Navigation NAU 102 Lesson 1

Introduction to Navigation What is “Navigation”? The means by which a craft is given guidance to travel from one known location to another. (Logsdon) The art and science of safely and efficiently guiding the movement of a vessel from one place to another. How is it “science”? How is it “art”?

Categories of Navigation Piloting Dead Reckoning Celestial Navigation Radio Navigation Satellite Navigation

Categories of Navigation Navigating in restricted waters (near land) Piloting Navigating in restricted waters (near land) Frequent determination of position relative to nearby geographic and hydrographic features. Visual bearings Radar ranges Depth of water

Categories of Navigation Dead Reckoning (DR) From Deduced (ded.) Reckoning Deduces position by advancing a known position along a course and speed line. Predicts where you are or will be based on where you used to be and subsequent courses and speeds. Ignores effects of wind, current, bad steering, etc.

Categories of Navigation (Not covered in this course.) Celestial Navigation The use of observations of celestial bodies (Sun, Moon, planets, stars) to determine position. (Not covered in this course.)

Categories of Navigation Hyperbolic navigation systems Radio Navigation The use of radio waves to determine position through a variety of electronic devices. Hyperbolic navigation systems (Loran – C)

Categories of Navigation Satellite Navigation The use of radio signals from satellites to determine position. Global Positioning System (GPS) GLONASS Galileo (Not covered.)

Problems of Navigation The job of the navigator is to determine: Position Direction Distance

Position – Where am I? An identifiable location on the earth. Stated relative to a fixed known location. e.g. 6 miles west of Golden Gate Or, stated using a coordinate system. e.g. Latitude & Longitude Accuracy and reliability vary depending of positioning method.

Types of positions, in order of reliability: Position – Where am I? Types of positions, in order of reliability: Fix Running Fix Estimated Position Dead Reckoning

A position based on solid information which can be safely relied upon. Position – Where am I? Fix A position based on solid information which can be safely relied upon. Obtained by crossing (nearly) simultaneous lines of position (bearing or range) from 2 or more objects. Piloting Celestial Radio Satellite

Position – Fix

Position – Where am I? Running Fix A position based on lines of position obtained at different times. Less reliable than a Fix Celestial Piloting Radio

Position – Where am I? Estimated Position (EP) A DR position corrected using extra information. Current Steering errors Wind One line of position

Direction – Which way? Direction – angular orientation between two points. Measured in degrees of arc from a reference. References: Geographic North = true direction (T) Magnetic North = magnetic direction (M) Ship’s heading = relative direction (R)

Direction – Which way? Definitions Course (C)– intended direction of vessel. Heading (Hdg.) – direction the vessel is pointed. Track (Tr) – intended path of travel Course over ground (COG) – actual path of travel Course made good (CMG) – resultant direction traveled between 2 points.

Direction – Which way?

Direction – Which way? Definitions (cont.) Bearing - Direction of one object to another

The spatial separation between two points. Distance – How far? The spatial separation between two points. Unit of measure = nautical mile (nm) 1 nm = 6,076.1 ft = 1.852 km 1 nm = 1.15 statute mile

Distance – How far? Related Concepts: Time – How long will it take? Speed – rate of movement 1 knot (kt) = 1 nm/hour Speed X Time = Distance

Problems of Navigation Definitions Speed of advance (SOA) – intended speed Speed over ground (SOG) – relative to the earth Speed through the water (STW) – relative to the water Speed made good (SMG) – resultant speed between 2 points Track made good (TMG) – resultant speed and course between 2 points.

Introduction to Navigation Questions?