Select to expand quoteeckas said..
1. GPSTC posting showing *only* 583km 2. ABC Gippsland reporting 659km. 3. Analysis above around 660kms.
Kato - I'd hate to think you undersold your achievement on GPSTC by the distance that most of us mere mortals manage on a good day!! 
GTC rules are for session's over a day local time. (midnight to midnight)
Kato's 24 hour 660km was over 2 days, he started at 9pm on the first day and finished around 8pm on the 2nd.
The ball is indeed in my court again Craig, however there is a story behind my record attempt on the 10th of August 2014. Your friend and chairman of the WGPSSRC Andrew Daff probaply filled you in on the details but to clarify to the rest if the community reading here the whole story.
I posted my record attempt on the record forum of Gps speedsurfing. The Gps record rules were well known to me since I already sailed 634 km in June 2013 to claim the world record.
I followed all the Gps settings on the record rule booklet. Because this record attempt was being done in August, I had two hours of daylight less than in June the previous year. To make sure I could read the display from time to time in the 8 hours of night sailing I put all Gps devices on low power modus.
After 24 hours i had a display distance of 720 km, this is where things went wrong.
It turned out that when in Low power modus, less satelittes are tracked.
This was not known by the WGPSSRC or by myself.
Since the record rules state a minimum amount of 5 satellites my claimed distance with 720 km could not by ratified by the WGPSSRC.
When lowering the number of sattelite fixes the distance was 695,7 km.
So here I am with a 720 km display 24 hr session that can't by formally ratified because I ventured out into the unknown both to WGPSSRC and myself.
For the last 5 years my 630 km was enough to claim the world record so I did not have to explain this major upset further.
What surprises my is that the record rules to this date have not been updated with the addition to put the GT 31 in full power modus.
So yes the ball is in my court, you can fairly claim the WGPSSRC world record.
My unofficial 696 km will not disappear but now it's easier for me to go back on the board and put out another 700 plus distance.
Please don't get me wrong Craig in your superb 24 hour achievement. I don't want to belittle it in any way shape or form. It's an amazing distance.
We are in mid winter with snow and ice so I'll have to wait a couple of months more before I can glue myself on the board again for 24 hours.
Cheers
Dennis Klaaijsen
NED-192
boardseekermag.com/features/24-hour-man/
www.windsurfing.nl/index.php/contact-windsurfing-nl/itemlist/user/64-mark?start=50
forum.windsurfing.nl/viewtopic.php?f=65&t=13888519
I think I see another anomaly.Select to expand quote
Note: Never clear your data-logger as this can be necessary for proof vie the SBP file.
It's my understanding that the data logger only holds 7hrs worth of data. that wouldn't be much help in any major distance attempt
Select to expand quotesailquik said..
Average speed of two devices = 27.508+/-0.370 (GPS#1 27.511+/-0.493 GPS#2 27.506+/-0.553)
After error deduction: 27.138 Km/h Record claimed average speed
= 651.312 Km Record claimed distance.
The +/- numbers shown are based on averaging the SDoP numbers for more than 80,000 points. This is the default setting in GPSResults for GT-31 data which makes sense for 10 seconds and 500 meters, but makes absolutely no sense for 24 hours. For long times/distances (definitely 1 hour and longer), gaussian error propagation needs to be used. The distance after subtracting a correctly computed error estimate is very close to 660 km.
...create a new GPSTC team consisting of just the two of you, both register your distances on the day of the sail-off, and create a GPSTC distance record unlikely ever to be beaten!
Craig...Your KA Team mates will step up and pitch in for some extra support on your next attempt. When you come in for a refuel we thought you might need a gentle back massage so we have lined this guy up.
DennisKlaai said..
Select to expand quoteeckas said..
...create a new GPSTC team consisting of just the two of you, both register your distances on the day of the sail-off, and create a GPSTC distance record unlikely ever to be beaten!
Interesting format
Can you use numerous devices, as long as they are acceptable, to get through the 24hr period. And splice them together at the end? Probably no device can go the distance on one charge.
Select to expand quoteBSN101 said..
Can you use numerous devices, as long as they are acceptable, to get through the 24hr period. And splice them together at the end? Probably no device can go the distance on one charge.
The GT31, has a battery life in weeks not hours. Well when it's new anyway.
I think the record requires two identical devices. I'm not sure if you could use 4 devices and splice them. In the GW52's case you'd need at least three to do 24hrs, the GW52 battery should make it with 2, but the memory probably wouldn't.
Exactly as Decrepit says re battery and memory. The GT-31 is really the only GPS suitable for a 24 hr distance at the moment, although it might be possible to do it with a Gyro GPS.
I can think of a couple of ways to make a custom GPS logger using Ublox M8 internals though that would be acceptable to the WGPSSRC.
Select to expand quotesailquik said..
Exactly as Decrepit says re battery and memory. The GT-31 is really the only GPS suitable for a 24 hr distance at the moment, although it might be possible to do it with a Gyro GPS.
I can think of a couple of ways to make a custom GPS logger using Ublox M8 internals though that would be acceptable to the WGPSSRC.
It may be time to update the rules. The GT-31 has not been available for years, and old units will fail eventually. I have a few dead ones lying around. The last one died after not being used for more than a year.
It certainly makes sense to require data from two devices for records, but it makes very little sense to allow data from a device that is known to be less accurate than newer devices like the GW-60 which are not permitted. Perhaps concerns about fraud were an issue when the rules were originally developed, as the requirement to dump the data from the GT-31 indicates; but if that's really an issue, custom devices certainly should not be allowed.
Select to expand quoteboardsurfr said..
It may be time to update the rules. The GT-31 has not been available for years, and old units will fail eventually. I have a few dead ones lying around. The last one died after not being used for more than a year.
It certainly makes sense to require data from two devices for records, but it makes very little sense to allow data from a device that is known to be less accurate than newer devices like the GW-60 which are not permitted. Perhaps concerns about fraud were an issue when the rules were originally developed, as the requirement to dump the data from the GT-31 indicates; but if that's really an issue, custom devices certainly should not be allowed.
New devices that are less accurate, are ok to be used - the GW60 is exactly an example of it, just look at the error data. It is ok *because the device spits out error-data*.
Fraud is an issue - which is why the rules state that you need someone to observe you do the sailing and thus verify that the device is logging reliably and accurately **. Whether you make a custom device or use a production device, shouldn't preclude a record claim - what matters is that you can prove that the data matches your claim and is and not forged (and it *isnt* that hard to forge it...).
** The "auto period" and "power save" features on most devices (such as the GT31) have always been known to produce datafiles which are not reliable and accurate - there were whole threads of discussion on GPS-Speedsurfing forums describing this phenomena (AFAICR, those discussion threads were lost in the hack, many years ago).
The rules to say "dont use power save" because if a device can use power-save and still log accurately/reliably, then that device should be allowed. ie: www.gps-speedsurfing.com/default.aspx?mnu=item&item=gpsother
... most "auto" and "power-save" modes either drop points (so not 1 Hz) and/or drop satellite-tracking to a minimum (causing per-point error to be very big, or that point is missing too many satellites for a stable-lock).
PS. if you have dead-battery GT31's, then just replace the battery... it will cost about $10 USD.
Select to expand quoteboardsurfr said..
It may be time to update the rules. The GT-31 has not been available for years, and old units will fail eventually. I have a few dead ones lying around. The last one died after not being used for more than a year.
It certainly makes sense to require data from two devices for records, but it makes very little sense to allow data from a device that is known to be less accurate than newer devices like the GW-60 which are not permitted. Perhaps concerns about fraud were an issue when the rules were originally developed, as the requirement to dump the data from the GT-31 indicates; but if that's really an issue, custom devices certainly should not be allowed.
The WGPSSRC rules have been updated, in 2016, with the addition of the newer (GW52) device and data retreival procedures for them. There is currently a problem with getting the updated rules onto the GPS-SS website.
The GW60 has not been officially added yet as we needed to evaluate it further. It will probably be added soon.
The GT-31 is still perfectly adequate for a 24 hr record at the very least, and 10 second and other records as well, as long as one accepts that they will incur a higher penalty for error deduction.
The WGPSSRC rules already include the possibility of using a custom Ublox GPS based device approved by the Committee:
Excerpt from current WGPSSRC rules regarding approved GPS devices. (candidates who seek to use Ublox based devices will need to receive prior approval from the committee of course, and will also need to carry a device that displays the saved speeds like a GT-31 or GW52/60 for witnesses if the approved Ublox based device does not have a display):
2.1 A device based on the Ublox 6, 7 or 8 series chipset that is set up to produce and save the required UBX binary data, including the UBX sentence UBX0112, at 10hz (or higher) directly to a connected SD card, or by Bluetooth to another storage device. Note that the record candidate must carry at least two approved Ublox 10hz GPS receivers and both must be set to record at the same hz rate of 10hz or higher.
3.1 Locosys GW-52
Here is an example of a twin 10Hz ublox based GPS logger, made by Manfred Fuchs, that has actually been tested at Luderitz next to GT-31's and the WSSRC gate timing:
Select to expand quoteAusMoz said..
Too much tech/nerd talk
, back to the focus - Well done Kato!!!!
This is the "GPS" sub-forum... maybe it is just too many simple-minded people that think brawn is better than brains?
Select to expand quotesailquik said..
The WGPSSRC rules have been updated, in 2016, with the addition of the newer (GW52) device and data retreival procedures for them. There is currently a problem with getting the updated rules onto the GPS-SS website.
The GW60 has not been officially added yet as we needed to evaluate it further. It will probably be added soon.
Top secret record rules - cool . I checked the rules on the GPS3 site after reading Dennis' post, but it did not occur to me that posting updated rules might take more than a year.Select to expand quotesailquik said..
The GT-31 is still perfectly adequate for a 24 hr record at the very least, and 10 second and other records as well, as long as one accepts that they will incur a higher penalty for error deduction.
I imagine Dennis and Kato duking it out on Lake George next year, and one of them winning by a few km because he used a few GW-52s, the other GT-31s. But then, I've been told my sense if humor is a bit unusual .
A bit more seriously - how to treat errors in 24 h attempts may deserve some discussion. With 5Hz and higher data rates, the calculated error pretty much disappears, which may be too optimistic (especially with GW-60s worn on the wrist). With > 400,000 data points at 5 Hz, the calculated error will be around or below 0.001 knots, which may be too optimistic. I have seen some device comparisons where the error estimates were too optimistic even for a nautical mile or 1 hour.
A simpler and more robust way would be to treat the results from the two devices (or sets of devices for GW-52 etc.) as the variables, and to calculate the standard deviation from these numbers. For Kato's tracks, that gives 0.002 knots (or 0.014%), the same number that GPSResults gives for "gaussian" error propagation. However, GPSResults reports a two standard deviations, IIRC. But even if you'd take three sigma to get 99.8% confidence, Kato's numbers would be darn close to 660 km.
There's always rules when you want to claim a record, but the main point is
there are windsurfers travelling over 500kms in a 24 hour period 
Bloody legends the lot of you
