Expedition Navigation Software 
1 of 1- Roddo
- Expert
Offline - Registered: 6/23/2016
- Posts: 13
Ideal Polar
I started off making a polar for my boat for every degree and every knot of wind until I figured that it was way too much. I've been trying to find some doco on the best polar grid combo ie, every 30degrees or every 5degrees etc. and also values for wind. So I'm not really sure what Expedition likes best, assistance would be appreciated,
Cheers
Rod
- ZeeZee
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- Registered: 3/30/2016
- Posts: 321
Re: Ideal Polar
Exp will interpolatre between the data points. So you don't need all angles and winds. However, logic tells me that there need to be some minumum of data points to get a somewhat reliable polar.
It also depends on your needs. If you only sail windward/leeward races then you only need a polar for upwind and downwind angles and there is no need for reaching data points.
- Roddo
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- Registered: 6/23/2016
- Posts: 13
Re: Ideal Polar
Thanks Zee Zee. Usage is for ocean racing. I've seen some polars start off with zero and every 30 and some that start at 30 and go every 10. Same with wind, some go 2,4,6,8 and some go 2,5,10.
I thought that Expedition might have a sweet grid to give the best results and I was searching for that.
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Thread Starter- ZeeZee
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- Registered: 3/30/2016
- Posts: 321
Re: Ideal Polar
Many people might start with the polar they get from their designer or e.g. their ORC certificate.
These are often for TWS 6, 8, 10, 12, 14, 16 and 20 and for TWA 52, 60, 75, 90, 110, 120, 135, 150 as well as the optimal beat and run VMG angles.
From their on you can further fine tune the polar using the nice options Expeditions offers. That's at least how I'm doing it.
- sheldon.haynie
- Expert
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- From: San Francisco Bay
- Registered: 1/13/2016
- Posts: 133
Re: Ideal Polar
You can assess your ability to meet/exceed the values and refine where you have divergence, and/or you can look at the curves and try to reduce inflections at TWS or TWA changes. If you have a boat that will surf/plane, you might put extra points around the transitions. Modeling a complex system you need more data points for when things change than when they are relatively constant.
Semiconductor Development Engineer, Retired Viticulturalist, Occasional sailor
"Lioness" 1962 Hinckley Bermuda 40 Custom Yawl