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:
“Chamberlain’s visit to Hitler today may bring things to a head or may result in a temporary postponement of what looks to me like an inevitable conflict within the next five years.”
—Franklin D. Roosevelt (1882–1945)
“If Shakespeare were alive today and writing comedy for the movies, he would be the head-liner for the Mack Sennett studios.”
—Robert Benchley (1889–1945)
“In times past there were rituals of passage that conducted a boy into manhood, where other men passed along the wisdom and responsibilities that needed to be shared. But today we have no rituals. We are not conducted into manhood; we simply find ourselves there.”
—Kent Nerburn (20th century)