Dear Speedfreak Forum,
Sadly, my GT-11 has surrendered to a lifetime of abuse (and salt spray)... RIP. 
Now some advice please. I read the GT-31 is not longer in production and available, so what do I use... and where do I find it?
One note... I use a Mac, so need to be able to interface with whatever GPS I acquire. Perchance someone out there in SeabreezeWorld is selling one?Cheers,Mark DeFriest
mark@markdefriest.com.au
I bought a gt-31 about 2 months ago. They should still
be available. Google is your shopping friend 
Select to expand quoteSimon100 said..
get a camore they cost half as much and cant really be any worse
Except that they are quite a bit worse.
Fangy has a canmore and a Mac, he's got it working. But it's not a direct replacement for the GTs, the files seem as accurate, when compared with a GT31 worn next to it. But it has none of the error checking output the GT31 has. Also it's small and the font is minute and of our divisions only gives max speed in Km/hr. But as a back up, on your head, it's good value.
Select to expand quotedecrepit said..
Fangy has a canmore and a Mac, he's got it working. But it's not a direct replacement for the GTs, the files seem as accurate, when compared with a GT31 worn next to it. But it has none of the error checking output the GT31 has. Also it's small and the font is minute and of our divisions only gives max speed in Km/hr. But as a back up, on your head, it's good value.
MANY thanks for all your input... I've just ordered a GT31 from Andy at Windsurfing Gear which cost $246 (which included the express post to WA). He actually sent me a confirmation email today (Christmas)... now THAT's service.
Select to expand quotemathew said..Simon100 said..
get a camore they cost half as much and cant really be any worse
Except that they are quite a bit worse.
how is it worse . i have one it seems to do its thing , doesnt display as much but also is way smaller so its a bit of a even trade off i think .
I emailed the guys from Gps-speedsurfing the other day. They are working on the thingsee solution for June.
In the meantime they suggested the tomtom multi sport watch.
Might be worth having a look.
Dan
Select to expand quotedanward79 said..
I emailed the guys from Gps-speedsurfing the other day. They are working on the thingsee solution for June.
In the meantime they suggested the tomtom multi sport watch.
Might be worth having a look.
Dan
Dan.... the Tom Tom looks very interesting... I kinda wish I'd read your post before committing to the GT-31.
Select to expand quotedanward79 said..
I emailed the guys from Gps-speedsurfing the other day. They are working on the thingsee solution for June.
In the meantime they suggested the tomtom multi sport watch.
Might be worth having a look.
Dan
The Tom Tom Multi sports watch suggestion is news to me. Did you get that from Dylan De Jong?
I see they announced contact with Tom Tom with a view to developing their devices for Windsurfing but as far as I know they still are not suited.
Select to expand quotesailquik said..danward79 said..
I emailed the guys from Gps-speedsurfing the other day. They are working on the thingsee solution for June.
In the meantime they suggested the tomtom multi sport watch.
Might be worth having a look.
Dan
The Tom Tom Multi sports watch suggestion is news to me. Did you get that from Dylan De Jong?
I see they announced contact with Tom Tom with a view to developing their devices for Windsurfing but as far as I know they still are not suited.
No, I had contact from Jan Hendrik de Bruin.
I am reluctant to buy a (B)GT-31 considering than they are so old. They are also like rocking horse poop. So I messaged them to see what they are up to. My thoughts are to use my Garmin Montana (although huge), until the ThingSee solution is sorted. I might also get the Mrs a TomTom watch ;-)
Select to expand quoteSimon100 said..mathew said..Simon100 said..
get a camore they cost half as much and cant really be any worse
Except that they are quite a bit worse.
how is it worse . i have one it seems to do its thing , doesnt display as much but also is way smaller so its a bit of a even trade off i think .
Battery life. Precision / Error. Screen size. Water resistance.
Select to expand quotemathew said..Simon100 said..mathew said..Simon100 said..
get a camore they cost half as much and cant really be any worse
Except that they are quite a bit worse.
how is it worse . i have one it seems to do its thing , doesnt display as much but also is way smaller so its a bit of a even trade off i think .
Battery life. Precision / Error. Screen size. Water resistance.
there the same accuracy , battery life yeah but who sails that long and although the gt31 looks like it has some sort of waterproofing it doesnt seem to work in the slightest
I'm keen to track 1 hours and be able to see current speed, average speed and duration (from start), preferably with the speeds in knots. Will the Tom Tom multi sports do all of this? I bought one of the cheaper Navig8tor GPS watches and it wouldn't do the average speed properly as you need to set it for laps and couldn't select 1hr.
Select to expand quoteSimon100 said..mathew said..
Battery life. Precision / Error. Screen size. Water resistance.
there the same accuracy , battery life yeah but who sails that long and although the gt31 looks like it has some sort of waterproofing it doesnt seem to work in the slightest
They aren't the same accuracy as they haven't undergone the some rigor for systematic error evaluation. ie, has there been an evaluation of say 2 even two Canmore's, side-by-side, while travelling many hundred km's, then checking every data point to verify that there is a consistency of the PVT and doppler error ? [ If there has, please share / point me at the info. ]
As for battery life... you obviously haven't heard of 500km per day. 
Finally, the waterproofing held up nicely where I had forgotten to close two of my GT31 cases last week... so it definitely works. ie: a GT31 isn't water-impact proof, but it is definitely splash/dunk proof.
Also, Canmore does not record positional data and therefore, AFAIK, it can't give the data need for calculating Alphas.
Select to expand quotedanward79 said..sailquik said..danward79 said..
I emailed the guys from Gps-speedsurfing the other day. They are working on the thingsee solution for June.
In the meantime they suggested the tomtom multi sport watch.
Might be worth having a look.
Dan
The Tom Tom Multi sports watch suggestion is news to me. Did you get that from Dylan De Jong?
I see they announced contact with Tom Tom with a view to developing their devices for Windsurfing but as far as I know they still are not suited.
No, I had contact from Jan Hendrik de Bruin.
I am reluctant to buy a (B)GT-31 considering than they are so old. They are also like rocking horse poop. So I messaged them to see what they are up to. My thoughts are to use my Garmin Montana (although huge), until the ThingSee solution is sorted. I might also get the Mrs a TomTom watch ;-)
I checked with Jan. No good for GPS windsurfing. He says they may be OK for SUP crossings.
GT-31 is still by far the 'state of the art' for GPS windsurfing! They only stopped making them because they could not get the Sirf111 chips anymore. Nothing else commercially available now comes close to its accuracy and utility for windsurfing. Grab one while you can still get it.
Locosys say they are still working on a 5hz replacement for the GT-31 and last I heard they were in testing phase. They are very tight with details though.
I cant complain about the waterproofing one of my GT31's had 45 min in our front loader washing machine in my shorts pocket no problems.
Select to expand quoteT 11 said..
I cant complain about the waterproofing one of my GT31's had 45 min in our front loader washing machine in my shorts pocket no problems.
I sneezed on my Canmore and just about killed it 
( that actually might say more about the quality of my sneezes....)
Select to expand quote
Got 2 left and not sure can get more with current demand..I got a spare..
Select to expand quoteT 11 said..
I cant complain about the waterproofing one of my GT31's had 45 min in our front loader washing machine in my shorts pocket no problems.
Hi Simon, if your just measuring just for 'fun' and don't want to post files or break official world records there are some great 'phone apps' for a few bucks and some amazing water proof hard phone covers, the readouts, reports and instant google maps and tracks on some of the apps are great.
And before I get shot down in flames , yes they are not as Acurate especially for the corners, but for 'fun' they are great cheap alternatives, and easy to use.
There are some 'garmin' products that work on KA72 wind wanderers and Freerace Qld software also, as does the Canmore.
Dylan at Ka72 maybe able to provide a list as I know he has been working hard at accomodating other products, it's a massive job, and it hurts my head when it's explained to me!
Select to expand quoteJonesySail said..
Hi Simon, if your just measuring just for 'fun' and don't want to post files or break official world records there are some great 'phone apps' for a few bucks and some amazing water proof hard phone covers, the readouts, reports and instant google maps and tracks on some of the apps are great.
And before I get shot down in flames , yes they are not as Acurate especially for the corners, but for 'fun' they are great cheap alternatives, and easy to use.
There are some 'garmin' products that work on KA72 wind wanderers and Freerace Qld software also, as does the Canmore.
Dylan at Ka72 maybe able to provide a list as I know he has been working hard at accomodating other products, it's a massive job, and it hurts my head when it's explained to me!
yeah i used a android app when my gt31 broke i dont think it was to bad really but i have a feeling it robbed the 2 second times a bit or maybe the ka72 software is more aggressive on those file types ? But i have the canmore now and its accurate , is there going to people complaining about canmores being used in gpstc ? . About the phone in corners isnt that where there would be less of a difference between them all as if there all logging at 1 second intervals and averaged over a distance of 500m that is where a position based reading would show less difference to a doppler one isnt it ?
The Canmores accuracy for any given track or run is not verifiable. Period. If you have a GT-31 to compare it with side by side, it may well give the same reading for most runs leading you to assume it is accurate. That assumption would be wrong. This is simply because if you use it on it's own you have no way to verify it's accuracy. You will not know when it has a hiccup and spits out rubbish which every single consumer GPS I have ever tested (GT-31 included) does sometimes. Unfortunately, the Canmore does not record the GPS position data. If it did you would have at least something to compare with the Doppler readings and something that may in some cases verify errors. This was the situation with the GT-11 before we were able to get accuracy data from the GT-31, and we still use the positional data as another comparison check.
Also, the 2 second speed calculations are far less reliable than those for 10 seconds or longer. Don't place too much faith in them, unless you are trying to one-up your sailing mates of course.
Devices that record Trackpoint data for speed calculations, like most sports GPS and perhaps Smartphone based apps, are inherently less accurate/reliable for measuring speed by a large factor. This is in the Canmores favor as it records Doppler speed, but you still can't properly say it is as 'accurate' as a GT-31. The results it produces may be pretty much the same most of the time, but you will never know if they are 'accurate', they may well be very wrong, and at times, hopefully rarely and obviously, they will be very 'inaccurate'.
Neither Trackpoint or Doppler based calculations are very 'accurate' for Alphas. They both have issues and this is why the WGPSSRC has not implemented any official records for this catagory yet. This may well change with better technology and higher Hz recording.
Take this information and use at as you will.
The GPSTC has allowed the Canmore for the fun rankings, but this does not make it 'accurate'. We strongly suggest those competing at the higher levels use only the GT-31.
Hi Guys,
I've read my name in some postings, and i thought it would be handy to post from first hand :) There have been some questions about the GT-31, and other GPS devices lately. I've just update the GPS-SPeedsurfing.com website with some new information about that, and i thought i would be handy to post this from first hand:
"Since the introduction of GPS-Speedsurfing.com we have used several approved GPS-Devices, in recent years we switched over to Doppler supported devices, first introduced with the GT-11 and later the GT-31. Sadly the production of the GT-31 has reached the “End of Life” status, so the availability will be very limited in the next months.The Technology team has been working on other GPS-Devices in the last months, and we are currently working on two parallel tracks. The first track is focused on the development of a new High-End GPS Devices, capable to measure with Doppler GPS functionality. This High-End Device will be based on the ThingSee, and will be equipped with our own custom software, making it fully equipped for our special features like the 10 seconds run, the Nautical Mile, Alpha speeds, etc etc.
The second track that we working on is the use of default GPS Devices, we realize that this standard devices will not reach the high-end specifications of Doppler GPS today, but the quality has increased that much thats it's suitable for normal day-to-day use, and the average surf-sessions this devices could be a nice alternative for some windsurfers. We are exploring the possibilities of enhancing the software of “standard” GPS-Devices. Target is to reach the current standards of GPS logging at GPS-Speedsurfing.com, so making it possible to measure at a 1 per second rate, and log the number of satellites.
In general we allow any GPS Devices that’s is capable of logging GPS Data with a sample rate of 1 per second and support the .GPX data format. Please notice that the use of .GPX format is not allowed for records, and is more suited for normal day-to-day surf sessions. The only fully approved format at this stage is the .SBN format, in general only supported by the (B)GT-11 & (B)GT-31. We expect to bring the new High-End device on the market in June 2015."
Kind Regards,
Jan Hendrik de Bruin
Marketing & Communications www.gps-speedsurfing.com
Thanks Jan, that makes things a lot clearer.
Do you have a rough idea of what the new device will retail for?
Select to expand quotedecrepit said..
Thanks Jan, that makes things a lot clearer.
Do you have a rough idea of what the new device will retail for?
Not sure at this moment, but we are aiming at $ 180 - 240 US Dollar.....
