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J30 Polars #8813
01/23/10 01:14 AM
01/23/10 01:14 AM
Joined: Oct 2009
Posts: 42
Seattle, WA
gmo Offline OP
Senior Member
gmo  Offline OP
Senior Member
Joined: Oct 2009
Posts: 42
Seattle, WA
I just realized that the polars that came on my boat are way different from those on the J/Boats website. For example, the one from the boat is dated 1994 and shows the optimal true wind angle in 8 kts of wind at 144.4. The one on the J/Boats website has the optimal angle at 161.

Newer: http://files.me.com/gradymorgan/gs5aww
J/Boats website: http://www.J/Boats.com/j30/j30polar.htm

Note that the newer is in apparent wind.

Anyone know where the newer came from, and if I should pay any attention to it?


Grady Morgan
Slingshot - Hull #112
Re: J30 Polars [Re: gmo] #8817
01/23/10 07:50 AM
01/23/10 07:50 AM
Joined: May 2007
Posts: 2,581
Portsmouth, RI
Rhapsody #348 Offline
Past J/30 Class President
Rhapsody #348  Offline
Past J/30 Class President
Joined: May 2007
Posts: 2,581
Portsmouth, RI
Reading the legend, it looks like the newer one was obtained under the US Sailing IMS program which appears to be the Performance Products Program now on the US Sailing web site.

I made a jpg so it is easier to see the figures and compare. I also added a picture using the trial version of Expedition that includes a sample J/30 polar. I captured a screen shot and provided both the raw text file Expedition uses, and the file converted to Excel so you can play with it.

I need to get better at using these. Can others post here on how you have used the polars to help your performance?

US Sailing Polar
[Linked Image]

J/Boats Website Polar

[Linked Image]

Expedition Polar
[Linked Image]
[Linked Image]


Attached Files
J30-Polars-USSailing.jpg [142.58 KBytes] - (13930 downloads)
J/30 US Sailing Polars
J30-Polars-Expidition-Sample.jpg [72.66 KBytes] - (5527 downloads)
Expedition J/30 Sample Polar
J30_Polars-Expedition.txt [0.7 KBytes] - (402 downloads)
Expedition Sample Polar Data
J30_Polars-Expedition.xls [17 KBytes] - (1917 downloads)
J/30 Polars from Expedition - Excel Format
Expedition-data-as-graphic.png [3.53 KBytes] - (4169 downloads)
Expedition data as a graphic
J30 Polars-from UK-Website.xls [18 KBytes] - (2029 downloads)
Last edited by Rhapsody #348; 04/20/10 01:45 PM. Reason: Added J30 Polars from UK website
Re: J30 Polars [Re: Rhapsody #348] #8819
01/23/10 09:22 AM
01/23/10 09:22 AM
Joined: May 2007
Posts: 1,234
Newport and Naples
Cap'n Vic Offline
Senior Member
Cap'n Vic  Offline
Senior Member
Joined: May 2007
Posts: 1,234
Newport and Naples
Dacron vs Kevlar ... just how much can that factor change these?

Love those "pinch" curves on US Sailing Polar .... indicates a more sophisticated simulation???

Re: J30 Polars [Re: Cap'n Vic] #8821
01/23/10 11:31 AM
01/23/10 11:31 AM
Joined: Apr 2003
Posts: 649
Marblehead, MA
dbows Offline
Senior Member
dbows  Offline
Senior Member
Joined: Apr 2003
Posts: 649
Marblehead, MA
For short 1-2mile W/L they are tricky to use and probably are a waste of time while you race. I think they are good to look at the relative angle changes as wind increases and decreases vs speed.

For distance races they are imperative because your sailing angles are so important. It is pretty easy to tell when you are beating if you are moving but when you have to crack off and sail 57deg for 4 hrs in 17knts the polars give you a good idea of what speed you should be making. This also will tell you if you are over powered (going over your polar) or under powered (not hitting your polar). Either case you want to change your sail combo to match the polars.

DB


David Bows
Mallorca - Hull# 397
~~~~~_/)~_/)~~~~_/)~~~~~~~~~~~~~~~~~~~~~~~~~|~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|~~~~~
Re: J30 Polars [Re: dbows] #8835
01/25/10 01:39 AM
01/25/10 01:39 AM
Joined: Oct 2009
Posts: 42
Seattle, WA
gmo Offline OP
Senior Member
gmo  Offline OP
Senior Member
Joined: Oct 2009
Posts: 42
Seattle, WA
There's a pretty big difference between the US Sailing polars and the manufacturer polars. Does anyone sail as high in light air as the US Sailing one recommends?


Grady Morgan
Slingshot - Hull #112
Re: J30 Polars [Re: gmo] #8836
01/25/10 08:25 AM
01/25/10 08:25 AM
Joined: May 2007
Posts: 1,234
Newport and Naples
Cap'n Vic Offline
Senior Member
Cap'n Vic  Offline
Senior Member
Joined: May 2007
Posts: 1,234
Newport and Naples
7kt, flat seas, NEW light 3DL sails?
and pinch happy ex j24ers?
I am impressed by the use of those pinch curls.
Next time you're out compare barely visible luff flutter to how the woolies work vs speed to two decimal places and contolled heel angle.

I can't concentrate enough to do all of this while driving, and my crew here are no sailmakers.

Re: J30 Polars [Re: Cap'n Vic] #8838
01/25/10 01:29 PM
01/25/10 01:29 PM
Joined: Apr 2000
Posts: 669
Maryland, USA
Bob Rutsch Offline
Governor at Large
Bob Rutsch  Offline
Governor at Large
Joined: Apr 2000
Posts: 669
Maryland, USA
Using just a compass and a knot meter, we don't fool much with true or apparent wind. I figure we generally tack through a bit more than 80 degrees, which appears to be consistent with these polars.

Re: J30 Polars [Re: Bob Rutsch] #8840
01/26/10 02:32 AM
01/26/10 02:32 AM
Joined: Mar 2005
Posts: 111
Bellevue, WA, USA
R
R II Offline
Senior Member
R II  Offline
Senior Member
R
Joined: Mar 2005
Posts: 111
Bellevue, WA, USA
I think the question pertains to 'off-the-wind' sailing angles. Any thoughts on optimum apparent wind angle on a light air run? 90 degrees apparent sure feels good, but how about the VMG?


AC
Re: J30 Polars [Re: R II] #8936
02/09/10 02:21 PM
02/09/10 02:21 PM
Joined: Oct 2009
Posts: 42
Seattle, WA
gmo Offline OP
Senior Member
gmo  Offline OP
Senior Member
Joined: Oct 2009
Posts: 42
Seattle, WA
Yes, I was mostly curious about down wind angles in light air. How deep downwind do you guys typically sail in light air?


Grady Morgan
Slingshot - Hull #112
Re: J30 Polars [Re: gmo] #8941
02/10/10 11:08 AM
02/10/10 11:08 AM
Joined: Mar 2009
Posts: 116
RI
Bob Rude Offline
Senior Member
Bob Rude  Offline
Senior Member
Joined: Mar 2009
Posts: 116
RI
On "Mmmmm" we don't have a masthead wind indicator to record windspeed and/or direction. Nevertheless, we've had the old J30 Polar chart on the boat since we bought it years ago and use it as a guide. We do try to sail to targeted speeds. After sailing for a while, you get pretty good at guessing the actual windspeeds and using that, along with our speedo, we shoot for targeted speeds. On beats, we know what that number should be on our speedo. On reaches, we simply use our Windex indicator which have the jibing angles set. Granted, it's not "data driven," but it keeps us in the ballgame.

Bob Rude


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