Talk:Dead reckoning

I think this article ought to be at Dead reckoning (which redirects here, but has something in the history, so I can't move it myself), which appears to be a far more common spelling for the same thing. However, as I don't know anything about the subject myself, and they might be different things for all I know, I won't do anything about it just yet. --Camembert

Ded reckoning is the older spelling, emphasizing the "deduced". But my Chapman's Seamanship and Bluejacket's Manuals spell the process "dead", so I'll make that change. --GABaker

If this term's etymology is indeed widely believed to come from "ded", short for "deduced", should we add the redirection "Deduced reckoning to this article here? --PutzfetzenORG (talk) 14:57, 21 March 2011 (UTC)Reply

To add to the confusion, Bowditch says:

... The expression dead reckoning probably originated from use of the Dutchman's log, a buoyant object thrown overboard to determine the speed of the vessel relative to the object, which was assumed to be dead in the water. Apparently, the expression deduced reckoning was used when allowance was made for current and wind. It was often shortened to ded reckoning and the similarity of this expression to dead reckoning was undoubtedly the source of the confusion that is still associated with these expressions.

Reference: Pub No. 9: American Practical Navigator, Vol. 1, (1984 edition). by Nathaniel Bowditch. DMA stock no. NVPUB9V1. p. 59. --Dairiki

Thanks, Dairiki. I think we need to put in an explanation of how this came to be. And do we have enough articles on seamanship? ----GABaker

We never have enough articles on anything :-) --Camembert

NP. Perhaps a Seamanship page to tie it all together would be a good thing? --Dairiki

I started a Seamanship shell.------GABaker

There is an article dwelling into multiple sources (more than the dip into dictionaries below) at http://www.straightdope.com/mailbag/mdeadreckoning.html

The phrase dead reckoning dates from Elizabethan times (1605-1615). The speculation, folk etymology, urban legend, sea cook's tale, or whatever you want to call it about "deduced reckoning" does not appear in any reputable dictionary -- Oxford English, Webster's Unabridged, Random House Unabridged, American Heritage, or Noah Webster's American Dictionary of the English Language from 1850, nor does it appear in Brewer's Dictionary of Phrase and Fable, nor in either of the standard etymological dictionaries I have here, Skeate's and Eric Partridge's. Nor does the expression ded reckoning appear in any of these sources. This just isn't so, entertaining though it may be.

Dead reckoning is navigation without stellar observation. With stellar observation, you are "live", working with the stars and the planet. With logs, compasses, clocks, but no sky, you are working "dead". No mystery here. Ortolan88 04:18 Oct 25, 2002 (UTC)

I think it's very likely that "dead" is used to mean "accurate", as in a "dead shot" or "dead right". Dave Gittins.

You also have the misspellings of the time. English orthography wasn't standardized for a while--nor was mine! --GABaker

dictonary.com has:

dead reckoning

n.

A method of estimating the position of an aircraft or a ship without astronomical observations, as by applying to a previously determined position the course and distance traveled since. Predictive calculation based on inference; guesswork.

[Possibly alteration of ded., abbr. of deduced, from deduce, to trace from the beginning. See deduce.]

But note, "possibly" -- Zoe

I will cheerfully put the least of my dictionaries up against dictionary.com any day. The "deduced" is a folk etymology. Ortolan88

The Oxford English Dictionary gives these quotes, dated 1613, 1760, 1840, 1891, 1917, and 1935:

1613 M. RIDLEY Magn. Bodies 147 Keeping a true, not a dead reckoning of his course. 1760 PEMBERTON in Phil. Trans. LI. 911 The latitude exhibited by the dead reckoning of the ship. 1840 R. H. DANA Bef. Mast xxxii. 124 We had drifted too much to allow of our dead reckoning being anywhere near the mark. 1891 Nature 3 Sept., The log, which for the first time enabled the mariner to carry out his dead-reckoning with confidence, is first described in Bourne's ‘Regiment for the Sea’, which was published in 1577. 1917 BOSANQUET & CAMPBELL Navigation for Aerial Navigators i. 4 In aerial navigation..Dead Reckoning is the position arrived at as calculated from the estimated track and the estimated speed made good over the ground. Ibid. 5 These data enable us to find a Dead Reckoning position. 1935 C. G. BURGE Compl. Bk. Aviation 477/1 Dead reckoning..is a compromise between pilotage and navigation.

That dictionary does not give an etymology. Michael Hardy 18:22, 31 Oct 2003 (UTC)

The Swedish term is "död räkning" (dead calculation, dead counting). Note the similarity (and ethymological relationship) between the words räkning and reckoning. I guess "dead" means it is done "in the blind", not from "live" data. --LA2 04:20, 26 January 2006 (UTC)Reply

According to www.garmin.com, the satellite navigator models Garmin StreetPilot 2650, 2660, and 7500 feature "dead reckoning capabilities, so you will continue to get navigation guidance even when GPS signals are obscured. To use this feature, a special dead reckoning cable must be connected to your vehicle's speedometer and backup lights [...]. Once installed, your StreetPilot will acknowledge your turns as well as your distance traveled when GPS reception is unavailable." Can anyone explain how it can detect turns by only sensing the speedometer? Doesn't that require a gyro or something? Can the built-in harddisk function as a gyro? --LA2 04:13, 26 January 2006 (UTC)Reply

The earliest known reference, available from many ships' logs from the early 1700s, is that "dead reckoning" began as "deduced reckoning," which was recorded in the ships' logs as "ded. reckoning." It wasn't pronounced as "dude" reckoning, but as "dead" reckoning. Over time, it began to be spelled as "dead reckoning" rather than "ded. reckoning." However, the American Practical Navigator's reference to the floating object thrown into the water as being "dead" in the water holds merit, and is perhaps just as responsible for the term as is the abbreviation for the word "deduced." - Mugs 14:42, 7 January 2007 (UTC)Reply

Your 1700s claim directly contradicts the very first note on this above. Do you have a reliable reference for this? I spent some time a few years ago trying to get to the bottom of this one and the explanation using "deduced" is uniformly assumed to be bogus by anyone that has looked further than a few old wive's tales. Something I wrote after investigating was:

Examination of old texts has shown it comes from the use of the word "dead" to mean completely or absolutely as in "dead ahead" or the modern "dead on."

It seems perfectly reasonable to assume that is the origin of the term. Michael Daly 06:00, 1 September 2007 (UTC)Reply

I agree with the above, that "dead reckoning" is more likely to be related to "dead aim" "dead ahead" etc, but it seems this was never really resolved because nearly two years later the article still uses the weaker theories. Anyone got a reference that has something beyond speculation? 152.91.9.219 (talk) 07:06, 6 April 2009 (UTC)Reply

I'm undertaking many edits to replace the rather stilted language with more modern terminology. Please bear with me until I'm fished. Shouldn't take more than two hours. - Mugs 13:43, 7 January 2007 (UTC)Reply

I'm just visiting here to note whether you'all have finalised your squabbles re "ded." reckoning?

Is clear that very few of youse have ever taken the trouble to research ships log-books of the period prior to a universal acceptance of the chronometer, which, in it's turn is, generally, only useful when landmarks are not visible.

The master of a vessel is so appointed because he/she [ or the OoW ] takes continual mental note of the behaviour of the craft and when it is time to mark-up/make-up the "logs" [ "rough" log or notebook on a watch-by-watch basis and the formal log on a daily basis - this formal log logically showing, of course, only the previous days activities ] the position verification is indcated as "deduced" [ abbreviated as "ded." ] in the absence of aforesaid landmarks. [ Kindly don't start a legend about the origins of OoW - if you don't know - ask!]

Sailors, generally not being educated, would overhear their betters discussing or boasting about the accuracy of their landfall and hearing only the abbreviation "ded." would write it as "dead". The term used by the ships masters would be "I used dead reckoning to cross the XXXX sea/ocean. Nothing at all to do with "dead-ahead" or "dead straight"!

Kindly look-up "deduced" in the Oxford [or I suspect, any other halfway decent dictionary]. I have done this, as confirmation, using my copy of the 1983 "Concise" edition to verify! If I lift myself away from this keyboard I have another 18 dictionaries at my disposal, which, of course I don't need!

Or, for those of you in the position to take a stroll to Lloyds HQ where some the ancient nautical history is stored and persuade one of the archivists for a sight of 20 or 30 of these rough logs to come to a sensible conclusion.

It always amuses me that persons pontificate and wax wroth when their pet theories/peeves are challenged and when all the needful information is exchanged it becomes obvious that the proper research has not happened!

Sadly, of course, many persons depend on this site for factual information and oft betimes are badly misled. This damages the reputation of this site and will, in the course of time, become the primary reason for it's eventual failure.

And to ol' Mugaliens|- Mugs - I'm still waiting to hear whether you are successfully "fished"? Cheers, Semperlibre (talk) 12:28, 12 October 2010 (UTC)Reply

Dead Reckoning is a mathematical process based upon scientifically measured inputs. Animals don't do math! "Path Integration" needs it's own topic space, not a disambiguation redirect to a process only humans perform. - Mugs 14:33, 7 January 2007 (UTC)Reply

I think this is more of a philosophical point than a problem in terminology. The net result of the animals actions is the implementation of a mathematical algorithm, whether or not the animals are consiously aware of it. AfD hero (talk) 01:41, 22 May 2008 (UTC)Reply

Perhaps this article needs to have aviation and marine sections. I am not familiar with a DR at every 300 miles and combined turns etc, it must refer to aviation? Also as far as I know the term velocity is not commonly used in marine navigation, in physics velocity refers to both speed and direction. Generally in marine navigation a DR does not include set and drift, I don't know what the practice is in aviation, in marine usage a DR corrected for set and drift is called an estimated position (EP), KAM 01:36, 27 March 2007 (UTC)Reply

According to FAA, wind information contributes to calculation. http://www.faa.gov/airports_airtraffic/air_traffic/publications/atpubs/pcg/D.HTM "DEAD RECKONING- Dead reckoning, as applied to flying, is the navigation of an airplane solely by means of computations based on airspeed, course, heading, wind direction, and speed, groundspeed, and elapsed time. --Natasha2006 16:15, 3 May 2007 (UTC)Reply

I notice that a large portion of the "Animal navigation" in this article was added by the anonymous IP User:81.178.46.51 in this change [1] This edits appear to copied from somewhere else, completed with square-bracketed numbers, likely from references. Could anyone deduce where the text came from? Flibirigit (talk) 06:42, 25 March 2008 (UTC)Reply

I believe its directly from the Homing pigeon article. I feel some of it should be trimmed drown, and or referred to that article. Flibirigit (talk) 06:43, 25 March 2008 (UTC)Reply

On the etymology of dead reckoning, Heinlein's humorous input might be worth a mention. In Time Enough For Love, I believe he said "dead reckoning," in the context of landing a fighter plane on a carrier just by sight, was called so because if you did it wrong, you were dead. 74.10.227.130 (talk) 21:32, 16 December 2008 (UTC)Reply

I work with other historians on the origine of medieval portolan charts. The question how accurate dead reckoning (DR) navigation by sails could be is of overwhelming importance there. We could not find much historic date because most nautic historians supposed DR had the accuracy of the portolan charts from the same time. But that is in doubt.

I created a page with the DR data I found so far. If you have data or sources, please send it there or to its discussion page. Besides historians, it may be of interest to present sail navigators too. -- Portolanero (talk) 15:36, 9 May 2010 (UTC)Reply

Some information on the history of dead reckoning usage would be really nice, and seems to be completely lacking at present.72.33.212.238 (talk) 13:35, 1 April 2013 (UTC)Reply

The caption and content of first image (showing a triangle and two dots, filename Dead-reckining.svg[sic]) seems to contradict that of the second, which describes the triangle as indicating a Dead Reckoning position ("Wind drift.png") and not the origin and tack, as in the first image.

I mean...watch, pen and paper presented as dead reckoning tools (in two pictures) is serious? — Preceding unsigned comment added by Ramas rtl (talk • contribs) 08:56, 15 November 2013 (UTC)Reply

This is my first time to visit this page, but yea, those pretty much are the tools of dead reckoning (plus straight edge and perhaps a protractor). --Unicorn Tapestry ^{say} 12:45, 3 January 2014 (UTC)Reply

The order of topics seem to be sprinkled in rather than planned. That is, the first section is 'Errors', which describes the down side of dead reckoning rather than what dead reckoning aims to accomplish. In a way, it tells what dead reckoning isn't rather than what it is.

At the same time, I recognize it shouldn't be dropped near the end of the article because its message is too important. I believe it needs a section prior to Errors, perhaps stolen from the introduction. A couple of the topics near the end should probably come under the heading Mechanical Devices.

Thoughts? --Unicorn Tapestry ^{say} 12:41, 3 January 2014 (UTC)Reply

this (and other content) should be in another topic but ok as a Link

also Dead reckoning for networked games is WRONG. it does not say the equations are physics equations

many games do not use physics motion equations fully or correctly because it's only a game, and modernly collision equations are used, and really the 3D and OS aspects, and cash for team to create and access to previosu works, and "level editor" aspects are more important.

MORESO video games can store "player position" it does not need to be dead recon AT ALL

Where else would you place this prediction of positions after movement? I don't see a better place. ----~~

that acutually uses advanced dr technique and can be used by sailors (or who else) when a transeiver tower(s) is close by

Also does not have any references. — Preceding unsigned comment added by 134.223.230.154 (talk) 22:52, 1 October 2014 (UTC)Reply

The theory that "dead reckoning" comes from "deduced reckoning" is wrong. It is not supported by professional etymological research, and it supposedly originated in a letter to the editor of the newspaper The Morning Post in the 1920s. Former versions of this page a few years ago stated this clearly enough. The current version of this page repeats the false etymology without comment or qualification in the opening line (using the strange structure of a parenthetical phrase within a parenthetical phrase (like this)). This should be repaired. 2600:1000:B02F:75EC:B127:6416:2794:E83F (talk) 17:06, 31 October 2014 (UTC)Reply

Why "dead" reckoning? Some information about the origin of the phrase would be a useful addition to the introductory paragraph. — Preceding unsigned comment added by 74.95.43.249 (talk) 21:44, 17 October 2016 (UTC)Reply

And how does the currently presented etymology make sense?

An "dead in the water" object is not moving; but the reason to have a separate term is that dead reckoning does assume and predict a moving object. 87.234.239.98 (talk) 12:48, 23 March 2024 (UTC)Reply

This section is full of jargon and I'm not even sure what the context is after reading it a few times. Suggest a rewrite by someone familiar with the topic.Dlthewave (talk) 22:18, 26 March 2017 (UTC)Reply

@Dlthewave i am also unsure if this is written by someone with english as a native language, which makes it hard to understand on top of the jargon. 46.15.58.191 (talk) 21:13, 17 February 2023 (UTC)Reply

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