Use & limitations of GPS/Chart plotters

Make candidates aware of the pros and cons and differences between GPS and Chart Plotters. 

Items to cover: 

  1. What is a waypoint? (Lat / Long)
  2. Mark two waypoints on a chart
  3. Join the two waypoints, measure the bearing (T) and distance
  4. Briefly explain where a GPS / Chart Plotter gets its position information from (satellites) 
  5. Turn on your GPS / Chart Plotter & show your students the basics of what they see on the screen/s i.e. Lat / Long, Speed, Track, Heading
  6. Input the two waypoints you have taken from your chart (check for clarity) 
  7. Show your students how to set and start a route between the two waypoints
  8. Wrap up the session by discussing the limitations of GPS / Chart Plotters

Limitations of GPS / Chart Plotters:

Human error - inputting the wrong position

No accounting for hazards, unlike satnav, a GPS/Chart plotter does not know where hazards are located. 

Technology error - satellite geometry, aerial damage or positioning

Using a fixed object (buoy) as a waypoint - you may well hit it!

Pre-set Variation & Deviation

True or Magnetic bearings?

Datum offset i.e. OS36 or WGS84?


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Teaching GPS at RYA Powerboat Level 2
Teaching GPS at Level 2.pdf
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