You look OK at the moment Adrian.

Approved GPS devices for posting on GPS-TC: The current policy of GPS-TC is that GT-31, GW-52 or GW-60 must be used for posting Doppler based data (D) by individuals vying for the top positions, and by team members contributing to monthly team ranking scores (commonly called "Jellybeans") The GW-52 and GW-60 should be set for 5hz logging. GPS-TC also allows the legacy pre GT-31 GPS (mainly Garmin) that only produced speed results from positional data (T), but only for those sailors not in the category mentioned above.

sailquik said..
You look OK at the moment Adrian.

Approved GPS devices for posting on GPS-TC: The current policy of GPS-TC is that GT-31, GW-52 or GW-60 must be used for posting Doppler based data (D) by individuals vying for the top positions, and by team members contributing to monthly team ranking scores (commonly called "Jellybeans") The GW-52 and GW-60 should be set for 5hz logging. GPS-TC also allows the legacy pre GT-31 GPS (mainly Garmin) that only produced speed results from positional data (T), but only for those sailors not in the category mentioned above.

I've actually contributed to quite a few jellybeans in the past using the Geko, so it seems I have been cheating!! I am not doing much sailing at the moment, so it does not make much difference. To that end, I don't plan to buy a device just for sailing because I would not get much use out of it. I do want a vivoactive 3 for other purposes, and it occurred to me that it may be a convenient option to use for sailing as I could read it much more easily than my geko while sailing.

Thanks for the info James!

jamesf said..
Hi Adrian, the datafield I use for on-water feedback on my Vivoactive HR is "Wind/Kite Surfing Datafield" by user FIN151. It works well and is usually close 2s peak to my GT31.

apps.garmin.com/en-US/apps/b820a772-e335-406a-85b7-2ac6a0e5b61a

The Vivoactive 3 doesnt appear on the "supported devices" list yet but thats probably because the developer hasnt had time to test it yet.

So I got my Vivoactive 3. Unfortunately the data-field from FIN151 does not support it at this time. I am sure there is a way to manually force it on but the Connect app will not download it on (anyone got tips on manual installation?). I think I can setup a windsurf activity that does most of what I need without the need for the data field (like just have a normal page with max speed, distance, time etc.). I have been using an old Geko for many years without data fields like 10s and alpha etc so I am used to sailing without the data until I upload later. The VA3 does have 1 second sampling (which is better than my Geko which only had 2s). It is nice that it uploads to Garmin Connect automagically through the phone. Connect can then upload to Strava automagically also, but would have to manually upload to GPS Team Challenge. I think this could be done easily by exporting from Connect and uploading via KA72 which should be fairly quick and simple.

It is a pretty nice smart watch... not as fancy as Apple, but looks more traditional and has much better battery life. It gives good notifications of messages and calls etc. It would be handy to have my phone with me when sailing so I can get alerts on the watch. Would be good to know if my family is trying to call or something as I have been caught out in an emergency while sailing and offline before. I will have to work out a tether as I have broken watch bands sailing with watches before and never seen the watch again. A light tether around the wrist in case the band/pin breaks should do the trick.

PLEASE !!!!! Use only the approved GPS devices, there's been enough agro over this issue ! Use whatever device for fun but for GPSTC and GPS3 follow the recommended devices.

kato said..
PLEASE !!!!! Use only the approved GPS devices, there's been enough agro over this issue ! Use whatever device for fun but for GPSTC and GPS3 follow the recommended devices.

There seems to be an issue here. Some people choose to pursue windsurfing as there big thing in life. They are very competitive about their performance in it, and they express this through the GPSTC. I am all for that, as I am like that with some other things I do. Others do windsurfing as an aside and enjoy the social aspects provided by GPSTC, but they are not that competitive and do not expect to make any real difference to anyone else on GPSTC. I am like that with windsurfing. If I contribute to a jelly bean, it is usually only because fast guys in my team were not out sailing that day. I am lucky to get out for a sail 5 times a year, but I love it when I do, and I enjoy the banter in my team on GPSTC as well as getting involved a bit on Seabreeze even if it is just living the life in my head rather than out on the water.

I am unwilling to spend as much on an approved GPSTC device I will use maybe 5 times a year as on a Garmin watch I wear daily and do fitness activities with it daily. My newest windsurfing gear is >5 years old with most of it being >10 years old. The Geko has been great, but it is a pain to upload data. I am going to use the Vivoactive which is likely to be more accurate than the Geko I have been using for years. If someone wants to kick me off GPSTC for something that effects nobody else, I would be disappointed but it would not sway me to buy an expensive device I will use occasionally.

Windsurfing with a GPS in Oz is not the exclusive domain of the GPSTC, so I trust we can still discuss this device here regardless of GPSTC approval?

+1 on sailquick's post!

You can enter 0s in the results column and post your ViviactiveHR results in the comments , that way your numbers are there, but not in the data base.
There's no other way around this that I can see, if you want to be part of the GTC.

Could we not have a system that allows unverified (without doppler etc,) data to be added to the database with the limitation that if the data sets a record or contributes to a team result in a way that effects monthly overall results, the data can be revoked?

I have lots of data from a Geko at 0.5Hz sampling already in the database and could continue to add more within the rules. The replacement device uses GPS and GLONAS at 1Hz sampling and is unlikely to provide worse data to the database than I can already legally add. I understand the notion that I may get some result that is inaccurate and may effect some overall team result, but I also recognise that if that happens, I am happy for it to be revoked.

Surely 90% of the people using GPSTC have minimal bearing on any team results or records yet they are all required to purchase a dedicated device with unproven reliability and support and significant cost just to be a part of it.

vosadrian said..
Surely 90% of the people using GPSTC have minimal bearing on any team results or records yet they are all required to purchase a dedicated device with unproven reliability and support and significant cost just to be a part of it.

That is actually not the case. If you watch the constantly changing team rankings, the "butterfly effect" is always in play.

One good team result in one category from a team that is not even in the top 10 can easily change around the positions in the rankings, and in the top few teams. It would be almost impossible to monitor the results acurately enough to know when your posting had an effect on the top ranking, let alone the middle ranking. Every team score has effects on the ranking.

The approved devices are not 'unproven'. Plently of people are using GT-31's that are many years, and many Nautical Miles old. Some are even selling them when they upgrade to a newer model. I suggest this may a good avenue to pursue.

The backup support from sellers and Locosys also reliable and proven. There are thousands of these devices being used with great reliability if you do your part. Sure, there are occaisional isolated issues, but these are addressed as with any other consumer device.

The cost is clearly not much of an issue for the many hunderds of GPSTC participants compared with the joy and satisfaction they get from being part if it. You said you also value the participation highly.......

As has been said many times, the cost of an approved gps is just a quite small component of the whole cost of this sport. There are few major components of your kit that cost less, even if you do buy second hand.

You can still participate under the rules with the options Decrepit and I have stated above.

End of subject.

vosadrian said..
I am unwilling to spend as much on an approved GPSTC device I will use maybe 5 times a year as on a Garmin watch I wear daily and do fitness activities with it daily. My newest windsurfing gear is >5 years old with most of it being >10 years old. The Geko has been great, but it is a pain to upload data. I am going to use the Vivoactive which is likely to be more accurate than the Geko I have been using for years. If someone wants to kick me off GPSTC for something that effects nobody else, I would be disappointed but it would not sway me to buy an expensive device I will use occasionally.

Separate to the rest of the discussion... This is just hogwash:
a) The Vivo isabout twicethe price as the recommended Locosys watch.
b) You are aware that a GPS-Watch can be used for say Running, cycling, or any other sport that collects location-data ? ... in fact it gives better results in some cases.

vosadrian said..
Whether it actually provides more accurate data is completely unknown. Nobody has done a serious effort at comparing the data for a Garmin, but all that have done a small effort have found it to be comparable.

Well I started to evaluate a doppler garmin watch but when I posted the results I got red thumbed, so I gave up.

I agree the watch data is possibly as accurate, but it can't be verified, because it doesn't record accuracy data.
Any GPS device can have the odd glitch, the difference with the newer approved devices is that the inaccuracies can be seen.


As a Garmin customer you could try asking them for a firmware update, so that the accuracy data is recorded, but I guess it's possible the chip they use doesn't output it.

vosadrian said..
What is the point in quantifying the accuracy of a device using a data parameter that cannot be verified?

You need to talk to Tom about that

yoyo said..
Vosadrian said "Garmin newer products use GPS and GLONASS. Not sure if the GW-60 does, but I see no evidence that it does. This would have to add a large benefit to accuracy"
This is NOT true!
GLONASS does not have the accuracy of GPS. The addition of GLONASS does not improve the accuracy. The main benefit is in acquisition time, as you have found. Additionally the GLONASS satellites are positioned more favourablely for higher latitudes than GPS which would be beneficial for users in those areas.
NB. In certain circumstances of poor gps reception (urban canyons, hiking/skiing/jogging under trees) ie real world situations Garmin are built for, GLONASS may improve accuracy but this is not the case with windsurfing where you are in the open with an unobstructed view of the sky.
I think Decrepit's idea is an elegant solution. Post zeros, comment on Garmin Viviactive results.
Andrew, I see where you are coming from about accuracy data. But surely if Mike had found that the Garmin in numerous trials gave essentially the same 2sec 10sec NM etc data as the Locosys watches then that should be good enough for average gpstc sessions and the higher standard can be reserved for records? A bit like gps-ss stipulating 2 Locosys units for records.

So this is not for windsurfing use, but on Garmin products you can optionally switch off GLONASS to improve battery life. Anecdotally there is an improvement in accuracy with GLONASS on. This improvement in accuracy is not measured with some calibrated test equipment (and neither is any of the verification done by GPSTC on the locosys products I presume), but is viewed in smoother tracks that follow running/riding/walking paths more closely. As you say, mostly in windsurfing you have a good view of the sky, but having GLONASS is not going to make things worse, and has the potential to improve things in some situations. I suspect Garmin has added it predominantly for improved acquisition time and it makes a great benefit to that. Instead of having to wait for a minute before commencing your activity you can pretty much just press a button and commence the activity immediately (within seconds) and have GPS position ready to go.

The way I see this is that the Garmin product makes some advanced hardware. Because of their sales volumes they can make advanced hardware at a low cost (but they sell at a price the market will accept and pocket the profit). But they are focused on fitness markets. Locosys have made a product more specific to windsurfing needs. It is low volume and they need to charge enough to cover development costs. It probably has less advanced electronics, but it has realised a niche market where speed accuracy is important and has optimised recorded data to enable accuracy to be assessed. Garmin products are likely as accurate, but they only provide the info they need to as extended GPS data would likely just cause them a support nightmare.

I understand the frustration for some here. I use Strava which is a competitive platform for cyclists. Basically you or others can create segments which are virtual time trial courses. Every time you ride a segment your time gets added to a leader board. Strava can be used on many platforms including phones with poor GPS capability. This often results in people taking the lead on a leaderboard due to GPS error. The good thing about strava is that any user can view the GPS (and other data) for a segment effort, and if there is GPS error they can flag it is an error and it is then removed from the leaderboard. This capability does not exit in the GPSTC. We trust the data entered by the competitor is accurate and cannot easily dispute it. I would prefer Strava users not use a phone, but atleast it is fairly easy to dispute it. I think if the GPSTC can provide a way to store logs and apply analysis to the file, it would be a big step up. Something like Strava would be awesome but probably achievable given the effort required.

In the case of GPSTC, I think there are so many ways for incorrect data to get into the database. I think that allowing legacy products with known GPS accuracy limitations is more of an issue than newer ones. But I think regardless of the device, the bigger risk is people blindly posting data that has GPS glitches in it. When I post, I expect my 2S peak to be about 1-3 knots quicker than my 5X10S. I expect all my runs in 5X10S to be within about a knot except on a short session with only a few powered up runs. I know what speed my Alphas are normally for the conditions. If anything looks out of whack I won't post it. I realise that having accuracy data in the log gives a means for people to prove data is inaccurate.... but realistically even that accuracy data is questionable. Simply looking at graphs of speed and the path taken will quickly show GPS issues.

kato said..
Why are we doing this again

Because it is a thread on a Garmin watch.....

yoyo said..
Andrew, I see where you are coming from about accuracy data. But surely if Mike had found that the Garmin in numerous trials gave essentially the same 2sec 10sec NM etc data as the Locosys watches then that should be good enough for average gpstc sessions

Well, it depends what you mean by 'various trials', and it depends what you mean by 'essentially'.

Almost any consumer type of GPS will give you 'similar' results to the approved devices some of the time, and some will even give you 'similar' results quite a lot of the time. They will also give you rubbish results some of the time. Sometimes that is reasonably obvious to the trianed eye, and can sometimes also be picked up by results processing filters in the software based on other factors. What really concerns us is the not quite so obvious errors, or the highly 'suspected' errors that are there that can easily, quite significantly, affect the GPSTC rankings and would otherwise be not able to be verified, even if we think they are suspect. The use of 'Doppler error data' performs that function very reliably. Without it, were have no way to reliably, consistently verify accuracy.

Wow, vosadrian that was a long post. Had a few " I suspect" and "probably"s in there. Lots of assumptions. I came across this in depth review of gps watches.
fellrnr.com/wiki/GPS_Accuracy
With some interesting observations.
"3.1 Progress of newer watches
I expected GPS watches to improve with time, but the opposite appears to be happening. With the Garmin devices especially, you can see that the older watches generally do far better than the newer ones. I suspect this is due to compromises to get better battery life and smaller packaging and the cost of GPS accuracy." and
12. GPS and GLONASS
I have found that GPS plus GLONASS produces less accuracy than GPS alone, something that is a little counterintuitive. I have no definitive explanation for this, and I do have a working hypothesis. My thought is.."
He is quite critical of certain Garmin GPS watches in regards to accuracy and precision. He also noted that some watches had quite different performance with different software updates.
This I guess leads to Sailquik's point, which I overlooked on my previous post, if you lessen the standard and allow one particular unapproved gps watch then you just open a can of worms where anyone with a gps watch or phone will say why not my unit.