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Polars

yurek

Jerzy Borzym
I'm trying to use routing program Luckgrib.
I'm looking for information where I can get polar diagram for Morgan.
Does anybody used this program?
 
You can use any boat with the same lwl and similar displacement. You will not get any better than that. I have the complete ORA polars for my Morgan, which I paid a handsome sum for. I used them a few seasons racing, followed by using them cruising. For much of that time, I adjusted them to better match real world performance, and never did they work any better than just picking a random boat (don't pick a planing boat!). So, I gave up. If the Islander 36 is available, that is close enough. If you are not racing(and good at it), you are probably sailing slower than the Morgan is capable of and it might even be better to pick a 30' boat.
Don't expect any magic from a routing program. They give you a general idea, that is all. Consider that if the wind direction on your grib is off by 3 degrees, that would be spectacularly close. But, it is enough that you can't sail that 3 degrees higher, so maybe you should tack. And then what? In reality, the twd might be 10 degrees off the forecast. Use the routing software for planning, then once you leave, use your own judgement and sail to the conditions, not the planned route.

The full polar set is an excel sheet that is many pages long. Here is what most routing software wants.

TWA
6​
8​
10​
12​
16​
20​
33​
0.00​
0.00​
0.00​
0.00​
0.00​
0.00​
36​
0.00​
0.00​
3.40​
3.85​
4.18​
0.00​
39​
2.80​
3.63​
4.29​
4.77​
5.28​
5.33​
50​
4.05​
5.07​
5.74​
6.21​
6.62​
6.75​
60​
4.66​
5.66​
6.36​
6.74​
7.06​
7.19​
70​
5.01​
6.02​
6.64​
7.00​
7.35​
7.51​
80​
5.29​
6.36​
6.91​
7.19​
7.58​
7.75​
90​
5.49​
6.53​
7.05​
7.38​
7.69​
7.96​
105​
5.43​
6.48​
7.03​
7.43​
7.94​
8.17​
120​
5.01​
6.11​
6.78​
7.23​
7.93​
8.50​
135​
4.14​
5.39​
6.30​
6.87​
7.66​
8.32​
140​
3.90​
5.11​
6.08​
6.73​
7.55​
8.22​
150​
3.49​
4.59​
5.61​
6.40​
7.32​
8.00​
165​
3.06​
4.05​
5.03​
5.86​
6.99​
7.70​
180​
2.84​
3.78​
4.71​
5.52​
6.76​
7.50​
 
Thanks Warren.: I'm always sailing to the conditions. Polar data can be used for planning. I'll see how it works.
 
Cool topic gents! Thanks for posting the data Warren! Looking at Warren's data and comparing to the wiki topic where I had to go to relieve some of my ignorance of the issue, I found a polar plot from Textor, Ken (1995) The New Book of Sail Trim, Sheridan House, Inc., pp. 228 ISBN: 0924486813. , pp. 52-3. The data is very similar -- at least the down wind data that I checked is close. I don't own the book and don't know where his data comes from but it supports Warren's claim that the source doesn't matter much if generally similar hull shape and sail config. But then I rarely race, and am pretty sure I am not good at it (after all, I have seem me do it).
 
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