|
|
21-04-2015, 17:53
|
#61
|
Registered User
Join Date: Apr 2013
Location: So Cal
Boat: Catalina 387
Posts: 967
|
Re: Help with (fictional) celestial navigation
Quote:
Originally Posted by jheldatksuedu
using the earth's moon for navigation on mars would be ridiculous,....
|
Yup. It'd be called "Earth" and be an oblong dot. We don't see mars as a disc from here.
Using either of Mars's moons would be tough too, as they whizz around the planet licketly split.
I like the concept alot. The fact that celestial has been out of favor for hundreds of years and the kids figure it out is neat. Quite Heinleinesque.
|
|
|
21-04-2015, 18:01
|
#62
|
Registered User
Join Date: Nov 2014
Posts: 1,778
|
Re: Help with (fictional) celestial navigation
I think I agree with Wotname and The Penguin. I have a vague memory in school of learning the exact lesson Wotname described regarding deduced reckoning.
Like my Astro, my chartwork terminology and labeling has been poorly exercised for many years.
I can dock the heck out of a ship though, that knowledge is doing just fine.
Sent from my SGH-I547C using Cruisers Sailing Forum mobile app
|
|
|
21-04-2015, 21:02
|
#63
|
Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
|
Re: Help with (fictional) celestial navigation
Quote:
Originally Posted by El Pinguino
|
And of course if you found it on the internet then it must be correct. After the internet always has correct information.
I confess I was always in the camp that believes the term derived from deduced and over time the abbreviation ded became dead.
But then when I did a google search I find this article. The Straight Dope: Is "dead reckoning" short for "deduced reckoning"? It documents the spelling "dead" back to 1708. Of all the dictionaries I checked that gave an etymology, the American Heritage Dictionary is most amenable to the "deduced" theory, saying "Possibly alteration of ded. abbr. of deduced." "Possibly" is the kindest treatment this theory is given in any dictionary I could find. The Encarta World English Dictionary says "probably from dead 'absolute' or 'exact,' although 'dead' may be by folk etymology from ded., a shortening of deduce or deduction." The Dictionary of Misinformation says of the "deduced" theory, "There is no evidence for such a belief." The Oxford English Dictionary says that the term is from the adjective "dead" and doesn't deign to even discuss the supposed derivation from "deduced". The Oxford Dictionary of English Etymology provides the final nail in the coffin: "a proposed etym. ded., for deduced, has no justification."
These sources agree on the derivation from the adjective "dead" but differ on what "dead" is supposed to mean in this context. One theory, supported by the OED, is that it's dead in the sense "complete(ly)" or "absolute(ly)," also found in "dead wrong," "dead ahead," "dead last," etc. The idea seems to be that the dead-reckoning position is one based completely on reckoning (calculation) and not at all on observation of landmarks. Others hold that "dead" means "unmoving," as in "dead in the water." The idea here is that dead reckoning is calculated with respect to an object (like the log) that is dead in the water (not moving with respect to the surface of the water). Yet another theory is that it comes from "dead seas" (supposed to mean "unknown seas"), where dead reckoning would be an important tool.
In the earliest dictionary entry I could find for the term (1708, Dictionarium Anglo-Britannicum), it is spelled "Dead-reckoning" (with the hyphen, but without any mention of "deduced"). It seems that the "dead" spelling is older than "ded." by more than three centuries.
And then there is this book from 1867, a very interesting read for many reasons. For one how some nautical terminology has changed and some has not. Since the Brits do seem to be sticklers for details and "proper" English I would put some credence to their spelling of the term as dead reckoning. Front page and xcerpts copied below.
http://www.gutenberg.org/files/26000...-h/26000-h.htm
THE
SAILOR'S WORD-BOOK:
AN ALPHABETICAL DIGEST
OF
NAUTICAL TERMS,
INCLUDING SOME MORE ESPECIALLY MILITARY AND SCIENTIFIC, BUT USEFUL TO SEAMEN;
AS WELL AS ARCHAISMS OF EARLY VOYAGERS, ETC.
BY THE LATE
ADMIRAL W. H. SMYTH,
K.S.F., D.C.L., &c.
REVISED FOR THE PRESS BY
VICE-ADMIRAL SIR E. BELCHER,
K.C.B., &c. &c.
LONDON:
BLACKIE AND SON, PATERNOSTER ROW;
AND GLASGOW AND EDINBURGH.
1867.
DEAD-RECKONING. The estimation of the ship's place without any observation of the heavenly bodies; it is discovered from the distance she has run by the log, and the courses steered by the compass, then rectifying these data by the usual allowance for current, lee-way, &c., according to the ship's known trim. This reckoning, however, should be corrected by astronomical observations of the sun, moon, and stars, whenever available, proving the importance of practical astronomy.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
|
|
|
21-04-2015, 21:58
|
#64
|
Registered User
Join Date: Aug 2013
Location: Back in Montt.
Boat: Westerly Sealord
Posts: 8,180
|
Re: Help with (fictional) celestial navigation
Having found it on the internet is just as good as having found it in a book shop.. most of the non sense on the 'net has come from books......
|
|
|
21-04-2015, 22:04
|
#65
|
Registered User
Join Date: Jun 2014
Location: San Diego, CA
Boat: Beneteau Oceanis 51.1
Posts: 584
|
Re: Help with (fictional) celestial navigation
If you just need your protagonist to be in the wrong place, the simplest explanation is that he's doing the celestial navigation correctly, but his time is wrong. This would produce a consistent error east or west every time even when doing everything correctly.
He can discover the time problem by referencing a better time, or by sighting against a landmark with a known position on the chart.
|
|
|
21-04-2015, 23:59
|
#66
|
֍֎֍֎֍֎֍֎֍֎
Join Date: Apr 2006
Posts: 15,136
|
Re: Help with (fictional) celestial navigation
Mars...yes, but wouldn't they need an almanac and tables developed for Mars rather than Earth? And the odds are, none will be developed for Mars because the technology is already so out of use. Even if their stolen rover somehow was equipped with a sextant, or even if they kludged one together with more accuracy than, say, the type of instruments Columbus used to take a basic height of the sun.
I'd have to take a double dose of "willing suspension of disbelief" to think that 100 years from now, navigation satellites would still be relied upon, yet unable to withstand solar flares. But I'm a hard audience.(G)
|
|
|
22-04-2015, 09:47
|
#67
|
Marine Service Provider
Join Date: May 2011
Location: Cruising Mexico Currently
Boat: Gulfstar 50
Posts: 1,979
|
Re: Help with (fictional) celestial navigation
dead vs ded
My copy (1976) of Oxfords Companion to Ships and the Sea gives the correct spelling as "Dead Reckoning".
It notes that the usage of "dead" goes back at least 400 years (cira 15XX). It noted that there were some who promoted "ded" as the original spelling as shorthand for deduced but found this to be unlikely as that deduced was not commonly used in the English language at that time. And especially not used in navigation at that time.
Further it states that sailors of the time referred to uncharted waters as 'dead" waters and that it was likely that during times where due to overcast etc the sun and other references were not visible (the times that dead reckoning was used) sailors would sail into "dead" waters as well. Thus Dead reckoning.
regards
|
|
|
22-04-2015, 10:09
|
#68
|
Registered User
Join Date: Mar 2013
Location: Homosassa
Boat: Purchase pending
Posts: 52
|
Re: Help with (fictional) celestial navigation
"dead" water probably correct as source. Never saw "ded (deduced) reckoning" since first sailing intro at age 5 (1936). Father was USNA, surely would have known correct term. In fact, since then this is the first mention of ded I have ever seen.
__________________
Hon. G. T. "BadBud" Martin, PhD. (Ret. O4 USN/USAF)
Scholar/Ediot/Publisher - Master Navigator DREAMER II.
KV4FR
|
|
|
22-04-2015, 13:05
|
#69
|
Registered User
Join Date: Aug 2013
Location: Back in Montt.
Boat: Westerly Sealord
Posts: 8,180
|
Re: Help with (fictional) celestial navigation
Given the levels of literacy 400 years ago 'dead' was probably how the scholars of Oxford or where-ever decided it should be spelt. In use by common sailor-men it was probably spoken as 'ded' or in certain parts.... 'dud' .... or maybe even 'deed'.
Getting back to Mars.... there will be no point in knowing where you are unless you have a chart showing where everything else , or at least where your destination is....
Likewise on earth.... no point in knowing where you are to three decimal places . Try giving some bloke in the Simpson Desert his lat / long and telling him to find his was home without a map.
|
|
|
22-04-2015, 13:20
|
#70
|
Marine Service Provider
Join Date: May 2011
Location: Cruising Mexico Currently
Boat: Gulfstar 50
Posts: 1,979
|
Re: Help with (fictional) celestial navigation
Quote:
Originally Posted by El Pinguino
Given the levels of literacy 400 years ago 'dead' was probably how the scholars of Oxford or where-ever decided it should be spelt. In use by common sailor-men it was probably spoken as 'ded' or in certain parts.... 'dud' .... or maybe even 'deed'.
Getting back to Mars.... there will be no point in knowing where you are unless you have a chart showing where everything else , or at least where your destination is....
Likewise on earth.... no point in knowing where you are to three decimal places . Try giving some bloke in the Simpson Desert his lat / long and telling him to find his was home without a map.
|
The chart is on their smart-phone of the age. Also a star chart and camera that can map their position....
|
|
|
22-04-2015, 13:49
|
#71
|
Moderator Emeritus
Join Date: Sep 2007
Location: Eastern Tennessee
Boat: Research vessel for a university, retired now.
Posts: 10,406
|
Re: Help with (fictional) celestial navigation
You want to shoot as many stars as you can get. The more LOP's you get the better. Why?...because it gets you a more accurate average. You weight the lines that you think are the most accurate and throw out or weight less heavily the lines that you believe are less accurate. This is one of those situations where navigation becomes more of an art than a science. You base your position on an estimate of what in your experience is most likely to be closest to your actual position at that time.
Two LOP's does not mean that you were where they intersect....it's most likely a worse fix than if you had shot five stars.
__________________
David
Life begins where land ends.
|
|
|
22-04-2015, 13:50
|
#72
|
Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
|
Re: Help with (fictional) celestial navigation
Quote:
Originally Posted by El Pinguino
Given the levels of literacy 400 years ago 'dead' was probably how the scholars of Oxford or where-ever decided it should be spelt. In use by common sailor-men it was probably spoken as 'ded' or in certain parts.... 'dud' .... or maybe even 'deed'.
|
Pronunciation certainly was odd compared to the written word in them olden days. Gunul for gunwale, foc'sl for forecastle, woostersheer for Worchestershire. People sure did talk funny.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
|
|
|
23-04-2015, 13:11
|
#73
|
Registered User
Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 9,704
|
Re: Help with (fictional) celestial navigation
Quote:
Originally Posted by budm303
"dead" water probably correct as source. Never saw "ded (deduced) reckoning" since first sailing intro at age 5 (1936). Father was USNA, surely would have known correct term. In fact, since then this is the first mention of ded I have ever seen.
|
Doesn't Chapmans &/or Duttons mention "ded" from "deduced?"
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, SR/FK, M25, Rocna 10 (22#) (NZ model)
|
|
|
23-04-2015, 13:29
|
#74
|
Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
|
Re: Help with (fictional) celestial navigation
Quote:
Originally Posted by Stu Jackson
Doesn't Chapmans &/or Duttons mention "ded" from "deduced?"
|
Looked in my most recent edition of Chapman and saw no mention deduced in the chapter on dead reckoning.
Don't have a copy of Duttons at the house. Checked The Mariner's Dictionary by Bradford and no mention there either.
I still think that the fact that the 1867 British book The Sailor's Work Book doesn't mention deduced a significant bit of evidence against.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
|
|
|
23-04-2015, 13:40
|
#75
|
Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
|
Re: Help with (fictional) celestial navigation
Quote:
Originally Posted by budm303
"dead" water probably correct as source. Never saw "ded (deduced) reckoning" since first sailing intro at age 5 (1936). Father was USNA, surely would have known correct term. In fact, since then this is the first mention of ded I have ever seen.
|
I can think of a number of sailing terms that also use dead.
Dead ahead or astern
Dead slow
Dead light
Deadeye
Deadrise
Surely at least some of these derive from some common use of the word dead.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
|
|
|
|
|
Thread Tools |
Search this Thread |
|
|
Display Modes |
Rate This Thread |
Linear Mode
|
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
Advertise Here
Recent Discussions |
|
|
|
|
|
|
|
|
|
|
|
|
Vendor Spotlight |
|
|
|
|