Quad versus twinzer or twin fin

this thread has got me thinking that i may "need" to have brian wynn build me a twinzer based on my campbell octafish...

 

Yes...

If you're talking about fins, foiled means curved. So single foiled means curved on one side (outside), uncurved, or flat, on the other (inside). Double foiled means curved on both sides, and can mean symmetrically foiled (same curve on both sides) or asymmetrically foiled (different curves... including concaves).

 

If you mean it has a mini swallow, that says to me it has more curve in the tail... pulling in the width from that 19 inch wide point to about 4 or 6 inches tip to tip on the swallows? That's quite a bit of curve compared to 16 or 17 tip to tip on a true fish. That translates into that rail to rail responsiveness I mentioned that the true retro fish does not have. But there are a number of things you can do to loosen up that wide, straight tail, the geometry of the cutout between the "pins" being a major one... the "taint" as they call it.

 

So an asymmetrical twin keels with an 80:20 foil, what's the best toe angle for it ?

 

Hi Charles, that depends, but to start with, asymeytrically foiled fins (e.g. 80/30 foil etc) need a few degrees of toe in just to bring them up to the zero angle of attack which double foiled fins have with no toe in.

If 80/20 fins are set with no toe in then they have negative effective toe in or angle of attack.

The reason for this is that asymmetrically foiled fins direct the water flow inwards towards the centreline of the board. The same thin happens with aircraft wings.

So the bottom line is that whatever angle of attack you want to achieve via toe in, asymmetrically foiled fins require a few extra degrees of toe in to get it than symmetrical fins do.