I've now had several sessions with the Garmin (F3) side-by-side with the GT31 and so far the F3 is consistently slower and records less distance, but not by much. When sailing this week the GT31 recorded a PB whereas the F3 didn't. Glad I had the GT31 and I will continue to wear it, but I love the feedback I get from the F3 and for every day sessions I probably won't bother pulling the memory card out of the GT31 for KA72 upload when the F3 does it wirelessly as soon as I walk in the front door 
As an example, here's the stats from my last session:
GT31
2 Sec Max: 37.497
5x10: 35.009
HR: 16.017
Alpha: 21.292
Nm: 24.545
Distance: 107.064
Garmin F3
2 Sec Max: 36.973
5x10: 34.679
HR: 15.777
Alpha: 21.264
Nm: 24.114
Distance: 104.851
Apart from the use for windsurfing, I just love the F3 for pool swimming and especially for soft sand training as it's got great settings for configuring fartlek and interval sessions. Plus all the other statistics a runner needs.
No, unfortunately it hasn't been approved for gpstc. Like Sean says, it's a great looking watch and has heaps of functionality.
Select to expand quoteN1GEL said..
I've now had several sessions with the Garmin (F3) side-by-side with the GT31 and so far the F3 is consistently slower and records less distance, but not by much. When sailing this week the GT31 recorded a PB whereas the F3 didn't. Glad I had the GT31 and I will continue to wear it, but I love the feedback I get from the F3 and for every day sessions I probably won't bother pulling the memory card out of the GT31 for KA72 upload when the F3 does it wirelessly as soon as I walk in the front door
As an example, here's the stats from my last session:
GT31
2 Sec Max: 37.497
5x10: 35.009
HR: 16.017
Alpha: 21.292
Nm: 24.545
Distance: 107.064
Garmin F3
2 Sec Max: 36.973
5x10: 34.679
HR: 15.777
Alpha: 21.264
Nm: 24.114
Distance: 104.851
Apart from the use for windsurfing, I just love the F3 for pool swimming and especially for soft sand training as it's got great settings for configuring fartlek and interval sessions. Plus all the other statistics a runner needs.
Just the fact that it in your example it consistently reads low is cause for worry. Half a knot low is a very large difference in GPS technology!
Select to expand quotesailquik said..
N1GEL said..
I've now had several sessions with the Garmin (F3) side-by-side with the GT31 and so far the F3 is consistently slower and records less distance, but not by much. When sailing this week the GT31 recorded a PB whereas the F3 didn't. Glad I had the GT31 and I will continue to wear it, but I love the feedback I get from the F3 and for every day sessions I probably won't bother pulling the memory card out of the GT31 for KA72 upload when the F3 does it wirelessly as soon as I walk in the front door
As an example, here's the stats from my last session:
GT31
2 Sec Max: 37.497
5x10: 35.009
HR: 16.017
Alpha: 21.292
Nm: 24.545
Distance: 107.064
Garmin F3
2 Sec Max: 36.973
5x10: 34.679
HR: 15.777
Alpha: 21.264
Nm: 24.114
Distance: 104.851
Apart from the use for windsurfing, I just love the F3 for pool swimming and especially for soft sand training as it's got great settings for configuring fartlek and interval sessions. Plus all the other statistics a runner needs.
Just the fact that it in your example it consistently reads low is cause for worry. Half a knot low is a very large difference in GPS technology!
Yeah, .5 is a lot on a 2 second. My Suunto Ambit 2S was never that far off the GT31. But if it's consistently lower then I'm only hurting my own scores by using the Garmin, right? Would you be interested in analysing the files if I send them to you each time I sail? It would still be good to get the Garmins approved for GPSTC use. Is the GPSTC commitee happy for people to use these so long as they're not PBs? Or even if they are? Thanks, Nigel
Nope! Thousands of test miles with multiple GPS and GT-31's side by side and seldom more than 0.02 difference between the GT-31's and other high end verifiable GPS.Select to expand quoteseanhogan said..
maybe the gt 31 reads higher ???? 
www.seabreeze.com.au/images/forums/icon_smile_big.gifhttps://www.seabreeze.com.au/images/forums/icon_smile_big.gif' />
Select to expand quoteN1GEL said..sailquik said..
N1GEL said..
I've now had several sessions with the Garmin (F3) side-by-side with the GT31 and so far the F3 is consistently slower and records less distance, but not by much. When sailing this week the GT31 recorded a PB whereas the F3 didn't. Glad I had the GT31 and I will continue to wear it, but I love the feedback I get from the F3 and for every day sessions I probably won't bother pulling the memory card out of the GT31 for KA72 upload when the F3 does it wirelessly as soon as I walk in the front door
As an example, here's the stats from my last session:
GT31
2 Sec Max: 37.497
5x10: 35.009
HR: 16.017
Alpha: 21.292
Nm: 24.545
Distance: 107.064
Garmin F3
2 Sec Max: 36.973
5x10: 34.679
HR: 15.777
Alpha: 21.264
Nm: 24.114
Distance: 104.851
Apart from the use for windsurfing, I just love the F3 for pool swimming and especially for soft sand training as it's got great settings for configuring fartlek and interval sessions. Plus all the other statistics a runner needs.
Just the fact that it in your example it consistently reads low is cause for worry. Half a knot low is a very large difference in GPS technology!
Yeah, .5 is a lot on a 2 second. My Suunto Ambit 2S was never that far off the GT31. But if it's consistently lower then I'm only hurting my own scores by using the Garmin, right? Would you be interested in analysing the files if I send them to you each time I sail? It would still be good to get the Garmins approved for GPSTC use. Is the GPSTC commitee happy for people to use these so long as they're not PBs? Or even if they are? Thanks, Nigel
Yeah sure. I would like to have a study. It might be possible to work out if it really is consistently low, or something else is at play.
My gut feeling is that it probably will not be approved as it is non-verifiable with SDOP error data.
Select to expand quotesailquik said..N1GEL said..sailquik said..
N1GEL said..
I've now had several sessions with the Garmin (F3) side-by-side with the GT31 and so far the F3 is consistently slower and records less distance, but not by much. When sailing this week the GT31 recorded a PB whereas the F3 didn't. Glad I had the GT31 and I will continue to wear it, but I love the feedback I get from the F3 and for every day sessions I probably won't bother pulling the memory card out of the GT31 for KA72 upload when the F3 does it wirelessly as soon as I walk in the front door
As an example, here's the stats from my last session:
GT31
2 Sec Max: 37.497
5x10: 35.009
HR: 16.017
Alpha: 21.292
Nm: 24.545
Distance: 107.064
Garmin F3
2 Sec Max: 36.973
5x10: 34.679
HR: 15.777
Alpha: 21.264
Nm: 24.114
Distance: 104.851
Apart from the use for windsurfing, I just love the F3 for pool swimming and especially for soft sand training as it's got great settings for configuring fartlek and interval sessions. Plus all the other statistics a runner needs.
Just the fact that it in your example it consistently reads low is cause for worry. Half a knot low is a very large difference in GPS technology!
Yeah, .5 is a lot on a 2 second. My Suunto Ambit 2S was never that far off the GT31. But if it's consistently lower then I'm only hurting my own scores by using the Garmin, right? Would you be interested in analysing the files if I send them to you each time I sail? It would still be good to get the Garmins approved for GPSTC use. Is the GPSTC commitee happy for people to use these so long as they're not PBs? Or even if they are? Thanks, Nigel
Yeah sure. I would like to have a study. It might be possible to work out if it really is consistently low, or something else is at play.
My gut feeling is that it probably will not be approved as it is non-verifiable with SDOP error data.
So the Canmore is not approved? (I thought it was)
Stretch the Canmore is approved, but not recommended for significant scores.
The big problem with a watch is the underhand grip, when the watch is facing the water.
The reflection off the water is probably stronger than the direct signal from the sky, leading to all sorts of errors. Then there's the wrist movement during a gybe, to add to the problem.
Maybe if it was worn in a pouch on the upper arm or shoulder, it wouldn't be too bad. But any scrutineers have no way of telling where the device is worn.
It's bad enough trying to educate people on the most appropriate way to wear a GT31/GW52, without putting something that's more conveniently worn in a inappropriate place, into the mix.
Mike, I'm well aware of the issues of a watch GPS. I agree and I'm certainly not pursuing it for GPSTC. I do like the watch for additional info.
my point is that sailquick indicated that non verifiable data was the reason it is not acceptable.
I think that's one of the reasons Rob, I think the fact it's a watch is the main reason.
Select to expand quotedecrepit said..
I think that's one of the reasons Rob, I think the fact it's a watch is the main reason.
Fair enough then 
Select to expand quotedecrepit said..
I think that's one of the reasons Rob, I think the fact it's a watch is the main reason.
Note that it isn't due to being a watch specifically... more that GPS technology has a very hard time scaling down in size to the dimensions used in watches... and as you point "reflections".
Aside: I *do* expect that we will have watch versions in the next few years, as the tech gets better.... just that we are not there yet.
For example:
- it would be possible to use a patch antenna "beneath" a touchscreen [ aka no interference from the screen and so smaller watch size ],
- and the ability to to have two antennas in the same device which would allow a variation of what we have for diversity antennas [ as used in microphones and WiFi ].
So you'd need one antenna in the watch and one in the strap, so you'd cover which ever way up your hand is.
One antenna would still be facing the sky and the other the water.
But I guess a smart enough device could tell which antenna is facing the sky.
As long as it could do it fast enough to keep up with the change of grip in a gybe, this would probably include time to re-establish sat connection.
Other wise there'd be some very strange alphas.
Nice idea
I think the issue is more watch/position related then size. I reckon the internal volume of my 920 would be as big as my Canmore, which from what I've read here provides quality data, but lacks the ability to verify
