Editing Sailing ship (section)

=== Navigation ===
[[File:Marine sextant.svg|thumb|The marine [[sextant]] is used to measure the elevation of celestial bodies above the horizon.]]

Early navigational techniques employed observations of the sun, stars, waves and birdlife. In the 15th century, the Chinese were using the magnetic compass to identify direction of travel. By the 16th century in Europe, navigational instruments included the [[Quadrant (instrument)|quadrant]], the [[astrolabe]], [[Jacob's staff|cross staff]], [[Calipers|dividers]] and compass. By the time of the Age of Exploration these tools were being used in combination with a [[Chip log|log]] to measure speed, a lead line to measure [[Depth sounding|soundings]], and a lookout to identify potential hazards. Later, an accurate [[Sextant|marine sextant]] became standard for determining [[latitude]] and was used with an accurate [[Chronometer watch|chronometer]] to calculate [[longitude]].<ref name = gettingthere>{{Cite book|url=https://books.google.com/books?id=xyGkCQAAQBAJ|title=Time and Navigation: The Untold Story of Getting from Here to There|last1=Johnston|first1=Andrew K.|last2=Connor|first2=Roger D.|last3=Stephens|first3=Carlene E.|last4=Ceruzzi|first4=Paul E.|date=2015-06-02|publisher=Smithsonian Institution|isbn=9781588344922|language=en|access-date=2019-06-24|archive-date=2023-10-27|archive-url=https://web.archive.org/web/20231027233637/https://books.google.com/books?id=xyGkCQAAQBAJ|url-status=live}}</ref><ref>{{cite EB1911|wstitle= Sextant | volume= 24 | pages = 765&ndash;767 }}</ref>

[[Passage planning]] begins with laying out a route along a chart, which comprises a series of courses between fixes—verifiable locations that confirm the actual track of the ship on the ocean. Once a course has been set, the person at the helm attempts to follow its direction with reference to the compass. The navigator notes the time and speed at each fix to estimate the arrival at the next fix, a process called [[dead reckoning]]. For coast-wise navigation, sightings from known landmarks or [[navigational aid]]s may be used to establish fixes, a process called [[Piloting|pilotage]].<ref name="Couch" />{{Obsolete source|reason=The definition of dead reckoning has changed since this book was written over 125 years ago|date=June 2022}} At sea, sailing ships used [[celestial navigation]] on a daily schedule, as follows:<ref>{{Cite book |title=Merchant Marine officers' handbook |date=1965 |publisher=Cornell Maritime Press |last1=Turpin |first1=Edward A. |last2=MacEwen |first2=William A. |last3=Hayler |first3=William B. |isbn=087033056X |location=Cambridge, Md. |oclc=228950964}}</ref>
# Continuous dead reckoning plot
# Star observations at morning twilight for a celestial fix
# Morning Sun observation to determine compass error by azimuth observation of the Sun
# Noontime observation of the Sun for noon latitude line for determination the day's run and day's set and drift
# Afternoon sun line to determine compass error by azimuth observation of the Sun
# Star observations at evening twilight for a celestial fix
Fixes were taken with a marine [[sextant]], which measures the distance of the celestial body above the horizon.<ref name = gettingthere/>