celestial navigation

[JiffyLube]

Originally Posted by Fishspearit

I agree, which is why I always keep track of set & drift, and a running ded reckoning track. It's the backup to GPS.
The sailors of old used ded reckoning as a backup to their celestial navigation. Now we use it as a backup to GPS, still 2 ways of keeping your position and course.
As long as you can ded reckon your way back to port, then celestial navigation is just a novelty. Once you venture out past the point of reliable DR, then the sextent becomes critical.

Weather permitting.

[Robertcateran]

I still use sextants for measuring distance off with both horizontal and vertical angles. Just a basic plastic one is close enough for this use. If I go offshore again, I will probably brush up again, as much as anything for the mental stimulation. If the GPS is seriously turned off, we'll have a lot of things to worry about, and I'll try and find a nice out of the way place to sit- Like some people thought Gaudalcanal was during WW2

[dana-tenacity]

Originally Posted by Jerry Woodward

I definitely plan on learning before I go cruising. Can anyone suggest good books or on-line courses?

Celestial Navigation for Yachtsmen by Mary Blewitt.

[Gene :^)]

Yes, USPS.

[Jolly Roger]

I’m amazed at the results of this poll. As one who was passage making before America even put the first satellite up, I couldn’t wait to get my hands on one of the little tin boxes. We still had to wait for three to come over the horizon, but this was tons better than mucking about with a sextant at midnight and shouting down to the wife, who often popped her head up to say, “sorry I didn’t get that”.
Even then GPS was more accurate, because we never got nearer than about 10 miles with our math. With GPS you can steer up a river in fog.
My Kelvin Hughes is now hanging on the wall in the living room, (best place for it, and worth quite a bit now), so I can’t understand why as few as only 2.44% responders say there is no reason to learn nowadays—because there isn’t. I think I understand why 46% say they would like to learn—the mystery of it, and being able to just drop it out in the bar. They would soon learn however, after a few tries on a heaving deck, that it is much easier, quicker and more accurate to be sitting in the warm cabin with a G & T. It is useful for other things, as others have mentioned, and if you were mid-pacific when the system was suddenly switched off you might wish you had learned, but if you are that worried you shouldn’t go to sea anyway. Students would be much better learning their knots and rope skills, which are still useful, and I’m also quite certain the navigators of old would have happily chucked the contraption overboard, if some time-traveler had produced a GPS. I wonder if we might have had the same response when the first engines were fitted on boats.
Whako! keep 'em coming lads, I really look forward to to morning read.

[JiffyLube]

I agree Jolly Rodger.

If I was in a situation were all my GPS backups failed (doubtful), and I was making a crossing form lets say Hawaii to California, then using a sextant would have value...even if I was 10 miles off. Depending on weather conditions though, a person might not be able to get a fix for days at a time...better than nothing I guess. I guess if my electronic calculator died, I could always break out the slide rule.

[David M]

Looks like it all boils down to opinion on whether or not backups are important. Personally, I think backups are important even if the odds are small. This must be why I wear my seat belt as well. I have never really needed my seatbelt since I have never been in a serious accident (knock on wood)..although I have put it on thousands of times. Do I really need to wear one? Come to think of it, I probably don't need a life raft, a safety harness, flares or a PFD either.

[JiffyLube]

Originally Posted by Gene :^)

Yes, USPS.

I've taken those course also at our local squadron...good place to learn.

[Jerry Woodward]

I was trying to think of a scenerio where one would loose GPS and then reading another thread on lightning strikes it hit me (like.... a bolt of lightning). If lightning knocked out all the electronics on your boat in the middle of a crossing, celestial navigation might be a lifesaver.

[Robertcateran]

It is still useful for coastal navigation. Sometimes the electronic charts are a bit off and you can easily check your position off landmarks.
Robert

[JiffyLube]

Originally Posted by Jerry Woodward

I was trying to think of a scenerio where one would loose GPS and then reading another thread on lightning strikes it hit me (like.... a bolt of lightning). If lightning knocked out all the electronics on your boat in the middle of a crossing, celestial navigation might be a lifesaver.

If that situation happened to knock all the backups out, then celestial navigation would have value if you could still see the sky.

[Robertcateran]

I'd keep a couple of gps's in a a Faraday cage against that eventuality.

[SkiprJohn]

Having covered this subject before on this forum I'll not wade in again but recommend the book, "Celestial Navigation by H. O. 249" by John E. Milligan. It is the simplest on Celestial that I could find and gives examples of sights here in Hawaii which puts it pretty close to home. My friend and I practiced a couple years ago. He wanted to learn because when there was an unusual amount of sunspot activity his GPS was not working properly. He wanted a backup.
Martin, Tony and I will be practicing on our trip from SF to Hawaii next month. You'll not hear from us if it doesn't work! : )
Kind Regards,
JohnL

[sandy daugherty]

I went 36 days without getting even a noon sight. Now I keep a battery operated handheld gps in a tin box in my ditch bag, with a pack of long storage life alkalines. Oh, and two chart plotters, with an additional receiver in my AIS. And that new handheld for the dinghy.... I suppose I could borrow a friend's Loran if I was worried about sunspots.
If I was ever close enough to correct a chart, it was because all my math errors exactly balanced out. We don't even require celestial nav at the Naval Academy anymore, it's strictly an option for Mids who want to qualify for offshore racing. Even that will go away when a couple more old crusties retire. I'll bet half the sextants in the Navy haven't been out of their cases more that 4 times a year.
I tried to pick out 5 Nav stars last winter, and I'm not going to admit the results. I'll bet there were a lot of old salts that wouldn't trust their vessels and crews to those new-fangled chronometers back in the 17th century either! I mean, what if the broke a spring or something?

[dhhudson]

The best single volume I have come across for teaching oneself celestial navigation is Mariners'CelestialNavigation written by William Crawford. The book starts with an explanation of time and time diagrams and runs you through to taking a typical celestial fix. Sunlines, LAN, sunrise, sunset, as well as times of lunar phenomena are fully explained in short, humorous chapters that are really, if you apply yourself, self teaching. Crawford emphasizes the use of the Nautical Almanac and Publication 229 which are partly reproduced in the tome, as well as use of the Rude Star Finder. (Anyone still got one of those?) Crawford also revels in the lore of seamen, explaining many of the sayings, habits, and beliefs that have developed over the ages.

The book is currently out of print, but there always seem to be copies available on line at Alibris.com or Amazon.com.

By the bye, if you learn nothing else about celestial, learning how to find your latitude at LAN is a simple task that will answer 50% of your questions about "where the hell am I?" It was good enough for the Europeans to find the New World.