Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 24-01-2013, 15:50   #31
Registered User

Join Date: Feb 2012
Posts: 2,441
Re: SExtant Newbie?

Quote:
Originally Posted by Bash View Post
Claiming you want to learn to use one because you don't trust electronic gadgets is like going into battle with a sword because you don't trust guns.
Hmm- if I was going into certain battle situations

(unlikely, being a rabid pacifist)

I would definitely take something(s) stealthier than a gun, like a knife, a garotting wire, a syringe....

Of course, being a determined coward, fond of staying alive, I'd take the best gun(s) available. And hope they didn't jam.

Peter Blake's gun jammed.
__________________

__________________
Andrew Troup is offline   Reply With Quote
Old 24-01-2013, 17:45   #32
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Learn celestial if you like to do it , a kind of hobby , that's what I like. Currently I'm working my way through Bruce Starks method of clearing Lunars to determine time
But don't other as a backup to GPs. You simply won't use it enough and when the time comes you'll be rusty and make errors. Unless you use celestial regularly the skills set fades.

The fact is you'll spend most of your sailing life waiting for all your gps devices to fail.

Dave
__________________

__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 24-01-2013, 17:48   #33
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by Andrew Troup
It never fails to amuse me when accuracy is advanced as the clincher for using a second GPS as sole backup for a GPS.

Because, quite often, the same person will (if pushed to acknowledge a certain degree of risk inseparable from having 'all eggs in one basket')

then turn around and say:

< <What's the big deal if you do get some sort of multiple failure ?:

It's not rocket science:you just sail west (or whatever) until you see land then turn right (or whatever) > >

I'm not sure why pinpoint accuracy is so essential to the first proposition,
when the second proposition flings it out the window.
There is no confusion, there is no need for precision position fixing to navigate by. GPS gives that but it is unnecessary. If or when it fails , an unlikely proposition, one can do elementary non precise navigation by a number of methods. No more then a competent navigator can reach land without a GPs, he can reach it without a sextant.

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 24-01-2013, 18:17   #34
Registered User

Join Date: Nov 2011
Location: Fethiye Turkey
Boat: Lagoon 440
Posts: 3,164
Re: SExtant Newbie?

Claiming you want to learn to use one because you don't trust electronic gadgets is like going into battle with a sword because you don't trust guns!

Great Analogy
__________________
"Political correctness is a creeping sickness that knows no boundaries"
Lagoon4us is offline   Reply With Quote
Old 24-01-2013, 19:39   #35
Moderator
 
Adelie's Avatar

Join Date: Feb 2010
Location: La Ciudad de la Misión Didacus de Alcalá en Alta California, Virreinato de Nueva España
Boat: Cal 20
Posts: 4,621
Re: SExtant Newbie?

Quote:
Originally Posted by Lagoon4us View Post
Claiming you want to learn to use one because you don't trust electronic gadgets is like going into battle with a sword because you don't trust guns!

Great Analogy
If you go into battle with guns and a sword and everyone else is just carrying guns, then you are a leg up on everybody else. And before you argue that the odds are infinitesimal that every gun could possibly you have on you jamming, remember this is an analogy about GPS not a discussion about guns.

There are situations that could lead to every GPS on a boat failing (low probability, but not that improbable, 3/100 to 1/10,000 per year depending on location). There are also situations that could render every GPS (and possibly the other systems too) useless. While these are essentially un-quantifiable events, I would guess that loss of one system will occur within the next 50yr and all of them within 200yr.

Still a good analogy except not with the moral originally offered.
__________________
A house is but a boat so poorly built and so firmly run aground no one would think to try and refloat it.
SailboatData
Adelie is offline   Reply With Quote
Old 24-01-2013, 20:29   #36
Moderator
 
Adelie's Avatar

Join Date: Feb 2010
Location: La Ciudad de la Misión Didacus de Alcalá en Alta California, Virreinato de Nueva España
Boat: Cal 20
Posts: 4,621
Re: SExtant Newbie?

Quote:
Originally Posted by goboatingnow View Post
Learn celestial if you like to do it , a kind of hobby , that's what I like. Currently I'm working my way through Bruce Starks method of clearing Lunars to determine time
Have you read Letcher's method of Lunars, much simpler than the traditional method, less dependent on good sextant technique those potentially very tedious and time consuming.

Quote:
Originally Posted by goboatingnow View Post
But don't other as a backup to GPs. You simply won't use it enough and when the time comes you'll be rusty and make errors. Unless you use celestial regularly the skills set fades.
You are making assumptions about how much practice the OP is willing to put into this and how good his recollection will be. I know people that can recall conversations almost verbatim which amazes the hell out of me. I on the other hand recall how certain technical processes work weeks and months after the last time I used the process, which amazes those same people. Keep in mind that the OP's technical recall may be better than yours and give him/her the benefit of the doubt.


Quote:
Originally Posted by goboatingnow View Post
The fact is you'll spend most of your sailing life waiting for all your gps devices to fail.
I hope to wait my whole life for GPS to fail, but preparing the boat as if it would never happen is not the smart way to play the odds if you are going to be out for an extended period. The same as having a fire extinguisher, or a large capacity pump or a drogue/sea-anchor/series drogue, all there to deal with low probability events.
__________________
A house is but a boat so poorly built and so firmly run aground no one would think to try and refloat it.
SailboatData
Adelie is offline   Reply With Quote
Old 24-01-2013, 20:58   #37
Registered User
 
rover88's Avatar

Join Date: Nov 2008
Location: Panhandle of Florida USA
Boat: Bristol 34
Posts: 328
Images: 4
Re: SExtant Newbie?

Quote:
Originally Posted by Lagoon4us View Post
Claiming you want to learn to use one because you don't trust electronic gadgets is like going into battle with a sword because you don't trust guns!

Great Analogy
A gun without bullets is an inefficient bludgeon. A GPS without power is an inefficient paperweight.

Why in 2013 does the USMC still issue the Kabar fighting knife? Not exactly a sword.... but you get the point (sorry.... there may be a lame pun there).
__________________
rover88 is offline   Reply With Quote
Old 24-01-2013, 23:45   #38
Registered User

Join Date: Apr 2012
Location: Vancouver, BC
Boat: Alberg 30
Posts: 344
Quote:
Originally Posted by rover88 View Post

A gun without bullets is an inefficient bludgeon. A GPS without power is an inefficient paperweight.

Why in 2013 does the USMC still issue the Kabar fighting knife? Not exactly a sword.... but you get the point (sorry.... there may be a lame pun there).
What's a sextant without sun?
__________________
jgbrown is offline   Reply With Quote
Old 25-01-2013, 02:23   #39
Registered User
 
GrowleyMonster's Avatar

Join Date: Dec 2012
Location: New Orleans
Boat: 1976 Cal 2-27
Posts: 1,298
Re: SExtant Newbie?

Quote:
Originally Posted by jgbrown View Post
What's a sextant without sun?
One that still has moon, stars, and planets.
__________________
GrowleyMonster is offline   Reply With Quote
Old 25-01-2013, 04:29   #40
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Re: SExtant Newbie?

Quote:
Originally Posted by SkiprJohn View Post
In my opinion if you think celestial navigation is easy then you must be doing it wrong!(...)
C'mon. Some things are easy for some and more difficult for others.


b.
__________________
barnakiel is offline   Reply With Quote
Old 25-01-2013, 08:26   #41
Registered User

Join Date: Apr 2012
Location: Vancouver, BC
Boat: Alberg 30
Posts: 344
Quote:
Originally Posted by GrowleyMonster View Post

One that still has moon, stars, and planets.
Fine, what do you call a sextant with constant cloud cover ?
Surely there must be a funny name for one when what it relies on to function is unavailable, like for gps or guns?

This could be a whole topic... what things are without what they use. An anchor without bottom is a poor fishing lure, an engine with no fuel is a ? a mast without sails is a ?

I like sextants, I am buying and learning to use one when I can, but it just struck me as extremely funny to define other tools by their use without what they require, when a sextant could have a similar issue...
__________________
jgbrown is offline   Reply With Quote
Old 25-01-2013, 08:33   #42
Freelance Delivery Skipper..
 
boatman61's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Jan 2010
Location: UK/Portugal
Posts: 20,210
Images: 2
Send a message via Skype™ to boatman61
pirate Re: SExtant Newbie?

You mean like a blind man with paper charts... and not in Braille
__________________


Born To Be Wild
boatman61 is online now   Reply With Quote
Old 25-01-2013, 08:59   #43
Moderator
 
Hudson Force's Avatar

Cruisers Forum Supporter

Join Date: Nov 2008
Location: Lived aboard & cruised for 45 years,- now on a chair in my walk-in closet.
Boat: Morgan OI 413 1973 - Aythya
Posts: 7,894
Images: 1
Re: SExtant Newbie?

Quote:
Originally Posted by GrowleyMonster View Post
I would say NO on the plastic sextant for learning. The reason is, the inherent inaccuracy of the plastic instrument ..................
There's a huge amount of wise information in this long post by GrowleyMonster; however, some may not agree with the inherent inaccuracy of plastic. I can not speak with my own knowledge of the effects of the temperature expansion coefficients of the plastic and metal or to the results of these characteristics, but my own use of a plastic Davis sextant placed me regularly within ten miles of my actual position. Some may not consider this as a good record of accuracy, but I think it's a realistic expectation for sextant position fixes.

I think most of us use what we have. I certainly enjoy the accuracy of GPS, but I keep a thought to my running dead reckoning and I write down my known times and positions.
__________________
Take care and joy, Aythya crew
Hudson Force is offline   Reply With Quote
Old 25-01-2013, 10:03   #44
Registered User
 
GrowleyMonster's Avatar

Join Date: Dec 2012
Location: New Orleans
Boat: 1976 Cal 2-27
Posts: 1,298
Re: Sextant Newbie?

Quote:
Originally Posted by jgbrown View Post
Fine, what do you call a sextant with constant cloud cover ?
Surely there must be a funny name for one when what it relies on to function is unavailable, like for gps or guns?

This could be a whole topic... what things are without what they use. An anchor without bottom is a poor fishing lure, an engine with no fuel is a ? a mast without sails is a ?

I like sextants, I am buying and learning to use one when I can, but it just struck me as extremely funny to define other tools by their use without what they require, when a sextant could have a similar issue...
You call it a sextant waiting for clear skies. Meanwhile, you still have your DR. They go hand in hand. Before GPS, before SatNav, before Decca and Loran C and Loran A and Omega, before RDF, there was sextant and DR. And it worked just fine. Sure, you sometimes go several days without a fix due to overcast. But with a careful DR, when you do get a fix, it is usually satisfyingly close to the DR position. Celestial navigation combined with a careful DR is the only realistic backup to electronic navigation. Its limitations are only limitations, not disqualifications. There are "issues" with every facet of sailing and every method we use to accomplish our objectives.
__________________
GrowleyMonster is offline   Reply With Quote
Old 25-01-2013, 10:21   #45
Registered User

Join Date: Apr 2012
Location: Vancouver, BC
Boat: Alberg 30
Posts: 344
Quote:
Originally Posted by GrowleyMonster View Post

You call it a sextant waiting for clear skies. Meanwhile, you still have your DR. They go hand in hand. Before GPS, before SatNav, before Decca and Loran C and Loran A and Omega, before RDF, there was sextant and DR. And it worked just fine. Sure, you sometimes go several days without a fix due to overcast. But with a careful DR, when you do get a fix, it is usually satisfyingly close to the DR position. Celestial navigation combined with a careful DR is the only realistic backup to electronic navigation. Its limitations are only limitations, not disqualifications. There are "issues" with every facet of sailing and every method we use to accomplish our objectives.
Yes I agree. Though you could replace days with weeks around here in the winter ... I simply think is sad that the sextant was left out of the funny list and was poking a bit of fun instead of getting all serious, when it seemed a bit odd to only poke the technologies that are more recent.




Seriously, it seemed to imply the utter reliability of a sextant, at all times which I don't agree with, the limitations of a GPS are simply different.
Both are better than either alone. Few things are infallible. On land I'd have both a lighter, and fire steel, only needed the latter once was good to have then.
__________________

__________________
jgbrown is offline   Reply With Quote
Reply

Tags
sextant

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
C. Plath Hamburg Stubbenhuk 25 - 1929 Sextant Mendozaco Product or Service Reviews & Evaluations 9 27-05-2013 07:22
Poll-Blue water. Is a Sextant Necessary? noelex 77 Navigation 219 25-11-2012 16:28
For Sale: Used Davis Instruments Mark 25 Sextant cran1 Classifieds Archive 0 08-06-2012 14:56
For Sale: Tamaya MS933 Micrometer Sextant livesonjura Classifieds Archive 5 20-01-2012 17:07
For Sale: Astra IIIB Sextant with Many Books and Artificial Horizon - $350usd svmaggieb Classifieds Archive 5 03-11-2011 17:58



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 03:43.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.