Polar formats and problems.

[rgleason]

1. I believe Weather_routing requires polar files that look like 1/2 of a heart that are completed from 0 to 180 degrees.
2. In the set of polars released with WRouting there are polars that do not look like 1/2 of a heart. These should be converted and improved so that they all work with WRouting or they should not be included.
3. Currently Polar_pi solves a number of format problems and permits export to various formats including OcpnCpn *.pol some of the problems solved are extra vertical columns of zeros at various wind speeds interspersed between actual readings, also the first line conversion and conversion to 5 degree formats.
   It also solves completing the diagram at the top of the 1/2 heart, by inserting a column of 0's at TWS=0 (sorry I may have had that wrong earlier) so that the polar diagrams are drawn to TWA=0 at the top.

It does not solve the bottom half of the 1/2 heart diagram. If the data is not included for the lower part of the diagram, going downwind, drawing the line from the end of the data to 180 degrees.

Weather_Routing does not work with these polars that do not include data from 180 degrees to 0 degrees.

How can we fix this?

1. Provide polars that show data from 0-180 degrees.
2. Modify all existing polar files so that they do this, or don't include them.
3. Perhaps somehow change the way Weather_routing works so that these polars will work?
4. Perhaps change or improve Polar_pi so that the bottom half is automatically completed.

Ideally both Polar_pi and Weather_routing will be changed to deal with these types of polars that do not have a full bottom line to 180 degrees.

[rgleason]

Sean has convinced me the problem is due to the polars not having a full range of TWS to boat performance.

Therefore I am closing this. - Not yet. There are some other ideas about...

[rgleason]

Lance,
In response to what you wrote. Thank for advising that you agree.

I have re written the wroute wiki and have provided example test polars from 0-60 tws knots
For new users.

I hope to make a pull request for these polars so they can be used.

Lance wrote:

I agree that this is the problem. However, what should OpenCPN do in this case? The routing code silently failed which I think is confusing. I submitted code that used the highest speed value in the polar, but it did not get merged.

What should the behavior be? Few people have the resources to extend their polars to wind ranges beyond what is given to them.

In my case I needed to supply values above 30 and 35 knots which is not uncommon off the California coast in the summer. I didn't really care about the routing exactness in those zones since when the wind gets that high we can't sail to the polars, anyhow. But I know this has effected other people.

Lance, where is your code, can you point us to it? Perhaps Sean will reconsider... I think we could use that code and color the isobars or the route a different "HIGH WINDS -Max Boat Speed used" color, Purple, perhaps?

[rgleason]

Here are some polar files from 0-60 knots. You can unzip them and put them in your directories. Use them when there is a "Polar:Fail" problem, to convince yourself that the problem really is the polar file. See the new weather_routing_pi documentation for more about how to use these files.
https://opencpn.org/wiki/dokuwiki/doku.php?id=opencpn:opencpn_user_manual:toolbar_buttons:plugins:weather:weather_routing

Polar-Test-xml.zip
polars-pol.zip

[rgleason]

The attached file names have been changed to make it clearer to new users.
They should be added to the boat polar files to be used as an example tutorial for the wxRoute Manual.

TWS-20-60.pol
TWS-0-6-Power.pol
TWS-6-20.pol
Test-TWS-0-20+60.pol (spans 0-60 knots with a single file)

Polars-Pol.zip

[rgleason]

Lance wrote and said he does not motor 0-6 knots and we should have a new user test file for

TWS-0-6.pol (which is sailing)

I think this is better because it shows the versatility of wxRouting.
By the way, wxRouting can also be used to help power boats save fuel and reduce emissions too.
So I'll add that TWS-0-6.pol sailing file next.
Of course these are only sample files, that do not represent your boat's performance.

[rgleason]

I believe this is fixed now.