Piloting#Piloting in channels and rivers

Depending on whether one is navigating on a water course, in the air or on land, a different chart applies for the navigator:

• Nautical charts – show coastal regions and depict depths of water and land features, natural features of the seabed, details of the coastline, navigational hazards, locations of natural and human-made aids to navigation, and human-made structures such as harbours, buildings and bridges.
• Aeronautical charts – for visual meteorological conditions depict terrain, geographic features, navigational aids and other aids to navigation. They vary in scale from 1:1,000,000 for world aeronautical charts to 1:250,000.
• Topographic maps – show landforms and terrain, lakes and rivers, forest cover, administrative areas, populated areas, roads and railways, and other man-made features.{{cite web

| url = http://www.nrcan.gc.ca/earth-sciences/geography/topographic-information/maps/9767

| title = National Topographic System Maps

| last = Government of Canada

| date = 2016-04-08

| website = Earth Sciences – Geography

| publisher = Natural Resources Canada

| access-date = 2016-05-16

}}

{{center|

;Cartography showing man-made and natural features that can be used as points of reference appropriate to the type of navigation.

}}

File:NOAA chart 25664 1976 detail.png|Nautical chart – includes water depth.

File:Minimum Safe Altitude.gif|Aeronautical chart – includes elevation.

File:Conness-topo.jpg|Topographic map – emphasizes contours – suitable for land navigation.

{{see|Maritime pilot}}

Coastal mariners often use reference manuals, called "pilots" for navigating coastal waters. In addition to providing descriptions of shipping channels and coastal profiles, they discuss weather, currents and other topics of interest to mariners. Notable guides include a worldwide series of "Sailing Directions" by the United Kingdom Hydrographic Office (formerly by the British Admiralty) that includes, most notably, the English Channel, the Mediterranean Sea, the Red Sea and the Persian Gulf.{{cite web

| url = http://www.ukho.gov.uk/ProductsandServices/PaperPublications/Pages/NauticalPubs.aspx

| title = Admiralty Nautical Products and Services – Paper publications

| last = Hydrographic Office

| date = 2015

| publisher = United Kingdom

| access-date = 2016-05-19

| quote = Often referred to as Pilots, Sailing Directions are designed for use by the merchant mariner on all classes of ocean-going vessels with essential information on all aspects of navigation. Sailing Directions are complementary to ADMIRALTY Standard Nautical Charts and provide worldwide coverage in 75 volumes.}} Another series worldwide series of Sailing Directions is by the US National Geospatial-Intelligence Agency,{{cite web

| url = http://msi.nga.mil/NGAPortal/MSI.portal?_nfpb=true&_pageLabel=msi_portal_page_62&pubCode=0010

| title = Sailing Directions Enroute

| last = National Geospatial-Intelligence Agency

| author-link = National Geospatial-Intelligence Agency

| website = Maritime Safety Information

| publisher = National Geospatial-Intelligence Agency

| access-date = 2016-05-19

| quote = Sailing Directions (Enroute) include detailed coastal and port approach information, supplementing the largest scale chart of the area. Each publication is subdivided into geographic regions, called sectors, which contain information about the coastal weather, currents, ice, dangers, features and ports, as well as a graphic key to the charts available for the area.}} which has planning guide and enroute portions. The "United States Coast Pilot", by the National Oceanic and Atmospheric Administration (NOAA) Office of Coast Survey, covers the coastal and intracoastal waters and the Great Lakes of the United States.{{cite web

| url = http://www.nauticalcharts.noaa.gov/nsd/cpdownload.htm

| title = United States Coast Pilot®

| last = Office of Coast Survey

| website = Nautical Charts & Pubs

| publisher = National Oceanic and Atmospheric Administration

| access-date = 2016-05-19

| quote = The United States Coast Pilot® consists of a series of nautical books that cover a variety of information important to navigators of coastal and intracoastal waters and the Great Lakes. Issued in nine volumes, they contain supplemental information that is difficult to portray on a nautical chart.}}

File:Enslinje Korpo 2009.jpg with solar-powered leading (range) lights at night.]]

Common types of visual reference point used for piloting and pilotage include:{{Citation

| last1 = Bowditch

| first1 = Nathaniel

| author-link = Nathaniel Bowditch

| last2 = National Imagery and Mapping Agency

| author2-link = National Imagery and Mapping Agency

| title = The American practical navigator : an epitome of navigation

| publisher = Paradise Cay Publications

| year = 2002

| chapter = Chapter 8: Piloting

| pages = 896

| chapter-url = https://books.google.com/books?id=pXjHDnIE_ygC&q=piloting&pg=PR1

| isbn = 978-0-939837-54-0}}

• Natural features: Mountains, hills, lakes, rivers and coastal features such as cliffs, rocks and beaches
• Navigational aids: sea marks (including buoys and beacons) and landmarks
• Other structures: Airports, cities, dams, highways, and radio antennas

• Lighted navigational aids: Lighthouses, lightvessels and lighted sea marks
• Lighted structures: Airports, illuminated towers and buildings

Depth, measured with a depth sounder or lead line, can be used to identify a bathymetric contour or crossing point. Similarly, elevation can be used to confirm a geographic contour or crossing point. Measurement of depth and altitude allow vessels and aircraft navigators to confirm clear passage over obstructions.

{{Main|Fix (position)}}

File:CompassUseTargetMarked.jpg

File:Visual-fix-by-three-bearings.png

On shipboard, navigators may use a pelorus to obtain bearings, relative to the vessel, from charted objects. A hand bearing compass provides magnetic bearings. On land a hand compass provides bearings to landmarks.Frazer, Persifor, A Convenient Device to be Applied to the Hand Compass, Proceedings of the American Philosophical Society, Vol. 22, No. 118 (Mar., 1885), p. 216

Mariners use position-fixing navigation, to obtain a "position fix" or "fix" by measuring the bearing of the navigator's current position from known points of reference. A visual fix of position can be made by using any sighting device with a bearing indicator to obtain position lines from the navigator's current position to each point of reference. Two or more objects of known position are sighted as points of reference, and the bearings recorded. Bearing lines or transits are then plotted on a chart through the locations of the sighted items. The intersection of these lines is then the current position of the navigator.

Usually, a fix is where two or more position lines intersect at any given time. If three position lines can be obtained, the resulting "cocked hat", where the 3 lines do not intersect at the same point, but create a triangle where the vessel is inside, gives the navigator an indication of the accuracy in the three separate position lines.

If two geographic features are visually aligned (the edge of an island aligned with the edge of an island behind, a flag pole and a building, etc.), the extension of the line joining the features is called a "transit". A transit is not affected by compass accuracy, and is often used to check a compass for errors.{{Citation

| last = Manley

| first = Pat

| title = Practical Navigation for the Modern Boat Owner

| place = Chichester

| publisher = John Wiley & Sons, Ltd

| series = Wiley Nautical

| year = 2008

| page = 68

| url = http://www.woodenboats.lt/Knygos%20public/Navigacija/Pat%20Manley%20-%20Practical%20Navigation%20for%20the%20Modern%20Boat%20Owner.pdf

| access-date = 2016-05-08

| isbn = 978-0-470-51613-3 }}

The most accurate fixes occur when the position lines are at right angles to each other.

Flying at low altitudes and with sufficient visibility, aircraft pilots use nearby rivers, roads, railroad tracks and other visual references to establish their position.

{{Main|Course (navigation)}}

The line connecting fixes is the track over the ground or sea bottom. The navigator compares the ground track with the navigational course for that leg of the intended route, in order to make a correction in "heading", the direction in which the craft is pointed to maintain its course in compensation for cross-currents of wind or water that may carry the craft off course.

File:Navigational Range.png

Where a channel is narrow, as in some harbor entrances and on some rivers, a system of beacons allows mariners to align pairs of daymarks, called "range markers", to form a "leading line" (British English){{Citation

| last = Bartlett

| first = Tim

| title = Adlard Coles Book of Navigation

| publisher = Adlard Coles

| date = February 25, 2008

| url = https://books.google.com/books?id=RWUQAAAAQBAJ&q=pilotage

| pages = 176

| isbn = 978-0-7136-8939-6 }} or "range axis" (American English),{{Citation

| last = United States Coast Guard Auxiliary

| author-link = United States Coast Guard Auxiliary

| title = National Short Range Aids to Navigation – Training Guide

| place = Washington

| publisher = United States Coast Guard

| date = December 19, 2013

| page = 28

| url = http://pdept.cgaux.org/Documents/ATON_Training_Guide.pdf

| access-date = 2016-05-08 }} along which to navigate safely. When lighted, these markers are called "leading lights" (British English) or "range lights" (American English). The relative positions of the marks and the vessel affect the accuracy of perceiving the leading line.

• {{annotated link|Navigation}}
• {{annotated link|Celestial navigation}}
• {{annotated link|Dead reckoning}}
• {{annotated link|Radio navigation}}
• {{annotated link|satellite navigation system|Satellite navigation}}
• {{annotated link|Land navigation}}
• {{annotated link|Maritime pilot}}
• {{annotated link|Pilot (aeronautics)}}
• {{annotated link|Underwater navigation (scuba diving)#Navigation using natural features|Underwater navigation by divers}}
• {{annotated link|Bowditch's American Practical Navigator}}

{{Reflist|30em}}

• [http://msi.nga.mil/MSISiteContent/StaticFiles/NAV_PUBS/APN/Chapt-08.pdf American Practical Navigator – Chapter 8: Piloting]
• [https://msi.nga.mil/Publications/APN American Practical Navigator (complete 2019 edition, Parts I and II available in both high- and low-resolution versions, and select older versions)]
• [https://en.wikisource.org/wiki/The_American_Practical_Navigator/Chapter_8 American Practical Navigator – Chapter 8: Piloting at WikiSource]

Category:Navigation

Category:Navigational aids

Category:Maritime signalling

Category:Underwater diving procedures