Ok, This is definitely not going to excite anyone with the speeds attained! I'm sailing a 1980's Division 2 board!


I wonder if anyone can lend me their experience with the whole gps logging thing. I'll explain what I've done and share a link to the .gpx file from this afternoon's sail..

On my Samsung Galaxy Core Prime I've installed 'Ultra GPS Logger' set 'trigger' to 'every second', triple bagged the phone and put it down the front of my westuit.

Here's the resulting .gpx file: www.dropbox.com/s/zu42zwm5qewx61q/23.11.15%20cleaned%20up.gpx?dl=0

I've tidied the file up a little (just trimmed the ends) and let it filter out the 4 results that were over 30 knots.

All good no worries - except that in my enthusiasm I've installed GPS Action Replay Pro, RealSpeed and GPS Results and they all come to different conclusions regarding my best 10 secs or 100m or whatever. What do I believe? What is the usual way to interpret this into some kind of meaningful result?

Thanks ! Mikey

Well you're asking for trouble having it under your wetsuit, while dry it won't be a problem but if the wetsuit gets wet, especially with salty water, then it acts as a screen to the gps signal.
The different ways of dealing with a dodgy signal could account for the differences you're seeing.

I'll see if I can download your file and get back with any conclusions I may come to.

Yep, your data is full of holes, some longer than a minute.

Was the phone display on?? Some phones we've tested have holes in the data similar to yours. But I suspect it's more likely because you had it under your wetsuit.

Most of us prefer to use the Paqua Midi waterproof pouch with armband, wear that on your upper arm and you get good reception. Try that, if your data still has holes in it, then you'll need to keep the display on. GpsLogit has the option to keep the display on, I'm not sure about ultra gps logger.

Gotcha, That makes sense and thankyou for the reply. I'll track down the pouch you suggest and do a bit of dry testing (boat or shore based) as well.

The phone display was off as was the data connection.

Cheers!

Thought I'd follow up here with success (Well it all looks good to me anyhow...)

Speedsailing this is definitely NOT! By the time I got out on the water this afternoon it was blowing 6 knots gusting 9 and then eased to 5 gusting 8. This from the weather station just 1nm downwind from where I was sailing.

I did exactly as decrepit kindly suggested and put my phone running Ultra GPS Logger in a Paqua case on my arm. It may have helped that it didn't even get splashed let alone wet. I changed the 'trigger' setting to 'max data rate' put the phone in airplane mode and headed out.

I've got no more holes in the data. The three analysis programs all agree within a fraction of a knot in each speed category. I take it that there being no readings significantly above those nearby and that the consistency of output is very good that I can take these results as being close enough to reality to satisfy any non competitive needs. Anyone care to agree or otherwise?

Here's the data: www.dropbox.com/s/9bl3n3ji7vjjo15/dec%201st%20trimmed.gpx?dl=0

Thanks again decrepit.

--------

As a complete aside and not expecting anyone to share my enthusiasm, I'm quietly chuffed that I'm getting 10 and 20 second runs around 10 knots in this little breeze, however it's actually the taking angles and the VMG that interest me most.

Cheers all.

Yes, all looks good, your phone seems to have good characteristics, it's got the high resolution of 0.02kts, doesn't have the display off syndrome, and has reasonable sat sensitivity, Pity it's not a bit cheaper, the best price I can see with a quick search is $160, half that and I'd be interested. My $40 phones are only accurate if I wear them on my head, which makes them a bit hard to see,

Haha, yeah. Luckily for me this one just happens to be the phone that I own so no added expense.


Thanks for your time. Cheers!