Might be time to buy a sextant

[Rhylsailer99]

My 14 year old son has just told me the world will end In 2 days.
After doing a google search it seems there is a chance of a huge solar storm knocking out satellites. I'm guessing gps could be wiped out temporarily.
I do have an interest in finding my way with the old ways and hope to buy one soon regardless .

 

[Bouba]

My 14 year old son has just told me the world will end In 2 days.
After doing a google search it seems there is a chance of a huge solar storm knocking out satellites. I'm guessing gps could be wiped out temporarily.
I do have an interest in finding my way with the old ways and hope to buy one soon regardless .

Does your son mean that there will be no more smartphones etc....or the end of life on this planet (or can a fourteen year old distinguish between the two) ?

 

[dankilb]

Apparently there are forecasts for space storms (new to me!): Space Weather

It is rather wordy, but lots of references to 'mild' or 'moderate' (G1 and G2 apparently are the weakest on a scale to 5). So not sure where the info on a huge storm comes from? But then again, it is only the Met Office ...!

GPS has worked for so long now, despite all the 'what ifs...?', that I'm happy to keep trusting it even while the world is ending!

 

[Rhylsailer99]

Apparently there are forecasts for space storms (new to me!): Space Weather

It is rather wordy, but lots of references to 'mild' or 'moderate' (G1 and G2 apparently are the weakest on a scale to 5). So not sure where the info on a huge storm comes from? But then again, it is only the Met Office ...!

GPS has worked for so long now, despite all the 'what ifs...?', that I'm happy to keep trusting it even while the world is ending!

On tik tok forecast is severe level 5 apparently.

 

[srm]

I do have an interest in finding my way with the old ways and hope to buy one soon regardless .

Using a sextant is easy, most of my students could take an accurate angle in about fifteen minutes from first picking it up.

However, it took quite a bit longer before they could confidently convert an observed altitude into a position line, and longer still to learn how to cross two observed altitudes to obtain a fix with an acceptable result. However, they were studying for Deck Officer certificates and had to show all the long hand calculations and were only allowed to use a calculator to check arithmetic. There are apps and software that will do all the thinking for you provided that they survive and solar storm.

 

[Rhylsailer99]

Using a sextant is easy, most of my students could take an accurate angle in about fifteen minutes from first picking it up.

However, it took quite a bit longer before they could confidently convert an observed altitude into a position line, and longer still to learn how to cross two observed altitudes to obtain a fix with an acceptable result. However, they were studying for Deck Officer certificates and had to show all the long hand calculations and were only allowed to use a calculator to check arithmetic. There are apps and software that will do all the thinking for you provided that they survive and solar storm.

I've bought a few books and I've managed to figure out a noon fix for longitude and latitude and I can get latitude from the North Star at night time. i am struggling with the dead reckoning and H029 calculations etc .when taking sightings at different times.

 

[Bouba]

Using a sextant is easy, most of my students could take an accurate angle in about fifteen minutes from first picking it up.

However, it took quite a bit longer before they could confidently convert an observed altitude into a position line, and longer still to learn how to cross two observed altitudes to obtain a fix with an acceptable result. However, they were studying for Deck Officer certificates and had to show all the long hand calculations and were only allowed to use a calculator to check arithmetic. There are apps and software that will do all the thinking for you provided that they survive and solar storm.

Do they also need a chronometer?

 

[DownWest]

Do they also need a chronometer?

Decent quartz watch does it. Just correct it off the BBC time signal on long wave. There is always Slocum's 'Tin Clock' (and Lunar system)

 

[srm]

and I can get latitude from the North Star

Not as easy as it seems, its not a very bright star. Clear enough to see on a dark night but it can be difficult to observe at twilight when the horizon is visible.

Keep at it though. There was something satisfying about using a sextant.

Do they also need a chronometer?

Indeed they do, other than for latitude by meridian altitude of the sun, as local noon is found by observing the highest altitude. However, a quartz watch is accurate enough if you can rate it from radio time signals.

You can also obtain latitude by meridian altitude of any other body.

 

[WindyWindyWindy]

How long would a trip have to be for a sextant to be useful for navigation?

 

[DownWest]

How long would a trip have to be for a sextant to be useful for navigation?

Depends on how good your DR is. I onced managed an 'on the nose' DR after five days out of sight of land, but I reckon I was lucky.
Some use them for measuring horizontal angles, as in two features, to get distance off.
If the GPS sats really do get put out of action, a lot more than yacht nav is in trouble..

 

[srm]

How long would a trip have to be for a sextant to be useful for navigation?

Pre GPS I used a sextant for coastal navigation as I could obtain a fix from a single lighthouse using distance off, by sextant angle and height of the light, crossed with a bearing. It also provided a confidence check on the Decca position at times once recievers came down to my yacht budget.

 

[Minchsailor]

In pre GPS days, I was crossing from Italy for the gap between North end of Sardinia/South end of Corsica. Managed to find it by noon position by altitudes the sun.

 

[DownWest]

I just looked on the shelves, and I have Otis S Brown's 'One Day Celestial Navigation' Probably not the best, but workable. Mary Bleuet's book gets quite a few votes. (spellng is way off)

In pre GPS days, I was crossing from Italy for the gap between North end of Sardinia/South end of Corsica. Managed to find it by noon position by altitudes the sun.

Snap! That was where I set off with a compass and spinner log for France. School atlas for a chart. Bonkers.

 

[Refueler]

I just looked on the shelves, and I have Otis S Brown's 'One Day Celestial Navigation' Probably not the best, but workable. Mary Bleuet's book gets quite a few votes. (spellng is way off)

Snap! That was where I set off with a compass and spinner log for France. School atlas for a chart. Bonkers.

Hate to admit this ... but was Ch Mate on a small Chemi tanker .. we rec'd orders to proceed to a small harbour in NW Ireland ... to load sterile fish-meal. Its 'food' for Scandinavian Mink / Silver Fox farms.
We informed Chrtrs we did not have charts for that location and were told that Pilot Boat would meet us offshore with chart etc.
So of we went .... as we approached - no sign of Pilot Boat .... we called on VHF ... and had reply ... "Don't Worry just keep on coming" ... by that time - we were using the plain B&W chartlet in the Chart Catalogue !
As we slowly edged our way in ... we had to pass between small islets .... Pilot would tell us "Port a bit ... Stbd a bit......" which along with a few buoys got us in.

Finally INSIDE the small harbour - Pilot boarded for the last few metres to berth alongside the pumping barge.

Chart ? Never did get one. For leaving ... Pilot sketched out on a sheet of paper ....

Before anyone asks .... no we did not have GPS Plotter / ECDIS ... this was early 80's .......

 

[Refueler]

Pre GPS I used a sextant for coastal navigation as I could obtain a fix from a single lighthouse using distance off, by sextant angle and height of the light, crossed with a bearing. It also provided a confidence check on the Decca position at times once recievers came down to my yacht budget.

Blimey ... we'll be talking about 'doubling the angle on the bow' next !!

I really miss Decca ...... after a long passage from Gulf and approaching Eng Ch ... it was nice to pick up Decca .....

 

[Refueler]

Depends on how good your DR is. I onced managed an 'on the nose' DR after five days out of sight of land, but I reckon I was lucky.
Some use them for measuring horizontal angles, as in two features, to get distance off.
If the GPS sats really do get put out of action, a lot more than yacht nav is in trouble..

A large % of charts are based on Sextant use by RN / Other Naval Officers ...... horizontal and celestial.

But just a small correction .... "Some use them for measuring horizontal angles, as in two features, to get distance off."

That will not provide solution as the angle needs at least one of the 'legs' to have a reference - Compass bearing. To get a position or dist off without compass bearing requires THREE legs (horizontal sextant angles taken of three objects). Trick then if you don;t have a Station Pointer to plot it .... piece of thin paper (tracing paper is perfect) ... draw the three legs on according to the angles measured ... place on chart and align all three objects with the legs ... the meeting point of the three legs - is your position.

 

[Refueler]

Using a sextant is easy, most of my students could take an accurate angle in about fifteen minutes from first picking it up.

However, it took quite a bit longer before they could confidently convert an observed altitude into a position line, and longer still to learn how to cross two observed altitudes to obtain a fix with an acceptable result. However, they were studying for Deck Officer certificates and had to show all the long hand calculations and were only allowed to use a calculator to check arithmetic. There are apps and software that will do all the thinking for you provided that they survive and solar storm.

Marc St Helaire or Long by Chron ??

I was so glad when I bought my Texas Ti59 ...... had full Nav module. Still have it today actually but batterys dead - I have powered up with alternative .. it works but with todays plotters etc. ??
Much better than the Tamiya Nav Calculator .... horrible RPN keyboard !!

 

[STOL71]

My 14 year old son has just told me the world will end In 2 days.
After doing a google search it seems there is a chance of a huge solar storm knocking out satellites. I'm guessing gps could be wiped out temporarily.
I do have an interest in finding my way with the old ways and hope to buy one soon regardless .

I’d say no need to buy a sextant as you won’t see the stars if there’s a sandstorm. Better stay put…

 

[jwfrary]

How long would a trip have to be for a sextant to be useful for navigation?

Not long at all if you use it for a vertical sextant angle, which I quite often do, quite nice to confuse everyone!

Recently the moon and the sun have been visible at the same time, which is quite fun as you can get two position lines on the sheet at the same time in the day!

I don't recall ever getting a fix on polaris, it's just so dim! Better chance with the planets, or some of the brighter stars. Reminds me I need a new rapid sight reduction table volume one as my epoch is a bit out. Might leave it till 2025 when it changes again!