What sextant ?

[Lew Decker]

Whoops. I remember that I paid $340 for my Tamaya, and that included the 7X scope. I just punched up the current offerings. All I can say is, "Dang!"

Since celestial navigation via sextant has been reduced to hobby status, you could use any type that falls into a decent price range. People have circumnavigated with the Davis instruments, so...

I also know of at least one cruising boat that made it out to Hawaii by following jet contrails. Hmmm. Maybe that's an old sailing myth?

I actually sailed to Tortola from St. Pete on a delivery and took exactly one star sight. True story. There were a lot of contrails.

 

[Loren Beach]

"Sky and Sextant" is indeed easy to understand. (Relatively speaking...)
It has been on my bookshelf for many years. When you want even more reasons to have a sextant handy, read his other book "Shoreline and Sextant".

I may never need/ to utilize this technology for my local sailing, but his books are accessible and understandable even for duffers like me.

Loren
(sailing 90 miles inland from the ocean.)

 

[bgary]

Dusting off an old thread.

I feel like relearning celestial. No particular reason other than a combination of long winter nights and the recognition that it was an interesting discipline.

I have my trusty old sextant, I have my HO-229, I ordered a 2020 almanac from Amazon, I figure I can use my GPS-sync'd watch as a chronometer. I might even go completely old-school and dig out my "star-finder" although the "stellarium" app on my phone is pretty amazing.

Given that it's been more than 20 years since I did my last sight reduction, I gotta believe the craft has evolved. Anyone have a favorite self-teaching book (I was once a fan of Blewitt's book, but open to suggestions.), a favorite sight-reduction form, or other hot tips?

Bruce

 

[Joliba]

Dusting off an old thread.

I feel like relearning celestial. No particular reason other than a combination of long winter nights and the recognition that it was an interesting discipline.

I have my trusty old sextant, I have my HO-229, I ordered a 2020 almanac from Amazon, I figure I can use my GPS-sync'd watch as a chronometer. I might even go completely old-school and dig out my "star-finder" although the "stellarium" app on my phone is pretty amazing.

Given that it's been more than 20 years since I did my last sight reduction, I gotta believe the craft has evolved. Anyone have a favorite self-teaching book (I was once a fan of Blewitt's book, but open to suggestions.), a favorite sight-reduction form, or other hot tips?

Bruce

Bruce,
I know that you wrote this a few months ago. But I just noticed it. I used my Heath sextant, which I still have, to navigate across the Caribbean and South Pacific in 1976-7. I have pulled it out to play with a few times since then. I learned to navigate from Dr. Frances Wright. Her book, Celestial Navigation is a short, very good way to refresh your techniques. If you want to try something more “high tech” the iOS app, Star Pilot, though pricy, has all you need to quickly reduce any celestial sight without need for tables or almanacs. It even picks out possible stars for sight planning. I hope to try a few sextant sights this summer myself.
Mike Jacker

 

[Teranodon]

I have a sextant but do not use it any more. It is very hard to use on a boat, and I would say that it would be pointless to take it up without intending to devote months to the project. That said, the learning process can be great fun, if one tries to actually understand the principles of celestial navigation, rather than just using the tables in a cookbook way. One of the fun things that one learns is spherical geometry, which is pretty mindblowing.

I cannot possibly worry about a failure of the GPS system. Short of nuclear war or a complicated terrorist attack, it just ain't going to happen. Anyone who is concerned nonetheless should get a multi-system receiver that picks up the Russian satellites. Then there is the European Galileo, and the Chinese are launching one too. I have GPS in my chartplotter and an additional Garmin handheld (these are mounted on the pedestal and work off my house battery), plus two old Garmin ETrex units that live in the nav desk, plus my iPhone, plus I sail in the San Juan/Gulf Islands, where I can see where I'm going...

 

[Joliba]

Sometimes I’ll use both the sextant and the GPS... just to check the accuracy of the GPS
Funny but the GPS is sometimes off by 50NM...Hmmm?

 

[toddster]

Odd... I have that stuff spread out all over the dining room table.
...It has been there for a month or two. I delve into a few problems when I need to procrastinate on something in the office.
The apps are neat, but it seems like the whole point is to be independent of anything electronic. It would also be neat to be independent of many pounds of reference books. When I'm done with this book, will delve into one of the one-volume methods. But on the other hand, it's getting to be outdoor fun season...
I'd say the only conceivable scenario to really need it is some local event that takes out all electronics and/or charging sources on the boat. Or posing for a facebook picture.
I've got a Davis Mk25 that I got for cheap on eBay - just trying to get a reproducible value for sextant error shows how fuzzy it is - but probably good enough to find a reasonably sized island.

BTW: Over the winter I read a few sailing books from the early 20th century, and it seemed as if suddenly discovering that one was a few hundred miles from the plotted track, due to silly math errors, was a regular occurrence, even on commercial ships.

 

[Tin Kicker]

I cannot possibly worry about a failure of the GPS system. Short of nuclear war or a complicated terrorist attack, it just ain't going to happen. Anyone who is concerned nonetheless should get a multi-system receiver that picks up the Russian satellites. Then there is the European Galileo, and the Chinese are launching one too. I have GPS in my chartplotter and an additional Garmin handheld (these are mounted on the pedestal and work off my house battery), plus two old Garmin ETrex units that live in the nav desk, plus my iPhone, plus I sail in the San Juan/Gulf Islands, where I can see where I'm going...

Ummm- Solar flares are a great equalizer, can, and have, knocked out GPS for periods of time; we just happen to be at a quiescent period in time as shown in the chart below. I know with some of the very best commercial airline and military GPS we periodically have problems in aviation because solar flares come in waves. It's the X's and some M's that interrupt GPS.

We should see an increase before long because well - it'd just fit for being 2020.

 

[Guy Stevens]

Ummm- Solar flares are a great equalizer, can, and have, knocked out GPS for periods of time; we just happen to be at a quiescent period in time as shown in the chart below. I know with some of the very best commercial airline and military GPS we periodically have problems in aviation because solar flares come in waves. It's the X's and some M's that interrupt GPS.

We should see an increase before long because well - it'd just fit for being 2020.

The current lack of sunspots has also made Ham radio the worst it has been in years too!
Waiting for them to find Unicorns are real......... And they eat people!
G

 

[1911tex]

Best place for a sextant and great for admiration by crew members, is on the wall of the salon! Gets a lot of attention on my sailboat! Most asked question: "Do you really know how to use it?". My answer always is..."I suppose".

 

[Loren Beach]

Carnivorous Unicorns... oh my, the things you find out about here!

 

[paul culver]

Go for it Sven! You can reduce noon sights with the simplest arithmetic and an almanac for starters. I used the S-table method for sight reduction. I think they still include it in the Nautical Almanac Commercial Edition. The sextant is also handy for viewing eclipses and if you use it sideways you can triangulate from two points on shore. There's no end to the fun!
When I was at the beach learning with a Davis plastic a women with toddler came up to me and asked "is everything still OK?". I told her yes. Maybe she worried we were slipping in our solar orbit. Maybe she thought I was nuts.
I'll dig out my old sights and see what sort of accuracy I was getting with the plastic sextant.

 

[beachologist]

Shooting stars from a small sailboat at sea is exceedingly difficult. The sun is a different matter. You can navigate pretty well with just sun sights, dead reckoning, and a running fix. This process is simply laid out in Sun Sight Sailing by S.L. Seaton. A heavier metal sextant like the navy ones are easier to get a good sight with (more stable). I have a Heath Co Hezzanith sextant.

 

[supersailor]

Hey guys! There is a reason that a landfall within 30 miles of your reckoning was considered awesome in the good old days. Now one can navigate into one's slip. The reason to learn Celestial is that electrical things can and do fail including the whole electrical system and it's really nice to know where you are even if it's 30 miles off when you are 1,000 miles offshore. Celestial is not meant for inshore travel. Feeling your way along and dead reckoning were the awesome methods then. I still dead reckon in the fog. It only works if you know your starting point. That means you are dead meat if your plotter stops working in a fog bank and you have no reference point. I also carry a backup GPS that has it's on battery built in. Haven't got lost yet.

 

[Christian Williams]

Offshore I have 6 GPS devices: iPhone, $30 hockey puck for laptop, Chartplotter, two obsolete handheld GPSs that still work, and Satphone. Five of them have independent power sources (batteries). The chances of losing GPS by gear failure are about zero. You do still need a paper chart and rudimentary charting skills and the presumption of no nuclear war to turn off the GPS faucet. .

My father's sextant is a display piece. I never was any good with it anyhow.

 

[wynkoop]

I learned celestial at the academy back in the late 1970's. Before I ever picked up a sextant I worked HUNDREDS of fixes from data provided by my instructors. By the time I set foot on a ship for the first time the calculations were second nature, yet my initial LOPs did not match those of the watch navigator.

The academy issued old surplus world war II sextants to midshipman going to sea. They were functional, but the optics were less than optimal for star sightings, so I purchased a used instrument from an instructor for $600 in 1978 dollars. It has served me well navigating me from New York to Capetown and Morgan City to Bombay and plenty of other voyages. I do not know what a quality instrument will cost today, but get the best brass instrument you can afford. Pay attention to the optics especially if you plan to shoot stars in addition to the sun and moon.

To those who say dead reconing, piloting and celestial are not needed in the age of GPS I say POPPYCOCK. A good mariner would never count on his electronics. I have a home built chart plotter on Silver Maiden, but I still carry charts. What if I have an electrical failure? What if the government introduces error into the GPS? In the New York metro area GPS was off by 5 miles just after the September 11 attacks. Count on your GPS then and you will drive right onto the rocks.

The key to celestial navigation is practice. I strongly suggest finding a work book with problems to work out before stepping out with the sextant. When you are good with doing the problems then start shooting the sun with your sextant. When you shoot be careful of false horizons caused by low clouds or fog in the distance. Once you are doing good with the Sun try for the moon. Moon shots are harder because it moves faster. Do the moon shots around civil twilight into nautical twilight.

Once you are good at the moon start identifying and shooting stars. It has been so long since I have shot stars that I doubt I could do any without real work on identifying them. Last star fix I did was probably in 1982.

Be aware that doing celestial from the deck of a small boat is much more difficult than from the bridge of a 600 foot freighter or even a 200 foot man of war. The smallest vessel I ever did celestial from was a 120 foot research vessel and even she was much more stable than our little boats. After you get good on the beach practice over and over again on your boat.

 

[wynkoop]

Christian your father's sextant is a fine instrument!

 

[Christian Williams]

The problem was never the instrument.

 

[Tin Kicker]

I learned celestial at the academy back in the late 1970's. Before I ever picked up a sextant I worked HUNDREDS of fixes from data provided by my instructors. By the time I set foot on a ship for the first time the calculations were second nature, yet my initial LOPs did not match those of the watch navigator.

The academy issued old surplus world war II sextants to midshipman going to sea. They were functional, but the optics were less than optimal for star sightings, so I purchased a used instrument from an instructor for $600 in 1978 dollars. It has served me well navigating me from New York to Capetown and Morgan City to Bombay and plenty of other voyages. I do not know what a quality instrument will cost today, but get the best brass instrument you can afford. Pay attention to the optics especially if you plan to shoot stars in addition to the sun and moon.

To those who say dead reconing, piloting and celestial are not needed in the age of GPS I say POPPYCOCK. A good mariner would never count on his electronics. I have a home built chart plotter on Silver Maiden, but I still carry charts. What if I have an electrical failure? What if the government introduces error into the GPS? In the New York metro area GPS was off by 5 miles just after the September 11 attacks. Count on your GPS then and you will drive right onto the rocks.

The key to celestial navigation is practice. I strongly suggest finding a work book with problems to work out before stepping out with the sextant. When you are good with doing the problems then start shooting the sun with your sextant. When you shoot be careful of false horizons caused by low clouds or fog in the distance. Once you are doing good with the Sun try for the moon. Moon shots are harder because it moves faster. Do the moon shots around civil twilight into nautical twilight.

Once you are good at the moon start identifying and shooting stars. It has been so long since I have shot stars that I doubt I could do any without real work on identifying them. Last star fix I did was probably in 1982.

Be aware that doing celestial from the deck of a small boat is much more difficult than from the bridge of a 600 foot freighter or even a 200 foot man of war. The smallest vessel I ever did celestial from was a 120 foot research vessel and even she was much more stable than our little boats. After you get good on the beach practice over and over again on your boat.

Thank you for the well written thoughts.

 

[wynkoop]

I also can not stress enough accurate TIME for celestial. When I was going to sea professionally I had an LED digital watch that was more accurate than the ships chronometer. I used it for my sites, but I checked it daily with WWV, WWVH, CHU, or JYY. If your watch is not ALWAYS dead on you need to know the error and you need to know the drift per day so you can apply the correction in case of not getting a recent radio time tick.

You all have at least one shortwave set on board to get time ticks right?

I am astonished that my modern digital watches do not keep accurate time!

If you are off by even a small amount on time you can be way off in your fix.