I usually carry my Garmin Etrex 20 with me when I'm out kite skiing so I can look back after the day is done and see what I've logged for the day. I've never second guessed my GPS until recently. Today I logged 52 miles but it didn't really feel like it. My moving average speed showed a higher number than my max speed which the laws of physics says isn't possible, so this makes me question how accurate my GPS unit is. Any insight to this? I always zero everything out just prior to launch, throw it in my pocket, proceed to ride, then when done shut the unit off. Does anybody else get weird numbers?

all the time, but for different reasons. I've never posted my top buggy speed because i would be with friends and passing people and often they would say they had higher speeds than what my gps was showing so I can wait until I'm 100% sure is faster than my friends that I'm passing before I'm going to post :evil: (but that's a whole different thing than what you are talking about). My friends that use smart phone apps on the lake often show me their speeds and i find it curious that they have big elevation changes on a flat lake - i keep missing their 60 - 120' jumps.

Regular GPS usually trust it but not the phone apps i think distance is okay but gusts will "speed" you up occasionally.

@Mark- must be why i am always on cloud 9 after a good day

Another thing is my moving time said 1hr and 18mins. Total miles skied was 52. Max speed was 30.9mph with a moving average of 40.3mph. All these numbers don't make any sense. Thought GPS's were pretty accurate these days, but now I'm second guessing how valid any of these numbers are. I realize it's not about the numbers but enjoying being out there, I just get a little annoyed when I spend money on technology that I can't always rely on.:evil:

The only erroneous info I've ever dealt with is while the gps is just sitting still. I look at my readout every time the light direction allows and I've never had a number that was not reasonable to how the day and runs were. I've had days that runs to 50 mph scared the crap out of me and days that I broke 60 mph without undue stress. Today, my buggy was parked for a couple hours with the gps on and reset and somehow it had hit 12 mph sitting there. Real moving speeds have always seemed correct and I've never had a superhero run show on the gps that didn't match up with conditions or the rest of the runs that day. Well, I've been in world record territory the times I've left the gps on while driving home with the buggy on the rack!

No problems with mine, although its worthy of note that if you wish to set a world record three are required, and then the variance is small.
I've only ever been interested in the top speed, and nowadays unless it's 20 knot winds or more there's not much point as I won't break my PB.

No world records here, lol. I only care about personal bests. I usually only care about top speed and total distance travelled. Those numbers seem to be believable most of the time. Bobby Muse makes a good case about odd numbers coming up when your sitting still. Once I caught my GPS with a max speed of 11mph while I was setting up a kite and know for a fact I wasn't doing anything faster than a walk. Perhaps these units get confused when they are on and not moving. I'll have to get a second unit sometime and do a comparison. All this talk about accurate numbers is strictly the OCD getting the best of me. Sometimes I see something that doesn't seem right and I want to know why is all.

Upload to KA72.com and scrub the data. If you have any spikes in the data it will remove them.
:D

I have run 2 at the same time with only tenths difference.