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apparent wind ?


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#1 THOR

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Posted 27 August 2013 - 04:42 AM

sorry if already answered somewhere else ...

 

lots of peeps are bitching about 22 knots or whatever windlimit .... what is the apparent wind when they go upwind and downwind ?

 

Thanks thor



#2 ProaSailor

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Posted 27 August 2013 - 05:07 AM

sorry if already answered somewhere else ...

 

lots of peeps are bitching about 22 knots or whatever windlimit .... what is the apparent wind when they go upwind and downwind ?

 

Thanks thor

 

http://www.sailingco..._calculator.htm

 

If true wind is 22 knots at a true wind angle of 45 degrees and the boat is moving at 44 knots (I have no idea if those numbers are accurate?), the apparent-wind would be 14.64 degrees off the bow at 61.55 knots!!

 

The true wind angle is much higher going downwind, of course, reducing apparent wind speeds dramatically.



#3 wraith

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Posted 27 August 2013 - 05:13 AM

sorry if already answered somewhere else ...

 

lots of peeps are bitching about 22 knots or whatever windlimit .... what is the apparent wind when they go upwind and downwind ?

 

Thanks thor

 

http://www.sailingco..._calculator.htm

 

If true wind is 22 knots at a true wind angle of 45 degrees and the boat is moving at 44 knots (I have no idea if those numbers are accurate?), the apparent-wind would be 14.64 degrees off the bow at 61.55 knots!!

None of the boats are ever going to manage 44 knots upwind!



#4 ProaSailor

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Posted 27 August 2013 - 05:26 AM

 

sorry if already answered somewhere else ...

 

lots of peeps are bitching about 22 knots or whatever windlimit .... what is the apparent wind when they go upwind and downwind ?

 

Thanks thor

 

http://www.sailingco..._calculator.htm

 

If true wind is 22 knots at a true wind angle of 45 degrees and the boat is moving at 44 knots (I have no idea if those numbers are accurate?), the apparent-wind would be 14.64 degrees off the bow at 61.55 knots!!

None of the boats are ever going to manage 44 knots upwind!

 

So...  What are more realistic values?  Pretty sure I've read of apparent wind speeds at "50 to 60 knots".

 

If true wind is 22 knots at a true wind angle of 100 degrees and the boat is moving at 44 knots, the apparent-wind would be 28.33 degrees off the bow at 45.65 knots,



#5 snaerk

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Posted 27 August 2013 - 09:53 AM

 

 

sorry if already answered somewhere else ...

 

lots of peeps are bitching about 22 knots or whatever windlimit .... what is the apparent wind when they go upwind and downwind ?

 

Thanks thor

 

http://www.sailingco..._calculator.htm

 

If true wind is 22 knots at a true wind angle of 45 degrees and the boat is moving at 44 knots (I have no idea if those numbers are accurate?), the apparent-wind would be 14.64 degrees off the bow at 61.55 knots!!

None of the boats are ever going to manage 44 knots upwind!

 

So...  What are more realistic values?  Pretty sure I've read of apparent wind speeds at "50 to 60 knots".

 

If true wind is 22 knots at a true wind angle of 100 degrees and the boat is moving at 44 knots, the apparent-wind would be 28.33 degrees off the bow at 45.65 knots,

 

The "50 to 60 knots" is strange becoz its not mathematickly possibel.

 

Yet, as you sudjest, sum of the hot sailerz on these botes hav been kwoted by farely relyabel sorsez as having sed it.

 

 

The max AWS is alwaze going to be atsheeved going upwind, unless or until they start going sumthing lyk 80 knots DW in 25knots of wind

 

Getting back to reality:

 

The TWA looks to be about 45 deg min to there CMG, and the max botespeed maybe 26 knots, maybe even a bit more, at that angle

 

(2 months ago max spd woud hav been maybe 23 knots, according to the umpires pennulty polars )

 

Whitsh ekwates to an AWA of abowt 21 deg and an AWS of abowt 44 knots


Whitsh woud be about the max - cracking off to 55deg TWA, assuming that got them up to 29 knots, the AWS woud only go up about a knot.

 

And I agree with your figure of 45.6 AWS for a 100 deg reech at 44 knots.

 

Saling enny deeper is going to reduce that.

 

SO, my gess is 45 knots is about tops for wind across the deck, for the moment.

 

Weev seen faster speeds upwind, but only with tyd behynd them.



#6 edouard

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Posted 27 August 2013 - 02:22 PM

You really want an answer?

 

Drop the shitty spelling for starters.



#7 THOR

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Posted 30 August 2013 - 02:07 AM

 f..... off ........playing the spelling police

 

I guess we can calculate some windspeed. But does anybody know what the apparent is down and up wind ?

Thanks for the answers so far

 

I am just interested as some wankers, the ed included, are harping on those limits, while they would get their panties in a bunch with much less :-)



#8 joeboy

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Posted 30 August 2013 - 02:14 AM

They can probably get the apparent up into the 50s on the reaching bits.



#9 snaerk

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Posted 30 August 2013 - 03:28 AM

They can probably get the apparent up into the 50s on the reaching bits.

 

Yup, but thay woud have to be saling at 50 knots or close to

 

(at 100deg TWA, 50 knots boatspd, TWS 22 knots, AWS= 51 knots)

 

 

But the character of the polars we hav seen indickayts that max botespeed

will be at 115 TWA min, or theerabouts, in 26 knots TWS; and deeper still in lyter windz.

 

To get 50 knots across the deck at 115 TWA in 26 knots TWS would take 55 knots of botespeed.

 

I dont think it will happen



#10 Kiwing

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Posted 30 August 2013 - 07:52 AM

^

I think you will be surprised !  55 is on, IMHO



#11 snaerk

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Posted 30 August 2013 - 08:25 AM

^ Thay woud hav to pop a shoot lyk a funny car when thay got to the mark soze not to overshoot

 

(let me gess- steam injection to the foils to inishyate supercavitayshun --

 

piped from the Nespresso masheen? )



#12 Tony-F18

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Posted 30 August 2013 - 08:37 AM

FYI: Dogzilla ran at 12 degrees AWA, I suspect the 72s are not very far of.

#13 ghost0070

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Posted 30 August 2013 - 12:32 PM

Something related occured last week. Windward start with 1 kt of current moving from right to left along the line. Boats moving about 5 kts. Which end favored?



#14 snaerk

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Posted 31 August 2013 - 03:21 AM

Something related occured last week. Windward start with 1 kt of current moving from right to left along the line. Boats moving about 5 kts. Which end favored?

 

insuffishent data



#15 Nutta

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Posted 31 August 2013 - 03:25 AM

My wife often accuses me of "apparent wind". I've observed that it is always to stern, never forward...

#16 Landlockedlubber

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Posted 31 August 2013 - 07:34 AM

Surely an ahole AoA function?

#17 Landlockedlubber

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Posted 31 August 2013 - 07:34 AM

Surely an ahole AoA function?

#18 Landlockedlubber

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Posted 31 August 2013 - 07:37 AM

My wife often accuses me of "apparent wind". I've observed that it is always to stern, never forward...


Would be a function of ahole AoA nevertheless

#19 Landlockedlubber

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Posted 31 August 2013 - 07:33 AM

Surely an ahole AoA function?

#20 Landlockedlubber

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Posted 31 August 2013 - 07:37 AM

Apologies - touch of the snarkes on 'send'




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