I was wondering what the difference is between heading, bearing, and course? I am setting the fields that show on the screen of my GPS (a Garmin Foretrex) and these are all options. I don’t understand the difference.
Thanks.
compass how to
– Last Updated: Mar-01-07 4:31 PM EST –
Heading = Direction the boat is pointed.
Course = Direction you want to go.
Bearing = Direction to some landmark.
If you are in your kayak and there is a lighthouse directly east of you, the bearing of that lighthouse is 90°. Another lighthouse directly south of you, would be at a bearing of 180°. It does not matter which way your boat is pointing, what we are measuring is the direction of the lighthouse from the boat as it would be shown on a chart. see accompanying picture
http://terrax.org/geography/compass/bearing.gif
muchas gracias NM
GPS Fields
Although the definitions given previously are correct when using a compass, GPS field definitions can add a few quirks. A GPS unit can not tell where you are pointed, it tells you which direction you are moving. If you are moving and there is no drift due to current or wind then the compass “heading” and the GPS “heading” would be the same. In some strong side winds I have seen as much as 20deg difference between the “heading” from my deck compass (where I am pointed) and the “heading” field on my GPS (where I am moving). With a compass you can get a bearing to anything you can see simply by pointing the compass (or boat if compass deck mounted) at the landmark and reading the direction. With a GPS you can only get a bearing to some waypoint that you previously marked or one for which you entered lat/lon. Either way once you get a bearing it is the same whether determined with a compass or GPS. For Garmin units you have a “Course” field and a “To Course” field. If I remember right from the manual the “Course” field is the equivalent of the heading but is only displayed as N,NE,S etc. While the “heading” field is shown in degrees. The “To Course” field appears to be the same as the “bearing” field but there also may be some display difference. You can check out these definitions in the appendix of your manual. Note: I am referring to a Garmin GPS 60CX manual so the Forerunner may be different. Point is to check out the appendix of your manual where they give definitions for the fields for your particular GPS. By the way my Magellan uses COG (course over ground) that is the same as “heading”. It also has a CTS (course to steer) that is a “modified bearing” that does not go directly towards your destination, but is a compromise to get you back on the original path as defined when you first selected a point to which you wanted to go.
If that is not confusing enough we could always talk about map datums.