Sport Today

Hello speedfreaks,

on request of many other speed-freaks who do not want to buy each year a better
and lighter board, i will now tell you more about my fin which makes my ordinary
sputnik 290 ('90) really fast, without getting spinouts at high speed.

I did not make this fin!, but i bought it from a german fellow, who i met at
the coast one windy day. He shapes these fins. He give me one of his fins to try
it out that day. I was very very impressed. I obtained a much much higher speed,
and i had sometimes a spinout, but that was not due to the fin, but to myself.
From that day i throwed my original f2-fin out my window. This fin was my first
love...
A few weeks later the Dutch windsurf magazine wrote an article about these fins.
I will use this article to explain the secret of this fin.
Maybe you will not understand everything, but that is because some dutch-words
can not translated directly to English and of course my English is not so good.

At***sight the fin is extremely small. The side of which the water hits the fin
stands in a corner of more than 80 degrees on the board.
The vin starts with a small base, then become very quick broad and run into a
extremely small top. The small top limits the lift. So you do not have
turn tendency at high speed.

Now comes the asymmetric story:
When you surf, you think you go straight ahead. The reality is different.
Because there is always drift, the board and the fin goes a little oblique through
the water. So the water comes not from the front, but hits the fin  on  the lee-side
When your couse gets higher (not stoned!), the angle gets 'sharper' (not dull!).
The waterstream follows the fin-profile at the lee-side and hits the luffstream.
Owing to this there arise vertebras. These vertebras have a restraining action.
You can observe there phenomenons through a plexiglass board!!!

CONCAVE PROFILE

All these vertebras did not exist when the luff and lee-side did not hinder
eachother. This is possible. The stream must lead to the back. To obtain this
goal, the fin is made of concave lee-side, which leads the water stream without
troubles to the back. More SPEED, more height and no spin-outs. Only you need
for every course another fin.
You could say: "make both sides of concave profile" to bad!, but this does not
work. The fin supplies scarcely lift and the board becomes very luffavaricious(!).
To accelerate you need certain lift.
The fin is a compromise that the advantages of a concave profile combine with
the advantages of a convex profile, where the disadvantages are minimum.
The fin has a double twofold asymmetric profile. The fin is divided in to halfs:
above: concave
below: convex
and the other side vice versa!

This is the story of the double asymmetric fin.

My own experience of this fin is that
1) you go in one direction faster that in the other
2) it is hard to stay at a certain height. But when you surf long distances
   you do not have trouble with height.
3) perfect at 5-6 bft with 5.8 (simmer) & 6.4 (arrows) sails
4) fin accelerate VERY fast!
5) you need a POWERBOX for this fin !

I hope you are satisfied with this.
I hope also you understand that when you want to go faster, you do not always
have to buy a new board that is 2-3 kilo lighter, or smaller than the board
you already have, but think of me and think of buying or shaping a NEW fin!!!

When you still have questions, you can mail me of course...
Hangloose,

Stan...

...... [stuff deleted] .....

 >Now comes the asymmetric story:

...[Stuff deleted]......

Interesting article,  I'm not sure I entirely understood you (not the
english but the fluids) , but what I think you are talking about is at
the back of the fin there is a "collision" of two masses of water from
either side of the fin.  The angle at which these flows collide is the
angle made by both sides of the trailing edge of the fin (as viewed
from above.) So this collision causes increased vortex (vertebras??)
shedding behind the fin which causes drag ( perhaps a bit more lift
too?).  If you decrease this angle by making one side of the fin
concave this vortex shedding is reduced and so is the drag (and perhaps
lift). Hopefully the net effect is an increased lift/drag.  Someone
please flame me if I am way off base here.

So you have a asymetric fin which is fast on one tack. Do the record
breaking speed sailors  use asym. fins. I think I recall someone saying
they did. They probably should.  The people who build airplanes have
known about this stuff for some time.  The tough design challange would
be to build a fin that can snap asymetrical  oreintations as the sailor
changes tacks.  Sounds kinda like our air fins (sails.)  I played
around with this idea a couple years ago by building fins that were
supported at the base by two pins pointed away from the board and into
the fin.  The fin was built so it was in compression between the two
pins.  This would force it to snap into a asymetrical configuration
depending which way it was loaded.   I just built some models to see
if it could work, but I don't know how someone would build something
strong enough like this to stand up to sailing loads.  Maybe some of
you structural/composites types out there could come up with
something..

Anyway here in Cape Cod/ Buzzards bay we usually sail in so much chop
that if you can control when your fin is in the water and when it isn't
you are in good shape.  Well good luck all you fin freaks out there.

-Peter

ps. has anyone sailed a Lightning bolt wave or slalom fin.  I saw one
in a shop and it had a nice template/foil. It was really light and
twisted pretty good. It seemed about half the weight of my normal glass
fins.  They are carbon with a foam core.... wonder how they stand up to
abuse.???  Any comments on them????

Hello speedfreaks,

on request of many other speed-freaks who do not want to buy each year a better
and lighter board, i will now tell you more about my fin which makes my ordinary
sputnik 290 ('90) really fast, without getting spinouts at high speed.

I did not make this fin!, but i bought it from a german fellow, who i met at
the coast one windy day. He shapes these fins. He give me one of his fins to try
it out that day. I was very very impressed. I obtained a much much higher speed,
and i had sometimes a spinout, but that was not due to the fin, but to myself.
From that day i throwed my original f2-fin out my window. This fin was my first
love...
A few weeks later the Dutch windsurf magazine wrote an article about these fins.
I will use this article to explain the secret of this fin.
Maybe you will not understand everything, but that is because some dutch-words
can not translated directly to English and of course my English is not so good.

At***sight the fin is extremely small. The side of which the water hits the fin
stands in a corner of more than 80 degrees on the board.
The vin starts with a small base, then become very quick broad and run into a
extremely small top. The small top limits the lift. So you do not have
turn tendency at high speed.

Now comes the asymmetric story:
When you surf, you think you go straight ahead. The reality is different.
Because there is always drift, the board and the fin goes a little oblique through
the water. So the water comes not from the front, but hits the fin  on  the lee-side
When your couse gets higher (not stoned!), the angle gets 'sharper' (not dull!).
The waterstream follows the fin-profile at the lee-side and hits the luffstream.
Owing to this there arise vertebras. These vertebras have a restraining action.
You can observe there phenomenons through a plexiglass board!!!

CONCAVE PROFILE

All these vertebras did not exist when the luff and lee-side did not hinder
eachother. This is possible. The stream must lead to the back. To obtain this
goal, the fin is made of concave lee-side, which leads the water stream without
troubles to the back. More SPEED, more height and no spin-outs. Only you need
for every course another fin.
You could say: "make both sides of concave profile" to bad!, but this does not
work. The fin supplies scarcely lift and the board becomes very luffavaricious(!).
To accelerate you need certain lift.
The fin is a compromise that the advantages of a concave profile combine with
the advantages of a convex profile, where the disadvantages are minimum.
The fin has a double twofold asymmetric profile. The fin is divided in to halfs:
above: concave
below: convex
and the other side vice versa!

This is the story of the double asymmetric fin.

My own experience of this fin is that
1) you go in one direction faster that in the other
2) it is hard to stay at a certain height. But when you surf long distances
   you do not have trouble with height.
3) perfect at 5-6 bft with 5.8 (simmer) & 6.4 (arrows) sails
4) fin accelerate VERY fast!
5) you need a POWERBOX for this fin !

I hope you are satisfied with this.
I hope also you understand that when you want to go faster, you do not always
have to buy a new board that is 2-3 kilo lighter, or smaller than the board
you already have, but think of me and think of buying or shaping a NEW fin!!!

When you still have questions, you can mail me of course...
Hangloose,

Stan...

[...]
|> ....the fin is made of concave lee-side, which leads the water stream without
|> troubles to the back. More SPEED, more height and no spin-outs. Only you need
|> for every course another fin.
|> You could say: "make both sides of concave profile" to bad!, but this does not
|> work. The fin supplies scarcely lift and the board becomes very luffavaricious(!).
|> To accelerate you need certain lift.
|> The fin is a compromise that the advantages of a concave profile combine with
|> the advantages of a convex profile, where the disadvantages are minimum.
|> The fin has a double twofold asymmetric profile. The fin is divided in to halfs:
|> above: concave
|> below: convex
|> and the other side vice versa!
|>
|> Stan...
|>
We have tried to make assymetric fins in Tromsoe too. But our problem is that
it worked only for one direction. For a speed fin this would be great and
I am surprised that most speed sailors still use symmetric fins. For normal
regatta sailing an assymmetric fin wound do no good, because the advantage
gained in one direction is lost in the other direction. An assymmetric fin that
could flip the profile when gybing or tacking would be better. But that's very
difficult to make. At least we haven't managed to do that yet or heard of anyone
that has.

PS: concave regions on convex fins is an old principle. The first fins with
concave regions I have heard of is Michael Boe's (Denmark) fins: Boe Stick from
1990.

Inventions like this is what makes windsurfing fun!
Arctic Surf Bums:-)
--

/// Computer Science Department       //    Phone : +47 776 44121    //
// University of Tromsoe             //    Telefax: +47 776 44580   ///
/ N-9037 TROMSOE, NORWAY            //                             ////

Hello speedfreaks,

on request of many other speed-freaks who do not want to buy each year a better
and lighter board, i will now tell you more about my fin which makes my ordinary
sputnik 290 ('90) really fast, without getting spinouts at high speed.

I did not make this fin!, but i bought it from a german fellow, who i met at
the coast one windy day. He shapes these fins. He give me one of his fins to try
it out that day. I was very very impressed. I obtained a much much higher speed,
and i had sometimes a spinout, but that was not due to the fin, but to myself.
From that day i throwed my original f2-fin out my window. This fin was my first
love...
A few weeks later the Dutch windsurf magazine wrote an article about these fins.
I will use this article to explain the secret of this fin.
Maybe you will not understand everything, but that is because some dutch-words
can not translated directly to English and of course my English is not so good.

At***sight the fin is extremely small. The side of which the water hits the fin
stands in a corner of more than 80 degrees on the board.
The vin starts with a small base, then become very quick broad and run into a
extremely small top. The small top limits the lift. So you do not have
turn tendency at high speed.

Now comes the asymmetric story:
When you surf, you think you go straight ahead. The reality is different.
Because there is always drift, the board and the fin goes a little oblique through
the water. So the water comes not from the front, but hits the fin  on  the lee-side
When your couse gets higher (not stoned!), the angle gets 'sharper' (not dull!).
The waterstream follows the fin-profile at the lee-side and hits the luffstream.
Owing to this there arise vertebras. These vertebras have a restraining action.
You can observe there phenomenons through a plexiglass board!!!

CONCAVE PROFILE

All these vertebras did not exist when the luff and lee-side did not hinder
eachother. This is possible. The stream must lead to the back. To obtain this
goal, the fin is made of concave lee-side, which leads the water stream without
troubles to the back. More SPEED, more height and no spin-outs. Only you need
for every course another fin.
You could say: "make both sides of concave profile" to bad!, but this does not
work. The fin supplies scarcely lift and the board becomes very luffavaricious(!).
To accelerate you need certain lift.
The fin is a compromise that the advantages of a concave profile combine with
the advantages of a convex profile, where the disadvantages are minimum.
The fin has a double twofold asymmetric profile. The fin is divided in to halfs:
above: concave
below: convex
and the other side vice versa!

This is the story of the double asymmetric fin.

My own experience of this fin is that
1) you go in one direction faster that in the other
2) it is hard to stay at a certain height. But when you surf long distances
   you do not have trouble with height.
3) perfect at 5-6 bft with 5.8 (simmer) & 6.4 (arrows) sails
4) fin accelerate VERY fast!
5) you need a POWERBOX for this fin !

I hope you are satisfied with this.
I hope also you understand that when you want to go faster, you do not always
have to buy a new board that is 2-3 kilo lighter, or smaller than the board
you already have, but think of me and think of buying or shaping a NEW fin!!!

When you still have questions, you can mail me of course...
Hangloose,

Stan...

Stan,
How can I get one of these fins?
George

well George, as for i know, you can buy these fins only in holand and in
Germany. I only say one place in Holland were you can buy them. The most
surf-shops don't sell there fins, i don't know why exactly, but i think
because the fin is shaped by a person, who has no company, but shapes it
only for pleasure.
I bought the fin for about 350 dollars. It is expensive for a fin, but it
cost a lot of time to shape this fin. I don't know where you can buy these
fins in Germany, i only know that the shaper is a german man.
But if you are really want this fin, i can send it to you.

Greetings Stan