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Old 3rd March 2010, 06:03 PM   #1
agrelon
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Default More Rake Fin = Better/Easier Jibing?

Currently I'm using a 36cm fin which is quite upright.

Will a smaller fin, 32cm, which is slightly more raked make it easier to jibe?
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Old 3rd March 2010, 11:55 PM   #2
sergio_k
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Quote:
Originally Posted by agrelon View Post
Currently I'm using a 36cm fin which is quite upright.

Will a smaller fin, 32cm, which is slightly more raked make it easier to jibe?
with smaller/less raked fin you get less resistance when you're turning, so jibe should be smother, on the other hand, fin creates lift (bigger more upright - more lift) and during
planning jibe you need lots of speed/power and too small of a fin could reduce that,
bottom line in windsurfing it's all about finding that optimal balance.
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Old 4th March 2010, 08:19 AM   #3
Roger
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agrelon,
In general, it's is not the Leading Edge (LE) rake angle that makes some fins jibe better.
The "planform" of a more wave sailing like fin, with a lot of curve in both the leading edge and trailing edge tends to be looser, and usually will be much easier to jibe.
Perhaps what your are looking for is more of a "swept pointer" fin that combines a fairly vertical and shallow LE angle with a more curved fin the deeper you go.
Swept pointers in general jibe significantly better vertical pointer fins (unless you are pro level, and can make hi speed plaing jibes on vertical race and slalom fins) but you give up a little on top end speed and pointing angles.
Hope this helps,
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Old 4th March 2010, 01:24 PM   #4
agrelon
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Quote:
Originally Posted by Roger View Post
agrelon,
In general, it's is not the Leading Edge (LE) rake angle that makes some fins jibe better.
The "planform" of a more wave sailing like fin, with a lot of curve in both the leading edge and trailing edge tends to be looser, and usually will be much easier to jibe.
Perhaps what your are looking for is more of a "swept pointer" fin that combines a fairly vertical and shallow LE angle with a more curved fin the deeper you go.
Swept pointers in general jibe significantly better vertical pointer fins (unless you are pro level, and can make hi speed plaing jibes on vertical race and slalom fins) but you give up a little on top end speed and pointing angles.
Hope this helps,
Thanks for your answer, Roger. Indeed, the new fin I'm looking at has more rake in both the LE and TE. It's also smaller and has a higher aspect ratio (TE-LE distance is smaller). I'm pretty sure it should be easier to jibe as my previous fin had basically no rake in the TE and was probably too big for my sail.
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Old 4th March 2010, 11:40 PM   #5
Roger
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Hi agrelon,
Check out this link:
http://www.trueames.com/wind.html
Look at the "Convert"; "Teardrop"; and "Sweeper".
Notice the curve toward the tip of the fin.
Compare it the the Series 2000 and Formula.
The "curved back" planform is what will make your board easier
to jibe.
Not just a narrower foil, but a foil that curves back.
Higher aspect ratio is OK, but it does not make a fin "turny" and
for easier jibing, "turny" and somewhat "loose" (like a wave fin (the "Enduro" on the link)) is
what you need.
I think we have some "terminology" issues in this discussion:
Rake is an inclination of the leading edge of the foil (back from 90 deg).
Span is the overal length of the foil (from the bottom of the board to the tip of the fin).
Aspect ratio is the ratio of the width (front to back) of the foil to the length of the foill
(or the Span).
Thickness is the thckness of the foil. (There are thick foils and thin foils).
In order to make a fin "loose and turny" the foil is usually fairly thin and the leading and trailing edges have lots of curve to them (like the Enduro wave fin in the link).
Thin foils allow for some "twist" and bend". Thick foils are more rigid and may bend along the span but only twist near the tip. The fin guru's use directional carbon to get the bend and twist to change from the base down to the tip.
Hope this helps,.

Last edited by Roger; 4th March 2010 at 11:43 PM.
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Old 5th March 2010, 05:14 PM   #6
agrelon
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Roger, thanks for the link and detailed response. I think the fin I've chosen will be good as it's closer to the convert which, from what ive understood, in being slightly more upright (with a bit less curve in the back) will be beneficial once I really aim to come out of jibes planing.

Thanks for your help.
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