Celestial Navigation? Forget it!

[haffiman37]

Setant as navigation aid on 'small' cruisers and yacht are a vaste of time. At the very best in flat sea, clear visibility and sharp horizon, perhaps an accuracy within a radius of 25 Nm may be obtained! As an entertainment and time consuming activity out in no-where-land = OK. What is interesting when you talk to people haveing sextants onboard as 'back-up' in case of lightening strikes and electronic failures, they all have the calculation programs on the lap tops! I have yet to meet someone with the old paper calculation set up!Back in my navy time in the late 1960's celestial navigation was part of the education. We tried it when possible and compared to dead reconning it was a constant looser. The only time we managed to get it reasonable close was when using xxxxx$ special gyro compensated platfom, actually the base of a radar unit for the gun battery.
A vast of money unless you need something to spend your time on.
I had a lightening blowing most of my electronics south of Singapore last year. What it did not blow was my battery powered Garmin 86!

[Hawkwind]

What if Lex Luthor were plotting to conquer the world and you were the only one who knew of his fiendish plot. He zaps your boat with his electro-disrupter, knowing that you'll never be able to navigate back to warn Superman in time. The world is lost because you depended on electronics.

Ok, probably won't happen exactly like that. Truth be told, modern electronics are almost too reliable. I only say that because I'm a electronic tech.

But there is something very cool about being able to measure a few angles, consult a table or two, do a little math and you've pinpointed your position on the globe. Almost magical, wizardly, etc. Like something a mad scientist might do. I doubt that many people need to learn celestial navigation, but I certainly understand why they want to learn it.

For my part, I might be able to do a noon site for longitude. I may learn it properly someday, maybe not. I still admire those who can work magic with what some percieve as an obsolete skill.

BTW, anyone else looking forward to the new Superman movie?

[Omatako]

Tomarto, tomayto - why argue about this? Each sailor has his chosen way. To call someone an idiot because he doesn't do things the same as you is just plain silly. Anyway, consider the following:

I have single-handed across the Indian Ocean, had 3 h/h GPS receivers and all the required CN stuff on board. I never had even one time in three months of sailing that I never got a decent GPS fix (Garmin Map76). I messed with the sextant when I was bored and never got to within 30 miles of the GPS location. I never had to use the other two receivers. I really envy the guys who can get down to half a mile with a sextant although I've never personally seen it done.
Most GPS units today are absolutely moisture proof, if yours isn't get a new one, it won't corrode internally. And like one of the other respondents said, don't use batteries, plug into the domestic electrics. Keep your AA batteries for the unlikely event that your wind gen fails, your solar panels die, your gen set won't start and the engine alternator goes belly-up all at the same time causing your domestic electrics to go flat. Talk about doom-prophets!!
CN is sometimes not possible for days, even weeks because of cloud cover. How long is the longest period anyone has experienced a GPS downgrade for? And when you're in the middle of the ocean, how far out relatively would that place you?
I treat my GPS like I treat my sextant. I use it to get a fix and at all other times it is in a safe location under my chart table. Damage it? No way!
And a lightning strike that's bad enough to take out my GPS in the locker will probably leave me with bigger problems than my current location.
Oh, and by the way, when your chronometer stops working, use the clock on your GPS reciever, it's pretty accurate.
Lastly, one of the most important issues about coastal navigation with GPS is that the GPS is probably far more accurate than the chart you're using so be sure to look out the window when you're navigating close quarters. It probably won't be your GPS that runs you aground, it'll be the reef that isn't exactly where the chart says it is.
And finally, lastly, never go to sea without paper charts for every possible destination on your route. And if you're going coastal, take a local Pilot with too!

Thanks for the chat

[sailingdog]

One mistake that people tend to make with GPS Chartplotters is that they think the icon for the boat is actually an accurate representation of where the boat actually is. It isn't. The little icon of the boat is a graphical representation of where the computer in the GPS unit has decided to place you, based on the radio signals from several GPS satellites, in a graphical interpretation of the real world by a group of cartographers, who may or may not be using accurate data.

In many cases, check the GPS chart data, and you will see that the charts are based on readings taken as far back as the early part of the last century. This is especially true in very remote, rarely traveled regions. The mapping of the major seaports and the coastal areas near major shipping lanes will be much more recent and far more accurate, as the shipping companies have a financial incentive to make sure that these areas are properly updated and charted.

In one case I know of, my friend found an island in the Caribbean is actually over half a nautical mile off of where it is on the GPS charts. This is probably due to a combination of changes in chart datum and the age of the survey.

Celestial navigation and GPS are both navigation tools. One can be used to back up the other. But the Mark I Eyeball is still a very necessary tool in navigation, especially in coastal areas. Accurate navigation isn't quite as crucial in the middle of the ocean, but when you're close to land, the level of accuracy in navigation goes up significantly.

[haffiman37]

Hawkwind:
Do You recomend me to bring along some pigeons as well in case the electronic communication fails?

[Hawkwind]

haffiman37

Pigeons? Sure if it works, use it.


Sigh!

I can't argue with the advantages of the new gear that is available. I kinda miss the old days though, and I'm not that old. Back in the dark ages of the mid 80s, I managed to take 3rd palce in a 17 mile race(Waukegan, Il to Kenosha, Wi) against larger, faster boats. The reason was that the mist/fog had cut visibility to about half a mile. The other boats hugged the shoreline while I went out into Lake Michigan, did one jibe, and headed back in to cross the finish line. I was quite proud of myself for hitting the finish line so exactly, using only a compass, a knot meter, a clock and my charts. Nowadays, the faster boat would always win. I think the better boaters and most sailors can still navigate the old fashioned way if needed but I know a lot of power boaters that wouldn't cross a 30 mile stretch of water without GPS, radar, etc.

[Ronbye]

Interesting views here. My son is a third mate on an ice breaker that regularly goes to the Artic and occasionally across the pond to Europe. He along with the other officers on board regularly do position checks using the sextant and celestial navigation as a backup to the multiple gps devices they have on board. In fact it is a requirement to do this. He is a young man who loves his electronics but he has said to me it is nice to know how to use celestial navigation by sextant when you have do.

[BigRed56]

Ahoy me mateys, I says it befiore I and says it again. De only time I needs celesterial navigation is when one of me ex-wives hits me wit something and I need to follow de stars to de nearest pub to clear me blooming head!@! Me father left me an old naval sextent and a ton of books and de only time it came in handy was as a drogue during hurricane Jean. Pirate of Pine Island.

[Artwerke]

This thread seem to go on & on. The idea that this august body , most of whom have invested hundreds of hours studying all sorts of arcane arts connected with this sport we all enjoy, would come to loggerheads over 1 more , which could possibly save your bacon someday, something that can't be said for that 11th coat of spar varnish on the cupholder! Why bother fine tuning your jib to point 1/2 degree closer upwind, just fire up the iron jenny and to hell with tacking altogether,hell,why even bother with sails at all. You'd think that anyone who would wax a bottom to pickup 1/2 a knot, spend hours practicing knots,replacing running rigging that would probably not fail in a hurricane, spend 5 grand on a feathering prop,or just having to have the latest wundercloth from the sailmaker, could try to understand the art that has seperated us from landlubbers for hunderds of years. Just knowing where you are never having been there before. Just my 2 cts. Art.

[sailingdog]

Well said Art.