Spinout

Spinout

Post by Laurence » Sat, 06 Jun 1992 01:47:24



Quote:

>|> >
>|> >The solution is to go to either a smaller sail (so you are not overpowered)
>|> >or a smaller fin. The fin gives you lift but its lift component of
>|> >the force is being overcome by the opposite force vector from the sail.
>|>
>|> Sorry Nick but I have to disagree about the fin. I won't go into the technical
>|> specifics but it has been my experience that too small a fin (for the sail size)
>|> will increase the chances for spinouts.
>|>
>|> If the fin is too small the sails power will in effect cause you to put more
>|> pressure on the fin (unless your technique is perfect). Small fins with big
>|> sails cannot handle the load and will easily spinout.
>|>

>I agree with Felix -- if you are spinning out you want to go for either a bigger
>fin or a better fin.  I can't imagine a plausible explanation for why a smaller
>fin would prevent spinout.  Taken to the extreme, such an argument would say
>that you could eliminate spinout by going to no fin at all!  However, I have
>read the same smaller-fin advice in an article in windsurf magazine, and IMHO,
>the author did't know beans about spinout or what causes it.

>Ned

I think there are times when going to a smaller fin can help reduce spinout.
I was sailing a 9' with an 11.75" Tuttle H17 which is an excellent fin and
*generally* not prone to spinning out.  I felt quite overpowered and I know
I should have been on a smaller board (which I didn't have with me) or I
could have downrigged or the quickest and easiest thing to do was to
switch to a smaller fin.  I swapped out my Tuttle for an 11" Rainbow Naish
Slalom and the problem of spinout went away.  In this instance the larger
fin provided *too much* lift such that I couldn't hold the board in a
proper position.  With the board jumping around, the fin became unsettled
and spinout occurred.  Incidentally, the water was choppy so between the
excessive lift and getting slightly airborne, I had a tough time keeping
the fin working.  For the majority of the time, I totally agree with the
notion of bigger fins = less spinout.

Larry

P.S.  WRT bigger fins, Tuesday at Coyote Pt. I FINALLY put my H7 Tuttle
      on my 9' with a 5.5m.  The H7 is a 14.25"(?) pointer, but not a
      blade.  It was great!  It felt incredibly solid against that sail.

Food for thought:  Many people say that bigger sails generate more force
and therefore push harder on the fin.  Don't we select a sail which we
judge to be appropriate based on how much force *we* can react due to
our strength?  We try to sail at our upper limit of strength so that
we can go the fastest.  Force due to the sail is now a constant.  What
varies now is our board speed and sail efficiency (i.e. induced drag).
In a *controlled* (controlled being in the laboratory sense of all else
being equal) sense, a small fin running at a higher speed can generate
just as much lift as a large fin running at a slower speed.  Now to
finally get to my point.  Shouldn't fin size be better determined by
considering board speed rather than a priori basing it on sail size?

 
 
 

Spinout

Post by Ned Stoffel 213 » Sat, 06 Jun 1992 05:39:06

Quote:
>>  [stuff deleted]
>> Slalom and the problem of spinout went away.  In this instance the larger
>> fin provided *too much* lift such that I couldn't hold the board in a>>
>> proper position.  With the board jumping around, the fin became unsettled
>> and spinout occurred.  Incidentally, the water was choppy so between the
>> excessive lift and getting slightly airborne, I had a tough time keeping
>> the fin working.  For the majority of the time, I totally agree with the
>> notion of bigger fins = less spinout.

Maybe the difference is that I am heavy enough (~200 lbs.) that I
never have problems keeping the force of the fin balanced.  I have
heard people claim that the windward rail tends to lift up when
they have too much fin under the board.  However, my normal problem
is that I have to work pretty hard to keep the windward rail up so
I can ride the fin.  Remember that you can always reduce the lift
on the fin by reducing the angle of attack, at least, if the board
is still under control.  When you have too big a board and/or sail
for the prevailing conditions, I agree that it is hard to keep from
spinning out on landings, but for me this is more a matter of not
always being able to control the attitude of the board in flight.
If you land any fin at a large angle, it is going to ventilate as
it re-enters the water.  I don't spin out on landings where I am
able to push the nose of the board off the wind before I touch down.
When it is really nukin' I am just happy to get down in one piece.

PS: This is sort of academic, since we haven't had any real wind in
New Jersey since the 6th of April :-(

Ned

 
 
 

Spinout

Post by Ross Ros » Sat, 06 Jun 1992 08:34:33

Everyone keeps mentioning how a large fin causes lift.  How is that?  The fin
is both symetrical and perpendicular to the plane of the water.  How does it
cause lift?

   Just curious,

      -Ross

----------------------------------------------------------------------------

8' 8" Mistral Stinger, 9' 2" Bic Presto, 4.6 Simmer Style, 5.2 & 5.6 Gaastra
 Slalomfoil.  And one big smile.

 
 
 

Spinout

Post by Laurence » Sat, 06 Jun 1992 07:56:50

Quote:

>>>  [stuff deleted]

>Maybe the difference is that I am heavy enough (~200 lbs.) that I
>never have problems keeping the force of the fin balanced.  I have

 ^^^^^ !

I'm ~190lbs

Reducing the angle of attack is not always an option unless you're
willing to bear off, but eventually you have to come home(except for
downwind runs).

Quote:
>for the prevailing conditions, I agree that it is hard to keep from
>spinning out on landings, but for me this is more a matter of not

I was referring to bouncing around in chop rather than actually trying
to jump.  By bouncing around in chop you are constantly changing the
orientation of the fin wrt the water and although the phenomenon may
be similar to what happens during an intentional jump, you unfortunately
don't have control over when it happens.  You can be ginger on your
feet and avoid some spinning out, but in what I considered VERY
overpowered conditions (gusting to two sail sizes smaller) it is
too difficult to maintain the proper sailing stance for very long.

Larry

 
 
 

Spinout

Post by Andrew Cond » Sat, 06 Jun 1992 18:47:28

Quote:

>Everyone keeps mentioning how a large fin causes lift.  How is that?  The fin
>is both symetrical and perpendicular to the plane of the water.  How does it
>cause lift?

They mean "lift", it acts in the horizontal plane. In other words, the fin is not only
resisting sideways movement, when moving forward it provides force to windward, just as
an aeroplane wing provides lift to oppose gravity.

Used to confuse the hell out me.
--
Andrew

 
 
 

Spinout

Post by Ned Stoffel 213 » Sat, 06 Jun 1992 21:57:43

|> Everyone keeps mentioning how a large fin causes lift.  How is that?  The fin
|> is both symetrical and perpendicular to the plane of the water.  How does it
|> cause lift?

The fin should be symmetrical, but the board is usually pointed
upwind with respect to the direction of travel due to leeway
(side slipping).  Therefore, the fin typically has a 5-10 degree
angle of attack in the water.  Lift is an aeronautical term and is
the force perpendicular to the plane of the foil.  If a jet is
doing a loop-the-loop, its lift vector will be downward for part
of the time.  This causes confusion with the normal sense of the
word 'lift'.  If you heel the board to leeward (windward), you can
get a part of the lift force to be vertically directed upward
(downward).  The former is called riding the fin.  Ideally, the
sail, the board, and the fin are all cooperating to support your
weight above the water.

Ned

 
 
 

Spinout

Post by felix.cabr » Sat, 06 Jun 1992 22:12:10

Quote:

>>>  [stuff deleted]

>PS: This is sort of academic, since we haven't had any real wind in
>New Jersey since the 6th of April :-(

Speak for yourself Ned :-) This past Sunday we had 25knots most of the day
from the SE. Well, at least further south in NJ. I was at Lakes Bay all
weekend. It was great! Saturday gave us 6.0 most of the afternoon. On Sunday
there were many guys your size on 5.0's while others wer on 4.5's. We also
had some pretty good racing saturday for the Lakes Bay Cup.

--

AT&T Bell Labs       {  att!mtgzz!felixc  }       a rad board, rad waves,
Middletown,NJ        {    (908)957-5081   }       and a company sickday!"

 
 
 

Spinout

Post by Juri Munk » Sun, 07 Jun 1992 02:22:42

Quote:


>>Everyone keeps mentioning how a large fin causes lift.  How is that?  The fin
>>is both symetrical and perpendicular to the plane of the water.  How does it
>>cause lift?

>They mean "lift", it acts in the horizontal plane. In other words, the fin is not only
>resisting sideways movement, when moving forward it provides force to windward, just as
>an aeroplane wing provides lift to oppose gravity.

>Used to confuse the hell out me.

When you slant the board, the lift also moves you up. Why else would the
"thai walk" problem exist when your fin is too big for the conditions?

Most of the lift is sideways, but it's sideways to the fin, so there's
a vertical and horizontal component. If you can keep your board totally
flat, the vertical component is very small.

Just try sailing a course board (equipe or similar) upwind with the
daggerboard fully out and it's very easy to understand how the fin
works similarly, but in a lesser way.

--
  Juri Munkki                                          Windsurf: fast sailing

 
 
 

Spinout

Post by Luigi Semenza » Sun, 07 Jun 1992 05:06:28

Do the new blade fins reduce spinout?  They are longer, so when the
board jumps a bit in heavy chop, it would seem that a larger part of
the fin would remain underwater, compared with shorter fins.  But
maybe this is a secondary effect.

What are blade fins good for anyhow?  Should I get one?

Luigi

 
 
 

Spinout

Post by Juri Munk » Sun, 07 Jun 1992 16:29:16

Quote:

>Do the new blade fins reduce spinout?  They are longer, so when the
>board jumps a bit in heavy chop, it would seem that a larger part of
>the fin would remain underwater, compared with shorter fins.  But
>maybe this is a secondary effect.

Let's put it this way: are pointer fins good? Do they reduce spinout?

The answer is of course that that good fins reduce spinout. My blade
does spin out in some extreme conditions, but it never lasts for long,
so I never loose a lot of speed because of spinout.

Quote:
>What are blade fins good for anyhow?  Should I get one?

For me, the blade added board control in all conditions. It made
jibing easier, because I don't have to worry about the footwork
or spinning out. Maybe it made me sloppy, but at least it has made
my sailing a lot more fun. I'm also a lot faster than I used to be.

If you can find a good blade and you know it when you see it, get one.
I can only suggest the Rainbow V2, since it's the only one I have tried.

If your pumping technique isn't correct, you may sometimes have
problems getting blade fins to hold in marginal conditions. If your
technique is correct, you'll be planing in lower winds than before
and having more fun.

--
  Juri Munkki                                          Windsurf: fast sailing

 
 
 

Spinout

Post by GARY BOAT » Wed, 10 Jun 1992 01:01:30

Quote:

>Path: dragon.acadiau.ca!nstn.ns.ca!news.cs.indiana.edu!spool.mu.edu!caen!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!cbnewsj!felixc

>Newsgroups: rec.windsurfing
>Subject: Re: Spinout (and blade fins)

>Date: 8 Jun 92 13:54:24 GMT
>Article-I.D.: cbnewsj.1992Jun8.135424.17065

>Organization: AT&T
>Lines: 32

>>Do the new blade fins reduce spinout?  They are longer, so when the
>>board jumps a bit in heavy chop, it would seem that a larger part of
>>the fin would remain underwater, compared with shorter fins.  But
>>maybe this is a secondary effect.

>>What are blade fins good for anyhow?  Should I get one?

>I own a V1 from Rainbow. It is 14.5" long. Its sail range is about 5.0 to
>6.5. You would think a long fin like this should handle the load of much
>bigger sails. It does'nt. Blade fins are so narrow they don't create the lift
>of wider fins the same size. Due to the width they also create less drag.
>The best thing about them (in my opinion) is they point like mad :-)
>I can put a WHOLE lot of pressure on the blade and it feels very solid and
>almost no spinout (at least not yet).  I can go upwind and jibe much easier
>with this fin as compared to a slalom fin.
>Since they are so thin they require very strong/stiff material such as G10.
>Other common materials would cause a fin this thin to flex like a credit card.
>Blade fins are FAST. They will improve your course slalom races tremendously
>with the right sail size and board. BTW, my V1 is recommended for boards 9'6
>and smaller only. I have a Finworks the same length but its much wider. I
>use it on my course board with sail sizes 8.0-11.0. I could not do this with
>the V1.
>--

>AT&T Bell Labs       {  att!mtgzz!felixc  }       a rad board, rad waves,
>Middletown,NJ        {    (908)957-5081   }       and a company sickday!"

I've noticed quite a diffenence in "blade' fins, some are thicker, some have
a deeper chord length, some are more verticle.  in the past I've bought
Ames and Tuttle fins exclusively.  I have a 14.25' hyperform blade that has
astounded me!! Used on a new flat bottomed board, I have not been
overpowered on this fin!! This includes four consecutive 3.6m days last
month in Hatteras - i switched to my 8'6" Angulo but you can bet I had lots
of time for experimentation.  Not the kind of fin to rip carving-type jibes
but I took delite in picking off hypertecs, priester builts and energys
while going to windward.  Everybody should talk to mr. Visa and get one, if
you have one of the new course/slalom boards and a finbox system that can
handle the strain.
 
 
 

Spinout

Post by Jim Munro x24 » Wed, 10 Jun 1992 04:11:05

Quote:

>Everyone keeps mentioning how a large fin causes lift.  How is that?  The fin
>is both symetrical and perpendicular to the plane of the water.  How does it
>cause lift?

>   Just curious,

>      -Ross

>----------------------------------------------------------------------------

>8' 8" Mistral Stinger, 9' 2" Bic Presto, 4.6 Simmer Style, 5.2 & 5.6 Gaastra
> Slalomfoil.  And one big smile.

In this case, the 'lift' is meant to indicate the force to windward.
The force generated by the fin is equivalent to the vertical 'lift'
generated by an airplane wing, except in this case the 'lift' is lateral
and provides the force which enables the board to go upwind.

If the board is tilted ever so slightly, the 'lift' will rail the board up
if the fin is too big.

Jim Munro

 
 
 

Spinout

Post by go.. » Thu, 18 Jun 1992 03:30:25


Quote:
(Ned Stoffel 21374) writes:

writes:
>|> Everyone keeps mentioning how a large fin causes lift.  How is that?  The
fin
>|> is both symetrical and perpendicular to the plane of the water.  How does
it
>|> cause lift?

>The fin should be symmetrical, but the board is usually pointed
>upwind with respect to the direction of travel due to leeway
>(side slipping).  Therefore, the fin typically has a 5-10 degree
>angle of attack in the water.  Lift is an aeronautical term and is
>the force perpendicular to the plane of the foil.  If a jet is
>doing a loop-the-loop, its lift vector will be downward for part
>of the time.  This causes confusion with the normal sense of the
>word 'lift'.  If you heel the board to leeward (windward), you can
>get a part of the lift force to be vertically directed upward
>(downward).  The former is called riding the fin.  Ideally, the
>sail, the board, and the fin are all cooperating to support your
>weight above the water.

You can also do this with a board with a centerboard. Remember
ceterboards? This is the reason (I think that it is recommended
that you heel a racing board slightly to leeward). I know on my
long board, it is possible to "ride the centerboard" to the point that
8-10' of the centerboard and much of the sailboard is out of the water.
IE the bow is 2' up, and the middle of the board  is 10" above the surface.
It isn't to stable a position, and it takes sensitive windward rail pressure
control to sustain it. Otherwise, the whole centerboard surfaces, flippoing the
sailboard to leeward rail ride mode, which is deadly at these kinds of
speeds;-)

Bill Crick

 
 
 

Spinout

Post by Thomas SM We » Fri, 19 Jun 1992 05:35:36

Quote:
>> Everyone keeps mentioning how a large fin causes lift.  How is that?  The
fin
>> is both symetrical and perpendicular to the plane of the water.  How does
it
>> cause lift?

>The fin should be symmetrical, but the board is usually pointed
>upwind with respect to the direction of travel due to leeway
>(side slipping).  Therefore, the fin typically has a 5-10 degree
>angle of attack in the water.  Lift is an aeronautical term and is
>the force perpendicular to the plane of the foil. [...]

This is a very nice, and IMHO, correct description, but to be
pedantic, lift is the force perpendicular to the free stream flow and
drag is the force parallel to the free stream flow.  It is pretty
common to assume that for reasonable angles of attack the sum of lift
and drag is more or less perpendicular to the max thickness of the
foil, but this isn't always the case.

-tom.
--
===============================================================================

 
 
 

Spinout

Post by Ned Stoffel 213 » Fri, 19 Jun 1992 21:36:23


|>
|> >The fin should be symmetrical, but the board is usually pointed
|> >upwind with respect to the direction of travel due to leeway
|> >(side slipping).  Therefore, the fin typically has a 5-10 degree
|> >angle of attack in the water.  Lift is an aeronautical term and is
|> >the force perpendicular to the plane of the foil. [...]
|>
|> This is a very nice, and IMHO, correct description, but to be
|> pedantic, lift is the force perpendicular to the free stream flow and
|> drag is the force parallel to the free stream flow.  It is pretty
|> common to assume that for reasonable angles of attack the sum of lift
|> and drag is more or less perpendicular to the max thickness of the
|> foil, but this isn't always the case.

I stand corrected.  By the way, I know that speed sailors have tried
asymmetrical fins because they always make their runs on one tack.
Does anyone know if this is common practice, or are they using
symmetrical foils.  If so, how much advantage does an asymmetric
foil give them?

Ned