opened the laptop for the first time in several days…
I’ve no issues eliminating the cutaway at the base of such a fin. I’d rather have the trailing edge vertical from hull.
I am afraid of too little base area, even with more depth, with such high aspect ratio fins. Could be an irrational fear, but slow speed drifty weirdness is a feature of high aspect fins, and reduced base width would seem to accentuate this. Tubercled fins being so happy in a stall/partial stall, only adds to this drifty weirdness. My multifin HWS’s all seem to be overweight and dull until a certain speed is achieved then crisp and much more responsive, above that minimum speed. Any fin which prevents that speed to be achieved initially, seems to ruin the ride and make me wish I chose to ride my longboard instead. I refuse to hop or spastically try and generate that minimum speed on weak waves where one needs to get some parallel to shore movement early in the weak wave, avoiding the bottom turn.
I’ve never tried curved rail fins, don’t know what to expect.
I can use the probox inserts for different cant/splay/camber and with no canted tabs I can more easily reinforce tab(s) with carbon rods. Not really big on fins sticking out beyond the apex of the rail. Having cut up my feet in my youth on such fins, ruining many a session.
As far as cambered foil rail fins I only have experience with the latest ‘batfin’ I made with the ~150% thickness drela AG10, and the jury is still out as to whether I like, it with only a few sessions in undersized underpowered waves. I am bothered by flat sides from a design standpoint, but still like their crisp responsive projection when underfoot.
The more ‘antiflat’ the inside of a rail fin is, the less I’ve liked them, unless in the rare more powerful larger conditions.
I am leaning towards the raked tip of traditional ‘dol-fins’ being a feel good ‘suspension’ with self centering ‘caster’ built in, with the tip flexing away from load and rebounding afterwards, with an acceptable amount of drag. High aspect with no tip to bend in reaction to the flow around it might have noticeably less drag, but is missing something, like the board not self centering to nearly the same degree and having to consciously do it, where that was never a consideration in the previous 37 years of wave riding experieneces. With multifins perhaps the rear fin(s) can provide that self centering and forward rail fins be optimized for max grip minimum drag, rather than 3/4 similar shaped sized fins of today’s perfomrance quads and thrusters. I certainly liked the feel of mrMik’s half sized Deaweeder fin in my thruster box which has a fair amount of sweep , with my HAR rail fins.
The ultra short turning radius of high aspect fins on my shortboard, when pushed hard, has been a bit weird to figure out, and makes one realize just how much resistance to turning the traditional fin outline imparts. Quicker and looser and different might be just be a short lived novelty if one cannot get it figured out and achieve the lines one intends when reading the wave face.
A happy middle ground of high aspect fin ratio and comforting raked tip’s self centering and rebound twang is likely quite personal. Combining high aspect ratio’s lesser drag combined with the comforting flexier self centering raked but draggier tip, likely needs a lot of trail and error to refine.
I think the deep ‘Peng Wing’ rail fin might be really fast and loose but still lack the comforting self centering and ‘loading the fins through a turn’ feel.
Can the center fin tame the turning radius without imparting too much added drag?
Can a thick foil counter the lack of self centering and slow speed drifty weirdness of high aspect ratio fins?
I guess there’s only one way to find out, and that’s to try it.
