We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.
Aviation

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

What is Dead Reckoning?

Mary McMahon
By
Updated: May 23, 2024
Views: 10,390
Share

Dead reckoning is a navigational technique dependent on using a known position and extrapolating a new position from that one by considering the speed and direction of travel. This technique was historically used by sailors and aviators, and is less commonly used today, although some navigational systems still rely on dead reckoning to some extent. The technique has a number of drawbacks, some of which can prove quite serious when there is a narrow margin for error.

In dead reckoning, the navigator starts with a known positional fix, taken with observations and other tools. This fix is noted on a chart with an indicator showing it is a firm positional fix, not an extrapolation. The next time the navigator wants to estimate position, the amount of time elapsed is considered alongside the recorded speed of travel and the course. Dead reckoning can also include adjustments for currents and winds, as these factors may take a vessel off course. A new position is entered on the chart to reflect the outcome of the calculations.

One serious problem with dead reckoning is the risk of cumulative errors. Recording positional information relative to previous positions, rather than with the use of new data, runs the risk of compounding an error. Even if the initial positional fix was correct, subsequent positions may be erroneous, and can grow worse over time. Imagine, for example, if a navigator gets the course off by three degrees, causing the position to deviate more and more by the day.

Mistakes using this navigational technique can create substantial problems. People may enter dangerous waters with shoals and icebergs without being aware of it, or they could drift into territorial waters where they are not welcome. Dead reckoning can also delay and hinder journeys considerably if people end up far from their originally planned destination. On aircraft, using this system at night or in bad weather can put people at risk of an accident, as they may drift out of their planned flight path and not be aware of it.

Some navigators joke that the derivation of this phrase comes from “dead wrong,” referencing the unreliability of this technique. Others suggest it is a derivative of “deduced reckoning,” arguing that historical records sometimes refer to it as “ded. reckoning.” Research into the origins of the phrase does not support either of these claims, although the term itself dates to at least the 1600s, when it began to be used by English navigators.

Share
WikiMotors is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a WikiMotors researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Discussion Comments
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

Learn more
Share
https://www.wikimotors.org/what-is-dead-reckoning.htm
Copy this link
WikiMotors, in your inbox

Our latest articles, guides, and more, delivered daily.

WikiMotors, in your inbox

Our latest articles, guides, and more, delivered daily.