Dead Reckoning

Huh… the meaning of Dead Reckoning seems obvious to me.

In all the other forms of determining one’s position, current information (the position of the stars, sightings of landmarks, etc.) are used: hence, “live” reckoning. When there are no landmarks, no stars… there is nothing in the present that will help, only the past from which to determine one’s location; hence, “dead reckoning.”

Of course, I could be dead wrong.

I have to admit that when I first encountered the term, I thought that “dead reckoning” must be derived from “deduced reckoning”. I’ll bet that the WWII flyboys felt the same way – regardless of the “real” origin (which seems vague enough in your piece), the people who use the term know where they think it comes from, and how they interpret it. This has, I think, a certain validity to it – the term might have gobe the way of a great many other terms and become obsolete, replaced by some other, newer term, if it were not for the fact that all of these modfern navigators had continued to use the term, reassured by the belief that it stood for “deduced” reckoning.

I’m not trying to use sophistry here – language is a living thing, influenced by many factors, and I think it would be wrong for someone to come along and say that “dead” reckoning only comes from “dead in the water” reckoning or something like that – the term has been kept alive and in use by people who really think it comes from “deduced” reckoning.

To give another example, in Tom Burnham’s wonderful Dictionary of Misinformation he talks of how “belfry” (as in “bats in your ____”) derives from an original form “berfry”. So, say some people, it has nothing to do with the “bell” that’s kept in the belfry at all. But, of course, it does. Generations of people have continued to use the “incorrect” term “Belfry” rather than “berfry” (or instead of inventing another term, like “bell tower”) precisely because they thought it had something to do with “bell”.

From the article:

“If “dead” is good enough for Lindbergh, it’s good
enough for me.”

Is this an intentional reference to the Herbert Hoover campaign song “If He’s Good Enough for Lindy, He’s Good Enough for Me?”

Nice report Bibliophage.

This is the first I’ve heard the theory that “dead reckoning” is a mutation of “deduced reckoning”. I guess that shouldn’t be surprising since I am neither a sailor nor an aviator. (My closest experience would be when I was in high school and coming home far too late thinking “I reckon I’m dead.”)

Back to the subject at hand. I always understood “dead” to mean “direct”, similar to the meaning of “absolute” as mentioned in the report. Dead ahead is directly ahead. Dead reckoning is directly from the information one has available.

Hey, if you want to get lost in a library, you should definitely go to the University of Illinois Champaign-Urbana. They have an underground library composed of two parts of several floors each. The floors from the two parts do not match up, and are only connected at a couple of floors. The exit is only reachable from one particular floor from one particular part. If you are in the other part you have to do something crazy like go to floor 4 where you can get to floor 2 of the other part, so you can go to floor 3 where the exit is.

Bring food, because you may be in there a loooong time.



Have only English-language references been considered? It seems to me that if the term DEAD means “fixed; not moving” or “absolutely” that it’s equivalent in French, German, Japanese, or Arabic ought to be something that means that in the language. And not something that sounds like an abbreviation of whatever they use for “deduced”. N’cest pas?:rolleyes:

Dead on? Absolute… as said above.? No variables because of no manner of determination? Last chance to figure it out before you are ‘dead’? he he he

Pilot and sailor and use it all the time and know what I am doing when doing it and don’t really care except to prevent me from reaching the ‘dead’ part. LOL YMMV

Welcome to the boards Marnie’s Dad.

I think you have an interesting idea for further inquiry. Does the term have an equivalent in other languages? Given its usage back into the 1600s, one would think so.

So let’s hear from all you Portugeuse navigators out there, locating yourself in the middle of a featureless blue sea; all you nomad camel herdsmen steering through days of shifting sand dunes; all you Vikings. We English-speakers use dead-reckoning to do this… what you YOU call it?

I always liked Heinlein’s derivation of the term in Time Enough for Love: it’s called “dead reckoning” because if a pilot doesn’t reckon correctly, he’s dead :smiley:

The Dutch call it ‘gegist bestek’; I can’t tell what this means – bestek is “reckoning,” more or less, but unless “gegist” is related to “gig,” it’s impenetrable to me. In Norwegian it is ‘bestikkseilas’. French ‘estime’, “estimate”; German ‘Logrechnung’, reckoning by speed/log, or ‘Gissung’ “guessing/reckoning.”

Dead reckoning position: French ‘point estimé’, German ‘Gegisstes Besteck’, ‘Gegisstes Schiffsort’.

It sure is beginning to look a lot like “deductive” to me…

Cal I can’t see how your example of belfry/berfry is in any way similar. While the origin of “belfry” is certainly “berefrei” or “berfrei”, these examples are related to before 1300 English. You’re dealing with many different languages coming together at that point. Not the case with the 1600’s and later English.

As bib shows, there was a phrase dead reckoning in print in English from 1613. The exact phrase was “Keeping a true, not a dead reckoning of his course.”

If you think the author of that phrase in 1613 was merely using a mondegreen for deduced, then show me where someone used the phrase/word deduced* of even an abbreviated form(i.e. ded.) prior to that in regards to navigation, etc.

As far as people keeping alive the term deduced reckoning, one searches in vain for anyone keeping it alive until it seems to appear magically in WWII. Is a scan from the Century Dictionary, which was published in 1914 or so. is great for this kind of stuff

At least it’s not as dangerous as Unseen University.


Not to me. It looks to me like most of the evidence points the other way.


I was thinking of “dead” as in “straight on” or “absolutely”. The non-English phrases all seem to indicate “calculating” or “estimating”, which is why I saw a relationship to “deductive”. That’s what I had been looking to the foreign languages to distinguish. I was being fascitious in my original post, as I really didn’t expect there would be any support at all for the “ded.” abbreviation theory once one moved beyond the only language in which the two words would be likely to share a similar sound.

I did look up the translation of ‘dead reckoning’ in several languages, but didn’t find anything conclusive enough to include it in the report.

davanden, I don’t remember hearing about the Hoover campaign song before, but it might have come from the back of my brain somewhere.

Karen, that library sounds a lot like Baker-Berry Library at Dartmouth. I barely managed to keep my bearings at that one.

[quote=“CalMeacham, post:2, topic:137907”]

I have to admit that when I first encountered the term, I thought that “dead reckoning” must be derived from “deduced reckoning”.

From American Heritage dictionary:

dead reckoning n. 1. Abbr. DR 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. 2. Predictive calculation based on inference; guesswork. [Possibly alteration of ded., abbr. of deduced, from deduce, to trace from the beginning. See DEDUCE.]

Welcome to the Straight Dope Message Boards, BrianR and robcaro, we’re glad to have you with us.

This forum is devoted to comments on Staff Reports. The OP, you will note, provides a link to the Report under discussion. The comments that both of you made are well covered in that report. Please, in future, READ the reference material that is being remarked on. It’s pretty much a waste of your time and ours when you just restate something that’s already in the source material.