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Re: New Nacra 17 [Re: Jake] #244035
02/14/12 12:52 PM
02/14/12 12:52 PM
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NacramanUK Offline
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Originally Posted by Jake
Originally Posted by samc99us
Originally Posted by Luiz
Originally Posted by mikekrantz
For the F20c, there is a definite "twist" to the boards. It's not a straight curve...



Not all curved foils were born equal.

Symetrical section curved foils with different angles of incidence along their span on the F20C, compared to asymetrical section curved foils with fixed angle of incidence along their span on the french maxitris.

It will take a while to fine tune curved foils in cats. And never forget the "S" foils that were barely tested.


Source? Some say the foil is symmetric, some say asymmetric on the F20c. What is on the new F17?

You can get by with 2 mold halves if twist is 0. Otherwise, forget about it. Doubt they are doing that in a production environment anyway, I am sure there are 4 mold halves at an easy $40k for the set.

If you have twist, which is one method of getting elliptical lift distribution, things get complicated really fast. For starters, simply modelling the foil in CAD becomes a nightmare-try 100+ hours of CAD work for the plug and then another 40 or so hours for the molds themselves.

I also realized the broken Nacra foils I own have Rohacell or similar high density foam cores. If the curved boards are similar, you would need to machine this core prior to putting it in the molds. That's probably $200 worth of machine time per core if you own the machine.

One way to look at this is by cost, and surely a foil that costs 30% more isn't going to make your boat 30% faster, hence its not worth it. IMO, $1300 is already a lot of money for a daggerboard, why not just pay the extra $400/board for a curved foil? Its a 3% increase in cost on a brand new F18, for example.


I think the Nacra curved foils actually have rib/spar construction inside.


I spoke to Peter Vink today to check what I already new and can confirm the F20 Carbon foils are symmetrical with a linear curve and NO twist. They have 2 main ribs with a number of stringers/spars combined with a foam core.

-- Have You Seen This? --
Re: New Nacra 17 [Re: pitchpoledave] #244039
02/14/12 02:32 PM
02/14/12 02:32 PM
Joined: Jun 2001
Posts: 1,021
Australia
macca Offline
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Australia
Really? No twist at all?


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Re: New Nacra 17 [Re: macca] #244041
02/14/12 03:14 PM
02/14/12 03:14 PM
Joined: Jul 2008
Posts: 129
Austin, TX
BoK Offline
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No twist until before you sail with them. The ones at the Great Texas looked pretty twisted to me.


Bo Kersey
Corsair 31-1D 276
Re: New Nacra 17 [Re: pitchpoledave] #244043
02/14/12 04:14 PM
02/14/12 04:14 PM
Joined: Jan 2008
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Portland, Maine
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ThunderMuffin Offline
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The brand new ones I saw right out of the box looks like they had twist to them.

Re: New Nacra 17 [Re: pitchpoledave] #244044
02/14/12 04:17 PM
02/14/12 04:17 PM
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Posts: 1,021
Australia
macca Offline
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Australia
They certainly do have a twist.


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Re: New Nacra 17 [Re: macca] #244051
02/14/12 06:07 PM
02/14/12 06:07 PM
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NacramanUK Offline
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Originally Posted by macca
They certainly do have a twist.


No twist-confirmed by Peter Vink today......

Re: New Nacra 17 [Re: BoK] #244052
02/14/12 06:13 PM
02/14/12 06:13 PM
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Originally Posted by BoK
No twist until before you sail with them. The ones at the Great Texas looked pretty twisted to me.

I will ask Peter Vink to personally respond to this discussion......

Last edited by NacramanUK; 02/15/12 03:28 AM.
Re: New Nacra 17 [Re: ThunderMuffin] #244053
02/14/12 06:14 PM
02/14/12 06:14 PM
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Originally Posted by Undecided
The brand new ones I saw right out of the box looks like they had twist to them.


Check your glasses...

Re: New Nacra 17 [Re: macca] #244054
02/14/12 06:17 PM
02/14/12 06:17 PM
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NacramanUK Offline
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Originally Posted by macca
They certainly do have a twist.


All the UK boats have a linear curve with no twist-spoke to Peter Vink today who confirmed this...

Last edited by NacramanUK; 02/15/12 03:30 AM.
Re: New Nacra 17 [Re: pitchpoledave] #244055
02/14/12 08:34 PM
02/14/12 08:34 PM
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Portland, Maine
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ThunderMuffin Offline
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I'm sorry, you can tell me all day long to check my eyes, but even after 5 retinal surgeries I was able to see that they had twist to them.

The hulls were still sitting in the shipping boxes.

Re: New Nacra 17 [Re: pitchpoledave] #244057
02/14/12 11:30 PM
02/14/12 11:30 PM
Joined: Sep 2002
Posts: 3,224
Roanoke Island ,N.C.
Team_Cat_Fever Offline
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Maybe the first ones that had the problems(per David Lennard- F-20c sailor) had twist and that was the problem. Mike Krantz said they had twist per post #243870 a couple pages back, and he's had to see a few. So maybe it's quality control instead of engineering genius.

Quote
For the F20c, there is a definite "twist" to the boards. It's not a straight curve...


"I said, now, I said ,pay attention boy!"

The cure for anything is salt water - sweat, tears, or the sea
Isak Dinesen
If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most.
E. B. White
Re: New Nacra 17 [Re: Team_Cat_Fever] #244063
02/15/12 12:41 PM
02/15/12 12:41 PM
Joined: Jun 2001
Posts: 733
Home is where the harness is.....
Will_R Offline
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Home is where the harness is.....
Originally Posted by Team_Cat_Fever
So maybe it's quality control instead of engineering genius.


Surely you jest! ;-)

Re: New Nacra 17 [Re: NacramanUK] #244066
02/15/12 03:34 PM
02/15/12 03:34 PM
Joined: Oct 2005
Posts: 49
Israel, Sdot Yam
Opher Offline
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Israel, Sdot Yam
Originally Posted by NacramanUK
Originally Posted by macca
They certainly do have a twist.


All the UK boats have a linear curve with no twist-spoke to Peter Vink today who confirmed this...


Our boards definately don't have any twist. Notice how they lay on each other perfectly in the picture. The other F20C here had first gen boards (the fragile type) and they where also not twisted - we fit them in our trunks

Attached Files
F20C Dagger.jpg (59 downloads)

Opher
Nacra F20C ISR1
F18 Cirrus ISR2
Sdot Yam, ISRAEL
Re: New Nacra 17 [Re: Opher] #244069
02/15/12 04:36 PM
02/15/12 04:36 PM
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NacramanUK Offline
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Originally Posted by Opher
Originally Posted by NacramanUK
Originally Posted by macca
They certainly do have a twist.


All the UK boats have a linear curve with no twist-spoke to Peter Vink today who confirmed this...




Our boards definately don't have any twist. Notice how they lay on each other perfectly in the picture. The other F20C here had first gen boards (the fragile type) and they where also not twisted - we fit them in our trunks


Thank you Opher for confirming the facts about the boards...

Re: New Nacra 17 [Re: NacramanUK] #244070
02/15/12 04:48 PM
02/15/12 04:48 PM
Joined: Aug 2007
Posts: 1,304
Gulf Coast relocated from Cali...
TeamChums Offline
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Gulf Coast relocated from Cali...
WOW. Then the ones Mike and Dave had on THIER F20C definately had a twist to them, I saw it too. Conspiracy?


Lee

Keyboard sailors are always faster in all conditions.
Re: New Nacra 17 [Re: pitchpoledave] #244071
02/15/12 05:08 PM
02/15/12 05:08 PM
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BadLatitude1337 Offline
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I took a look at a set of f20c foils that we have here in Pensacola. And the do NOT appear to have any twist in them. Maybe people are seeing twist due to an optical illusion? we have 2 sets and they don't have any twist.


Open20NA 1337 FOR THE WIN!!!
Re: New Nacra 17 [Re: BadLatitude1337] #244072
02/15/12 05:45 PM
02/15/12 05:45 PM
Joined: Oct 2011
Posts: 217
Palm Harbor, FL
daniel_t Offline
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Palm Harbor, FL
Originally Posted by BadLatitude1337
Maybe people are seeing twist due to an optical illusion? we have 2 sets and they don't have any twist.


Could it be that the twist develops over time? The stress on the boards is uneven after all.


Daniel T.
Taipan F16 - USA 213
Re: New Nacra 17 [Re: pitchpoledave] #244074
02/15/12 07:40 PM
02/15/12 07:40 PM
Joined: Jan 2005
Posts: 6,049
Sebring, Florida.
Timbo Offline
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If it's a built in twist, wouldn't the dagger slots have to have a little slop built in to accomodate that, when you raise and lower them?

OR...the dagger trunks would ALSO have to be built with a twist, and that would be a bee-och to do!


Blade F16
#777
Re: New Nacra 17 [Re: Timbo] #244076
02/15/12 08:39 PM
02/15/12 08:39 PM
Joined: Sep 2002
Posts: 3,224
Roanoke Island ,N.C.
Team_Cat_Fever Offline
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Roanoke Island ,N.C.
Originally Posted by Timbo
wouldn't the dagger slots have to have a little slop built in to accomodate that, when you raise and lower them?


Dude ,It's a NACRA, slop comes standard.


"I said, now, I said ,pay attention boy!"

The cure for anything is salt water - sweat, tears, or the sea
Isak Dinesen
If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most.
E. B. White
Re: New Nacra 17 [Re: Team_Cat_Fever] #244084
02/15/12 10:50 PM
02/15/12 10:50 PM
Joined: Aug 2007
Posts: 1,304
Gulf Coast relocated from Cali...
TeamChums Offline
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TeamChums  Offline
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Gulf Coast relocated from Cali...
NICE!!!!


Lee

Keyboard sailors are always faster in all conditions.
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