Celestial Navigation? Forget it!

[JeffC_]

I''m disappointed, Jeff: I thought I''d get a chuckle out of you.
I was only trying to bring up the inconsistency of the "GPS only" argument. If you want to dispatch one type of equipment that uses natural forces but keep another, that''s an inconsistent, um, "position" to hold (sorry). And if you realize that they are in the same family of tools, and continue to advocate axing one while not letting the other climb up on the chopping block, that''s being dishonest in your argument. I''m just relying on the rational, logical rules of rhetoric. I''m not trying to split hairs. I found this entire thread both illuminating and entertaining.
Not quitting my day job,
Jeff

[piclarke]

In this instance I agree with EscapeArtist. I have been sailing for 35 years ocean racing and cruising. I''M a professional sailor and boat deliverer. I have three G.P.S.''s a hand held, a 126 & a 2010 Chartplotter. ALL Garmin. The 126 & 2010 have a capacity of being used up to 40 volts. According they have male cigarette lighter fittings permanently fix on the end of the cords so as they can be used either by ships power or my power. They are mounted on a plastic container ( food storage container). In the containers I have wired a battery holder to hold (4) 9 volt Energizer batteries which are in turn are wired to cigarette lighter water proof female holder on the side of the container. ADDITIONALY I have made up another water proof container containing 24 D cell batteries wired up the same way. I carry a bag full of replacement bateries and a rechargable system and rechargable batteries. The rechargeable system is both AC & DC. all contained in water proof containers. Accordingly when the ships electrical systems are working including inverters I''M fully operational and if it goes down I''M fully operational.

If the vessel is rolled and sever damage is caused then it''s time to set of the E.P.I.R.B. I also have a personal E.P.I.R.B.

Most crew members these days have their own hand helds. I have been on numerous boats where 8 handhelds have been available. Additionally I give preference to crew members that have their own G.P.S''s

So you see EscapeArtist IS COMPLETELY RIGHT.
I''M not waiting 20 years either.My sextant is up for sale any buyers.
Fair winds and clear skies.
PHIL::
<img src="http://members.sailnet.com/profile/uploads/piclarke/PhillipClarke_pic.jpg">

[928frenzy]

It''s great to have electronic redundancy. However, I still wonder how effective all those GPS systems will be if/when the military decides to degrade the signal? Wouldn''t they will all indicate the same ERRONIOUS location?

As long as the military does not control the location of the Sun, Moon, and other celestial bodies - the sextant (and knowing how to use it) will remain a part of my navigational tools.

~ Happy sails to you ~ _/) ~

[piclarke]

Hi 928frenzy:

They have been saying/predicting a degrade of the signal for 10 years now. It''s not going to happen. It''s a rumour being spread by owners of sextants and the publishers of sight reduction tables.

Phil:

[928frenzy]

Actually, they''ve already degraded the signal several times, they just don''t tell anyone when and for how long they do it.

You can bet that the signal will be degraded if/when missles are ever launched against us or any of our allies. :^(

Besides, the cost of a decent sextant is no more than the cost of a decent GPS, and the sextant never needs batteries. Moreover, practicing how to use it helps exercise the ole'' gray-matter, and when you''re cruising beyond the sight of land - a little mental exercise can be refreshing. ;^)

Happy sails to you ~ _/) ~

[piclarke]

In this part off the world sailing around reefs where accuracy is vital, sextants are dangerous and a sure fire way of ending up on a reef, as sextants are not accurate to within 40 miles.

It is my unnderstanding that the signal is at it''s most accurate during a conflict the U.S. in involved in. I excercise my grey matter by avoiding going on a reef and being distracted for 20 minutes working out the figures is a sure way of being where you don''t want to be. Each to there own I suppose.

Your grey matter would certainly get a lot of excercise trying to work out how to get of a reef.

[928frenzy]

I don''t know what kind of sextant you''re talking about, but mine can be accurate to within a 10th of a nautical mile (less than 600 feet). Some sextants have Vernier scales that allow an experienced user to determine their position within 60 feet. ;^)

By your argument, everyone who has sailed without the benefit of some electronic device was doomed to go hard aground. So just how did folks navigate around the world before there was GPS and even before loran? History does not seem to support your contention. True, many experience sailors did indeed go hard aground, but usually because the waters the were sailing in were uncharted (or poorly charted) or due to bad weather. Today''s charts are far better than those used in the past. That''s not to say that one can not go aground while using a sextant, but it can happen (and it has) with a GPS too.

Happy sails to you ~ _/) ~

[928frenzy]

I forgot to add, that if a missle or other form of attack were made against us or one of our allies, the US Military would degrade the GPS signal worldwide! They know how much it they degraded it, and have the code built into their GPS systems to compensate for that degredation. All non-military GPS units would not have the code needed to correct the degradation, and would be rendered worse than useless.

Just some food for thought.

~ Happy sails to you ~ _/) ~

[piclarke]

I know of no sextant that is acurate as you claim let alone take a sunshot in the open sea with 30 knots blowing and be acurate to within 40 miles, it''s impossible. When was the last time you actually took a sunshot if at all. Whats more the sun does shine at night.

[928frenzy]

Our Sun shines 24/7, but we usually cannot see it for about half-a-day. ;^) Fortunately, on a clear night, other planets, our moon (for three out of four weeks) and suns (which we call stars) can be seen by the naked eye. Many of them are listed and tracked in the Almanac.

Getting an accurate fix to the minute (one mile) is not too dificult. Getting a refined fix to the 10th of a minute can be done with a decent vernier scale. Getting a fix to 100th of a minute is possible with the finest scale and interpolation. All these very accurate fixes depend on a clear sky, a calm sea, a very accurate chronometer, and a steady hand.

Getting a fair fix in rolling seas is difficult, but it can be done. Just wait for a momentary lull in the roll. Getting a fix with heavy cloud cover is impossible.

Hey, I never said a GPS is uselss. I only said that a sextant is not useless, and still has a place in a well rounded navigator''s tool chest.

~ Happy sails to you ~ _/) ~