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Board » General Discussion » Compute Optimal VMC and more

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Posted by
AGage


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2008-12-27 10:31:57
2012-05-09 09:54:08 - Re: Compute Optimal VMC and more
Rod said @ 2012-05-06 00:51:59:
Agage' I don't understand the theory behind your new tool---Do you care to conduct a seminar on the care and feeding of such an exotic 'animal'?
=============================
Not really a seminar, but on the Links page above the 3 Blogs - by 76T, SWE54 and myself all have articles on VMC and VMG - and mine has links to yet more articles
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Posted by
K3 (Bernd)


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2008-08-25 12:34:07
2012-05-09 20:13:45 - Re: Compute Optimal VMC and more
Hi Aaron,

thanks for your detailed answer, the tool itself and V2!

My browser looses the connection, when I set the iMac asleep. When it wakes up, the red time display appears for some seconds until the new connection is established. The AngleTools (V1) misses the re-connection sometimes (and doesn't shows it).

I try to explain the %-thing. When I want to go a higher or lower than opt VMC or VMG I can enter for example 95% BB or SB in my own xls-sheet and get a TWA that takes care of bumps in the polar better than a fixed offset from the opt TWA.

ciao
Bernd (K3)
Posted by
AGage


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2012-05-10 06:52:07 - Re: Compute Optimal VMC and more
I cant really think why the tool shouldnt reconnect to, but it does use different code to handle the boat updates (I just pinched the polar code from the client - everything else is new)

Cant figure quite what 'BB' and 'SB' stand for....

I did have in mind to add ability to constrain TWA for VMC calculations (mostly for bumpy polars as you mentioned)
Would this give the same effect? Ie you could constrain TWA to be within 100-140. Often times the answer will just be with 100 or 140, but with bumpy polars setting the TWAs either side of a bump can produce results somewhere between the constraints
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Posted by
A2


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2009-10-26 00:39:42
2012-05-10 13:08:04 - Re: Compute Optimal VMC and more
My guess is

BB = Boat Bearing
SB = Speed of Boat
None so blind
Posted by
Schakel


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2008-12-19 09:19:00
2012-05-10 14:56:07 - Re: Compute Optimal VMC and more
My guess is

BB = Port (Backbord)
SB = Starboard (Steuerbord)

--
Cheers,
Philip

--- Last Edited by Schakel at 2012-05-10 14:58:42 ---
Posted by
AGage


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2012-05-14 11:16:33 - Re: Compute Optimal VMC and more
A Flash version is now available online here
This version has a nice 'Cobalt' theme to!!

This is the original version, hence only supports logging into a single race, but unlike the AIR version, you can open more than one instance.

I help develop the client interface for the best online ocean racing sim there is... __/)/)_/)__
Posted by
captjack1942


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2012-05-21 22:19:42 - Re: Compute Optimal VMC and more
Funny thing about the stand alone widget tool. It seems fond of giving TWA as NN.99 or NN.49. At least it seems that is all I ever see.
The flash version at least isn't derived from a fuel station pump price.

:-)
Posted by
AGage


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2012-05-23 07:34:43 - Re: Compute Optimal VMC and more
Can you send me a screenshot or something Jack?

And please, be a little more specific, ie TWA for what calculation? All of them, or just VMC to a heading or what?
I help develop the client interface for the best online ocean racing sim there is... __/)/)_/)__
Posted by
captjack1942


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2012-05-23 15:31:30 - Re: Compute Optimal VMC and more
Doesn't seem to be doing it now. But I swear for the last two short races (Aland and Perth) it would give TWA as a decimal .99 90% of the time and .49 the other 10%. Either VMC to next mark, course or a WP that I entered. I would get something like Port:...TWA=-55.99...

:-)
Posted by
AGage


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2012-05-24 08:41:38 - Re: Compute Optimal VMC and more
Bear in mind that internally the program is comparing velocities computed to some 10 decimal places - as is the SOL client and server.
Quite often it happens that the TWA for max vmg or vmc is a whole number (or atleast is displayed as 142.00 or whatever)
The program just loops over all possible headings or TWAs, incrementing by 0.01°, and reports which has the highest value - which can sometimes be angles like 40.68 for upwind vmg...

If it is consistently giving result of N.99 or N.49 - just think of this as (N+1).00 or N.5 but because of the precision of the values as held internally, it is probably well beyond the 4th decimal place that this angle is faster
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