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Which GPS to buy ?

Created by LeStef > 9 months ago, 7 May 2008

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WA

NSW

QLD

SA

VIC

TAS

ACT

514 posts

Hi, I am thinking of buying a GPS to record my sessions.
Which one do you have ? How much ? Where do you order it from ?
I am not planning to beat any records, just would like to download the runs...
Thanks.

hardie

WA

4129 posts

hardie

WA, 4129 posts

If starting from scratch the best advice to begin with is to buy the new Lycocos NAVI GT31, read posts belowto find out who has them.

maxp

QLD

5 posts

maxp

QLD, 5 posts

Hi Guys, I am thinking of going to Al Green's speed event this year, and I need to update my GPS (I am currently using my boyfriends old fortrex). I can't see what the advantage is in buying the GT31. The GT11 appears to be the same and it is only $150.

I have seen claims that the GT31 is "Three times more accurate in wind speed reading than the GT11" (one of the caloundra shops is advertising this). Since when does a GPS measure wind speed?

I need some help to make the right choice. Is there any difference (that matters) or is it just a way to make me pay more money for no real advantage.

Max

LeStef

ACT

514 posts

LeStef

ACT, 514 posts

maxp said...
[I need some help to make the right choice. Is there any difference (that matters) or is it just a way to make me pay more money for no real advantage.
Max

I got an email from bc. He sent me a comparison of the 2GTs at : boardcrazy.com.au
It doesn't seem to be more waterproof though.

May be they ment "windsurfing speed" for the accuracy.
Good luck.
Stef

firiebob

WA

3172 posts

firiebob

WA, 3172 posts

I think for most of us, the GT11 will be fine, I'm not going to change up for sure.
Me, if I wamted a new GPS and could get a GT11 for $150, I'd grab it.

vando

QLD

3418 posts

vando

QLD, 3418 posts

I Think the GT11 is fine if there are any around still.
I do Know that Pierre Has 2 and is seliing his spare one with Aqua-Pac for $130.
It has only been used a few times .

sailquik

VIC

6165 posts

sailquik

VIC, 6165 posts

maxp said...

Hi Guys, I am thinking of going to Al Green's speed event this year, and I need to update my GPS (I am currently using my boyfriends old fortrex). I can't see what the advantage is in buying the GT31. The GT11 appears to be the same and it is only $150.

I have seen claims that the GT31 is "Three times more accurate in wind speed reading than the GT11" (one of the caloundra shops is advertising this). Since when does a GPS measure wind speed?

I need some help to make the right choice. Is there any difference (that matters) or is it just a way to make me pay more money for no real advantage.

Max

While it is true that the GT-31 is better in many ways, particularly in it's speed accuracy, the GT-11 was still by far the next best GPS for speed sailing and will do everything you need and more for anything less than world record attempts with high accuracy. If there is more than $50 difference I would suggest that the GT-11 would be fine if you can still find any available.

By the way, the field is wide open at the moment for any fast girls who fancy a serious tilt at speed to make a name for themselves. Hope to see you at Sandy Point in October.

Gestalt

QLD

14627 posts

Gestalt

QLD, 14627 posts

now that the GT31 has been released will the firmware for the GT11 still get updates for the speed crew.

or will all of that focus now be directed towards the GT31?

cheers.

maxp

QLD

5 posts

maxp

QLD, 5 posts

Thanks for the quick reply's.
No one has given me any real reason as to why the GT-31 is better, the comparison link didn't make me think that I should buy a GT-31 (just for slightly longer battery time and a different "Chip Set") so I think that I'll get the GT-11.
They are still available and if any one else wants one , I found some here ~~http://caloundracitysailboards.com.au/gps_dvd.html~~

Max

decrepit

WA

12763 posts

decrepit

WA, 12763 posts

I hope you bought yours before you posted that link, you may just get there too late!!!!

sailquik

VIC

6165 posts

sailquik

VIC, 6165 posts

maxp said...

Thanks for the quick reply's.
No one has given me any real reason as to why the GT-31 is better, the comparison link didn't make me think that I should buy a GT-31 (just for slightly longer battery time and a different "Chip Set") so I think that I'll get the GT-11.
They are still available and if any one else wants one , I found some here ~~http://caloundracitysailboards.com.au/gps_dvd.html~~

Max

There are some really good advances/advantages in the GT-31. It has longer battery life (the GT-11 was quite OK though), greater sensitivity/reception (less chance of bad data points) has better speed accuracy in 'Doppler' by a large margin and preliminary experiments suggest possibly twice as good again if used in '2D' mode (which the GT-11 can't do) which means we may be getting to an accuracy of better than 0.02 knots (Thats 2 hundredths of a knot!!)

When we get around to deducting the error off our speed in the rankings to reflect the 98% (or even 99.9% some are talking about now) probability we have done the speed claimed , it will be a big advantage to have the GT-31 over the GT-11.
Oh........, and you might as well forget about the Garmin Foretrex which needs about a whole knot deduction just to get in the ballpark and a huge deduction for 99.9% confidence.

sailquik

VIC

6165 posts

sailquik

VIC, 6165 posts

Gestalt said...

now that the GT31 has been released will the firmware for the GT11 still get updates for the speed crew.

or will all of that focus now be directed towards the GT31?

cheers.

I doubt there will be much, if any firmware development on the GT-11 from now. Focus of development will certainly be on the GT-31.

maxp

QLD

5 posts

maxp

QLD, 5 posts

Hi Guys,
I'm wondering what all that technical quackery evaluates to in the difference between the GT11 and the GT31.

Using the gpsss time of 10 seconds and with a sailor doing 40 knots, she would travel approximately 205.777 metres. How much variation in actual distance is there likely to be between the two gps's.

Is this definite or only a possibility..???

Are we talking mm or cm. ????

Max

sailquik

VIC

6165 posts

sailquik

VIC, 6165 posts

maxp said...

Hi Guys,
I'm wondering what all that technical quackery evaluates to in the difference between the GT11 and the GT31.

Using the gpsss time of 10 seconds and with a sailor doing 40 knots, she would travel approximately 205.777 metres. How much variation in actual distance is there likely to be between the two gps's.

Is this definite or only a possibility..???

Are we talking mm or cm. ????

Max

Approximately 205.777 meters????!!!! Wow, that is very approximate!

It is definite that there will be a much higher possibility that the speed calculated from the GT-31 will be more than twice as accurate.

Since we do not use distance to calculate our speed anymore (we use direct measurement of speed using the Doppler principle), the distance recorded by the GPS is not important anymore, but the GT-31 is more accurate in track-points as well as I understand it, I just don't have a figure on it.

The actual numbers are still being tested. Data in side by side tests is being compared. Preliminary data suggests that the accuracy of the GT-31 is in the order of about 0.02 knots with 99.9% confidence whereas with the GT-11 it is more like 0.2 knots with 99% confidence. (Don't take these figures as gospel because I don't have the actual data with me, this is just the rough comparison as I remember it)

I will try to confirm these preliminary figures and post again.

hardie

WA

4129 posts

hardie

WA, 4129 posts

Max if money is an issue and you are not concerned with finding the closest possible truth in your speeds, and you are interested in knowing and observing your approximate speeds, as well as adding some fun to your windsurfing then the GT-11 will be perfect for you.

fullmoon

WA

314 posts

fullmoon

WA, 314 posts

Correct answer.

sailquik

VIC

6165 posts

sailquik

VIC, 6165 posts

fullmoon said...

Correct answer.

Agreed.

LeStef

ACT

514 posts

LeStef

ACT, 514 posts

Ok guys, so now who is upgrading, and who is selling his GT11 ?

Lowlife

QLD

47 posts

Lowlife

QLD, 47 posts

Hi All

Are the trusty old fortex's still going to be allowed in competition?

sailquik

VIC

6165 posts

sailquik

VIC, 6165 posts

LeStef said...

Ok guys, so now who is upgrading, and who is selling his GT11 ?

Sold one GT-11. Kept two for statistical comparison with GT-31's. I would keep one anyhow because there are some esoteric things the GT-11 does that the GT-31 doesn't (that would not be noticed by 99% of users) although I am not sure I will ever need them anyhow.

sailquik

VIC

6165 posts

sailquik

VIC, 6165 posts

Lowlife said...

Hi All

Are the trusty old fortex's still going to be allowed in competition?

Yes, and I suspect they will be for some time. If/when we ever go to 'corrected speed' or 'claimed speed' in the rankings or comps you will be at a distinct disadvantage though as the correction necessary for 99.9% confidence will be huge. The results are always highly suspect now anyhow. In GPS-SS they have already asked all posters in the top 30 or so to post with GT-11 this year and they note the GPS type in the results so people can see the degree of confidence they can place on the result.