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Old 10th December 2008, 05:29 AM   #11
Del Carpenter
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The picture of Allison Shreve at the following URL may be an example of totally riding the fin: http://www.midwestspeedquest.com/page86/page86.html
The picture shows Allison Shreve demonstrating Starboard's FOD package while competing in the Midwest Speed Quest in Worthington MN in June 2008 during the USWA Nationals. Is it a picture of Allison at the beginning of a jump or is it a picture of Allison at the start of a period of riding the fin? I think the board angle shows she is definitely not trying to jump.
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Old 10th December 2008, 07:46 AM   #12
Roger
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Hi Del,
Well, Allison is definitley "on the fin" in the photo, but I think she was quite a bit overpowered and you can see the big splash right behind the board that indicates
she just "hit a bump" and the board went into "wheelie" mode for a few seconds.
That's what separates the pro's from the rest of us.
They can set things up so they can "handle" almost "wheelie mode" far more of the
time.
R
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Old 11th December 2008, 05:11 PM   #13
andretsin
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Roger,
but i think, when you roll the board, the hull is not producing lift properly, even more, being rolled he is trying to turn downwind, so we have to put the sail more to the back to compensate it, so we are putting more load to the fin (board wanting to go downwind, sail counterresting, and weight of the sailor). Also, the leeward rail is in the water, so we are increasing the wetted surface by that side.
Even all that, i can feel perfectly how my raceboard increases the speed when rolling it downwind, but i always thought it was because is the wind who is lifting the board and that is why i'm reducing the wetted surface. Is it possible that it is like this?
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Old 13th December 2008, 12:04 AM   #14
Ken
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andretsin,

The photo of Allison is simply a little chop hopping on a Formula board. For those that race or do a lot of fully powered free sailing, heading up wind frequently "requires riding the fin". It is my experience that it happen more frequently on smaller boards while pointing as high as possible while overpowered. The leeward rail rolls down, the windward rail lifts up and the nose lifts up with only the tail of the board and the fin in the water.

As the fin rolls toward the surface of the water, extra vertical lift is generated by the fin, which helps lift almost everything off the water. It is possible to maintain control in this state.

The same thing can happen on a formula board, but it is a lot more dramatic because the wide board has so much surface area for the air to get under. The board will literally fly with the nose reaching a meter or two in the air before any control can be regained. It happens very fast and usually results in a big crash. Been there a few times - it's quite exciting. It usually happens when you are on a very fast reach, and then head quickly up wind with a lot of speed.
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Old 13th December 2008, 12:31 AM   #15
carlosgp5
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Hello roger,
Could explain to me a bit better, sorry Im no native english speaker:
"Pull up a little with the front foot, push hard across the top of the back of the board with the back foot (in a horizontal direction, not down, toward the water), and the fin "cants" (top or root of the fin to leeward)
very slightly, and this causes the fin to generate much better upwind force, and as a result you get a tiny "upward" (away from the water towards the sky) force."
Ive done it before, however not by my efforts, I was lucky I guess... ehehhe
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Old 13th December 2008, 09:37 PM   #16
Roger
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Hi Andretsin,
Perhaps there is some upward force generated by the rig, but with it raked all the way back and locked down on the deck, I would think virtually all the force is sideways and forward.
If you "hook" your tip upwind, then the potential for more "uplift" from the rig is there for sure.
Most sailors strive to keep the rig as vertical (side to side here) as possible, but I've know some wave sailors who really looked "light on the water" who were very fast on slalom gear and sailed with their rig raked upwind quite a bit.
Unfortunately, we don't really have all the "science" to all of these aspects of fin/rig/hull design as no one has the $$ millions it would take to discover what the "science" really is.
Boards are still shaped by master craftsmen (then copied by CNC) same with fins and sails.
So much of the "science" of windsurfing is still "black magic" from master craftsmen and
lots of on the water testing.
Can't go to the "cookbook" and put together all the right things and expect it to work perfectly right out of the box.
As the CNC technology blends with the black magic of the master shapers, and sail designers, we are getting ever closer to knowing what works in certain situations, but
the "pure science" of it still alludes us.
Hope this helps,
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Old 13th December 2008, 09:51 PM   #17
Roger
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Hi carlosgp5,
What part of this is difficult for you to understand?
As I suggest in the previous answer, exactly why this works is pretty much a "guess" on my part,
but I'm completely sure it works for me and virtually all other sailors with the skills to sail wide boards fast.
You lift up away from the water and pull upwind away from the centerline of your board slightly with your front foot in the front footstrap (this is why many sailors "curl up" their toes when going fast upwind).
You push horizontally across the top of the fin like you are trying to push the back of the board away from you sideways across the top of the water.
Your weight is "suspended" from the harness so you are really not pushing "down" toward the water at all. Nor can you push "down" when you are that far off the rail of the board.
The idea is to roll your board slightly "lee rail down" to tip or angle the fin so the base of the fin is a little downwind of the tip of the fin so the fin is no longer perpendicular to the water but has a slight downwind angle to the leeward side of the fin.
This slight angle seems to be what develops the much better upwind angle and VMG when you "torque" your board (using your hips and legs) to sort of twist the nose of the board upwind by pulling with your front foot and pushing away with your back foot.
When sailing smaller wave and slalonm boards (< 95 liters and with soft round rails) you alter your stance to stay a bit more upright and you do put a little weight on the rear of the board, but these small boards do not go upwind real well.
The Isonics (with the blocky cutaway tail) are an interesting innovation in that they go upwind much better than Sonic slalom boards that preceded them.
If this is unclear in your language, let me know the parts that are unclear and I will rephrase them.
Hope this helps,
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Old 15th December 2008, 04:19 PM   #18
carlosgp5
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Thanks Roger, it was very clear... If I get it figured out in the water Ill let you know.
But I guess its gonna take a lot of practice... It feels very hard to maintain this leward inclination, the leward side of the board starts to get in the water... I dont know maybe because of my FW147 doesnt have all that volume of the new boards...? Like I stay feeling that Im "on the air" for like 2 seconds but then Im down again... For sure with some practice and your last explanation Ill make it better, I didnt have in my head that the fin has to be also inclinated.
Cheers
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Old 15th December 2008, 08:57 PM   #19
Roger
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Hi Carlos,
Hmmmm.... maybe we aren't communicating very well here.
Are you trying to get your FW147 to go upwind at the highest angle
and best speed (max VMG) ?
OR
Are you trying to get your board up out of the water and sail "on the
fin" as several of us have described in this thread?
I have not be able to sail "on the fin" (with no part of the bottom of the
board touching the water) in many years and for sure not on a wide board
like the F-147.
And, even if you were to get an old F2 slalom board like I had when I was
"on the fin" the time the board was off the water was probably only a few seconds
and I only really was able to accomplish this "feat" one day in one location.
And that day I was not trying to go upwind at all, only trying to sail on a beam reach
as fast as possible. The conditions were perfect..... vert flat water, slowily increasing and decreasing winds of about 20 knots, 5.5 m2 North Prisma race sail....... everything added up to very perfect conditions.

To go upwind "on the fin" on your F-147:
To "incline" your fin, you lift with your front foot, straight up off the water (not pushing forward) against the footstrap to "lift" the upwind rail slightly.
The forward "push point" on your board is the mast foot.
Your weight is totally suspended from the rig through your harness lines and the boom.
There is virtually no weight on the back of the board..... only lift from your front foot,
and push (across the top of the fin in a horizontal (parallel with the surface of the water) direction.
This allows you to "roll" your board slightly to leeward.
You do not need to tip it much.
Tip it too much and your board will head off the wind.
Your rig must be fully raked back with the foot of your sail
right down on the deck.
If you "unrake" your rig slightly, you will head off downwind for sure.
Hope this helps,
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Old 15th December 2008, 10:59 PM   #20
carlosgp5
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For sure Im pointing my maximum upwind angle mate. And for sure Im asking you all this questions with the only objecive of getting greater speed/performance.
Thanks very much for your help. All your explanation is gonna be very useful next time I get out sailing.
Cheers.
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