On the economies of navigation

[Ross]

I guess that a little balance is in order today. I have been thinking about the cost of navigation in a small boat(anything less than 150 feet).A very good sextant can be purchased for about 750 dollars, the sight reduction tables cost 20 dollars per volume, the almanac costs about 25 dollars per year, pencils and paper we all should have.With good skills and careful work a position fix within 2 miles is posible, and it takes about ten minutes to work it out. A Garmin 72 GPS costs about 125 dollars and will provide a fix with the push of a button in about one minute. Mine reliably fixes the position of the front of the house at.01 minute south of the back of the house.So for the 800 dollars spent for a sextant,almanac, and sight reduction tables you could put a Garmin 72 GPS in service and have five spares and a lifetime supply of batteries.You still must have paper charts, at the very least small scale planning charts, harbor charts can be had for electronic display.

 

[Stu Jackson]

But...

you can get a used sextant for a lot less than $750, and a usable plastic one that'll get you to Hawaii or Bermuda (your coast, your trip!) for even less than that. I don't know, but I'm guessing sooner than later the almanacs will be available online, if not already. It's good to do calculations, keeps your fuzzy parts still working. Darn, the whole GPS system could go down when one of the guys on the Politics page of this site turns out to be right!But you're right in general. Would seem that going offshore it would be prudent to have a backup. For daily stuff, probably not an issue.

 

[Robert Gainer]

It’s not a question of cost or convenience.

Why do people keep debating this question of which is better, a sextant or a GPS. They are too different approaches to the solving same problem. It’s not a question of cost or convenience. It’s much like debating the choice of powerboats or sailboats being the best boat. Some people like modern boats and some prefer antique boats, some like power some like sail. Each has different pros and cons but the bottom line is that each person selects a hobby that he enjoys and enjoying a sextant as a hobby or even as the primary means of navigation is just another choice to be made. What’s right for me is not necessarily right for someone else.All the best,Robert Gainer

 

[Ross]

Stu I have a Davis Mark 3 with a slide verneer

and no optics that will allow me a ten mile fix and can give me 2 mile accuracy with a noon sight. I figure that if I were blown off course in a storm with my quartz watch and any almanac I could find the latitude for the entrance to the Chesapeake Bay.

 

[abe]

Keep in mind GPS is for the military....

...and they can switch it off or change signals at any time if they need it in time of war.

 

[Brian D]

Embrase technology...

But always have a back up plan. I have GPS, but I also have paper charts. they both work independently and simultaneously together. Sextant? On the horizon it is for me.

 

[Ross]

Abe, If what you say of the arbitrary

ability of the military to disable GPS is true then we will have commercial transportation in a mess that will make war look like a peaceful demonstration. All commercial aircraft depend on GPS. Turn GPS off and you will have chaos in the skies and on the ground. The military is at present working on counter measures that will electronically disable GPS receivers within a protected perimeter. How difficult and time consuming will it be to reprogram all of the GPS units in use by the military if your prediction were to be valid?

 

[Tom Spohn]

Why not both?

The GPS will give you greater accuracy and is much easier to use, but for those days when you want a challenge or if the system ever goes down (doubtful) pull out the sextant and charts.http://www.brassbell.com/gifts/dept.asp?s%5Fid=1&dept%5Fid=857&WT%2Esvl=deptnav1&gclid=CODProiP8okCFRZlggod7lBWKQ

 

[tom]

there is a calculator method

there is a calculator method that removes the need for almanacs.So it's possible with a calculator $10 and a plastic sextant $50 . I have the book somewhere and a $25 sextant but have never tried using it yet.  But it's the trip!!! If I want to go somewhere I don't go by boat and definately not by sailboat. I would never sail to Hawaii as a way to get there. A lot of sailing is the trip. Skills such as celestial navigation can be part of the fun. A trip by sailboat to Mobile by my sailboat takes nearly two weeks. I can drive there in 4 hours(almost legally) or about 5 leagally.

 

[Dan]

Never know

>>or if the system ever goes down (doubtful) <<Or if the Chineese blow the satalites out of space........Isn't that just what they did? Prove they can disable the global GPS system?

 

[Warren Milberg]

As a coastal cruiser...

I think exactly like Ross: a GPS or two will meet most -- or all -- of my needs. And at a fraction of the cost of a sextant (which I have, but haven't used for years), reduction tables and antacids (needed for the aggravation of it all). Yet if I were going offshore to any place further than say Bermuda, I would dust off my sextant, buy the latest tables and review the procedures (which Bill Buckley makes simple for everyone). I'm a believer in the "stuff happens" theory of life and sailing. There are any number of reasons for the GPS system to fail, to be dithered with, or to limit capabilities of non-official users. You don't want to be to be forced into dead reckoning toward the Azores or Tuamatu when this happens.

 

[C36-2000]

Commercial aviation

would see little loss if GPS were shut down as they still have VOR, DME, Inertial and in many cases LORAN. GPS provides a very convenient correction for inertial but any other fix can be used with some more effort. Aircraft were able to pinpoint their positions and even land automatically before widespread use of GPS.The reason that selective availability was finally turned off by the government was that they acquired to spoof selected areas and no longer needed the widespread degradation of GPS accuracy.That said, I wouldn't go far from home without my paper charts, plotting tools, hand bearing commpass, etc. or withour my backup GPS and backup laptop.

 

[NewportVic]

gee guys ... Hey I carry a 76 in my backpack ....

just so I can find my way back to the boat at night. You guys actually use it while sailing too? That's a great idea.But seriously ... I find that the 76 looses satellite way more than the old 48.Vic

 

[tom]

someone needs to write a program

It should be very easy in concept to write a program for a lap top computer that will tell where you are from a sight and time input.. Probably a handheld top end programable calculator would work also. Someone out there with the programingability and desire could write the program and let us all download it and save it on a cd for a just in case event."Celestial Navigation Made Easy (using a pocket calculator)" by Francois Meyrier tells exactly how to do the calculations. Any programers out there wanting a project for these cold winter nights??? I took a course on FORTRAN programing 30 years ago but I don't think that fortran even exists now. The last time I programed anything was my old TI calculator.....it died a long time ago.

 

[Moody Buccaneer]

Globe and protractor

You could sail anywhere with less than $10 worth of tools.By a inflatable globe, a protractor, a watch and a radio.Pick out where you want to go on your globe and note the Lat Lon. Within a degree or two should be easy enough.Use the protractor and bit of string to fix your latitude. Look at the globe ... sail north or south to the right Lat. Tune the radio to any station when the sun is high where you are, and get the location and time where they are. If it is early there (They say it's 9 am and it is noon where you are), you are East of that location. Looking at your globe you now know what ocean you are in and what heading to steer.If you want to get really tricky, you set your watch to Zulu time and compare local noon to your watch to get a good guestimate of Lon.When you reach land, you should be relatively close to where you wanted to be. If you are trying to find an Island, like Hawaii, use the radio as a direction finder and get a LOP from there.Spend the rest of your $750 on booze and women. If you make a boo-boo, the globe can be a flotation device ...

 

[Ross]

Randy, you are too randy!D:

That would work. Not too well but it is better than what old Chris had.

 

[Stu Jackson]

Tom, I think someone already has

done that. Check out the calculators at: http://www.celestaire.com/

 

[Moody Buccaneer]

There is a point ...

Arrgh! Thanks RossIn my mind there are two terms. Coastal Navigation that I consider Piloting, and open water Navigation.Navigation is what you do between areas where you use piloting skills.It seems to me that as long as your Navigation skills and equipment get you close enough to use Piloting skills, they are good enough.Once you are into piloting range no fancy tools are needed. Helpful yes, but not required. If you are in the middle of the Atlantic Ocean, how close does your fix have to be? 20 miles? 50? It would be nice to make your landfall within sight (8 miles?) of your destination. But do you really need super accurate fixes to get you there?Granted, if the target is an Island, you have to be more precise. But even Islands make themselves known beyond a 10 mile radius.