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. 20’ 30’

7. Speed and Distance ► Subtraction: 60 sec=1 min, 60 min=1 deg  So you’re subtracting time 5 82 36° 22’ 36° 22’ -34° 42’ 1° 40’ 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