Projection and math help.

[+sinemora]

If I have a known point E383691 and N4752911 and a direction of 84.8degrees and a distance of 8790meters-----The bearing is from due east and in grid north not magnetic.

 

If I use the projection mode on my Magellan do I need to use math, or do I need to add or subtact declination to find the new coord's? This is in Idaho.

 

Also if due east on a compass is 90 and I need to go south 84.8 degrees, shouldn't my new location be almost south at 178 degrees? If it is 178 do I need to change my declination for southern Idaho about 18 degrees plus or minus so either it would be about 196?

SineMora

 

[This message was edited by -SineMora- on October 03, 2003 at 12:13 AM.]

[+EScout]

Yes, you can do this with a Meridian (which I have) and probably other current Magellans. In setup, set "North Reference" to Magnetic, "Nav Units" to KM/KPH. In the Position screen, press Menu and then Projection. The GPSr uses the declination at the starting point of the projection-- one would assume.

[+JMBella]

Uhhhhhh....2

 

Two roads diverged in a wood, and I-

I took the one less traveled by,

And that has made all the difference.

Because now I am Lost.

[+Brian - Team A.I.]

I thought it was '42'.

 

Brian

Team A.I.

[+JMBella]

Only when you multiply the circumference by the oblique angle of the hypothesis. Thus creating a manifestation in the constellation constipation. Then of coarse the answer has to be ‘42' Ya feel me?

 

Two roads diverged in a wood, and I-

I took the one less traveled by,

And that has made all the difference.

Because now I am Lost.

[+Waterboy]

Taking a look the information you sent it was not a problem to discover which geocache you were referring to. (I will not mention the name since the hider of this cache may not want this info publicly available.) Please note that this cache is only rated 1.5/1 stars. It should not be too difficult.

 

Given a bearing from due east is a rather odd form, but understandable. Using everything in meters and grid makes the problem easier.

 

With this info we can derive the equations:

E(f) = E(i) + D*cos(

N(f) = N(i) - D*sin(

 

Where:

E(i) = Initial Easting coordinate

N(i) = Initial Northing coordinate

E(f) = Final Easting coordinate

N(f) = Final Northing coordinate

D = Distance (in meters)

B = Bearing angle in reference to east direction

 

This uses straight forward two dimensional trigonometry, looking at the cache sheet I believe this is what the owner of the cache wanted. The math above can be done with a pocket scientific calculator, like the one on my Garmin Rino 101.

 

Can this problem be solved with a Magellan in projection mode? Sorry, I do not own or know much about the Magellan equipments.

 

I will be emailing you with more details, that should not be on the web.

[+Team GPSaxophone]

Although you have a Magellan GPSr, it should be similar in function to the Garmin models:

• Change your display units to UTM (instead of Deg min.min)

• Look up the waypoint (on Garmin do a FIND)

• On the drop-down menu select 'project waypoint'

• Enter the bearing and distance you desire and name the waypoint

• FIND this new waypoint and select GOTO

voila! No math needed

 

Took sun from sky, left world in eternal darkness

[+fizzymagic]

Grid north does not require a declination, but it's a weird way to represent an angle since grid north is neither true north nor magnetic north, and it can be hard to compute.

 

I think that what the person wants you to do is to calculate the new coordinate using UTM, as was mentioned above. I will just add that, in general, that's a very bad idea. UTM is quite good for calculating distances between points, but not appropriate for projections.

 

Also, I will add that trying to do this projection with your GPS will give you the wrong answer, since the GPS never uses grid north for projections.

[+Team GPSaxophone]

I can set my GPS to true north or magnetic north. Projections will be based on whichever north I set.

 

Took sun from sky, left world in eternal darkness

[DiverMan]

Dang, I just reset my tripometer on my truck

 

DiverMan

 

Dive Down, Dive Deep

[Vacman]

Abject Sill(y)iness to follow:

 

The problem here is that you are not taking into account the fact the the chronic-synclastic infidibulator should have been zeroed in first.... BEFORE you reset your tripometer.

 

--------------------------------------------------

When everything is coming your way, you're in the wrong lane.

[+blindleader]

Warning: It is imperitave that when zeroing any infidibulator, you must hold down the interositor magneto clutch lever to prevent the snitlatch from going into rebimbulation.

[+Waterfall]

I feel like I should be a finder for this... I did it on my Etrex -Vista and it placed me a a cord location that looks goood..

 

will email the how to the user in a form he can use..