precision: UTM or LL 2 digits?

[CacheMonkeez]

I have a Magellan GPS 310. It has only 2 digits after the decimal point. That means when I enter in the coords from the website, I have to round them off (e.g., 28 05.416 becomes 28 05.42).

 

However, if I use UTM coordinate system, I do not have to round off. I can enter the value as is.

 

Does this mean that UTM is more precise than LL to 2 digits?

[JDMC]

UTM would be more precise. Here's the math (for latitude, which has constant parallels):

There are 60 nautical miles / degree

There are 60 minutes / degree

So 1 nm = 1 minute of latitude

or 6080 feet = 1 minute

or 1853.184 meters = 1 minute (1 m = 0.3048ft)

or 18.53184 meters = 0.01 minute

 

UTM is precise to 1 meter without a decimal place.

 

(I hope I didn't make a mistake)

[+Renegade Knight]

As I understand it. UTM is a meter based grid, so what you say for accuracy makes perfect sence.

 

Wherever you go there you are.

[Stefanoodle]

I agree with the reasoning above. I also did the maths once, as I have a Magellan Trailblazer XL which also has a 2 decimal point readout. At first I tried between deg.min.sec vs. deg. decimal min, but that didn't help as far as a more accurate readout was concerened. Now I use UTM most of the time, especially for inputting the co-ordinates of the cache (you don't introduce rounding errors like that). That way, when there are no distinct landmarks when I'm close to a cache I can take a reading and then know that I must move a certain number of metres north or south, east or west to find the cache. And considering the Trailblazer is such an old instrument, I'm constantly being surprised by the accuracy and the success rate of this method.