Fins (again) and spinout (again)

Fins (again) and spinout (again)

Post by Ni » Fri, 02 May 1997 04:00:00


I know there have been recent postings about fins, but I don't think my
questions have really been answered.

I'm started using a 75 liter board with a 5.0 sail. I weigh 115 lbs. When
I try to really sheet in and rake the sail back, the fin has a tendency to
spin out. It is a True Ames Teardrop fin (10.75") which I suspect is
rather small for the sail size. Any recommendations on the correct fin
length (assuming that I'm looking for a swept blade or pure blade?) Or can
I help the situation by setting something else differently (like moving
the mast track or the boom height).

Does having too large a fin really matter? (ie does it mess you up badly?)

Also, is there any good method of recovering from a spinout short of
unhooking, getting out of the straps and basically dropping out of a
plane? Can I omit any of the above steps?

Sorry if this is the billionth time these topics have cropped up :) just
never bothered me before so I didn't read the postings.

Nik

 
 
 

Fins (again) and spinout (again)

Post by Wolfgang Soerge » Sat, 03 May 1997 04:00:00

Quote:

> I know there have been recent postings about fins, but I don't think my
> questions have really been answered.

Indee, a search in dejanews might be worthwhile.

Quote:
> I'm started using a 75 liter board with a 5.0 sail. I weigh 115 lbs. When
> I try to really sheet in and rake the sail back, the fin has a tendency to
> spin out. It is a True Ames Teardrop fin (10.75") which I suspect is
> rather small for the sail size. Any recommendations on the correct fin
> length (assuming that I'm looking for a swept blade or pure blade?) Or can
> I help the situation by setting something else differently (like moving
> the mast track or the boom height).

10.75 does not seem small to me on a 75 l board with 5.0 sail - maybe
even already a bit on the large side.
So i suspect you just need a bit to get used to the board. I suspect
that
when you "really sheet in and rake the sail back" you give probabely too
much pressure on the back foot, kicking the tail away. Keep the front
leg straight, stay upright over the board, maybe try to shorten
the harness lines a bit, practice and you should be alright

If you have a US box fin, moving it forward may help. You can also
try to lower the boom a bit to increase pressure on the front foot.

Quote:
> Does having too large a fin really matter? (ie does it mess you up badly?)

Larger fins may plane a bit earlier but they are also ultimately slower
and board control gets worse, especially in jibes at high speeds there
will be a tendency to bounce, do unwanted aerial jibes.

Quote:
> Also, is there any good method of recovering from a spinout short of
> unhooking, getting out of the straps and basically dropping out of a
> plane? Can I omit any of the above steps?

You can
+ do a windward jerk with the back foot, pulling the board under your
body
  while not applying any sideways pressure at all.
+ do a little chop hop (if you can land without spinning out again)
+ bear off the wind (sometimes not easy and can give nice launches)

The earlier you try to recover the better. Often you'll hear a spin
out before really feeling it.

W.
--
Wolfgang Soergel                  
Lehrstuhl fuer Nachrichtentechnik   phone: ++49-9131-857781
Universitaet Erlangen-Nuernberg     fax:   ++49-9131-303840
Cauerstrasse 7                      email:

D-91058 Erlangen, GERMANY
http://www.nt.e-technik.uni-erlangen.de/~wsoergel

 
 
 

Fins (again) and spinout (again)

Post by Ian Knigh » Tue, 06 May 1997 04:00:00

Ni

Quote:
> I'm started using a 75 liter board with a 5.0 sail.

When
Quote:
> I try to really sheet in and rake the sail back, the fin has a tendency to
> spin out. It is a True Ames Teardrop fin (10.75") which I suspect is
> rather small for the sail size. ).

...
> Does having too large a fin really matter? (ie does it mess you up badly?)

> Sorry if this is the billionth time these topics have cropped up :) just
> never bothered me before so I didn't read the postings.

> Nik

It never used to bother me on my previous board with it's permanently
shimmed in tuttle h12 fin.
 I found the fin great, (if not ideal ? how was I to know?) for most 5.0
and 6.0 conditions.  However as the wind got a bit above 5.0 m it was
extremely difficult to control. A real handful on a broad reach, no
sense of being in control,  and unable to go fast without unwanted
launching.  OK to windward, just, but who wants to go to New Zealand?
Back on shore the experts advised "smaller fin , new gear".

Now, like you, I am plagued by spin out. But I think modern gear needs a
significantly different approach. A more upright stance, less lift from
the sail but less drag from the fin, which turns out to be faster. (the
new board and fin is certainly faster when i'm not going sideways)

My theory is that the new fins don't develop enough lift such that you
can  really lean out and  sheet in until they are going at their max
design speed .  So you have to sail on eggs until you get there.  If
spinout is not a problem your fin is too big for maximum speed?  But I
won't get a chance to fully test this theory until the strong winds
arrive next season. 2nd opinions anyone?

Hopefully, with a bit of practice, treading lightly on the fin will
become second nature, but until then I sympathise with you.  

Ian

 
 
 

Fins (again) and spinout (again)

Post by sailquik (Roger Jacks » Tue, 06 May 1997 04:00:00

Nik:
I totally agree with what Wolf had to say. 5.0/75 ltr/10.75 Should be
a very good combo, but as Wolf said it might be a little on the big
side.

Quote:
>(like moving the mast track or the boom height).

Yep! Try moving your mast base forward from the farthest back it will
go. Move in 1-2 CM increments and it may help!

Quote:

>Does having too large a fin really matter? (ie does it mess you up badly?)

Yep! As Wolf said, big fins might help with early planing, but too
much fin is  much  worse than not quite enough.
Quote:

>Also, is there any good method of recovering from a spinout ?

Wolf covered it pretty good, the only thing I might add is a very
quick dip of the lee rail usually works for me, but watch out you
don't "catch" the rail cause as Wolf said "it's over the handlebars
time" real quick.
Something Wolf didn't cover that may be happening is on a fin this
small, you have to head off a little and get some speed before you
hammer the fin. Smaller fins stall (spinout) real easy at low speeds,
until you get some water flowing, then you can hammer them pretty
hard.
Just watch out for lulls, as if you are really pressuring the fin, a
lull will cause it to spin out in a hearbeat. Just lighten up the
pressure a bit and no problema, but keep on pushing and you'll spin it
out for sure.
Another thing, are there weeds in the water where you sail???

Don't be afraid to ask questions!!! There are no such thing as stupid
questions, just folks too dumb or too shy to ask. We've all been
there, so ask and perhaps you can benefit and shorten your learning
curve.

L8r
sailquik (Roger Jackson) US 3704  Ph. (301) 872-9459
F2 Thommen; North Sails/Rigs; True Ames/Rainbow Fins; SpeedTech.

 
 
 

Fins (again) and spinout (again)

Post by Ni » Wed, 07 May 1997 04:00:00

Thanks for the input so far! Really helped a lot!

Funny how I checked out the web page for True Ames, and found that the
10.75" Teardrop fin is actually for sails from 3.8 to 4.2! You can verify
it for yourself at http://www.west.net/~trueames/. Strangely enough, the
length varies by a lot depending on the type of fin, which makes sense
considering that it is actually fin area that determines how much the fin
can take or give.

I guess fin length as a metric isn't exactly as accurate as, say, sail
area which we are all more familiar with... But how accurate are the
fin-makers' recommendations?

I agree with Ian that sailing with new fins is like riding on eggs as
compared with my old fin that came with the E-rock (circa 1991?) that has
a slot in it. It seems much more game to take on lots of sudden lateral
pressure compared with the new fin. It must be a lot slower though.......

On a tangent, I have another question about raking the sail back to close
the slot (for purposes of speed). I tried all the suggestions today when I
sailed at Candlestick Point (near SF, where the Giants/49ers play) which
is completely flat water with winds of about 20-25 knots. (No weeds :) ) I
used my old E-rock first, and was able to trim the sail very well, raking
the sail back until the slot was closed and the foot of the sail pressed
against the footstraps - textbook style sail trim for max speed. Then I
switched to my 75 liter board (ASD custom) and found that I couldn't rake
the sail back without rounding up or inviting spinout. I'm wondering if
new equipment eliminates some of the need for things like closing the slot
because the balance point seemed to occur when the sail was still
relatively far forward.

A possible explanation I can give is that since the board is much smaller,
its tail is not as far back as before, and so the balance point (CLR and
CE) is now further forward with respect to the sail. Is that right, or can
I still do something about it? Or am I really being too obsessed with
closing the gap?

Oh, and since it blowed 4.2 (for me) today, the problem with the fin being
too small was moot for the day.

Later,
Nik

 
 
 

Fins (again) and spinout (again)

Post by NLW TFW » Thu, 08 May 1997 04:00:00

Two schools of thought include:

1. Use the biggest fin which will still let you carve jibes, and
2. Use the smallest fin you can keep under you in the reaches.

I'd guess one approach would be to start large to avoid spinout, then go
smaller as your skills improve. Some racers use 11" extreme blades with
very little area under 6 meter sails in heavy chop because they can
predict and avert spinout, other sailors have no problem spinning out 13'
boards. The difference? Technique.

But there are many other factors. Is your main bugaboo jibing? Then buy a
fin with some curve, maybe more so than your Tear Drop. This will also
reduce spinout in heavy chop. It's slower than going forward on a
straighter fin, but much faster than going sideways. If yuor bigger
problem is spinning out in reaches, borrow a bigger Tear Drop and see if
that helps.

But the single most important factor is operator experience --- water
time. And not just time; you must constantly be trying something different
and paying attention to the results. You won't learn squat just repeating
the same proper or improper technique over and over. Change stance,
adjustments, technique, equipment, etc. And you won't learn much if you
stay dry, either.

Mike \m/
Never Leave Wind To Find Wind

 
 
 

Fins (again) and spinout (again)

Post by Jonathan M Richards » Thu, 08 May 1997 04:00:00

: I agree with Ian that sailing with new fins is like riding on eggs as
: compared with my old fin that came with the E-rock (circa 1991?) that has
: a slot in it. It seems much more game to take on lots of sudden lateral
: pressure compared with the new fin. It must be a lot slower though.......

If you can't control the board you can't go fast. B&J sailing is best
with a B&J fin, not a pointer (which is for slalom).

: On a tangent, I have another question about raking the sail back to close
: the slot (for purposes of speed). I tried all the suggestions today when I
: sailed at Candlestick Point (near SF, where the Giants/49ers play) which
: is completely flat water with winds of about 20-25 knots. (No weeds :) ) I
: used my old E-rock first, and was able to trim the sail very well, raking
: the sail back until the slot was closed and the foot of the sail pressed
: against the footstraps - textbook style sail trim for max speed. Then I
: switched to my 75 liter board (ASD custom) and found that I couldn't rake
: the sail back without rounding up or inviting spinout. I'm wondering if
: new equipment eliminates some of the need for things like closing the slot
: because the balance point seemed to occur when the sail was still
: relatively far forward.

Did you try moving the mast track forward?

-Jonathan.

USWA Member #US233
Boards: Seatrend 9'0" and 8'6", Mistral One Design
Sails: Waddell
Spars: Fiberspar

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| Jonathan M. Richardson           |    http://world.std.com/~jthan    |

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