What's the difference in performance between riding a swallow tail set up with quad fins as opposed to a squash?
To me, it's essentially the same difference as you'd feel if you were comparing a swallow and a squash with a thruster setup. All other things held constant, meaning... if you took a squash tail, and just notched out a swallow, you'd have less planing surface. This means the tail would more easily engage on a turn (people call it "more bite") and would add more control at speed.
However... you have to be careful making that comparison, because all other factors and generally not held constant. Usually you see swallow tails on boards that have wider tails (measured a foot up) designed for smaller waves. These boards will have generally straighter outlines from the widepoint back for gutless surf, but if the tail's too wide behind the fins, you get what I call a "skipping stone" effect... you lose responsiveness, and it gets too hard to get on a rail when you get going fast. To compensate, you use some kind of relief feature... some kind of cutout tail shape, like a swallow, bat, crescent... to reduce planing surface.
good thread ,,,great info ... Fitz , I think Rider65 is referring to the foil (50/50) (80/20) of the fins not the front/rear size ratio...
I really love the quads ,but it may take a little different approach and a more time to get things dialed in but it's worth it !
The outline of the board, the fins,the composition ,the placement ,the foil, the rider, the surf all play a big part in the ride.... I am 6'1" 190 lbs. My boards: # 1 is a 5'10" HP shape I settled on PC-7 front GX rears ..that board is fast and easy to ride. # 2 is a 5'8" rusty dwart ,,,thicker ,wider.. I like the stretch quad set on that board ...the rears are set closer to the stringer,not out on the rail so you get a predictable hold and release. the narrow tail combined with the rear fin placement make vertical turns easy on that board. #3 Is a 5'6" fishcuit ...the fattest of the bunch and the hardest for me to ride.I use the stretch quad fronts and 375 pivots in the rear. It used to be difficult to turn on the backhand as you described , but LESS fin solved that for me as the tail is so wide it might be not as easy to turn. #4 Hanel Quad fish with the LOKBOX system ... this allows you to move the fins fore and aft to really fine tune the ride.
Best of luck and let us know how it goes ~
Absolutely right Henny..........MFitz73 we are talking about fin foil. Look at the center fin for a thruster and that is a 50/50 foil. 80/20 has IFT or inside foil technology where the flat side is actually scooped or has a small concave in it. And ofcoarse Flat is well..... flat. If you put 50/50 foil rears in your quad setup you will have more control and less squirt which is what your complaint was all about. The fins that came with your board to me are still kinda big except for on big days. If you have a fish I would reccomend the SF4 Quad set http://surffcs.com/us/products/fins/Quads/SF4Quad.aspx . Very stable yet very responsive and just a great fin for a fish design. For a shortboard I would go with the Q-5xc fins since they have the GX's in the rear with the 50/50 foil. If you are bent on keeping the M7's then just pick up a rear set of GX's with 50/50 foil. http://surffcs.com/us/products/fins/Quads/Q-5Xc.aspx .Hope this helps you out. Im also curious to just what exactly your board dimensions are also.
Last edited by wave1rider65; Feb 3, 2012 at 05:54 PM.