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Topic: Foils |
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steveb |
Posted: 29-Mar-04 08:56 |
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Does anyone sand down the centre board & or rudder so the trailing edge is at the minimum thickness allowed and if so does it make any appreciable performance improvement. |
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Pete Lindley |
Posted: 29-Mar-04 18:27 |
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Yes and yes.
It needs to be a straight edge and 2mm. Only sand the area that is in the water when fully down. I seem to think that you can only sand down 2" in from the trailing edge as well, but I could be wrong.
With a fat trailing edge, air bubbles and eddies can be produced of the back edge. These will pass back through the water onto the rudder and produce a cavitation effect for the rudder (rudder steering through air similar to the prop on a rescue boat going through air). Cavitation is bad and produces a lack of steering and control.
Pete |
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steveb |
Posted: 30-Mar-04 08:47 |
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Thanks Pete, I will get my sander out. |
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Graham Shaw |
Posted: 30-Mar-04 16:51 |
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It used to be a most flagrant transgression of the class rules to alter the profile at the trailing edge on either of the foils! The trailing edge had to be as close to the original manufactured profile, the only alteration allowed was to repair a damage and even then it had to be as close tom the original as possible. Or was there something I missed in the new class rules? If not I shall be protesting you at the very earliest opportunity, Mr Lindley! |
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Pete Lindley |
Posted: 30-Mar-04 19:10 |
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Carry on Mr Shaw.
2mm is my trailing edge and nothing less. It is a graded 2mm and 2" from the edge it is.
If you want foils to be equal, best check the mold as they come out with lumps and bumps all over the place! But that is another argument.
Look after those foils, they win and lose you races as well.
(Don't use a sander, just wet & dry sandpaper is all you need)
[Edited by Pete Lindley on 30-Mar-04 21:37] |
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Ian Paterson |
Posted: 12-Apr-04 19:48 |
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Interesting info here. Does this legal mod to the foils only apply to ISO's or does it apply to the other classes too?
As far as commenting on the fair racing due to one design goes, my Buzz daggerboard is only a class one design in terms of length, it is thicker, with a very different cross section profile from others I've compared it with, and barely fits in the casing. Toppers reaction was all foils are different shapes as they are hand made!
Given this variation (which would not be tolerated in many other classes) why can't we sand the foils to produce a more standard shape, defined by the class association, rather than just taking whatever falls out from Topper's moulds? |
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Pete Lindley |
Posted: 13-Apr-04 20:10 |
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How do they hand make them? Over the makers knee?
They come out of a mould and are stuck together - Buz style ones that is. There are design specifications and tolerences for every bit of kit manufactured and these should be obided by!
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Ian Paterson |
Posted: 16-Apr-04 20:06 |
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Just telling you Toppers tale, Pete. There is a difference between should stick to tolerences and whether they do - my buzz foil suggests not unless the tolerence is VERY big! Clearly they were not interested in my complaints about my foil.
Anyway does to 2mm rule (see above postings) apply to Buzz/Spice foils or not? My Spice trailing edge is 5.2mm currently and the Buzz is similar. Can I sand them? |
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Pete Lindley |
Posted: 17-Apr-04 00:24 |
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If allowed, then yes. If not, then I would propose you do!
Don't forget your boards are hoolow so too much sanding may make the foils very thin and fragile!
I'll leave it to you to investigate further - sorry.
Pete |
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