Are you transfinbic?

Discussion in 'All Discussions' started by grainofsand, Mar 30, 2021.

  1. grainofsand

    grainofsand Well-Known Member

    411
    Jun 26, 2014
    most grovelers have had the 5 fin option, but with many pros making keels and large twins look fun, there are many hating on the thruster. Stop the Hate
     
  2. La_Piedra

    La_Piedra Well-Known Member

    Oct 9, 2017
    I think it's pretty cool that twin fins and keels are finding their way back into the lineup. Back in the day they were high performance grovelers. Now they're a versatile arrow in a quiver.

    But yeah, thrusters are the mainstay. Quads are closer now, but 3 fins are the daily drivers
     
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  3. antoine

    antoine Well-Known Member

    Mar 10, 2013
    So. Who's the many that's got you worried about thruster set ups on grovlers? I won't grovel
     
  4. La_Piedra

    La_Piedra Well-Known Member

    Oct 9, 2017
    I know the 5-fin setup isn't made to ride with all 5 fins, but I want to know who's tried this and what it felt like
     
  5. grainofsand

    grainofsand Well-Known Member

    411
    Jun 26, 2014
    actually, there are center 'nubs' that you can get for about $15, doesn't really change the losseness and lift too much, maybe more mental
     
  6. LBCrew

    LBCrew Well-Known Member

    Aug 12, 2009
    The nub acts adds a bit more drive (although to me, not really discernible) but what I think it really does is allow the quad to go rail to rail a bit smoother. I experimented a few times in the same session with and without the nub, and that was the only thing I felt different. Some people say it's a "stabilizer"... I didn't notice that either, even after deliberate experimentation, paying attention and LOOKING for that sensation. I thought MAYBE a touch more drive through turns, but DEFINITELY a smoother "rolling" sensation when going rail to rail with the nub in vs. without it.

    Quads on grovelers make sense to me. A second set of single foiled fins toed and canted can almost double the amount of thrust and lift compared to the thruster. The center fin only adds directional stability and drive... no lift. Quads add 25% more fin area, and that makes a difference.

    I've never NOT had a twin or fish in my quiver... ever. A different feel completely, and IMO not a substitute for a good groveler.
     
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  7. La_Piedra

    La_Piedra Well-Known Member

    Oct 9, 2017
    Yeah I've seen guys using the nub, but not for a few years now. I think they have a reputation for not doing much at all.

    I know I could probably go to Swaylock's and find threads to give me answers to my questions, but I like keeping it local and hearing what average Joe's have to say. Besides, it's good content and this place could use some.

    Since the nub hasn't really had any intended effect other than taking hard-earned $$$ out of the pockets of curious surfers, I'm wondering if another style or size would ever work, or if 5 fins of any style or arrangement is just clogging up the works.

    I remember thinking that about the Thruster for a minute back in '81.
     
  8. antoine

    antoine Well-Known Member

    Mar 10, 2013
    Lets talk Longboard fins. High performance board set ups vs nose riding. What's the best fin for each.

    For me I've been focusing on nose riding so I've got a 9'0 single pivot fin 9 inch. I find I get plenty of turn and the ability to lock it in the wave. Good bottom turns. The board is poly
     
    Last edited: Apr 1, 2021
  9. simod5

    simod5 Super Moderator

    296
    Jan 26, 2014
    the nubster is useful. on mushy/higher tide surf, swap it out with the center fin and you get a much looser board with just a little bit of hold, for a bit more wiggle on the slow spots...doesn't quite spin out the way it would with no center fin at all.
     
  10. headhigh

    headhigh Well-Known Member

    Jul 17, 2009
    I’m having a twin shaped right now and grabbed a set of these wild looking keels to go with.

    Almost everything about this board is local: Shaped by one of my old friends, Fins designed locally and the the fin guy is glassing the board. Even the epoxy resin was developed by a professor here in town at my alma mater.

    ETA for delivery of the board is 4/20:cool:

    fins.png
     
  11. antoine

    antoine Well-Known Member

    Mar 10, 2013
    Nice fins.. What's a alma matter ?
     
  12. headhigh

    headhigh Well-Known Member

    Jul 17, 2009
    The university from which I received a very expensive piece of sheep's skin.
     
  13. curl

    curl Well-Known Member

    312
    Apr 30, 2013
    La Piedra , a true 5 fin defeats the ride of a quad with that nub . Digressing with LB , fins dont create lift , they produce cavitation which creates drag . Adding more cav negates thrust .
     
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  14. curl

    curl Well-Known Member

    312
    Apr 30, 2013
    984EDFF7-BD3B-44E3-A195-B47E7097C4B0.jpeg Antione , I cluster a cutaway up in the box with a pair of Pancho s L . A great setup for good waves with thrust and shortening the turning radius .
     
  15. antoine

    antoine Well-Known Member

    Mar 10, 2013
    Sweet set up on the fins. I never thought of that so I will put it to the test. Thanks for the info and pic
     
  16. La_Piedra

    La_Piedra Well-Known Member

    Oct 9, 2017
    The board in that pic has a lot of foil and tail rocker to be a longboard, I'm guessing 2+1 mid-sized?
     
  17. LBCrew

    LBCrew Well-Known Member

    Aug 12, 2009
    Here's my understanding... A single foiled fin (convex on one side, flat on the other) must create a lifting force in the direction of the curved surface. We know that as the velocity of a fluid increases, the pressure decreases and an imbalance of forces is created. So a canted fin creates a lifting force that is both railward and upward... and if toed, also creates forward thrust.

    Going down the line, a well foiled fin reduces the chance of cavitation and typical board speeds. Even a well foiled fin will cavitate at high speeds, but those speeds are not typically reached on surfboards, even in big surf. A poorly foiled fin, however, will most definitely cavitate at surfing speeds, and you'll often hear the fin hum as a result. You'll also feel the board "put on the breaks" too... cavitation creates enormous drag.

    All fins create drag. That's why they work. Keep in mind that drag... the force that opposes motion... is what we rely on to turn. All fins drag AND cavitate through a turn. The goal is to create a fin that has efficiency down the line and functional drag through turns.
     
    Last edited: Apr 3, 2021
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  18. La_Piedra

    La_Piedra Well-Known Member

    Oct 9, 2017
    I know nothing of physics, and I have a hard time understanding the theories.

    So if canting and toeing creates thrust and lift, why do double foiled keels set perfectly in line with the stringer seem as if they go much faster? Though making turns is noticeably stiffer.

    You might have to dumb it down a bit for me to get it
     
  19. antoine

    antoine Well-Known Member

    Mar 10, 2013
    BAM KNOWLEDGE!
    I just learned more about fins than I thought possible. Now that my brain hurts ima show off my knowledge to my dumber friends!
     
    Carson likes this.
  20. curl

    curl Well-Known Member

    312
    Apr 30, 2013
    240D13DC-2038-4AF6-8296-F4735D441972.jpeg La P , HPLB , 9 ft , thin at 2.625 which is his standard thickness and needs tad more glass .
     
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