Potential for Celestial Navigation?

[Capt. Crash]

I know we live in a world of GPS but has a sextant been considered for true old chart and plotter navigation?

Thank you!

[sleat]

Celestial Navigation is an _extremely_ valuable skill, especially since it requires no batteries, and relies on very little in the way of technology, as long as a chart and tables are to hand.

I'd _love_ to be able to practice both sailing and CN in the same sim!

[Surveyor]

Count me in.

[Surveyor]

To be honest, I don't think celestial navigation is all that hard to implement in the sim... We just need a means to measure a particular object in the sky's angle above the horizon and note the exact time it was performed at. Theoretically, knowing the current FoV (which should have an appropriate option in the menu), simply taking a screenshot might already provide enough info for a rough position estimation.

[Pacific Seacow]

I would love somthing like this in the sim!

[Zubenelgenubi]

Would be great to have, and any races with it would be fun too.

[simon.morice]

Originally posted by Surveyor:

To be honest, I don't think celestial navigation is all that hard to implement in the sim... We just need a means to measure a particular object in the sky's angle above the horizon and note the exact time it was performed at. Theoretically, knowing the current FoV (which should have an appropriate option in the menu), simply taking a screenshot might already provide enough info for a rough position estimation.

I agree. There are lots of apps and programmes for performing calculations as well as the traditional way. One of the apps even works with a picture from the phone camera. Selecting a celestial body and making an observation of altitude is the bit the sim could do. This, and other enhancements, will make it a really useful tool for practising for advanced qualifications - or just for interest.

[Surveyor]

Originally posted by simon.morice:

Originally posted by Surveyor:

To be honest, I don't think celestial navigation is all that hard to implement in the sim... We just need a means to measure a particular object in the sky's angle above the horizon and note the exact time it was performed at. Theoretically, knowing the current FoV (which should have an appropriate option in the menu), simply taking a screenshot might already provide enough info for a rough position estimation.

I agree. There are lots of apps and programmes for performing calculations as well as the traditional way. One of the apps even works with a picture from the phone camera. Selecting a celestial body and making an observation of altitude is the bit the sim could do. This, and other enhancements, will make it a really useful tool for practising for advanced qualifications - or just for interest.

Using those apps, however, would defeat the purpose of the celestial navigation training facility, should it get implemented in the sim. I'd say we should only be given a sextant, a chronograph and the tables (or we could look up the latter elsewhere). Also, a tutorial would definitely be a great addition. Many probably don't even realize it's possible to find out one's location on the globe using such a low-tech instruments.

[coda]

So, what's our backup now? More satellites doing the same thing? Pardon my ignorance, but watching this go down was a little emo.

[coda]

Thank you so much, as always, for sharing your knowledge. I read the New Yorker article (I have a couple of New Yorker covers hanging on my wall.)

This gives me vertigo. I remember before TV, when sending and receiving information was done with a three party line telephone you had to crank. The Pony Express was long before my time, tho. Sending messages by drum has worked out pretty well. Everyone loves a good drum.

[Surveyor]

Definitely, a navigation challenge like that would spice things up (I would also suggest adding a mode with no hints whatsoever and enforcing it for the challenge).
As for radio navigation systems, that would be a little too much too ask indeed. And I'm not quite sure why it is expected they are less prone to fail than GPS...

We do have a backup, after all. Chronograph, sextant and the tables. Or the other satellite-based systems. What's wrong with that? If we have to pick radio signals for navigation anyway, better pick them up via an unobscured line of sight, i. e., right from the sky. If you want a real back up, you need to think up something non-radio based...

Having an extremely high precision clock always available to anyone is actually a huge advantage. And even if it can be jammed/disrupted, well... what alternative do you propose?

[Surveyor]

Originally posted by Storm Petrel, Jr.:

A recent boating blog post about "What to do if GPS fails" has a three step solution:

1. Use your backup GPS (assuming the problem is with your primary GPS system). This assumes the problem is not a failure of the GPS system itself.

2. If you don't have a backup GPS device, or the problem is the system, try manual navigation.

3. If you can't do manual navigation, call for rescue.

In the event of a major GPS failure, however, I'm not sure how many "call for rescue" systems will be working.

"this is why it’s important to learn—and maintain—manual navigation skills."

Source: https://oceangrafixblog.wordpress.com/2017/02/25/how-to-handle-gps-failure-at-sea-and-why-its-absolutely-crucial-to-be-prepared/

That's why I think it's best to have other GN systems capable receivers onboard as well. And, of course, to learn to do manual navigation. Coast-based radio navigation systems are about as prone to fail as GPS. They can't be considered a backup any more than other satellite based systems.

Well, at least we both agree on the manual navigation part. This is a must. Nobody should be allowed to go offshore if they are not able to manually find their own location.

[Cygon_Parrot]

@Captain Crash:

I'm in absolute agreement with you. I just picked up Sailaway, and not only would celestial navigation be a "nice additional possibility", I consider it a vital option to have, for those who want to learn or keep alive an age old skill.

All the sim needs is a sextant, now. The chronometer we already have, as the game is real time, and the Nautical Almanac is downloadable for free.

Devs! Please include it! :)

[sleat]

Originally posted by Surveyor:

To be honest, I don't think celestial navigation is all that hard to implement in the sim... We just need a means to measure a particular object in the sky's angle above the horizon and note the exact time it was performed at. Theoretically, knowing the current FoV (which should have an appropriate option in the menu), simply taking a screenshot might already provide enough info for a rough position estimation.

Indeed! One additional view required; the sextant view.
As long as the sim also carries accurate time/date, the user does the rest.

The user picks the celestial object, switches to sextant view, and "shoots" the star.
The sextant tool returns degrees/minutes/seconds above the horizon.
The user notes the time, object, and angle.

Shoots as many additional objects, sun, moon, star, etc, as they want, noting time.

Does normal CN "sight reduction" by whatever means they prefer, paper or app.

Note well that the sim does not need to process what star the user is pointing at, only supply the date, time, and render the relevant stars in the sky in such a way that the "sextant view" pointing at any such star would return its exact elevation for that particular date and time.

From a programming standpoint, assuming the stars are already accurately rendered, this is simply an additional view and a bit of trig on the angle of that view when a button is pressed.

For anyone who sails IRL, this method is fail-safe if the sky can be seen and it's done correctly. It could save your bacon if you know how to do it. As for me, I think everyone should be able to do at least rudimentary CN.

[Surveyor]

Originally posted by sleat:

Indeed! One additional view required; the sextant view.
As long as the sim also carries accurate time/date, the user does the rest.

The user picks the celestial object, switches to sextant view, and "shoots" the star.
The sextant tool returns degrees/minutes/seconds above the horizon.
The user notes the time, object, and angle.

Shoots as many additional objects, sun, moon, star, etc, as they want, noting time.

Does normal CN "sight reduction" by whatever means they prefer, paper or app.

Note well that the sim does not need to process what star the user is pointing at, only supply the date, time, and render the relevant stars in the sky in such a way that the "sextant view" pointing at any such star would return its exact elevation for that particular date and time.

From a programming standpoint, assuming the stars are already accurately rendered, this is simply an additional view and a bit of trig on the angle of that view when a button is pressed.

For anyone who sails IRL, this method is fail-safe if the sky can be seen and it's done correctly. It could save your bacon if you know how to do it. As for me, I think everyone should be able to do at least rudimentary CN.

That would definitely make the sim much more useful.

[Hein Blöd]

I tried to simulate celestial navigation with sailaway in the easiest way by "shooting" polaris, just measuring the vertical distance to the equator. There seems to be a linear correlation between the angle of horizon and distance measure to horizon (distance measured with mb-ruler), when your position is not too fare in the north. Once calibrated properly, it is possible to get a rough value for your latitude position. Unfortunatly the celestial equator is not well aligned, will say, polaris is not where it is expected to be all around the globe (if your boat is on the equator, polaris should be very near to the horizon line). In some areas the position is correct, in others you can see polaris several degress above horizon. Maybe it is possible to correct this malalignement by a correction factor (subtracting from the measured vertical distance), but this makes the calcualtion of your position even more unprecise. Maybe Richard can adjust the celestial orbit. Once the adjustment is correct, in theory it should be possible to "shoot" all the other celestial objects too. Last step (for an experienced programmer) is to program an overlay (similar to mr-ruler), showing the view through a sextant .