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F16s now officially slower... #206928
03/27/10 12:47 PM
03/27/10 12:47 PM
Joined: Sep 2004
Posts: 2,584
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Tony_F18 Offline OP
Carpal Tunnel
Tony_F18  Offline OP
Carpal Tunnel

Joined: Sep 2004
Posts: 2,584
+31NL
According to the Texel Rating the F16 is now 2 points slower then F18s (102 vs 100).
http://www.knwv.nl/data/documents/Zeilen/Texelrating/numdet%2014-3-2010.pdf

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Re: F16s now officially slower... [Re: Tony_F18] #206934
03/27/10 03:20 PM
03/27/10 03:20 PM
Joined: Nov 2006
Posts: 404
Chattanooga, TN
Joanna Offline
addict
Joanna  Offline
addict

Joined: Nov 2006
Posts: 404
Chattanooga, TN
What was it before?


Joanna

Blade F16
"Too Sharp to Touch"
Re: F16s now officially slower... [Re: Tony_F18] #206938
03/27/10 05:05 PM
03/27/10 05:05 PM
Joined: Jun 2001
Posts: 3,116
Annapolis, MD
Mark Schneider Offline
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Mark Schneider  Offline
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Joined: Jun 2001
Posts: 3,116
Annapolis, MD
What changed in the formula ???


crac.sailregattas.com
Re: F16s now officially slower... [Re: Tony_F18] #206942
03/27/10 06:27 PM
03/27/10 06:27 PM
Joined: May 2006
Posts: 954
Mumbles Y.C Wales U.K
Mark P Offline
old hand
Mark P  Offline
old hand

Joined: May 2006
Posts: 954
Mumbles Y.C Wales U.K
I've always liked the TEXEL rating system and now its just got a whole lot better.
Sorry Scooby but SCHRS is way behind the times blush


MP*MULTIHULLS
Re: F16s now officially slower... [Re: Joanna] #206943
03/27/10 06:30 PM
03/27/10 06:30 PM
Joined: May 2006
Posts: 954
Mumbles Y.C Wales U.K
Mark P Offline
old hand
Mark P  Offline
old hand

Joined: May 2006
Posts: 954
Mumbles Y.C Wales U.K
Hi joanna
Before this amendment the F18, A'Class and single handed F16 were all off 101.
Now it's 100 F18, 101 A'Class and 102 F16 single and two up.


MP*MULTIHULLS
Re: F16s now officially slower... [Re: Mark P] #206944
03/27/10 06:53 PM
03/27/10 06:53 PM
Joined: Feb 2005
Posts: 4,118
Northfield Mn
Karl_Brogger Offline
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Karl_Brogger  Offline
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Posts: 4,118
Northfield Mn
How does the Texel system determine the number?
Portsmouth is all based on reports, right?
And the SCHRS is strictly measurements, right"

Re: F16s now officially slower... [Re: Karl_Brogger] #206945
03/27/10 07:45 PM
03/27/10 07:45 PM
Joined: Feb 2008
Posts: 242
Brisveagas
Aido Offline
enthusiast
Aido  Offline
enthusiast

Joined: Feb 2008
Posts: 242
Brisveagas
Texel is done on measurements. So something in the formula must have changed.


Aido
Viper 288
Re: F16s now officially slower... [Re: Mark P] #206977
03/28/10 01:27 PM
03/28/10 01:27 PM
Joined: Feb 2004
Posts: 3,528
Looking for a Job, I got credi...
scooby_simon Offline
Hull Flying, Snow Sliding....
scooby_simon  Offline
Hull Flying, Snow Sliding....
Carpal Tunnel

Joined: Feb 2004
Posts: 3,528
Looking for a Job, I got credi...
Originally Posted by Mark P

Sorry Scooby but SCHRS is way behind the times blush


Nico and I are talking ;-)


F16 - GBR 553 - SOLD

I also talk sport here
Re: F16s now officially slower... [Re: Aido] #206980
03/28/10 02:06 PM
03/28/10 02:06 PM
Joined: Jul 2001
Posts: 67
Netherlands
geert Offline
journeyman
geert  Offline
journeyman

Joined: Jul 2001
Posts: 67
Netherlands
As I'm also involved in this; indeed the formula is changed this year.

The differences are not big but we try to get closer to reality.

The document can be found on http://www.texelrating.org/ (open cats)

The text on the website is:

-----------
Update for 2010
New method of rating sails
Since 1982 the aspect ratio has been used to calculate the efficiency of sails.. Modern square top mainsails are more efficient than triangular mainsails. The aspect ratio approach is not correct for ‘modern’ sails. In Australia a new system already has been introduced in 2008. In the OMR, (offshore multihull rule), for around 140 cabin multihulls of the multihull yacht club of Queensland. In 2008 comparable new formulas have been tested in Holland which will be introduced in the Netherlands, Germany and Norway and other countries.
The new formula for the mainsail is a combination of two values. One is the measure of rectangularity of the main. That is sail area main divided by the rectangle p times e. (p being the height of the sail (vlm), the length of the luff, e being the dimension e, the length of the foot of the main). The other ratio is the ratio (p/e). A higher and narrower mainsail is more efficient. The product of both values gives: msam_ex_mast / (p * e) * (p / e) = msam_ ex_mast / e ^ 2.
The formula to find the right efficiency factor is:
Efficiency factor main = c 1 * (msam_ex_mast / e^2) ^ p 1. For beach multihulls
The constant c 1 = 0.67, the power p 1 = 0.3
The efficiency of jibs is based on the ratio: msag / lpg^2.
Lpg is the perpendicular from tack to luff. The formula being used is:
Efficiency factor jib = c 2 * (msag/ lpg^2). ^ p 1
The constant c 2 =0.72, the power p 1 = 0.3
For cabin multihulls the formulas are the same as the one for the beach multihulls., The rated areas will be:
rsam = eff. factor main * msam_ex_mast + area mast (if a swivelling mast). For open cats msam always includes the area of a swivelling mast if that is the case. No separate adding of the mast area.
rsag = eff. factor jib * msag.
Basic TR formula
To harmonize the basic Texel Rating formula with the ones used since 1997 in Australia for a group of around 170 cabin multihulls and in France for a group of around 120 multihulls, the decision is made to return for the open cats to the formula used here before 2002, resulting in TR = 100 / (1.15 * RL ^ 0.3* RSA ^ 0.4 / RW ^ 0.325). For all cabin multihulls the constant 1.15 is lowered to 1, like in both foreign countries. That changes the absolute values of the rating numbers, but not their relative positions..
Correction for no dagger board(s) or centre board(s)
The correction factor for designs without efficient dagger board or centre board is changed from 1.03 in 1.04
-------

Geert


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