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Polar file format question

  • HeatWave
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2 years 9 months ago #698 by HeatWave
Polar file format question was created by HeatWave
Hello, I'm trying to create a polar file for a J/111. The polar file format is simple enough, but it seems to lack the optimum upwind and downwind targets. For example, a few lines from an Expedition polat format (similar to other systems) is:

4 0 0 47 4.6 55 4.8 60 5.1 70 5.35 80 5.7 90 6.2 100 6.38 110 6.11 120 5.76 130 5.22 137 4.4 180 2.28
6 0 0 45 5.6 55 5.9 60 6.1 70 6.35 80 6.6 90 7 100 7.15 110 7 120 6.75 130 6.32 141 5.5 180 3.37
8 0 0 43 6 55 6.95 60 7.2 70 7.35 80 7.6 90 7.8 100 7.92 110 7.94 120 7.75 130 7.43 145 6.75 180 4.47


So at 4 knots TWS, target is 47 degrees and 4.6 knots, at 6 knots target is 45 degrees for 5.6 knots and so on.

But the format you have seems to omit that capability, so that I need a target boat speed for each combination of TWA and TWS. How does qtVLM figure the optimum targets when beating or running?

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2 years 9 months ago #700 by maitai
Replied by maitai on topic Polar file format question
Hello,
qtVlm calculates itself the beating and running angles limits based on the polar values. You can also force it in the boat's settings.
You can see the result of these calculations in boat->Wind Polar Analysis.
-- Philippe

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2 years 9 months ago #701 by HeatWave
Replied by HeatWave on topic Polar file format question
Thank you Philippe...

About forcing, it looks like I can only do that for a single angle for upwind and another for downwind, but this varies with TWS. Is that correct?

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2 years 9 months ago #702 by maitai
Replied by maitai on topic Polar file format question
Yes, if you force it that will apply for all TWS
That is why it is much better to let qtVlm calculate it.

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