Today
Ships and boats commonly use electronic aids to navigation, mostly the Global Navigation Satellite Systems. However celestial navigation, which requires the use of a precise chronometer, is still a requirement for certain international mariner certifications such as Officer in Charge of Navigational Watch, and Master and Chief Mate deck officers, and supplements offshore yachtmasters on long-distance private cruising yachts. Modern marine chronometers can be based on quartz clocks that are corrected periodically by GPS signals or radio time signals (see radio clock). These quartz chronometers are not always the most accurate quartz clocks when no signal is received, and their signals can be lost or blocked. However, there are quartz movements, even in wrist watches, that are accurate to within 5 or 20 seconds per year. At least one quartz chronometer made for advanced navigation utilizes multiple quartz crystals which are corrected by a computer using an average value, in addition to GPS time signal corrections.
Read more about this topic: Marine Chronometer
Famous quotes containing the word today:
“Indeed, the best books have a use, like sticks and stones, which is above or beside their design, not anticipated in the preface, not concluded in the appendix. Even Virgil’s poetry serves a very different use to me today from what it did to his contemporaries. It has often an acquired and accidental value merely, proving that man is still man in the world.”
—Henry David Thoreau (1817–1862)
“The great majority of people in England and America are modest, decent and pure-minded and the amount of virgins in the world today is stupendous.”
—Barbara Cartland (b. 1901)
“I became the Incredible Shrinking Mother the year they started junior high. If our relationship today depended on physical clout, I would have about the same influence with them that the republic of Liechtenstein has on world politics.”
—Mary Kay Blakely (20th century)