SchobiHH said..
Impressive. Nobody can argue against your opinion, and if this is what you and other "pro" surfers feel fine. And I am very happy for you and your customers.
I'm not at all saying that there is a discontinuity involved, just that all interesting stuff happens within a few degrees of difference as far as toe in goes. Surely between 0 and 4 for a symmetric front fin in a typical placement as far as draggyness in a straighline goes.
The fins in fact makes up quite a bit of the drag of the whole board. This is why it feel magic to ride a speed board when a dedicated super small speed fin, as opposed from a slalom fin. More fins add more drag and with side fins the board cant autoadjust in the same way as with a single fin. So drag is gonna matter.
SchobiHH said..
But from what I read from your statements is that even a tiny wrong angle does make a hugh difference, like the board turns or does go straight.
No, not like that. What I said was that _for me_ at some point if feel drag coming into play and I don't like that feel so I want less toe in than that. And from the other side, I prefer a little toe in because of how toe in changes bottom turn initiation. The inner fin, in particular if it is relatively powerful play an important role in a turn. And because of how turning dynamics work (Bouke has it explained in the thread) toe in will in practice affect the "time of engagement" for the inner front fin. More toe will very slightly but importantly let the board roll a little bit more into the turn (and let the tails start to slide out just a little bit more) before the inner fin starts to generate lift to stop the tail from sliding further. And the most important "turning error" a (good) sailor makes is to push the board to hard before it has settled into the turn. On a multi fin board more toe in angle means this happens a bit more seldom. (And recall, even the best surfers one their most trusted boards at, say, Jaws, have it happen to them so it will always happen not and then, it more about making it happen less. And of course the same thing happens often on single fins too, it is not a front fin issue as such.)
I set my toe in to compromise those two aspects drag and turn entry feel. Luckily it seems to exist a good compromise, and Bouke-style theory supports it.
In general I feel this is a bit like the edges in a top level prepared slalom ski. Of course you feel the difference between a 0 and 1 degree hang angle.
SchobiHH said..
So what I do not understand is how can the behaviour of something change abruptly if all forces applied to it don't.
Again. I'm not saying it does.
SchobiHH said..
But somehow it reminds me on an interview which Patrick Diethelm once gave in the Windsurf Journal in 2008 I think.
I remember this story. It can happen. So it is very important to try to have all your riders report without prejudice. And as far as yourself go you need to work all the time to minimize your biases. This is in fact why I downplay theory in discussions like this. I like thinking theoretically... and discussing too. But in the end the issues are theoretically complex and theoretically misunderstood, so you must always confirm with what sails well.