Dart 15 Forums

Look what the Canadian Albacore Class do with a GPS system on some of their regattas.
You can watch the tactics as the race develops. Very impressive.
Does anyone have access to a system we could borrow for the Nationals?

http://www.albacore.ca/node/166

PS George was the bright green boat on this display

Well done George & well done technology, simply amazing !

Hi Bob,

A nice idea. I've found a couple of websites that can do that:

http://www.mapmytracks.com/ (uses GPS enabled mobile phones)

http://www.race-trax.com/ (very expensive! but professional quality)

The first one maybe worth a look at although I found its demo a little slow on my work pc. I don't have a GPS enabled phone myself but if anyone wants to give it a go and see what happens be my guest.

Martin S.

I know the Musto Skiffs used mapmytracks at their nationals a couple of years ago http://www.yachtsandyachting.com/news/?article=140746. No idea how easy the whole system was to set up though. Does anyone have any hot skiff sailors at their club they could sound out? I'll have a look into it too.

There were a number of Queen Mary sailors there, some of whom were tracked. Hopefully I'll get to QM this weekend, and I'll try to find out more from them - if they're there too!! If I'm not there then maybe Gordon will be.

Only a small proportion of the competitors were tracked in each of the 3 races tracked. My guess is that the QM sailors had 3 GPS enabled mobiles between them.... and some swapped for some of the races so others could be recorded as well.

I wasn't too impressed with the quality of the mapmytracks "reports" of the 3 races that were tracked. That only 3 races were tracked suggests that cost came into the equation, as well as the need for GPS phones.

I'd be v surprised if we could borrow a system......

PS I couldn't make it to Thorpe Bay - I had a wound that was still stitched and had been told not to be vigorous to avoid the tight stitching tearing apart. OK now, except that confirmation that the excised tissue was not dangerously cancerous is presumed by the lack of urgent contact to return to hospital.

Inclined to agree on the quality issue George - Even the demo information on the website looked confusing and unclear.

As you said as well, I don't think anyone would be inclined to lend us a set of kit they have specifically created for the job we want it to do!

Still, it's worth a bit more looking into!

RobBowen wrote:Inclined to agree on the quality issue George - Even the demo information on the website looked confusing and unclear.

As you said as well, I don't think anyone would be inclined to lend us a set of kit they have specifically created for the job we want it to do!

Still, it's worth a bit more looking into!

Did you look at the link I posted? The Canadian system was outstanding. It was very clear, all boats and the course were plotted and the boats were plotted as boats in the correct orientation. You can even tell when they were getting headed or could point up. I suspect that our racing would not make quite such a good example of tactics as catamarans tend to bash the corners upwind more than monohulls.
I asked George who supplied the kit and he reckoned "The devices were supplied by a company called kattak I think. Just looked like a cell phone in a box to me...."
I'll root around a bit more.
Cheers
Bob

Yes the company was called kattack, here is their web site:

http://www.kattack.com/

The device we had was just a regular cell phone in a waterproof box. They had some older units which were bigger and heavier (it was pot luck if you got a light or heavy one). The regatta had all sorts of dinghy and yachts competing all with these devices, there must have been 100-150 boats in total.

You can see from the trace my huge screw up in race 4. While leading the race I mistook the gybe mark for the leeward mark and headed upwind taking 2nd and 3rd places with me. I lost out most as I tacked and was going totally the wrong way. A very effective way to go from 1st to 15th....

Another company used by the Albacores is velocitek. Here is their website: http://www.velocitek.com/.

A few of the top boats were fitted with these at the 2007 world championship in the US. It caused a huge debate on the Y & Y forum as the devices showed top speeds over 20 knots on a day when it was so windy that the races were abandoned and the boats were reaching back and forwards to see who could go the fastest.

There is some info about this on the US Albacore website here:

http://usaa.albacore.org/speed_trials

But there was a big long debate on Y & Y about how could a slow Albacore
go so fast.

http://www.yachtsandyachting.com/forum/ ... +velocitek

I was there are it was very windy, were boats really going that fast? I'm not so sure...

The funny thing in all this is that although digital compasses are allowed on Albacores you are not allowed tactical devices that can tell you when to tack or give you speeds or VMG information. The upshot is that the velocitek and other similar devices are not allowed to be used while racing and you have to put tape over the displays. When they get smaller and cheaper they will be really good for training when you can experiment with setting the boat up in different ways.

George

Reading the website for Kattack the other day I thought they only did regattas by coming to them which for a N. American company would be impractical for us but I can see that they also have another option (in the club section) that allows you to be able to upload a *.gpx data file to the website and it'll playback, I like the viewer app that it uses all for a fee of course.

My garmin wrist mounted GPS unit (and I presume other GPS units) can produce such a file I do believe so this would appear to be another option. They talk about buying boat kits on their site but nothing much about them in their public area.

It would appear that some mobile phones with suitable apps installed can also export data in such a format. ie iPhone. So I guess you'd need a whole army of people to gather the data after each days racing to upload everything to the website so it can be replayed.

Martin S.

George,
Many people have misconceptions about the speeds sailing boats can attain in the right conditions. They tend to think that planing is the only fast speed mechanism involved. But when there are big winds there are usually big waves on which boats can also surf.
Now the maximum driving force useable from the wind based on max allowable heeling force for most small non-trapezing dinghies like an Albacore is around 20 lbs and I assume it would take all of that to make the Albacore plane on a beamy reach. But when floating on a wave the driving force is derived from gravity and equals the total weight of the boat times the Sin(of the slope of the wave surface) which for an Albacore of weight including crew of around 600 lbs and a wave slope of 30 degrees gives a driving force of 0.5*600 = 300 lbs which is enormous in comparison to the driving force from the wind alone. So in my view it is completely feasible that on the very windy day in question, the boats attained the speeds mentioned of 25+ mph surfing and planing down the face of a wave.
And note that these surfing forces are the reason Round the World yotties head for the Southern Ocean, because in the big waves and wind found there even huge heavy keelboats surf at speeds well above their nominal ‘hull speed’


I have a Velocitek Speedpuck which I use for analyses after sailing with the GPSAR programme. The device is not much good when actually racing and I turn the display off. But they are an amazing combination for analyses (and to play with) and if you go to http://www.mustoskiff.com/replays/2007/ ... gpsar.html
you will find an example of the output; and you will be able to play with all the various graphs, outputs etc. because it is ‘live’.

Cheers

Jim Coleman

Hi,

I spoke to Leigh Albrecht today at Queen Mary about the Whitstable 2008 event.

He said that (some) competitors were provided with Velocitek GPS phones, which were in sealed boxes and taped to their boats. (so it was much like the kattak system described by George Carter as far as equipment on boats is concerned).

The tracking was part of the sponsorship deal that the Musto Skiffs did with Mapmytracks - and Leigh did not know how this was set up - it was part of the cost competitors paid as far as he was concerned. Neither did we have time for him to tell me anything more about the tech set up that pulls the GPS based data together - if mapmytracks were open about it...

He was very enthusiatic about the information that could be selected for analysis and made available at the event - which seems to have been on a par with the kattak output that we have seen online for Albacores. I still think that what I could look up on mapmytracks for Whitstable was poor, but perhaps it's a condensed subset of data? Or my PC, or broadband?

Musto Skiffs have used this system at other events, including Worlds at Lake Garda, so they must have been pleased enough to repeat (with sponsorship/advertising by/for mapmytracks).

PS What was taken from my arm was not dangerous. The arm is healing well, given the strain of today's envigorating sailing. So I expect to make it to Seasalter.

check out the MyLaps software that was used for Solent slog in june.
were given a little reciever to put on the mast and the link was online for anyone to watch the racing in real time.

http://spectator.mylaps.com/56045

you can click on any boat and see their speed, heading, position etc.
after the race they showed it sped up on big screen
quite impressive

Kyle Stoneham wrote:check out the MyLaps software that was used for Solent slog in june.
were given a little reciever to put on the mast and the link was online for anyone to watch the racing in real time.

http://spectator.mylaps.com/56045

you can click on any boat and see their speed, heading, position etc.
after the race they showed it sped up on big screen
quite impressive

Yes - I like the way they show catamarans in the display.
I reckon that race is well named. It certainly looked like a bit of a slog.
Cheers
Bob

Here is an interesting GPS race.

I haven't seen the write up yet but this is the scenario I think.

Hugh Styles leading the event into the final race. Olivier Backes in 2nd place, Darren Bundock and Will Howden 3rd. Bundock/Howden cannot mathematically win, but they can get 2nd if they sail Hugh Styles down the fleet. Hugh hit a press boat and got redress for two races in the series, the redress score is an average of all races including the discard. If Bundock/Howden can sail Hugh down the fleet his redress score will include a bad result, Oliver Backs will be world champion, Bundock/Howden will be 2nd and Hugh 3rd.....

Here is the GPS track from the race, Hugh is GBR 7, Bundock/Howden AUS888... Robert Sheidt & Ben Ainslie but in cats....

Takes a while to get the race going. You can zoom in and out and if you click on a boat it will centre on them.

http://www.traclive.dk/events/event_201 ... 1e0bdc1ba9


George

Yep - they certainly got sailed out of it