Celestial Navigation? Forget it!

[sailingdog]

medcaldendoctors-

thanks for screwing up your spam post. now piss off and don't bother us again.

[thedudeistoocool]

sorry I'm late, I would have been here a week ago but I got lost

There is another intersting book called THE LAST NAVIGATOR written by Steve Thomas of This Old House fame

it's about the Caroline Island Aborigines and their navigation techniques
No sextant No Compass No chart and No GPS jsut using the wind the waves the stars and birds and knowledge of where their destination lies they been doing it for a thousand years until the white man came along and ruined everything - it's now a dying art if it's not dead already


The book isn't really written all that well but I've still managed to read through it 3 times

[Boasun]

When the Hippies abounded all over the place. Some sailed to Hawaii from San Franciso by following the contrails of the jet air planes going that way. Most were lucky and found the islands.

[sailingdog]

If you like that book, get The Barefoot Navigator. It talks a lot about the techniques used by the Polynesian navigators, among others.

Originally Posted by thedudeistoocool

sorry I'm late, I would have been here a week ago but I got lost

There is another intersting book called THE LAST NAVIGATOR written by Steve Thomas of This Old House fame

it's about the Caroline Island Aborigines and their navigation techniques
No sextant No Compass No chart and No GPS jsut using the wind the waves the stars and birds and knowledge of where their destination lies they been doing it for a thousand years until the white man came along and ruined everything - it's now a dying art if it's not dead already


The book isn't really written all that well but I've still managed to read through it 3 times

[kennya]

Let’s see now. A GPS tells us the direction to steer, the time of day, our current heading, and how fast we are crossing the surface. With all this information at hand we don’t need CN, or a compass or a knot meter or a time piece. Add a chart plotter and throw out paper charts and a depth sounder. Look at all the money we can save. Ops I need the knot log cant calculate a course to steer (Have to have boat speed not ground speed)need the charts and tables the have an idea as to what direction I want to go and if there is an (ocean, lake, river, etc )current to factor in. With the GPS surly I can set a course and get to my destination, sure I may have to constantly change my course if there is a strong current but I’ll get there eventually. If I only had GPS, when I took my flight training. All those hours poring over charts plotting a course the going aloft and executing the plan, not to mention the satisfaction of reaching my destination and at the planed time

I thank the theory behind teaching the paper way verses the electronic way is the same whether in the air or on the sea. The more ways you know to accomplish something the stronger the possibility of accomplishing that task are regardless of the situation at the time. I use my GPS but I don’t rely on solely on it. It’s just another tool.

[sailingdog]

Hmm... remember when the Hughes IV satellite failed about 10 years ago...and about 80% of the pagers in the country stopped working... That isn't all that unusual an occurrence, and the majority of the US's GPS satellites are getting a bit long in tooth... so seeing some of them fail spontaneously would not be a surprising thing.

Good coastal pilotage does not require a GPS, nor does it require a sextant. A sextant is really only necessary for bluewater passages, as is GPS. There are many other methods to determine your position when within sight of land. When you are in the middle of an ocean, being off by the 1-2 nm that is often the case with celestial navigation is generally not an issue, since there isn't really any difference between the two points, and given the magnitude of the distances involved, 1-2 nm is not all that significant. Once you get close to your destination, coastal pilotage takes over from CN or GPS... and your charts and eyes become the best way to navigate.

[Valiente]

SD, while I agree that a sextant is not absolutely necessary for coastal pilotage, when shore "sights" are taken with the sextant on its side, you can get far more accurate angles (and clearer views, thanks to the typical 4x magnification) of shore features and thus can accurately calculate distance off shore. I've done this with a pelorus, and with the "45 degree angled tape on the coaming and wristwatch" method, and in the absence of known nav aids, this works pretty well...if you carry paper charts.

If you have a shore feature of a known height above water, you can do the same in one vertical shot by measuring its "altitude".

[sailingdog]

Valiente-

Yes, it is convenient to have a sextant to do things like angles between two landmarks, distance off from known height landmarks... but not necessary.

[Sapperwhite]

Originally Posted by sailingdog

Hmm... remember when the Hughes IV satellite failed about 10 years ago...and about 80% of the pagers in the country stopped working... That isn't all that unusual an occurrence, and the majority of the US's GPS satellites are getting a bit long in tooth... so seeing some of them fail spontaneously would not be a surprising thing.

Tin whiskers! Yes, even in the vacuum of space electronics fall prey to tin whiskers (and other metal whiskers). No cure. NASA Goddard Tin Whisker Homepage

Oh yeah, and what about solar flares??? Solar flares will disrupt GPS in 2011 - tech - 29 September 2006 - New Scientist Tech

Holy crap, did they just site known gps disruptions through at least 2011???

Does this mean that during high periods of SMD the backup GPS won't work either?....uh yeah. Uh oh....I'm half way across the Atlantic....now how does this crazy sextant thingy work again????

[sailingdog]

Some pretty neat photos of the 1-4 molecule wide tin whiskers on that site IIRC. Solar flares are relatively temporary... the satellite kicking the bucket is much more permanent.