Polar
Create your own Polar Files from Instruments
Links
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Maintenance Source: https://github.com/rgleason/polar_pi
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Download:https://opencpn.org/OpenCPN/plugins/polar.html
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Forum: CF Polar_pi Thread
2. Install
The OpenCPN Manual has general information in Plugin Download, Install and Enable for installing this plugin.
3. Standard actions
Modes of Operation
The Polar plugin has 4 modes of operation:
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Data from logbooks: This mode will read from all logbooks found in the logbook/data directory. If enough data points are found, a polar will be created.
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Data from NMEA: This mode will read data from the NMEA stream and create a Polar from this data.
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Data from VDR File: This mode will read a given VDR file and will use the NMEA messages in the file to create a Polar.
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Edit Manual: This mode allows the user to create a Polar manually.
It is possible to switch between modes. For instance edit manually a Polar and then switch to Data from NMEA and Start Record. This will add and update the data for the polar.
Data Collection
Data will be collected in 5 degree wind directions and 2 knots of windspeed and this information will be saved.
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The plugin will also interpolate middle steps, eg 6 and 7 degree will be added to the 5 degree step and 8 and 9 will be added to 10 degree step. The windspeed is divided by 2, so column 2 knots hold the speeds from 2 till 3.99 and column 4 knots will hold the speeds 4 till 5.99. etc up to 40 knots.
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If reading in other polar files polar_pi tries to fill in the wind direction in 5 degree steps with 2 knots of wind similar to the input from NMEA. The same sampling will be used as above.
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Polar_pi can read badly formatted polar files with lines of all zeros and can save the file out with the zeros removed.
4. Create your own Polar File
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Confirm that your Wind and BSP/STW instruments are properly calibrated and that the nmea0183 data stream is working properly with full sentences and good checksum. Confirm that you can record the data.
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Record Nmea0183 data while sailing in various wind conditions, at a wide range of wind angles, with the same set of sails trimmed properly, preferably with a clean bottom, average weight in the boat, and no current.
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Make several of these recordings for different sea states and sets of sails and reefing.
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Using Polar_pi load one of the files.
Load Nmea0183 Recorded Data file
Open Nmea0183 Recorded Data file
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Edit the file. You will want to normalize the data and make it regular, by eye.
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Save the file with a new name, using some version of [Boat-Sails-Conditions].pol
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Now you can use it in Weather_routing as one of your Polar files.
Note that in Weather__routing you can load multiple polar files such as:
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Very light wind under power
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Light to medium wind under mainsail and genoa
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Heavy wind under mainsail and jib, etc.
This plugin does an excellent job of building and preparing polars for use in Weather Routing Plugin.