1 / 10

Marine Charts and Navigation

Marine Charts and Navigation. Oceanography 2014. Latitude Parallels of arc 0º-90º N-S from the equator to poles 1º = 60’ (1’=60 sec) small circles. Longitude Meridians of angle 0º (prime meridian) -180º E-W pole to pole Prime meridian is measured at Greenwich England great circles.

tobias-landry
Download Presentation

Marine Charts and Navigation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Marine Charts andNavigation Oceanography 2014

  2. Latitude Parallels of arc 0º-90º N-S from the equator to poles 1º = 60’ (1’=60 sec) small circles Longitude Meridians of angle 0º (prime meridian) -180º E-W pole to pole Prime meridian is measured at Greenwich England great circles Earth Coordinate System

  3. Marine Charts • Water depths • Configuration of the shoreline in coastal waters • Navigational lights, buoys, landmarks • Chart title block • Nature of the bottom (hrd, rky, g, sh, s, co) • North is the top, latitude scale on side, and longitude on top and bottom • Many charts cover less than a 1º of lat or long, so be careful when “fixing” a position

  4. Units of Distance • Statute vs. nautical miles • 1 nautical mile = 1’ of latitude • 1 nautical mile = 1.15 statute miles • 1º of latitude = 60’ = 60 nautical miles • 1º = 60 nautical miles = 69 statute miles • Use a drafting compass or dividers and spread points to apply to chart bar scale to determine distance

  5. Units of Speed • Knot = 1 nautical mile/hour • 1 knot x 1.85 = km/hr

  6. Plotting a Course • Magnetic vs. true (geographic) North • Use the “Compass rose” on the chart • The compass is graduated from 0º-360º and broken into 32 points on the compass • Cardinal points (0, 90, 180, 270 degrees) • Intercardinal points (northeast, southeast, southwest, northwest) • Cardinal-intercardinal points (ie. east northeast = 67.5º and south southeast = 157.5º)

  7. Cont’ Course • Intended direction of travel • Expressed in degrees • However, influenced by winds, currents, and pilot error Heading • The direction in which the ship is actually traveling regardless of prescribed course Bearing • Direction from one point to another • Expressed as an angle from North • Traditional expressed as relative parts of the vessel

  8. Time and Earth’s Rotation • Earth rotates on its axis once in 24hrs = day • Each rotation is 360º = 24hrs • Longitude 0º (prime meridian at Greenwich England) when sun is directly overhead is 12:00 noon • Therefore at 180º the time is 12:00am (midnight) • Therefore, every 15º of longitude E or W of Greenwich = 1 hour of time (Zulu or Z. time) • 360º/24 = 15º

  9. D.R. Navigation • Also known as Dead Reckoning or “Ded” Reckoning • Method of navigating using the following from a KNOWN position: • Time • Speed • Distance • Direction • Note: Does not account for error or currents

  10. Formulas • Distance = Speed x Time • Speed = Distance / Time • Time = Distance / Speed Use 60 D = S * T (for minutes) D S T

More Related