boardsurfr said..








Sorry I had missed that, thanks for posting it again. Here's a few things I noticed looking at the track. First, a comparison of the doppler and positional speeds for the entire track:

The "33 knot" region is where the green line is. What jumps out is that there are many spots where the positional speed is much higher than the doppler speed, up to 100 knots. That's unusual - for comparison, here is a recent Canmore track where there are only small differences:




It is quite common to see spikes in the speed graph during crash/swim episodes. Here is an example from another recent Canmore file (I used the Canmores as loaners for GPS competition at our East Coast Windsurfing Festival last week):




As theGPSlooses and gains reception, the position jumps a lot, and this sometimes "goes through" to doppler speeds. Similar artifacts while swimming/crashing can be seen with Locosys andu-bloxGPS units.

During the first hour of Callan's session, there are just two speed spikes, and they both seem linked to crashes (the first one is a "maybe"). Here is the second crash:

This is a clearcut case of a crash in a jibe, and did not affect doppler speed.

Now to the "33 knot" region:





This does not seem linked to a crash (Mike was correct in this assessment). But the speeds are quite spiky before the "33 knots", with large differences between positional speed and doppler speed. This indicates that the GPS did not get a good reception. The run was after a longer break or swim. There is a 60 knot spike in the speed graph about 80 seconds earlier, probably because the upper arm was completely in the water. It's likely that the armband moved during this break/swim so the GPS was below the arm, and/or that water got into the GPS.

Overall, though, the picture is quite simple. The amount of missing data points in the file (about 30%) is way too large. There are 332 missing single points with doppler speeds above 10 knots, that's roughly one every 30 seconds (I got the numbers by copying the track points table data from GPSAR, pasting them into a spreadsheet, and sorting by time difference and speed). So the decision to remove the post completely was definitely appropriate.

AUS3333 said..














Check out this file posted with Garmin non approved device follow link and check out distance PB gpsteamchallenge.com.au/sailor/view/5501
Remember when i did 325 kms at lake catharabah and my gt31 didnt have sd card it only recorded 150km, every one knew i did it but post was removed because Peter cochrane flagged it ( so Ian told me so), One rule for everyone please

TGale said..
^^^ Is that Garmin accurate - you should have burnt some calories sailing 315km??

Cocky2 said..






Yes the Garmin was accurate. More accurate than the Canmore and lasted longer than the GW52.
It was a great day sailing with mates who also got PB's for distance. Bananas are the best for distance days.

AUS3333 said..




I don't know the facts but others here will jump in i hope.
Only recently was canmore approved but when you did this post the canmore was not allowed for contribution of team scores.
Check
Is there rule bending going on here or just rule changing to suit certain people.
I have never checked anyone's file or flag a one, this forum is a giggle if anything

Cocky2 said..




#The Canmore has been approved for use as it sits somewhere in between those already mentioned. It has the potential accuracy of the GT-31 as it is a Doppler based device, but it has very limited verifiability. If you are posting results that are counted in the team challenge in a competitive team you should inspect the results closely in a stand-alone analysis program (GPS-Results/GPSAR-Pro/RealSpeed) for unusual results and errors. Preferably, team captains or the team 'tech guru' should help with this, and if there is any doubt the files should be sent to one of the GPS-TC technical advisors for a second or third opinion.

AUS3333 said..






Check out this file posted with Garmin non approved device follow link and check out distance PB gpsteamchallenge.com.au/sailor/view/5501
Remember when i did 325 kms at lake catharabah and my gt31 didnt have sd card it only recorded 150km, every one knew i did it but post was removed because Peter cochrane flagged it ( so Ian told me so), One rule for everyone please

tbwonder said..
Not sure of the exact date, but here is a post from Sailquik from June 2015

Hroar said..




Shannon I didn't flag your session, quite a few of us talked about including Anne the Vikings captain who couldn't be bothered looking into and was happy to let it go to my disgust, apart from what was on the screen of your gt31 you could not produce a two files to prove it as are the rules in GPSTC when you are going for a Pb. You only have yourself to blame if you didn't think to put a SD card in your GT31 & carry a Canmore GP102 as backup. If you don't re-zero a GT31 after every use the distance odometer keeps adding up and Max speed stays in there as well. I'm sure Daffy & Decrepit will agree with this as has constantly been discussed off late in these forums.
Thankyou, Peter Cochran.

Hroar said..
... apart from what was on the screen of your gt31 you could not produce a two files to prove it as are the rules in GPSTC when you are going for a Pb.