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Tuning tips!!

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Created by Wind Foiler > 9 months ago, 19 Jan 2011
Wind Foiler
WA, 142 posts
19 Jan 2011 10:23PM
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Sailing code red (09). 7.7m with isonic 96l. Choco weedie 33cm.
Sailing in around 15 knots. Could not get the board to become slippery. Ended up with mast track all the way back and still nose was sticky. Raised boom with no luck.
Wondering if any one has any solutions. Sail felt light enough. Downhaul maybe??? When rigging up, Down hauled to spec. Looked like if i gave it anymore would flatten lower section totally. Leech fell away just below 2nd battern above the boom.

decrepit
WA, 12761 posts
19 Jan 2011 11:02PM
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Does the board trim better with other sails?

If not can you move the foot straps further back?

Bender
WA, 2235 posts
19 Jan 2011 11:11PM
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I would have raised my boom or try a smaller fin.
More downhaul...

Wind Foiler
WA, 142 posts
19 Jan 2011 11:31PM
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Footstraps back seem the idea. Have moved the backstrap forward of late, but thaught this wouldn't have that greater impact as front strap is still in same location. Also noticed a lot of back foot pressure today, i was thinking this says not enough downhaul but like I said sail already seemed very flat. Could this be too much or not enough cam pressure? Bloody confused

Wind Foiler
WA, 142 posts
19 Jan 2011 11:35PM
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Bender, did try a smaller fin today, board just got stickier. If Raised my boom any higher would have lost too much front foot pressure (dangerous in swell). Bit confused.

Waiting4wind
NSW, 1871 posts
20 Jan 2011 9:01AM
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The 7.7m could be on the limit of the 96L Board particularly if you're a heavy weight. I found my 7.8m to be a perfect set up on IS 111.

I've also found that the Isonic liked a powerful / bigger fin to make it trim nicely, particularly if not very powered up. I would think that the weed fin wouldn't have as much drive.

I use my 7.8m on my Exocet TB62 (90L) occassionaly in the 15knot range and the stock 35cm fin works nicely.

Wind Foiler
WA, 142 posts
20 Jan 2011 8:31AM
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Going to try moving straps back 1, both front and back, hopefully this will compensate for the lack of lift (weedie).
I'm still not sure whats delivering so much back foot pressure. Normally, downhauling more would push drive in the sail further forward right??

choco
SA, 4175 posts
20 Jan 2011 11:12AM
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you need a bigger fin to give you that lift and free the board

Ian K
WA, 4155 posts
20 Jan 2011 9:07AM
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Yes I think big fins are underrated. Small fins became the go when speedsailors on skinny boards found they'd go 3 knots faster when they dropped 3 cm in fin size. It was put down to reduced fin drag when it was possibly just that the board now felt balanced and more comfortable?

Trouble with shortening the fin to make it balance board width is that you may get short on the essential fin lift. I suspect that's why the latest speed fins are short and fat?

A theoretical speculation of mine is that if you extend a line drawn thru your hips and the bottom of your back foot where it contacts the rail it should pass thru the centre of lift of the fin.

Then you'll be sailing with nice comfortable pressure on the rail without too much levering up or down via the straps.

Wind Foiler
WA, 142 posts
20 Jan 2011 9:25AM
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Waiting4wind said...

The 7.7m could be on the limit of the 96L Board
I've also found that the Isonic liked a powerful / bigger fin to make it trim nicely, particularly if not very powered up. I would think that the weed fin wouldn't have as much drive.

I use my 7.8m on my Exocet TB62 (90L) occassionaly in the 15knot range and the stock 35cm fin works nicely.


Totally agree it's a fin issue. Weedies don't generate the lift a pointer does, and the problem being that if I go any bigger with a weedie the drag kills board speed so much, it cancels out any benefit. Was hoping someone had a suggestion on rigging the code red to drive forward more.
Thanks for the suggestions!!

Wind Foiler
WA, 142 posts
20 Jan 2011 9:42AM
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Ian K said...

Yes I think big fins are underrated. Small fins became the go when speedsailors on skinny boards found they'd go 3 knots faster when they dropped 3 cm in fin size. It was put down to reduced fin drag when it was possibly just that the board now felt balanced and more comfortable?

Trouble with shortening the fin to make it balance board width is that you may get short on the essential fin lift. I suspect that's why the latest speed fins are short and fat?

A theoretical speculation of mine is that if you extend a line drawn thru your hips and the bottom of your back foot where it contacts the rail it should pass thru the centre of lift of the fin.

Then you'll be sailing with nice comfortable pressure on the rail without too much levering up or down via the straps.


Ian, this is exactly what I am trying to do. Reduce fin size and maximize the straight line speed of a bigger board/sail combo. Light wind speed sailing I guess.

I agree with your theory about body pressure being through the centre of the lift on the fin. The balance of this pressure on a horizontal plane is where I'm having problems. I'm thinking this may come down board width and the how the angles of your body changes as width of your board changes. I've found that the narrower the board, the more a feel Im sailing underneath the boom. Like my legs aren't long enough, until you turn down wind. I guess this is why 44cm wide boards on 6.5m sails work for speed runs off the wind.
Maybe the 96l (59cm wide) combined with 7.7m is the equivalent of a speed setup geometrically speaking

JayWright
WA, 38 posts
21 Jan 2011 10:32AM
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Reduce the tension on the top 4 batterns, it will help exhaust the wind better. When you are on the beach with your sail rigged, hold the boom end up so you can see the "twist off" in the sail. Make sure non of your top batterns have a curve in them, they should all be flat.
Give it approx 10mm more down haul than what they recommend. I reckon the top 5 panels (between the batterns) should be floppy.
Reduce your out haul so the back 33% (or so) of the sail is touching the boom when loaded up. This may reduce your pointing ability so you may want to tighten that up at the bottom of the run.
I never pull on the bottom strap, however I know others do. I find the sail is too tight, reducing top end speed, however, if I'm underpowered, that's the first thing to be adjusted. Then I'll tighten up the top batterns, reduce the down haul etc.
If you are ever down at Melville, say hello and I'll have a look at your rig. Go the Code Reds!!!

aklimek
WA, 3 posts
23 Jan 2011 2:56PM
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It's not a sail issue here. 7.7 in 15knts with 96isonic & 33cm weedie. Just not enough wind for your setup. Yes, agree fin is definitely the problem. Needs to be @35-40cm Deboichet & u will fly on that setup in those conditions.
Weedie = lots of drag esp if too long, therefore not slippery & fast.
So unfortunately you are in a tough spot here if u have to use the weedie.
If you want to fly in 15knts with a weedie u need a different board with the 7.7 or windier conditions. You could experiment with different weed fins but none are really that fast with an isonic. It's sort of like putting winters tires on a Porsche & racing against guys on DOT specific slicks.
Sorry for the bad news. The sails are awesome so just rig them as per the instructions & they will work, you don't need to do anything magical here.

Wind Foiler
WA, 142 posts
23 Jan 2011 2:58PM
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thanks Jay,
I've ended up with one of Claude's CR. It seems to hold a very hollow mid to low section even when over down hauled, where as my 7.7 flattens out very quickly. Noticed a lot of cam pressure so going to play with the spacers.
Battern wise I'm all good. If I downhaul extra 10mm sail flattens right out. I'll see how cams change this.
Thanks again. I will say gday if im down your way.

JayWright
WA, 38 posts
27 Jan 2011 9:53AM
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Good to hear Tom. They are a great sail with huge wind range- subject to correct tuning.
See ya on the water soon.



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"Tuning tips!!" started by Wind Foiler