KA72 full stop

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Boston! said..

Mathew, I am not being nasty to anybody for using multiple GPS's. The GW60's are so crappy that you would be mad to use only one source if going for any records. I lost a distance PB last year when one failed mid session on me. I am currently waiting on my third GW60 to arrive in the post. (only one store in Australia has any stock) Until then the rules state that I cannot use my Garmin to post my two lightwind sessions to GPSTC as it is against the rules. I think this rule sucks but I will abide. It's also against the rules to "cherry pick" data from multiple sources, something which you appear to be either advocating or practising or both. I've asked you to confirm this either way.
You seem reluctant to answer my question and have instead answered with another question and yet another graph.

I wasn't reluctant - I took about a hour to draw up a graph to explain the technicalities of how data-science works in the real world and thus I answered your question with technical detail.

Now you are being an ass. If you dont like that answer, that is just your interpretation... nobody is holding a gun to your head.

To keep everyone happy why not have 2 classes of GPS Challenge users.

1. Those people who follow the rules and use the required GPS as set down and have there results checked to verify there results.

2, Those that are not fussed about the rules call them casual GPS Challenge Users.

You can select what type of user you want to be and to keep users that follow the rules happy results tables can be filtered by user type so then you would know your numbers would be being compared like for like.

Additionally a Casual user would have a C displayed by there numbers for all to see that that number has not been derived from a approved GPS or that the user is just casual an not really fused about having there numbers checked they just post what ever numbers show up on their GPS.

I feel this would enable those that want to be more serious about it to be happy that they are only comparing there numbers with others being serious about it and those that want to be casual about it can partake without being to concerned about there number they are just having fun and any number they post are not taken to seriously.

With team results if they include numbers from Casual team members a C can be placed next to the team result.

It seems like a solution that would keep everyone happy and keep people go out GPS sailing.

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Boston! said..

"So. er Mathew, is that you admitting to "Cherry Picking" or simply trying to sell us on the merits of it?"


It's not a technical question mate it's an ethical one.

So what really is your problem Jeff?

Cant you read and understand what has been written? Go back an check. All the answers to your strangely confused, and pointedly insulting queries are already there.

And you didn't answer my question. Are you calling me, and the others who asked, a cheat because we often choose to sail with more than one GPS, even though you, yourself clearly aknowledged the logic behind it, and, that it is expressly permitted, and actually encouraged in the rules written on the GPSTC website for ALL to see.

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Boston! said..
.......What I don't think is right is that the majority have been following this "one GPS" rule (and the rest of the rules) while you guys appear to have been ignoring your own rule while quite likely, gaining an advantage while doing so. (I'm assuming that would be the main reason for doing it?)
Are there any other rules in the GPSTC that we have been following that we need not have? Rules for the plebs?
I know a few people who wouldn't mind being kept in the loop!

OK Jeff "old mate". Here is the problem, Note what you actually wrote above. I can read perfectly well and in your words above you clearly accused all of us who use multiple GPS's of cheating, and ignoring our 'own rules'. I'm sorry 'old mate' but if you go around accusing all of us of cheating, just because you can't write exactly what you mean to write, you have a serious problem.

But thanks for clearing up that you didnt mean what you actually wrote.

Now as far as Mathew goes. There is no suggestion at all, apart from your own complete misreading of what he has said, that he in any way has ever posted different session catagory results from different GPS's. In the many years that I have sailed with him, and in many occasions we have analysed our results together, can tell you without a shadow of doubt, that he would never even think of doing such a thing. I can only think that he thought the question you asked of him was too ridiculously insulting to answer. (I do too).

If you have a specific case where you think he has done the wrong thing, please speak up with specific dates and results. Otherwise, pull your head in and focus on your own sailing.

Are yes, saying what you mean, is a big problem! ( it gets harder as you get older),
In a much earlier life as a chippy, I was handed a length of 100 X50 and told to rip it down the middle, which I did with a little trouble. On handing the two pieces back, I got a mouth full of abuse. "#@%^ idiot I wondered why you were taking so long, all I wanted was it cut in half!."
He didn't take kindly to me telling him that's not what he said.
Ripping means cutting with the grain, along the length of the timber.

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sailquik said..

Boston! said..
.......What I don't think is right is that the majority have been following this "one GPS" rule (and the rest of the rules) while you guys appear to have been ignoring your own rule while quite likely, gaining an advantage while doing so. (I'm assuming that would be the main reason for doing it?)
Are there any other rules in the GPSTC that we have been following that we need not have? Rules for the plebs?
I know a few people who wouldn't mind being kept in the loop!

OK Jeff "old mate". Here is the problem, Note what you actually wrote above. I can read perfectly well and in your words above you clearly accused all of us who use multiple GPS's of cheating, and ignoring our 'own rules'. I'm sorry 'old mate' but if you go around accusing all of us of cheating, just because you can't write exactly what you mean to write, you have a serious problem.

But thanks for clearing up that you didnt mean what you actually wrote.

Now as far as Mathew goes. There is no suggestion at all, apart from your own complete misreading of what he has said, that he in any way has ever posted different session catagory results from different GPS's. In the many years that I have sailed with him, and in many occasions we have analysed our results together, can tell you without a shadow of doubt, that he would never even think of doing such a thing. I can only think that he thought the question you asked of him was too ridiculously insulting to answer. (I do too).

If you have a specific case where you think he has done the wrong thing, please speak up with specific dates and results. Otherwise, pull your head in and focus on your own sailing.

So, Daffy, when Mathew and yourself dont understand a question that's my fault? I think it was pretty straight forward question. Kato it seems had no such problem understanding it and offered a swift rebuke in the first post following mine. ("and no I just post from one if it's any of your business" ) Easy. (you would think?) But you and Matt? No. I imagine when your natural tendency is to pontificate and condescend, a simple answer just doesn't allow one to get their rocks off! What led me to my suggestion that "you guys" were breaking the rules was based on Matt's multiple opportunities to deny that he was "practising" this method as well as, both of you claiming there was no technical reason why it shouldn't be allowed. In light of this misunderstanding on both sides. I withdraw the accusation. I don't think Matt found the question insulting. I'm sure he would have called me a name if he did, as is his style. I think he just misread it.

And Daffy, I don't think it is within the boundaries of your GPSTC high priesthood to tell people what to focus on.
I'll focus on whatever the hell I want.

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legless said..
To keep everyone happy why not have 2 classes of GPS Challenge users.

1. Those people who follow the rules and use the required GPS as set down and have there results checked to verify there results.

2, Those that are not fussed about the rules call them casual GPS Challenge Users.

You can select what type of user you want to be and to keep users that follow the rules happy results tables can be filtered by user type so then you would know your numbers would be being compared like for like.

Additionally a Casual user would have a C displayed by there numbers for all to see that that number has not been derived from a approved GPS or that the user is just casual an not really fused about having there numbers checked they just post what ever numbers show up on their GPS.

I feel this would enable those that want to be more serious about it to be happy that they are only comparing there numbers with others being serious about it and those that want to be casual about it can partake without being to concerned about there number they are just having fun and any number they post are not taken to seriously.

With team results if they include numbers from Casual team members a C can be placed next to the team result.

It seems like a solution that would keep everyone happy and keep people go out GPS sailing.

Thats a really stupid idea Gareth.

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legless said..

Mehore said..

Thats a really stupid idea Gareth.

You have yet to disappoint me with my opinion of you.

Cheer up mate its just my opinion.

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Mehore said..

legless said..
To keep everyone happy why not have 2 classes of GPS Challenge users.

1. Those people who follow the rules and use the required GPS as set down and have there results checked to verify there results.

2, Those that are not fussed about the rules call them casual GPS Challenge Users.

You can select what type of user you want to be and to keep users that follow the rules happy results tables can be filtered by user type so then you would know your numbers would be being compared like for like.

Additionally a Casual user would have a C displayed by there numbers for all to see that that number has not been derived from a approved GPS or that the user is just casual an not really fused about having there numbers checked they just post what ever numbers show up on their GPS.

I feel this would enable those that want to be more serious about it to be happy that they are only comparing there numbers with others being serious about it and those that want to be casual about it can partake without being to concerned about there number they are just having fun and any number they post are not taken to seriously.

With team results if they include numbers from Casual team members a C can be placed next to the team result.

It seems like a solution that would keep everyone happy and keep people go out GPS sailing.

Thats a really stupid idea Gareth.

X 100 Micko

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mathew said..
I choose the GPS that has the highest speed because it measured the highest speed - why would I use a gps which had a low speed ?

Because the rules state:
"users should select the complete set of data from only one of the devices to post, preferably from the device with the lowest +/- numbers"

If you always choose the highest numbers, regardless of the accuracy estimates, you are cherry picking. Not really surprising if people get upset about that.

BTW, your "technical response" has a number of mistakes in it. Both GPS units in your graph would pick the top 2-second range a second later than you show, at which point the speed difference is a lot lower. GPS units tend to be synchronized to GPS time; when recording at 1 Hz, they will generally measure at exactly the same time (the "full" second, not in the middle).

The thing that's more likely to cause differences between different GPS units is random noise. Chances are high that the unit with the higher numbers also has lower accuracy; that's a logical consequence of the algorithms used. Here's a picture with an example from a test sail today:


The GW-52 on the left has a higher speed and a higher error estimate. Using the numbers from this GPS would overstate the speed by almost 0.2 knots. The unit on the right has the better accuracy and should be used. It also agrees more with the numbers that the three other GPS units I used in this test showed ( 16.806 on GW-60, 16.709 and 16.745 on 10 Hz u-blox 8 prototypes).

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mathew said..

... the idea of "claimed speed" was put forth, which specifically addresses this key point of claiming a higher-number than we can be certain of (within statistical certainty).

On a tangent...

The idea behind "claimed speed" - assuming the device had an error-model -> all future time-keeping would not need to know what device was used (with whatever inaccuracy), because the entry/value itself would have the error-adjustment already applied.

There is a lot to be said for simplicity -> the record keeping would just be the single number.
The alternative is lots of argument about who went faster, given how/what/where a device is used.

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decrepit said..
Are yes, saying what you mean, is a big problem! ( it gets harder as you get older),
In a much earlier life as a chippy, I was handed a length of 100 X50 and told to rip it down the middle, which I did with a little trouble. On handing the two pieces back, I got a mouth full of abuse. "#@%^ idiot I wondered why you were taking so long, all I wanted was it cut in half!."
He didn't take kindly to me telling him that's not what he said.
Ripping means cutting with the grain, along the length of the timber.

Ha ha ha ah ah been there done exactly that!!!!!! Wise old teacher once said to me .....say what you like but choose what you write very carefully as it stays for ever.

Hey its going to be windy @ Budge on Friday! Weeds thick so remember to bring your balls along and a Kestrel or Delta. XT won't cut it. Ill be keeping it simple and using my Gt31 and Gw60 and posting my fastest result through Ka72 my slow result will be private so good luck working it out haaaaa. Cmon guys. You do know that you can delete your posts and we all share the passion but in different way with different opinions as every one is different with different opinions and journeys. The beauty of what we do is that we share the love with so many people, but we're all different with different opinions. Am i repeating myself? Cmon guys thats what your doing. Lets just play by the rules and be thankful we have the GPSTC and Ka72!
GO MARAUDERS!!!

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sailquik said..
Look at it this way. If someone posted a 2 sec result from their one and only GPS with an error margin of +/- 0.381, we would have no problem with it.

You are correct - if someone uses one GPS only, I don't have a problem posting it. But following this topic, I got the impression that some people think using multiple GPS, and then picking the one with the highest numbers to post, is a rather questionable practice. I certainly can see that point, and think the non-binding suggestion in the rules to use the one that appears most accurate makes sense.

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sailquik said..

Actually Peter, you are really close to overzealous nitpicking here in this example, your statement is incorrect and your unjustified.

It would be true to say that the higher GPS could overstate (or understate) the speed by up to 0.381 knots, but the difference in the readings is less than the max probable error reported, and within the range normally seen, and therfore both results are totally valid.

There are rather solid theoretical arguments to be made that support my statement - in noisy data, a "search highest" algorithm will generally pick higher numbers in lower accuracy data. That's the nature of the algorithm and the data. But no theory is needed in the example I posted. The two u-blox 8 prototypes had ranges that did not include the 17.049 knots from the GW-52 #1. One unit had 16.709 +/- 0.074, the other one16.745 +/- 0.113. While neither of these units is approved, there are plenty of indications that they are more accurate than Locosys units. So the GW-52 with the lower accuracy actually does appear to overstate the speed by roughly 0.2-0.3 knots.

But I'll shut up now rather than being called an overzealous nitpicker. I'll just adopt the same practice of picking the GPS with the highest numbers whenever I wear multiple approved GPS units, and will make sure to indeed wear more than one unit when I think a session matters. I don't need approval for my prototypes for that, either, since I still have three GW-52s, a couple of GW-60s, and a GT-31 or two around.