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"to course" vs "Course to steer" in Garmin GPS


Levacher Family
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With no outside/zero affects both will be the same. Generally applies in aviation or boating situations.

 

However in a current/wind situation the "Course to Steer" is that as it is affected by the current/wind etc component.

 

In simple terms from your present position the "to course" might be due north (0 degrees) but if the current is running to the west then the "course to steer" will be somewhere east of north depending on the amount of currect.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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Not exactly. Course to steer is a nautical term which takes into account currents such as tide and leeway caused by the wind. Read Kerry's last paragraph again. If the current and/or wind is pushing you off course, even though your "pointed" directly to your destination then you would need to change your direction either to the left or right of your destination to counter these forces. That would be your course to steer. Correct on the definition of Course.

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Well, I've run across this in a airplane. If the GPS knew the direction you were pointed (it cant know that, it only knows the direction you are going). Some aircraft gps's do know your "heading" that is the direction you are pointed (not the direction you are going). Then they can compute wind direction and speed (sweet!!!)

 

If thats true then how can the gps know anything but the direction from where you are NOW to where you are going...seems like that would be the "course to steer". What else could it be?

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I don't think it was mentioned that the GPS knew which way you are/were pointing (it can't) just that if you were "pointed" directly to where you wanted to go and being pushed sideways then one would have to steer a course to counteract that and give you the most efficent way to stay on course to your destination.

 

The GPS knows where you started from, where you wanted to go. It also knows where you currently are and heading (not pointing), which isn't really a heading as it's based on past information (sometimes referred to as Course Over Ground) but it's close enough (but still technically doesn't tell you a heading) given the time frames.

 

Similar with Speed and Velocity Made Good as if one was heading directly to the destination with no influences then speed and VMG is the same. But with wind/current influences then your speed is different to your VMG and if one was going sideways (at a certain Speed & Course over Ground) then VMG to the destination is almost zero (or even negative).

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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quote:
Originally posted by KB9NVH:

Some aircraft gps's do know your "heading" that is the direction you are pointed (not the direction you are going). Then they can compute wind direction and speed (sweet!!!)


 

It can only know your heading if it has an internal compass or is getting heading data via the serial port, which is also where the wind data would be coming from. The Garmin Map76S can display depth, sea temperature, and boat speed and heading via the serial port.

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Yep, I'm not trying to be difficult..just to understand the nomenclature. Seems like a couple of the items are identical on my gps V

"course to steer" and ahh, I cant remember the other one..but they both read the same no matter what...

 

I really dont know the purpose of "to course" either...seems like that would always be the heading you would take for the shortest distance back to your course line? I suppose thats worth something but when you reach your course you better make a "90" pretty quick or TO COURSE will instantly have you doing a U turn..LOL

 

Yes, I think most of the GPS's for airplanes (The TSO'ed ones approved for flight navigation ) have interfaces to the directional gyro so they can know the way the airplane is pointed. On my airmap 100 I could put that in manually and then it would tell me wind speed and wind direction. Pretty Kool.

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quote:
Originally posted by KB9NVH:

I really dont know the purpose of "to course" either...seems like that would always be the heading you would take for the shortest distance back to your course line.


Not the heading for the shortest distance, but the most efficient heading to get back to your course. As far as course to steer, if you have no way to enter in current set/drift or leeway, then it would be the same as bearing to destination. My Map76S does not have course to steer, but does have to course.

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