Download
navigation and bathymetry n.
Skip this Video
Loading SlideShow in 5 Seconds..
Navigation and Bathymetry PowerPoint Presentation
Download Presentation
Navigation and Bathymetry

Navigation and Bathymetry

0 Vues Download Presentation
Télécharger la présentation

Navigation and Bathymetry

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Navigation and Bathymetry

  2. Why is it important for you to be able to read maps and navigate? • What’s wrong with GPS? • Rely heavily on power and satellites • Salt water and batteries • Sun spot activity breaks down radio transmissions • Always good to know how to use a map and compass

  3. Finding locations on maps • On graphs, there are X and Y coordinates • Need to adapt these coordinates for a spherical world • Lat and Long

  4. Latitude- parallels, 0-90 °N&S of the equator (always put the letter); always the same distance between each latitude line • Longitude- meridian, meet at the poles so always different distances between the longitude lines, 0-180°E&W • Writing: degrees(°), minutes(‘), seconds(“) Conway= 35° 50’ 9” N, 79° 2’ 53” W

  5. On the charts • Lat and long do not have letters, why? • Its on a small scale, you should know where you are • What hemispheres are we in? • Lines are straight, why? • Small scale

  6. 30’ 20’

  7. Speed and Distance • Subtraction: 60 sec=1 min, 60 min=1 deg • So you’re subtracting time 5 82 36° 22’ -34° 42’ 1° 40’ 1’ of latitude=1 nautical mile= 1.15 statute (land miles) Why latitude?? • Speed is measured in knots (1 nautical mile per hour) --a line with knots on it • 30’ latitude in 1 hour = 30 knots

  8. Plotting courses • Read the course headings as 0-360°, not NSEW letters • Geographic North Pole- ‘true’ north, the top point of earth where you normally think of the north pole • Magnetic North Pole- magnetism of the Earth, moves around and sometimes flips to the geographic south pole • Therefore we need to make corrections, because our compasses point to the magnetic north pole, not geographic north

  9. Bathymetry • Study of the depths, ocean floor • Old days- drop a lead-line and determine how much rope was let out, then measured it in arm lengths, or FATHOMS • 1 fathom=6 feet, 3feet=1 meter • Current way- sonar or echosounding • Sound has a speed of 1500m/s in water

  10. Soundings- the depths at particular points, these are shown on the charts as single numbers • Contour lines- lines that connect equal depths (5fm, 10fm, 100fm, 1000fm) • Bathymetric profile- an X-Y graph of depth versus distance