I am new to the GT-31. When I go to upload a file after a sailing session, there are 5 smaller files instead of one complete file. 
I use a 2 GB Sandisk and card reader to record the info and dowload it.
It was only a 2 hour session so not very long.
Any helpers out there who have had this problem?
Go to settings, there is a part which calls up file size, change that to "Card size"
Thanks for the quick reply, Elmo
It appears to be in "memory card" rather than "settings". I had the file size on 128kb but now have it on card size.
Hopefully this was the problem. 
Thanks again.
Logically that would fix it but it still gave me 6 files. Of these, there were two that made up the session and they are on the KA72 site (Weyba Downs).
Two files were SPD (max speed) files that were in between the two session files.
The other two were very small (SBN) files, but had no data.
Not sure what the problem is
Nebbian
Thanks for the link. A friend sent me the link when I first got the GPS and I used it to set it up. I did not worry about the firmware upgrade (or any steps in part B) as it is version 1.4 and a new GT-31 (hopefully this is right).
I went to part C and went through the settings (although I did have the file size set at 128KB and now it is on card size).
I had an old SD card (128 MB) in it when i first tried it & thought that might have been the problem (although the card formatted and the GT31 recognised the card).
The next step I was thinking was resetting the defaults and redoing the settings again (a bit like uninstalling and then reinstalling on a computer).
Any further thoughts?
Redsurfbus
Not sure why it is in two files either.
I was out on the water and did not switch it off and on again. I would think it is extremely unlikely to have switched off, then on again by bumping it (considering it is the small button and you have to hold it down).
I will have a look at your sight tomorrow.
Thanks
on-fix means it stops recording when theres a spike or not enough sats, change it to on and see if that fixes your problem. It seams to have been the cause of mine
G'Day Jeffro,
Glad to see you're in a team!
Where are you wearing the gps? it needs a clear view of the sky to keep the satellites "fixed". Under a wet wetsuit will also screen it and cause problems.
As kato says selecting "on" instead of "on fix" will stop this creating multiple files, but you'll still have annoying gaps and spikes in your data.
Better to make sure of good satellite reception.
I've just downloaded your files, fi you like I can join them together and email back to you, but you'd better PM me with your email address.
here's the two files together.
notice the gap between the 2, that's obviously where the gps lost the satellites. it's 5min long and there's not much movement, too long for you to be underwater. Perhaps you were walking the rig with GPS shielded in some way?
OK merged the files and got these results, using GPSarPro. set to doppler
Total Distance : 33.178 Km
5 best 2 second (at least) average = 35.46km/h [19.14Knots]
2 second run n°1 = 37.64km/h [20.32Knots] (20.9 m. in 2.000 s.)
2 second run n°2 = 36.12km/h [19.50Knots] (20.1 m. in 2.000 s.)
2 second run n°3 = 35.07km/h [18.94Knots] (19.5 m. in 2.000 s.)
2 second run n°4 = 34.27km/h [18.51Knots] (19.0 m. in 2.000 s.)
2 second run n°5 = 34.18km/h [18.46Knots] (19.0 m. in 2.000 s.)
5 best 10 second (at least) average = 33.96km/h [18.34Knots]
10 second run n°1 = 34.96km/h [18.88Knots] (97.1 m. in 10.000 s.)
10 second run n°2 = 34.67km/h [18.72Knots] (96.3 m. in 10.000 s.)
10 second run n°3 = 33.69km/h [18.19Knots] (93.6 m. in 10.000 s.)
10 second run n°4 = 33.44km/h [18.06Knots] (92.9 m. in 10.000 s.)
10 second run n°5 = 33.06km/h [17.85Knots] (91.8 m. in 10.000 s.)
5 best 3600 second (at least) average = 6.34km/h [3.42Knots]
3600 second run n°1 = 19.12km/h [10.32Knots] (19,119.4 m. in 3,600.000 s.)
3600 second run n°2 = 12.56km/h [6.78Knots] (12,559.8 m. in 3,600.000 s.)
5 best 1852 meter (at least) average = 24.23km/h [13.08Knots]
1852 meter run n°1 = 26.55km/h [14.33Knots] (1,858.3 m. in 252.000 s.)
1852 meter run n°2 = 25.51km/h [13.77Knots] (1,856.5 m. in 262.000 s.)
1852 meter run n°3 = 23.79km/h [12.85Knots] (1,857.1 m. in 281.000 s.)
1852 meter run n°4 = 23.29km/h [12.58Knots] (1,856.7 m. in 287.000 s.)
1852 meter run n°5 = 22.01km/h [11.88Knots] (1,852.3 m. in 303.000 s.)
5 best Alpha-500 average = 18.06km/h [9.75Knots]
Alpha-500 run n°1 = 20.92km/h [11.30Knots] (499.8 m. in 86.000 s.)
Alpha-500 run n°2 = 18.32km/h [9.89Knots] (498.7 m. in 98.000 s.)
Alpha-500 run n°3 = 17.63km/h [9.52Knots] (499.4 m. in 102.000 s.)
Alpha-500 run n°4 = 17.01km/h [9.18Knots] (496.0 m. in 105.000 s.)
Alpha-500 run n°5 = 16.44km/h [8.88Knots] (497.8 m. in 109.000 s.)
Thanks all of you for your comments and help.
I have sent PM's to some of you, but here is what I will do:
I have set file size to card reader (yesterday).
I will set log switch to "on".
I will adjust the GPS more firmly (if I can) on my arm to try and keep a good "connection".
The graphs Mike did are great and explain what I was doing.
For those interested, it was:
I was on a JP super light wind board (SLWB) at first but there was only about 6 knots. After about ¾ hours I swapped boards with a friend, Peter (end of the red charts) and put my 7.5 Ezzy on his Tyronsea 370 (I am around 57kg). We would have stopped for 5 mins or so. I suspect that is where the GPS broke its signal.
Peter (about 98kg) put his 10.7m on the SLWB. He started planing as the wind picked up (around 10-15 knots) but had a fair bit of trouble getting upwind. I suspect the 56cm fin was way too small with his sail??? When we swapped back again I had no trouble with the 7.5)
I got going well on the longboard (yellow graph) & you will see where I slowed right down at the turns (It was about 8 knots then). We swapped boards back again near the end of the session (you can see the break) and then I got going on the SLWB.
The wind picked up after about an hour & ½ into the 3 hour sail (10-15 with possible gust to 17 for a short time). I suspect the graph had more data to go on it as I was going well on the SLWB but had more than 2 runs (about 5).
Hopefully we will get a bit of a breeze this arvo & I will post the outcome.
that is usually happend when download via card reader. I never do that. Using usb cable and dowload direct from GT to software (gps results) never have more then one file. On card can't be backuped more segments, depends of settings (min speed, sat lodt, onfix....) I have on-fix, min speed 3, read direct from data logger, save file and that's it
after that: misc, delete, delete all, and allways empty 4 tomorrow
yes, important is: memory card-card size. suggestion, try another sd card, put log switch to off, format card, return log switch to ON, and try it
on of my friend had this multiple files problem becouse of SD card, with another never again
so check, try and let us know
NO WIND ??? here same scenario, check it with car or bike ;)
for checking is ok
Just to throw a spanner in the works,
I had no end of problems with my GT set to ON. What happens here is that even if it knows that it's lost, it will still write its best guess to the card. This does lead to massive spikes in your data, as well as the first data point logged on a new day being equal to where you were when you turned it off the last session...
After pulling my hair out I set mine to ON-FIX which solved all these issues. I always only have one file. ON-FIX won't make multiple files, it just stops writing to the file if it gets lost, then continues on when it finds itself again.
I would only recommend setting your GT to ON if you are experienced in analysing data (like kato), and can recognise when the GT is just writing its best guess to the card. For most mere mortals I strongly recommend using ON-FIX as it 'just works'.
ON-FIX is not your issue, I would suspect that your navi reset itself for some reason (perhaps the battery plug isn't making good contact with the pins on the circuit board or something).
Hi Guys
I went out today and the GT31 worked like a dream
Thanks to you all for your help & comments!
I put the log switch back to on-fix as Nebbian suggested.
I will update the firmware as redsurfbus suggested (although when I upload to ka72 it doesn't say old firmware).
Cheers
Jeffro
Chances are the old firmware is fine, but the new is better, a few features that save time like the delete all under the misc option......quick way of clearing the top speeds when you go for a session. I see no point in keeping my top speed on the unit as then I dont see my top speed for the session and if I am improving through the session. Suppose everyone is different as I know some people keep their pb loaded......
My unit froze twice (dont worry we can fix that as well.....) with the old firmware, have not had that problem with the new.....
Great stuff that its now working correctly for you.
