so secret it didn't have a name at the time. It was a radio
phase difference measuring system. You had to tune in, then fiddle
with oscillograph cursors to measure phase differences.
Could it have been the British "Decca Navigator" system, or some
ancestor of it? As I recall - and it's about all I recall, after not
thinking of it for more than forty years - it used CW signals, not
pulses like loran
There was something like that used for aircraft navigation that I
recall from reading war tales in my childhood. All I recall is that if
the plane was on the correct bearing (reciprocal or not), the
navigator/radio operator would hear a solid tone, and a "dashed" tone
if they wandered off course.
I think it was used to get bombers both to target and back home at
night/bad weather, and was used as well by Pathfinder squadrons.
It could well have been the military precursor of the Decca system
which was an analog of Loran in North America.
R.
Before Tacan, the "A","N" radio beacon system was used. Left of the |
track you heard an "A". Right of the track was an "N". On track was a
solid tone. Flew all around Alaska in the early 60's using this system.
krj |
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rhys
Guest
|
| Posted:
Wed Nov 23, 2005 1:08 am Post subject:
Re: Wanted: Quality Sextant |
|
|
On Mon, 21 Nov 2005 15:23:43 -0000, "Jeremy Parker"
<JeremyParker@compuserve.com> wrote:
| Quote: |
"News f2s" <jimb@seesignature.f2s.com> wrote in message
news:dlk872$rfi$1@news.freedom2surf.net...
"otnmbrd" <otnmbrd@earthlink.net> wrote in message
news:RA8ff.1874$jI5.1667@newsread1.news.pas.earthlink.net...
Sounds like you're talking about Loran A, not "C"..... two
different animals. <snips> > LOL sounds like you're
talking about the old WW2 sets
Exactly. Murmansk convoys. I'm not even sure it was Loran since it
was so secret it didn't have a name at the time. It was a radio
phase difference measuring system. You had to tune in, then fiddle
with oscillograph cursors to measure phase differences.
Could it have been the British "Decca Navigator" system, or some
ancestor of it? As I recall - and it's about all I recall, after not
thinking of it for more than forty years - it used CW signals, not
pulses like loran
|
There was something like that used for aircraft navigation that I
recall from reading war tales in my childhood. All I recall is that if
the plane was on the correct bearing (reciprocal or not), the
navigator/radio operator would hear a solid tone, and a "dashed" tone
if they wandered off course.
I think it was used to get bombers both to target and back home at
night/bad weather, and was used as well by Pathfinder squadrons.
It could well have been the military precursor of the Decca system
which was an analog of Loran in North America.
R. |
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| Back to top |
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Brian Whatcott
Guest
|
| Posted:
Wed Nov 23, 2005 5:52 am Post subject:
Re: Wanted: Quality Sextant |
|
|
On Wed, 23 Nov 2005 01:48:18 GMT, Gary <plumperNOSPAM@shaw.ca> wrote:
| Quote: | rhys wrote:
On Mon, 21 Nov 2005 15:23:43 -0000, "Jeremy Parker"
JeremyParker@compuserve.com> wrote:
"News f2s" <jimb@seesignature.f2s.com> wrote in message
news:dlk872$rfi$1@news.freedom2surf.net...
"otnmbrd" <otnmbrd@earthlink.net> wrote in message
news:RA8ff.1874$jI5.1667@newsread1.news.pas.earthlink.net...
Sounds like you're talking about Loran A, not "C"..... two
different animals. <snips> > LOL sounds like you're
talking about the old WW2 sets
Exactly. Murmansk convoys. I'm not even sure it was Loran since it
was so secret it didn't have a name at the time. It was a radio
phase difference measuring system. You had to tune in, then fiddle
with oscillograph cursors to measure phase differences.
Could it have been the British "Decca Navigator" system, or some
ancestor of it? As I recall - and it's about all I recall, after not
thinking of it for more than forty years - it used CW signals, not
pulses like loran
There was something like that used for aircraft navigation that I
recall from reading war tales in my childhood. All I recall is that if
the plane was on the correct bearing (reciprocal or not), the
navigator/radio operator would hear a solid tone, and a "dashed" tone
if they wandered off course.
I think it was used to get bombers both to target and back home at
night/bad weather, and was used as well by Pathfinder squadrons.
It could well have been the military precursor of the Decca system
which was an analog of Loran in North America.
R.
Decca might still be in use in Europe. It is completely different from
Loran A or C. Omega is the other old radio nav aid. I have used them
all. Loran C was easiest followed by Decca and I used them asrecently
as 10 years ago. Loran A was phased out in the 80s and Omega I'm not
sure about. Omega was good way out off shore while the others had range
limitations.
|
There's something fascinating about those navigation systems - Loran
A,B,C; LFF/Lorenz, Shoran, Decca, Dectra, Omega, Babs, Rebecca,
Eureka, RadioRange VOR, RDF, ADF, VDF, UDF, INS, GPS, GLONASS,
GNSS,DME, TACAN, Consol, Gee, Oboe, Knickebein, Elektra Sonne,
Galileo, Delrac, POPI, Radux, Draco, Chaka, Transit, Eurofix, (for
this one, take Loran C, mix in a little DGPS, add a pinch of
magic.....)
Brian Whatcott Altus OK |
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Gary
Guest
|
| Posted:
Wed Nov 23, 2005 7:48 am Post subject:
Re: Wanted: Quality Sextant |
|
|
rhys wrote:
| Quote: | On Mon, 21 Nov 2005 15:23:43 -0000, "Jeremy Parker"
JeremyParker@compuserve.com> wrote:
"News f2s" <jimb@seesignature.f2s.com> wrote in message
news:dlk872$rfi$1@news.freedom2surf.net...
"otnmbrd" <otnmbrd@earthlink.net> wrote in message
news:RA8ff.1874$jI5.1667@newsread1.news.pas.earthlink.net...
Sounds like you're talking about Loran A, not "C"..... two
different animals. <snips> > LOL sounds like you're
talking about the old WW2 sets
Exactly. Murmansk convoys. I'm not even sure it was Loran since it
was so secret it didn't have a name at the time. It was a radio
phase difference measuring system. You had to tune in, then fiddle
with oscillograph cursors to measure phase differences.
Could it have been the British "Decca Navigator" system, or some
ancestor of it? As I recall - and it's about all I recall, after not
thinking of it for more than forty years - it used CW signals, not
pulses like loran
There was something like that used for aircraft navigation that I
recall from reading war tales in my childhood. All I recall is that if
the plane was on the correct bearing (reciprocal or not), the
navigator/radio operator would hear a solid tone, and a "dashed" tone
if they wandered off course.
I think it was used to get bombers both to target and back home at
night/bad weather, and was used as well by Pathfinder squadrons.
It could well have been the military precursor of the Decca system
which was an analog of Loran in North America.
R.
Decca might still be in use in Europe. It is completely different from |
Loran A or C. Omega is the other old radio nav aid. I have used them
all. Loran C was easiest followed by Decca and I used them asrecently
as 10 years ago. Loran A was phased out in the 80s and Omega I'm not
sure about. Omega was good way out off shore while the others had range
limitations. |
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David Lee
Guest
|
| Posted:
Wed Nov 23, 2005 9:08 am Post subject:
Re: Wanted: Quality Sextant |
|
|
rhys wrote...
| Quote: | On Mon, 21 Nov 2005 15:23:43 -0000, "Jeremy Parker"
There was something like that used for aircraft navigation that I
recall from reading war tales in my childhood. All I recall is that if
the plane was on the correct bearing (reciprocal or not), the
navigator/radio operator would hear a solid tone, and a "dashed" tone
if they wandered off course.
I think it was used to get bombers both to target and back home at
night/bad weather, and was used as well by Pathfinder squadrons.
It could well have been the military precursor of the Decca system
which was an analog of Loran in North America.
|
That was "Oboe", used for precise indication of bombing release position -
it was only used for during final approach of a bombing run. The technique
was based on secondary radar and the aircraft carried two transponders that
responded to signals from two ground stations in England codenamed CAT and
MOUSE. The aircraft (usually a pathfinder Mosquito) flew a circular course
at constant distance from CAT, which automatically broadcast Morse code dots
if the range was too short and dashes if too long. When the aircraft was
exactly on course (in practice within range plus or minus 17 yards) these
merged and the Mosquito pilot heard a continuous tone.
MOUSE monitored the range and velocity of the aircraft (accuracy 17yds /
0.5mph) and its computer (THE MICESTRO!) continuously updated the solution
for the release point based on this and met data. MOUSE then broadcast a
series of Morse code signals counting down to the target, culminating with
the release signal - five dots and a dash.
The aircraft had to be under Oboe control for at least 10 minutes and so the
maximum number of runs controllable by a single pair of CAT and MOUSE
stations was only six per hour. However by controlling pathfinder
Mosquitos, dropping marker flares, the system permitted bombing with
unprecedented and devastating precision.
David |
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Peter McLelland
Guest
|
| Posted:
Wed Nov 23, 2005 3:11 pm Post subject:
Re: Wanted: Quality Sextant |
|
|
"Jeremy Parker" <JeremyParker@compuserve.com> wrote in message
news:dlvpqs$1nb$1$8302bc10@news.demon.co.uk...
| Quote: |
"News f2s" <jimb@seesignature.f2s.com> wrote in message
news:dlk872$rfi$1@news.freedom2surf.net...
"otnmbrd" <otnmbrd@earthlink.net> wrote in message
news:RA8ff.1874$jI5.1667@newsread1.news.pas.earthlink.net...
Sounds like you're talking about Loran A, not "C"..... two
different animals. <snips> > LOL sounds like you're
talking about the old WW2 sets
Exactly. Murmansk convoys. I'm not even sure it was Loran since it
was so secret it didn't have a name at the time. It was a radio
phase difference measuring system. You had to tune in, then fiddle
with oscillograph cursors to measure phase differences.
Could it have been the British "Decca Navigator" system, or some
ancestor of it? As I recall - and it's about all I recall, after not
thinking of it for more than forty years - it used CW signals, not
pulses like loran
Decca which used phase comparison was first used for the D Day landings. |
This was almost certainly Loran A which used time comparison to generate the
hyperbolic patterns.
Peter |
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News f2s
Guest
|
| Posted:
Wed Nov 23, 2005 3:45 pm Post subject:
Re: Wanted: Quality Sextant |
|
|
"Brian Whatcott" <betwys1@sbcglobal.net> wrote in message
news:ssn7o1t31n8umjh24frap9s1m37uur6001@4ax.com...
| Quote: | On Wed, 23 Nov 2005 01:48:18 GMT, Gary <plumperNOSPAM@shaw.ca
wrote:
There's something fascinating about those navigation systems -
Loran
A,B,C; LFF/Lorenz, Shoran, Decca, Dectra, Omega, Babs, Rebecca,
Eureka, RadioRange VOR, RDF, ADF, VDF, UDF, INS, GPS, GLONASS,
GNSS,DME, TACAN, Consol, Gee, Oboe, Knickebein, Elektra Sonne,
Galileo, Delrac, POPI, Radux, Draco, Chaka, Transit, Eurofix,
(for
this one, take Loran C, mix in a little DGPS, add a pinch of
magic.....)
Brian Whatcott Altus OK
|
Yup. Almost all of them were first developed for military
purposes.
JimB |
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