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11/12/2023 6:17 pm  #1


Comparing polars with actual data from log files

I have both log files and 'cleaned' log file reports (with constant phases extracted using Tools).
What is the best way to overlay this data and see how close the actuals are with the polars?

 

11/12/2023 8:57 pm  #2


Re: Comparing polars with actual data from log files

Have you seen the Edit polars function?

Also the Stripchart tests, although that is more work ...

 

2/25/2024 11:43 am  #3


Re: Comparing polars with actual data from log files

Where can I find nourishment understanding the edit of polar files to improve accuracy of the basic polar file?  I have explored the operation and find I still lack understanding of how the edit changes to the polar graphic display interacts with the base text file.  It looks like a powerful connection, but I keep screwing up the base file, getting changes to the data that I don't understand.  Nick, can you please comment?
Thx, pjl

 

2/26/2024 3:10 am  #4


Re: Comparing polars with actual data from log files

You might find this course usefull https://learn.asa.com/p/expedition-polars-sail-charts/
Mr Isler explains very well. He has more courses at NorthU and his own website.
 

 

2/26/2024 7:36 am  #5


Re: Comparing polars with actual data from log files

thx, hefty price!!  is there an economy version?  a list of graduates?

 

2/27/2024 9:01 am  #6


Re: Comparing polars with actual data from log files

iterative edits solved my problem.  I've got a clean and rational polar now!!

 

3/18/2024 8:14 am  #7


Re: Comparing polars with actual data from log files

Can anyone comment on how the route optimization algorithm works regarding interpolation of values between the values in the polar file, which represent "steps" in the  curve?  The polar edit function shows very illogical curves in some cases as I attempt to adjust values based on actual experience.  Logic says that the shape of the curve should be smooth, not have bumps and valleys.  Thx for your thoughts and comments.

 

3/18/2024 9:33 am  #8


Re: Comparing polars with actual data from log files

How many data points do you have?
If you have too much data in your polar when you adjust one point based on experiance it can generate wonky curves as it tries to fit all the data into the polar

It is better to have a sparse but accurate polar.

 

 

3/18/2024 11:01 am  #9


Re: Comparing polars with actual data from log files

Good point.  As another test, I have generated a set of polar files with minor changes with only the original input points, i.e. heading, wind speed and boat speed.  When I examine the polar edit function in Expedition, I can still see wonky curves.  I can eliminate the wonky curves by editing the displayed plot, which seems to change the data in the array of data in the original polar selected for examination.  This raised my question of how the program works.  Meaning does the optimization process use the data from the smooth curve formula that seems to be generated by a curve fitting process to the plotted data.  Does that make sense?  Maybe Nick will add some knowledge to this thread that will eplain what's going on.  Thx, pjl

 

3/18/2024 11:27 am  #10


Re: Comparing polars with actual data from log files

Exp fits smooth curves to the data you give it.

You would have to post a picture to explain, but 'wonky' curves suggests an issue with teh values you are changing the polar points to.

 

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