polar graph

Does one exist for the F16?

I never found one.

Ditto for the F18.

I think I once saw one for the classic Tornado and the single trap C class..

I would very much like to see a reliable one! (not mathematically derived from a sailmaker)

What does it take to make one?

A very good sailor with good sails.
A GPS
Patience
Time

The crew needs to sail all courses in different windstrenghts with optimum speed and record the results. Then repeat to build a statistical base.

Well, that ain't happenin'! Plan b: what does it take to get one from a sail maker?

Contact North Sails and ask for it. Prepare to pay for a development program in F16 sails before asking

Why North? Wouldn't one of the lofts making F16 sails be better?

Depends on the software and expertise the software have available. North have some nifty software for generating polars as part of their in-house software environment.

Well, you're looking for a quality activity why not cobble one together?

What would a polar graph for the F16 look like? I'm guessing concensus from the group would provide a reasonably accurate graph.

I've made one for a yacht a few years ago, pretty easy to do when all of the instruments are networked together.
You do really need wind instruments to calculate VMG accurately though, not easy to do on a small cat (and expensive!).

I was thinking to put some points on a graph generator, purely out of conjecture, then talk it to death until we believe it is accurate.

With all the small, cheap gps units out there we should be able to get a huge amount of data.

I think you need accurate TWD and TWS as well as cog and speed (to account for any current, right?).

Wire up your boat Pete and sail a lot. Post your data and someone can crunch the numbers...

Processing the numbers is not hard. Getting accurate data is.

Nope. On second thought, the graph generator isn't even necessary.

We just need someone to plot the points and keep the chart. If people would submit their gps tracks or individual data points, in time we'd have a very accurate graph. The bs data would fall far outside the norm leaving the rest as valid.

To obtain accuracy can you not simply plot the raw data from a variety of sources and deduce best possible vmg?

Example: plot the course of two boats to weather. The higher boat is likely to be going slower but not necessarily making the best vmg. The data can be obtained on different days on opposite points of the globe. With enough data points an accurate picture will emerge.


http://forums.sailinganarchy.com/index.php?showtopic=127515&st=0#top

A polar shows the best performance for given windstrength and heading. Comparing the results from weekend warriors will create a suboptimal polar

If two boats are going to weather and one is pinching waaay too high and another is footed off to a reach it is still possible to plot their data, yes?

Though neither represents the optimal course, the best vmg will lie between the two, correct?

If so, it is then only necessary to have the two alter course gradually towards each other. One or the other must then sail the optimal course if only by accident.

Plotting large numbers of isolated data will eventually demonstrate the optimal course.

You are right Pete. There is just one problem..

For best performance we need really good sailors when doing the averages. If we have "average" sailors, the polars will indicate less performance than what really is in the boat.

Remember that the polar is supposed to show the best speed obtainable on the different courses at the different windspeeds. The "sailor" variable is pretty large I would say.

Maybe polar is the wrong term for what I'm interested in. I'd just like to see what people of all skill levels are doing in the real world. It would be nice if everyone carried a Spot during regattas.

In the GPSAR program you can upload gpx files.
Then you can get the spikes out (which I didn't do now) and get your polar of that day. (bases the winddirection upon the angles you sail around the course) This is ofcourse only a polar for upwind/downwind and not anything in between.
I guess this will enable you to compare performance of a specific boat at a specific event.

Ofcourse windshifts, wind lanes etc. will influence one time off measurements as these.

Gill

Thanks Gil.

Pete,

You are not going to get any real numbers worth you could sort.

1 guy is pinching a bit, going slow and sideways. Boat 2 generated a bit of hull speed and rode his foil lift up to the same angle of attack but is maintaining speed and going twice as fast.
Maintaining hull speed on a downwind point of sail is even a larger performance gap generator.
Technique generates speeds and watching tracks from the very top F18 guys at NA and worlds, huge spurts of speed came with pressure and once you drop out angle of attack and VMG are all over the place even with the very best of the drivers.

I am sure the AC programs are working on this with huge budgets on instrumentation and computer modeling. At least to date this is obviously not working there. Boat handling and reading the conditions is way the more important factor. Coutts has been made to look like an amateur at times. I would bet he is relying on his past experience and trying to be scientific rather than reacting. If you have to tell somebody to do something or wait for a number to tell you to go, it is too late on cats. Anticipation is key to ultimate speed.

If all you want is something to compare against to know that you are doing:

under average,
average,
above average,

without further quantification, then I think getting som GPS plots is good enough.

I'm lost...

That is a good place to be! Then you are close to not being lost anymore
Just consider how many are lost without realising so.

Pete, let me know if you want any others to check.
Or just let us know what trim you want to know more about :-)

Hey, please post as many "personal polars" as possible! They are great for comparison!

http://connect.garmin.com/activity/91690890

Here's a gps track, how do you get started?

Download http://gpsactionreplay.free.fr/index.php?menu=2

Then import your GPS datafile into GPSAR. Create polar is a menu choice

I was unable to get the raw data out of the Garmin page.

Pete, I think that the PC version (as opposed to the web version) of Kattack will allow you to do polars on any boat in any race. For example, you could go to the CRAW races and do a polar on me, Karl, Mark, or Daniel.

I'll play around with it...

Hi guys,

Ive been messing around with the Prostart and GPSAR and it spits out polars quiet easily.

Ive attached a polar of my old viper in 20 kts. I supose the you need to get different ones for wind and wave conditions.

After a second look the wind direction my be a little out of whack but you get the idea. GPSAR has great statistics on top and average speeds and also shows you the runs on the map.

Heres the proper one with the wind orientated the right way. I think the interesting thing is that the upwind vmg seems quite wide. So you can still get good upwind VMG even when you put the bow down pretty hard.

I've tried working with GPSAR and had little luck.

Pro Start is your friend Pete. It talks to GPSAR perfectly. I love it. Although there is almost zero time to look at it while sailing unless its light. But it records 40 hours of sailing on it. Its fun to go back through it and see where you went wrong. The detail is quite amazing.

I got my metal working mate to make me up a very light aluminium bracket that i sew to the tramp between the mast and the starboard hull just behind the front beam. It seems to work really well there. The jib self tacker seams to protect it from the spin sheets.