fin spin

[Lessacher]

When I work speedfins between 18 to 28cm i work they very stiff so they cannot produce a lot of
twist and flex. When,than a little flex for lift and not 2 things ,flex and twist at the same time ,one works against the other. A twisting fin need more power for flexing. That reduce the speed. I worked a fin with
20cm for one way. The idea is, to work flex in the fin,for a little lift of the end of the board.The fin stay
in an angle of 10° to the left or right side.So you need only the half power for to get flex and later the lift.
The power you need for flex ,reduce the speed a little. I work only 100% carbon fins,the reaction of
carbon is the shortest,I know,( bending and back). I worked a fin inside only with rowings.I lay the rowings
in epoxy and do powder of ceramic around the rowings. that makes the fin stiffer than all the other things.
So I try and try. Wolfgang

[Lessacher]

You make a jump or you surf over choppy water. If you come in the water ,two things. Leewards pressure,
On the other side from the coming in the water more vavuum. That takes a mixture of air and water from
the boardbottum to the end of the fin, and goes down to the tip,make bubbles and sometimes spin out.
Have you a cut out at the base of the fin,there goes the water and air mixture in an angle of 30-40° behind the fin from leeward,the pressureside, to the other side aned take all it away from the fin, so it cannot
come something to the tip.If you saw what in Netherland happend ,sorry I stopped in the half, so I cannot say what it was, but it is to easy to say it was the Windsurfer. I hope that some of you try to make such a cut out at the base,take a old fin and try it.It is not so that I want to work for you here fins, I want only to show some People what we can do against spin out. Please look here:
www.cameraid.com/Lessacher/tech.html
There can you see the cut out. And how the diagonal concaves are. Wolfgang

[Lessacher]

There the cut out is 3cm wide, so is the end of the fin 3cm behind the cut out,the water goes a little earlier through the cut out. The end of the fin comes a little to late. 3 cm.to late. Wolfgang