Jtim3032

@rogerw @klindy I'll mention it to Steve the next time I see him :)

@rogerw @Splasheye The original photo of Sammy Duvall at the Worlds in the UK 1987 was taken by Steve Sopp and was the basis of this "acrylic on canvas" painting by Louise Cobbold. The painting (and additional prints signed by Sammy) were auctioned off as part of a British Tournament Water Ski fundraiser last Autumn. Definitely one of my favourites of all time. Not only is it a great photo, it absolutely sums up the atmosphere and spirit of competition at the event.

@jjackkrash It's very easy to move between sites. You just recall the files you saved when setting up the base and when mapping the course. The main thing you have to watch out for is that the base antenna must be placed exactly where it was when you originally set it up otherwise you have to remap the course....but that doesn't take long anyway.

@Chad_Scott 100% agree...

@jayski @jjackkrash @Horton Sorry I should have chipped in a couple of weeks ago. The Rules do indeed define the level of movement a boat is allowed "toward" the skier at each buoy before it is deemed to be "unfair" or pattern driving and that is via the accumulative deviations. The positive deviations at each buoy add up as you go down the course and the max allowed total is defined for each buoy. The maximum total at buoy 6 is 49cm so it is easy to see that if the boat was more than 8cm on average (it is not linear) towards the skier then this breaches the cumulative rule. Of course there is a legitimate debate about what the allowed values at each buoy should be or indeed where the boat is when measuring the deviation at each buoy. Now we are able to easily collect accurate data, we can start to do some meaningful analysis on this so that future versions of the rule can be written based on real analytics.

@jjackkrash only the gates are needed for Sure-Path do its stuff in that it draws a virtual line between the centres of the two gates and tells you the deviations from that line. HOWEVER, if the rest of the course is badly out (ie if the boat lane is bent or varies in width), the driver will find it very difficult to drive that line since all his reference points will be the boat lane guide buoys as he travels down the course. Sure-Path can survey all the rest of your buoys in the course and tell you how far from ideal they are. You can also export that data into one of the approved homologation software applications for an "official" homologation to be done. James

@paul it is possible to use radio modems for the link between base and rover albeit we don't usually recommend it on reliability grounds. It also adds a lot to the cost. All the real computing power is in the GPS onboard chips and the rover phone. The online server is just a relay station and does not do any processing as such. For lakes with no cell coverage, we are working on getting a WiFi system together which we know will work. We are not far off that now. WiFi has all sorts of advantages also for transmission of video from boat to shore for judging purposes. Keep an eye on the website for progress on this. James

@klindy @Stevie Boy yes data collected by Sure-Path and similar systems will almost certainly be used in some sort of monitoring program, even if only for internationally ranked drivers. One thing however that has been markedly missing until now is a proper privacy policy that ensures that drivers know how and when the data is collected, stored and the purposes to which it will be used. You may have heard of the GDPR regulations which already exist in Europe. Maybe other (con)federations need to publish something similar. James

@MattP the problems with using Sure-Path to give co-ordinates for ZO are twofold: 1: The Sure-Path co-ordinates are not accurate with respect to absolute position, rather they are only super accurate with respect to the base antenna position, and the base position is only plotted typically to within 10 metres (because it doesn't need to be). Therefore, entering SP co-ordinates into ZO could give wildly wrong results. 2. ZO itself is only accurate to +/- 2 metres in ideal conditions (so called Differential GPS or DGPS) and therefore, even if the co-ordinates from Sure-Path were accurate in an "absolute" sense, ZO readings could still be up to 2 metres away from that position. Anyone who has watched a GPS "scatter plot" live will know that this variance occurs over quite short periods of time (ie one or two minutes) and so no two passes will be the same in terms of course start timing. I have been in the boat many times when the driver and TC map the course at the start of competition and when they do a return pass to check, the result seems wrong by a metre or so. This is not because they mapped the course wrong, rather it is inherent in the technology. James

@Horton yes, yes, yes....I need to have an FAQs page on the web site. There is already a "Troubleshooting and FAQs" but this needs expanding to a general questions page where the details of the technology can be explained better. A lot of stuff can be answered by going back to the IWWF Rules which changed quite a lot this year in regard to boat deviations. For the nerds...the official deviation figures in the "Tournament Mode" summary screen are "the average of the two highest deviation readings towards the skier in a range from 10 metres before the buoy to 10 metres after the buoy". However, this 20 metre range is a little large and the resultant figure can mislead a driver who might get a reading of say +10cm for buoy one when in actual fact he offsided the skier when the skier was actually at the buoy. He could do this for instance by being -10cm "at the buoy" but +10cm at 9 metres after the buoy. Thus at the request of some very senior drivers, I added "Training Mode". This gives the boat's deviation at the first reading taken after the boat is at the guide buoy and therefore gives the driver a better picture of what he is actually doing to the skier. The numbers however cannot be used in tournament as they are not calculated strictly according to the Rule. Some background...the 20 metre range was introduced to stop a driver weaving his way down the course to help the skier even whilst staying within the 20cm tolerance. The 20 metre range catches the maximum deviation towards the skier and you fail the cumulatives very quickly indeed, usually by buoy 2. The rule does this very well but as previously explained, does not really say what is happening to the skier. Going forward, as we collect and analyse "big data", we will get a much better picture of how the rule should be worded in order to stop undesirable driving whilst still giving a good picture of how the skier is being affected. For driver development, it won't be long before we can offer drivers on demand analytics of their driving, either over a tournament, during a day or over longer periods of time. Things like deviation distributions at each buoy for a given rope length and boat speed will be available as well as cool things like how the boat moved predominantly at/after each buoy. James

@MattP @disland Sorry guys I am so busy right now that I can't always follow the BOS threads. Sure-Path is currently fine for collecting GPS co-ordinate data for use in an approved homologation (survey) program such as Emmanuel Lion's "Water Ski Homologation". After marking the entrance gates, Sure-Path can indicate how far off "ideal" any buoy is, but the actual official homologation has to be done within software that also compares the buoy's distance from various adjacent buoys (axials and diagonals). So think of Sure-Path as an approved replacement for the Total Station traditionally used for surveying buoy positions. James

@Laz @MISkier in fact these are from the IWWF Rule book. Sections 1.09 and 8.15 are the ones to look up regarding boat path and deviation tolerances. Here is a link to the latest IWWF Rules https://iwwf.sport/wp-content/uploads/2020/06/World-Waterski-Rules-2020_V4.pdf

@Laz first you have to remember that for each of the deviation numbers at each buoy, positive is towards the skier and negative away from the skier (ie not left or right). Then the cumulative is literally the straight sum of the individual deviations at each buoy, ie 4.7 - 1.2-3.1-0.6-3.7-2.8 = -6.7

It's amazing where a view of the back of your head crops up! :)

@Horton @jayski regarding apparent "offsides", under the current rules, the numbers displayed are the average of the two highest readings towards the skier in a zone from 10 metres before the buoy to 10 metres after the buoy and so does not necessarily show where the boat was when the skier is actually at the buoy. This was done to pick up so called "pattern" driving and it makes weaving show up in the cumulatives very quickly indeed. If you want to know where the boat is at the guide buoys, then use "Training Mode" and this gives you a better idea of whether you are offsiding or not. Obviously don't use in competition :)

@Horton the offset figure is the average of all the deviation readings measured for the pass. Although at first glance you might think it tells you whether you are generally left or right, the course is actually quite a long distance and it is easily possible to be significantly left in the first half of the course, then significantly right in the second half of the course and get an overall offset near to zero. So I would say it's a useful "at a glance" number but treat with caution.

@Jimbo already replied to your email, but for other readers, yes it does.

@skierjp prices are on the web site. Lead time at present is up to 4 weeks. DM me via the web site.

@RAWSki you just need an additional rover unit for a second boat (assuming the boats are used concurrently and you don't want to move kit between boats).

@BraceMaker @Horton is correct, the generally accepted limit is 10km (about 6 miles) before accuracy begins to degrade although at some stage I intend to test at longer distances.

@Horton a straight SMA male to SMA female extension is what you need. Do NOT get anything that says RP in the connector name (e.g. RP-SMA male) as these are "reverse polarity". One customer is using a 50' extension with no problems and I suspect you could even go to 100'. You can also get a TNC to SMA adapter to use at the antenna which would allow the extension to go straight on to the antenna. If it's appropriate I can give example Amazon links.

@gsm_peter This is not a cheap solution (or at least not as cheap as you are hoping for) but since it uses RTK GPS, it is accurate to the cm. It also gives you lots more besides to help your driving improve. http://sure-path.com/for-homologators.html

@jayski absolutely agree about reducing the number of judges required for tournament. That said, an rtk setup needs an antenna at least 4" in diameter and thus, for now at least it is not feasible to mount on the ski or skier. Give it time though :)

@Xpropman as you well know my colleague (who does not work for me and is just a friend trying to help) had a family emergency at the time which meant he went off grid for a while. He subsequently apologised profusely to you for the inconvenience caused and I think your comment is quite uncalled for.

@monza man I am at Swiss from lunch time Sat 7th through till Tuesday 10th. I am doing some work with the guys there but if you let me know a date/time that suits you then I am sure we can work it out. Probably best to DM me or email james@ppcphoenix.com