What is a Chronometer?
Chronometer watches are highly accurate timepieces that have undergone a series of strict precision tests over a period of time in a host of different circumstances.
Chronometer watches are highly accurate timepieces that have undergone a series of strict precision tests over a period of time in a host of different circumstances. Historically, they were used by sailors for their extraordinary accuracy. This accuracy aided the measurement of longitude when at sea, becoming the standard for most ships from the 1730s to the invention of radiotelegraphy time signals. Today, watches must be certified as chronometer watches by certain testing facilities. Due to the nature of these precision tests, chronometer watches are an incredibly rare type of watch.
What makes a Chronometer different to a normal watch?
The strengths of a chronometer watch lie in its accuracy, which is ensured through rigorous testing by groups such as the Contrôle officiel suisse des Chronomètres. This accuracy, although rarely used in modern sailing, remains a testament to engineering precision in watchmaking.
This incredibly high level of accuracy is the main benefit of chronometer watches. Moreover, these watches require intricate craftsmanship and engineering. The inner mechanics make chronometer watches very attractive and collectible timepieces. The combination of high accuracy, rarity and ingenuous craftsmanship means the value of chronometer watches will appreciate over time.
A History to Chronometer Watches
Due to temperature changes and the motion of ships, ordinary clocks were of no use in navigation in the 18th century. After a series of disasters at sea caused by poor navigation, the British government created the Board of Longitude. The aim was to seek an inventor to develop a chronometer that could calculate longitude within half a degree at the end of a voyage.
The first marine chronometer was invented in 1735 by English horologist and self-taught carpenter, John Harrison. His following chronometers were smaller and more accurate than their predecessor, all meeting the standards set up by the Board of Longitude.
Modern chronometers are based on Harrison’s successful invention and are accurate to within 0.5 seconds per day.
Chronometer Testing
Watches are only awarded chronometer certification if they pass a series of intense precision tests. The watches are tested for 15 days in 5 different positions and multiple circumstances, such as, extreme temperature, humidity and pressure. For more detail about how watches are certified to be chronometer, read our article on chronometer certification.
The positions the watches are placed in are 3 o’clock, 6 o’clock, 9 o’clock, dial up and dial down. Each watch remains in each position and given temperature, pressure or humidity level for 24 hours. The watches are measured daily and compared with two atomic independent clocks.
The precision criteria chronometer watches must be within –4 and +6 seconds of variation per day.
These tests don’t just measure a chronometer watch’s accuracy but also its durability.
How accurate is a Chronometer?
Chronometer watches are engineered to measure time to the highest standard of accuracy. They are tested to ensure they have very little second variance per day, usually within -4 and +6 seconds. This is verified through a period of 15 days of vigorous testing. They can also determine longitude at sea.
Chronometer vs Chronograph: what is the difference?
Chronometers and chronographs are often thought to be the same, however, they are very different in their functions and purpose. A chronometer watch is engineered to be extremely accurate, whether it is mechanical, electronic, or quartz. A chronograph is a traditional watch with a stopwatch function, allowing the wearer to time sports-related activities. Chronograph watches can also measure speed and distance.