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Underwater Navigator

Knowledge Review - Part 1

Five benefits of learning to navigate underwater:

  • builds confidence and puts you in controls of you dive plan
  • saves energy
  • makes dive planning more effective
  • keeps buddies together
  • reduces air consumption

Estimate distance using kick cycles by swimming a known distance and counting the number of kick cycles used. Divide distance by kick cycles.

Estimate distance using elaspsed time by swimming a known distance and tracking the total number of seconds it took. Divide distance by seconds.

Four predive observations to assist with natural navigation:

  • water movement
  • sunlight
  • offshore objects and formations
  • depth finder and charts

Descend head up to aid navigation.

Six natural references that can help you navigate during a dive:

  • light and shadows
  • water motion
  • bottom composition
  • bottom contour
  • plants and animals
  • noise

To maintain an accurate heading you should hold and swim with a compass so that the needle doesn't lock and you are aligned with the lubber line.

Set a heading:

  • point lubber line in desired direction
  • turn bezel until index marks bracket the compass needle

Set a reciprocal:

  • stop and turn bezel for a new heading 180 degrees from original
  • turn until compass needle is bracketed by index marks

Hints for using a compass underwater:

  • trust your compass - but not entirely
  • use natural references
  • practice on land
  • work with your buddy
  • adjust for the effects of currents
    • ignore current and plan for relocating objective
    • use compensated start point
    • use an adjusted heading
    • create intentional error
    • navigate point-to-point
  • swim slowly
  • know your limits

Knowledge Review - Part 2

Estimate distance using cylinder pressure by noting your starting air pressure, swimming a known distance, then subtracting the current air pressure by the starting pressure and then dividing that by the distance.

Navigate a square/rectangle pattern by:

  • swimming initial desired heading and distance and then stopping
  • reset heading for 90 degree turn by subtracting 90 for a left turn, or adding 90 for a right turn
  • repeat the above process 3 more times

Navigate a triangle pattern by:

  • swimming initial desired heading and distance and then stopping
  • turn right by reset heading by adding 120 degrees (outside of triangle)
  • repeat the above process 2 more times

Navigate a U-pattern by:

  • swimming initial desired heading and distance and then stopping
  • assuming navigating towards right, make a 90 degree turn to right
  • swim half the distance from which you could spot desired object
  • turn right 90 degrees swimming same distance and opposite heading from start
  • repeat with alternating turns

Fix a dive site for relocation using permanent landmarks by:

  • staying where you are
  • selecting two inline permanent landmarks on shore
  • rotating between 60 and 120 degree
  • selecting another two inline landmarks
  • documenting information

Fix a dive site for relocation using a compass by:

  • staying where you are
  • selecting a permanent landmark on shore and noting heading
  • rotating between 60 and 120 degrees
  • selecting another permanent landmark and noting heading

Two electronic dives that can assist with underwater navigation:

  • GPS
  • hand-held sonar

Use a course plotter to track your location during a dive by:

  • moving compass ring until initial heading lines up with compass heading arrow
  • plotting distance traveled from center of grid
  • turning wheel to next compass heading arrow
  • plotting distance from end of previous plot line
    • repeating

Find the heading and distance back to the start point using a course plotter by moving wheel until the end of previous plot line touches the heavy grid line directly below the center. The number on the compass ring aligned with the compass heading arrow indicates heading.

Set a heading calculator to get the heading for a counterclockwise square/rectangle simply by setting the initial heading. The calculator will then have necessary headings.