Expedition Navigation Software 
1 of 1- sheldon.haynie
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Log File parameter questions
A few questions on specific fields.
I have SOG, COG, HDG, BSP,AWA, AWS which are direct measurements from my H5000, and calculated TWA, TWS, TWD, SET and DRIFT & Leeway which all make sense.
I also have Target BSP% and POLAR BSP% which are not the same, one is about 85% of the other, but not consistently Do they point to different polar tables? From Appendix A I would guess that POLAR --> NAV and Target --> Performance polar?
Similarly target AWA, Target TWA, which would point to Performance Polar?
but Target TWA Nav points to Nav polar (and if labeled Polar TWA would be consistent?)
then the target and polar Heel & leeway (using target speeds respectively on heel polar?
Semiconductor Development Engineer, Retired Viticulturalist, Occasional sailor
"Lioness" 1962 Hinckley Bermuda 40 Custom Yawl
- Nick
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Re: Log File parameter questions
Target bsp% is % of targets, whereas Polar bsp% is % of your polar speed.
These use the perf polar. There are also numbers for the nav polar
- sheldon.haynie
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Re: Log File parameter questions
Must be missing something, isn't the Target bsp from a lookup/interpolation of one of the polars?
I can understand with multiple polars for navigation, performance, starting & heel
that they could/would be different, and thus looked at appendix A and am not resolving.
from appendix A
'Polar bspThe polar boat speed at the current wind speed and angle.
Polar bsp%The fraction of the current boat speed to the polar bsp, expressed as a percentage.
Polar heelThe polar heel angle at the current wind speed and angle.
Polar leewayThe polar leeway at the current wind speed and angleTarget awa
Target bsp
Target bsp navTarget boat speed upwind or downwind based on the current performance polar.
Target bsp %The fraction of the current boat speed to the target bsp, expressed as a percentage.
Target heel
Target heel upwind or downwind based on the current heel polar.
I guess which should I be trying to match while sailing in mid buoy race?
I would assume that would be the Performance set, and the Nav set would be detuned to cover distance/deliveries.
Last edited by sheldon.haynie (7/11/2016 3:38 pm)
Semiconductor Development Engineer, Retired Viticulturalist, Occasional sailor
"Lioness" 1962 Hinckley Bermuda 40 Custom Yawl
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Thread Starter- Nick
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Re: Log File parameter questions
Targets refer to the upwind and downwind targets. Hence you have target bsp and twa at any wind speed.
Polars are at any twa & tws.
So, upwind you have a target twa & tws that maximise vmg. When reaching, targets don't have any/much meaning so you use polar bsp. Polar bsp% is useful as it is just one number, else you have to compare polar bsp with bsp.
- sheldon.haynie
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Re: Log File parameter questions
Aha !.. thanks that breaks the conceptual blockage.
Doing target speed while not doing target AWA or TWA is not what I want !
Wondered why I was meeting "percentage" numbers and getting arse kicked.
Last edited by sheldon.haynie (7/11/2016 4:16 pm)
Semiconductor Development Engineer, Retired Viticulturalist, Occasional sailor
"Lioness" 1962 Hinckley Bermuda 40 Custom Yawl
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Thread Starter