GPS COMPUTER VS SEXTANT/ASTROLABE/Old ways/manual

[SmithDoor]

Interesting reading these posts.

Only partially related, I designed an Astrolabe back in 1993 (on Generic CADD) but it only got to the paper model stage (looks terribly beat up now). It was a PITA because I could not place text on a curve so had to do it letter by letter (or number) and in addition anticipate a vertical offset when the letter was printed. Like I said on my web page at the time I tested it in Canada with one plate and another in St. Lucia (I had plates for every 5deg) and in all cases it was bang-on accurate. What fantastic night skies in St Lucia! I even predicted a solar eclipse and that it would be a grazing partial. I was never able to get photogrametric plates made and lost the source design went I moved on to another job - it was on a work computer back in 1993.
http://surfin_dude.tripod.com/creative/astronomy/astronomy.html#Astrolabe

Previous to that, what got me interested in such things, was a 18” brass sundial design I did which, amongst a host of other things, tracked the sun’s progress across a map on it’s face thought each day and the course of the year. Tricky to etch an 18" dia - 3/8" thick plate or the 1/2" thick gnomen.
http://surfin_dude.tripod.com/creative/astronomy/astronomy.html#Sundial

Now, I keep it simple and use my “Yes V7” watch. Similar but better than the Prague astronomical clock. Used by NASA astronauts & Hollywood movie producers wanting to keep track of daylight. They have a successor to the V7 coming out soon. It will tell you sunrise/set, twilight, moon rise etc a whole host of other things after you program in your city (or manually if your city isn't on the infinitely long list).


No end of fun in this field!

How well dose it work?

Dave

Auto correct on my phone and forgetting to prof read .again

 

[jonpowers]

⫷⸻❋Conclusion❋⸻⫸ ​

.
The old about same century

1. Sextant is 10 minutes within 11 miles on the open ocean
2. Astrolabe is 15 minutes or within 17 miles on the open ocean

*** The Navy using some best today is within 1½ miles or apx 1 minute


Dave

I will comment based on sailing a 24 foot sail boat trans Pacific San Diego via the Pacific Islands to New Zealand: Given the low height of eye, height of waves on horizon and the motion of the sea way I always counted on a 30 (nautical) mile tolerance to produce a cocked hat position fix of Dead Reckoning, morning line of position and noon sight. I always found where I was going. The Polynesians were great travelers judging there position by the eye only estimate of height of celestial objects, based on using basket woven maps, said to be 1/2 degree precision same as I did with a sextant!

Jon

 

[SmithDoor]

I used new technology (home built CNC machine) to engrave this old technology. They look a lot cooler than a GPS chip.

I read about 40 years ago the first navigation tool was simple like astrolabe

I will comment based on sailing a 24 foot sail boat trans Pacific San Diego via the Pacific Islands to New Zealand: Given the low height of eye, height of waves on horizon and the motion of the sea way I always counted on a 30 (nautical) mile tolerance to produce a cocked hat position fix of Dead Reckoning, morning line of position and noon sight. I always found where I was going. The Polynesians were great travelers judging there position by the eye only estimate of height of celestial objects, based on using basket woven maps, said to be 1/2 degree precision same as I did with a sextant!

Jon

Thank you

I was told about same over 50 years but think did I hear that right. So nice hearing again to refresh my memory.
I always remember high noon then dead reckoning till high noon .
I could remember from old western movie everthing happened at high noon.

It nice reading my background is in Aviation and need location almost real time nere mountains. Dead reckoning is used a lot but still needing information faster.

Thank you for sharing
Dave

 

[SmithDoor]

⫷-❋ TIME LINE OF❋-⫸
⫷-❋ NAVIGATION ❋-⫸ ​

The history of navigation dates back to ancient times, with significant developments in various civilizations.

The first part
Celestial navigation, use of landmarks, and early navigational instruments

Celestial Navigation: Ancient navigators used the positions of celestial bodies, such as stars, the sun, and the moon, to determine their position and direction during travel. The North Star (Polaris) was particularly significant in the Northern Hemisphere

Use of Landmarks: Sailors relied on visible landmarks such as mountains, cliffs, and coastlines to orient themselves. When landmarks were absent, they used dead reckoning, calculating their position based on speed, direction, and elapsed time

Early Navigational Instruments: Tools like the astrolabe, a device for measuring the altitude of celestial bodies, and the compass, which provided a way to determine the direction of travel, were crucial for ancient navigation

These techniques and tools enabled ancient sailors to navigate vast oceans and uncharted territories, expanding trade and communication across vast distances

Indo-Pacific Navigation: Began with the Austronesians from Taiwan, who spread southwards into Island Southeast Asia and Island Melanesia around 3000-1000 BC. They used tools like star navigation and wave detection to navigate the Pacific

Greek Navigation: By the third century BC, the Greeks began using the Little Bear (Ursa Minor) to navigate. They also used circumpolar stars to determine latitude


Chinese Compass: In China between 1040 and 1117, the magnetic compass was developed and applied to navigation, allowing sailors to continue their course even when visibility was limited


Portuguese Exploration: In the 16th century, Portuguese explorers took the lead in long-distance oceanic navigation, opening a network of ocean routes covering the Atlantic, Indian, and western Pacific oceans.


Modern Navigation: The invention of the sextant in 1757 and the chronometer in the late 18th century revolutionized navigation, allowing for accurate determination of longitude and latitude.

Open to public after 1983.
The Global Positioning System (GPS) was developed in the 20th century, transforming navigation into a modern technological marvel .
Flight 007 from Alaska to Japan open up GPS.

THE EVENT
(Korean Air Lines Flight 007 (KE007/KAL007)was a scheduled Korean Air Lines flight from New York City to Seoul via Anchorage, Alaska. On September 1, 1983, the flight was shot down by a Soviet Sukhoi Su-15 interceptor aircraft. The Boeing 747 airliner was en route from Anchorage to Seoul) This even that open up GPS TO World

Dave

 

[SmithDoor]

⫷- For longitude -⫸

⫷-It time keeping -⫸

​

• 1642: Galileo proposed an accurate sea clock with a pendulum for a Dutch longitude prize

• 1717: John Harrison completed his first marine chronometer, H1

• 1759: Harrison developed the H4 chronometer, which passed sea trials with flying colors.

Dave