: > This is something that has been bothering me for some time..
: > What makes a slalom (blade/pointer) fin feel and work so differently
: > from a strongly curved wave fin?
: Here's my guess.
: A fin that has a high aspect ratio (long) and very little rake should
: act like a sailplane wing, generating more lift than a wave fin with
: the opposite characteristics. However, by being more vertical, some of
: the inherent stability of a swept back wave fin is lost.
[stuff about "X Planes" deleted]
: .... This is the extreme case, but it may help you to visiualize why
: a near vertical fin isn't as forgiving as a swept back fin that
: naturally wants to self correct the board back into the path of least
: resistance (straight ahead). Even when you carve a jibe, the fin is
: basically following the front of the board, since both are banked over
: a bit and following the same arc. Thus the sweep of a wave fin doesn't
: really hamper turning, but still enhances stability. (I hate spinning
: out in a jibe!)
: Ultimately, the leverage on a long straight blade fin may try to lift
: and rotate the board along the center line. Whereas more of the
: leverage on a wave fin is trying to straighten out the board along a
: vertical axis through the fin. Basically a wave fin's design gives more
: directional stability (like a rudder) while a blade fin gives more lift
: (like a wing) at the expense of stability.
My thoughts on the subject - The reason the wave fin is considered "a
better turning fin" has to do with the drag created by the curved
trailing edge. This is what causes these fins to be slower in a
straight line than blades, but this is a big help in turning due to
the larger, effectively, area for the sailor to push against; hence
Blades can turn really nicely but I think that it has more to do with
jibing ability than the fact that the fin is less stable, by design,
than wave fins. Because blades are faster, you can really rip into a
turn the sudden changes of which can destabilize a fin quite easily. The
sailor that is "smoother" with the transition is going to avoid spinout
better than the "rougher" sailor.
I'd like to know if anyone has done a turning experiment by comparing
a blade and a wave fin of the same area in sq. in.? I wonder if the
wave fins might possibly make the transition from one direction to
another better in this situation or could it be becouse they are
often just smaller in overall area than the blades?
~|\ If you're not planing, Adam S. Zais
~|-\ then you're complaining. Atria Software, Inc.