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Revolutionary Centerboard!!
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charlie w View Drop Down
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Posts: 84 		Post Options Post Options   Quote charlie w Quote  Post ReplyReply Direct Link To This Post Topic: Revolutionary Centerboard!!
    Posted: 17 May 06 at 1:00pm

Don't most boards "flex" beneath the hull anyway?

The prob we always have with Gybing boards (aka accentuating the lift/wing shape) is that they can fall out of gybe, and end up giving you lift the wrong way...!

You could try a movable max chord, which swings side to side where the  system comes out of the top of the blade - like an Int 14 rudderblade.

I like the idea of a flexier blade that you could lock off in either "gybe" as that would surely present a lifted shape to the water, and thus more lift, without the downside of needing to keep pressure on the blade to keep it in gybe.

Mind you - that is awfully tweaky....and that from a 505 sailor...!

Cheers

CW

 
Quality never goes out of fashion.
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I luv Wight View Drop Down
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Posts: 628 		Post Options Post Options   Quote I luv Wight Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 06 at 10:37pm
It's been done before in 1993 - a college project and tested in toppers.
Jim Hill-Jones - moth sailor was involved in this project

and look - adam may as a nipper!



I think the problem was changing the foils during tacks, and clearing the boom with a completely lifted half-foil.



Edited by I luv Wight
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I luv Wight View Drop Down
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Posts: 628 		Post Options Post Options   Quote I luv Wight Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 06 at 10:49pm
The lift from a foil is constant ( or depends on the sail force which depends on righting moment ), so a more efficient foil gives less drag, not more lift.
More efficiency means less area, which is fine if it everything is working good.
But a nasty tack or a gust may mean a foil overload and stall, so small low drag foils are not always good.
Alternatively, the same area but used at less angle of attack to keep the same lift, but then the wetted surface is the same, and drag may not be significant.
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tickel View Drop Down
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Posts: 408 		Post Options Post Options   Quote tickel Quote  Post ReplyReply Direct Link To This Post Posted: 18 May 06 at 9:32am
And you all thought that the centreboard was just too
stop you drifting sideways into the dam!!
tickel
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HannahJ View Drop Down
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Posts: 861 		Post Options Post Options   Quote HannahJ Quote  Post ReplyReply Direct Link To This Post Posted: 20 May 06 at 9:21pm
or as a depth sounder
Out of interest, and not really onthis topic, does the width of the centreboard/daggerboard have any effect on upwind progress?
MIRROR 64799 "Dolphin"
The pessimist complains about the wind; the optimist hopes it will change; the realist adjusts the sail
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NickA View Drop Down
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Posts: 784 		Post Options Post Options   Quote NickA Quote  Post ReplyReply Direct Link To This Post Posted: 24 May 06 at 11:13pm
Originally posted by Boatboy

on the subject of building foils you have a multitude of choice depending on the class rules of the boat. personally i would use very high density foam 200kg/m3 plus and uni directional carbon

B*££#R class rules.  Once it's painted white who's to know!!!! 

Though in truth my play boat already conforms to no known class and I'm sick of taking chunks out of the foils with trap hook.  Gel coated foam is just too fragile.  Carbon wrapped foam sounds a good bet.  How about aluminium sheet wrapped round wooden forms?
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JimC View Drop Down
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Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 26 May 06 at 8:51am
Originally posted by NickA

B*££#R class rules.  Once it's painted white who's to know!!!! 


The only thing is if you do get caught you probably cop a rule 69 protest and a two year ban from ISAF...

We sign up for the game, rules and all. If you don't like the rules then change class rather than deliberately break them.
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NickA View Drop Down
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Posts: 784 		Post Options Post Options   Quote NickA Quote  Post ReplyReply Direct Link To This Post Posted: 01 Jun 06 at 2:13pm

Originally posted by JimC

We sign up for the game, rules and all. If you don't like the rules then change class rather than deliberately break them.

or better still .... get the class rules changed to something sensible.  When changes that save cost or increase strength but don't change performance are banned, but changes which evidently do change performance, but cost a mint (like buying a new boat every year) are allowed, you have to ask who the rules are written for, the sailors or the manufacturers?

However, rest assured, any boat I race meets the rules pertaining to that race.  But happily there's more to sailing than racing.  
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