Projecting Waypoints

[Troutbum2]

I have a Magellan Sportrak Map GPS, and I recently attempted a geocache which required that I project a waypoint. The instructions for the cache was to project a waypoint at a given bearing at a distance of 0.10 miles. I followed the instructions in my owner's manual and projected the waypoint. However, when I then started the "Go To", it said that I was 0.21 miles away from the projected waypoint I had just made. That didn't make any sense to me...if the projected waypoint was set at 0.10 miles away, why did my GPS then tell me that I was 0.21 miles away from it? Is there a glitch in my GPS or am I doing something wrong? Thanks for your input.

[+Cardinal Red]

I have a 3 or 4 year old Garmin. I have given up on it's useless project waypoint feature. Supposedly the newer models have been improved.

 

Obviously something is wrong with a .10 mile projection that points you .21 miles away.

 

I would just forget about the GPSr and use Compute lat/lon given radial and distance from a known point

 

Or download and use GeoCalc

[+plook]

Or even better, use CacheMate. VERY accurate waypoint projections.

[+BaldEd]

plook wrote

Or even better, use CacheMate. VERY accurate waypoint projections.

 

Interesting. How do you do that in Cachemate? Do you need a special plugin program?

[+GeoForse]

Interesting. How do you do that in Cachemate? Do you need a special plugin program?

You may need the math plug-in. When your at a cache description page. select Cachemate, Calc, Project Waypoint. Then you fill in the bearing and distance to get the new waypoint.

 

GeoForse

[Tally Dragon]

I was attempting a similar cache the other day and used a different approach. It gave me a bearing and a distance of 100 feet. So I walked in that direction while maintaining a goto back to the beginning spot. When I got 100 feet away, I walked around until I had the reverse bearing back to the original spot. This seemed like an easier method for me at the time, I don't know if it will work for you.

[+BaldEd]

GeoForse wrote.

You may need the math plug-in.

You are right. I had unknowingly deleted the MathLib.prc when uninstalling Cachemate a couple of days ago prior to installing a new version. I thought that seeing other programs also used MathLib that it wouldn't be removed. Reinstalled it and am happy to report that the Cachemate projection works just fine. Thanks. I know a cache where I may use this facility in conjunction with my old 12XL. I previously had to use Tally Dragons technique but always had an element of error as the 12XL only counts down in 10m jumps. My new 76CS happily does waypoint projections very easily, even down to decimals of a metre.

[+EScout]

Troutbum2:

When you do your projection, it gives you the choice to project from your current position, or you can choose a waypoint. If you use your current position, you must have a good position fix. I prefer to project from a saved waypoint. You can do this from anywhere -- you do not have to be in the field or have a position fix. Save and name your projected waypoint at this time, then do a Goto.

 

Make sure you have the correct things in setup:

Nav Units: statute miles or nautical miles (NM)

North Reference: true or magnetic, degrees or mils.

 

Magellans have an excellent projection feature, giving you an accurate Great Circle calculation, as good as any computer program.

[+Miragee]

I was attempting a similar cache the other day and used a different approach. It gave me a bearing and a distance of 100 feet. So I walked in that direction while maintaining a goto back to the beginning spot. When I got 100 feet away, I walked around until I had the reverse bearing back to the original spot. This seemed like an easier method for me at the time, I don't know if it will work for you.

There is a cache here that required a waypoint projection, but your method wouldn't have worked . . . the distance was .85 miles.

 

We figured it out on a Mapsource map on the laptop and got within 40 feet of the cache location when we went to our final waypoint.

[+WaldenRun]

I was attempting a similar cache the other day and used a different approach. It gave me a bearing and a distance of 100 feet. So I walked in that direction while maintaining a goto back to the beginning spot. When I got 100 feet away, I walked around until I had the reverse bearing back to the original spot. This seemed like an easier method for me at the time, I don't know if it will work for you.

There is a cache here that required a waypoint projection, but your method wouldn't have worked . . . the distance was .85 miles.

Why wouldn't his method have worked in your case? If .85 miles is too far to walk, you can drive.

 

-WR

[+Miragee]

That part of San Diego has dead end streets, canyons, a freeway, a very large park, and other impassible areas. Driving around to figure out .85 miles on a bearing of 35 degrees (TN) just wouldn't have been feasible.

 

Figuring it out on the map took about two minutes . . .

 

Once we knew where the waypoint was, we still had a hard time finding parking and then had to walk about half a mile to get to the cache.

[+sept1c_tank]

I was attempting a similar cache the other day and used a different approach. It gave me a bearing and a distance of 100 feet. So I walked in that direction while maintaining a goto back to the beginning spot. When I got 100 feet away, I walked around until I had the reverse bearing back to the original spot. This seemed like an easier method for me at the time, I don't know if it will work for you.

There is a cache here that required a waypoint projection, but your method wouldn't have worked . . . the distance was .85 miles.

Why wouldn't his method have worked in your case? If .85 miles is too far to walk, you can drive.

 

-WR

Yeah, what he said.