One for fin placement experts!

[coldsup]

Loving my quad but like to experiment now and again with different fins. Considering buying a set of keels but wondering with where the fin boxes are placed it will work well or just be a disaster?

Any advice welcome.

Here's a piccy of the where the fin boxes are placed. Thanks

[coldsup]

Suppose what I am really asking is are the front fin boxes just too far up for keels and are the rear too far in? Hope that makes sense.

[1tuberider]

Not that I am an expert (does 50 years core experience make one an expert) but have you tried

pull the front two fins and use the back ones only. I have been using this configuration for almost
three seasons and I love it. Fast and loose but with back foot pressure and paddle enough bite to make
sections and then loose when you want to slide. If you try this you will need to give it more than 1
try as you adjust to this setup. Its worth it.

[supsurf-tw]

The board overall is wrong for keels. Don't waste your money. You'll have better luck playing around with more "standard" fins to find the right combo

[coldsup]

Thanks ......it didn't look like it would be right so sometimes that is enough to ask the question. First quad I have surfed and can't see me going to anything else except a twinnie.....maybe! I will stick to playing with fin sizes etc. Thanks for saving me cash on a set of keels!

[Larry Allison]

Loving my quad but like to experiment now and again with different fins. Considering buying a set of keels but wondering with where the fin boxes are placed it will work well or just be a disaster?

Any advice welcome.

Here's a piccy of the where the fin boxes are placed. Thanks

I agree with TW keels are not a opt for your board. Placements are all wrong working against each other. Center fin box is always a good option to add a kick fin for projection and control of tail slide due to alot of volume in standup boards over surfboards. Mahalo,larry

[ninja tuna]

Ok Larry,

Quit posting the shots of that dudes boards with the halo's.  Those fins look so cool.  Are you going to make any that will fit the pro-box's?

[Larry Allison]

Ok Larry,

Quit posting the shots of that dudes boards with the halo's.  Those fins look so cool.  Are you going to make any that will fit the pro-box's?

Already making ProBox Halo's Tuna. Here's another guy in your neck of the woods riding ProBox Finsystem with Halos.

Quote from Chip Bock:

 you don't see the Hatchet and Halo's much here on the Right Coast , but the Hawaiians rock this fin set up - cant wait to get them wet in this swell and share this new Aloha with the East Coast - BTW; for those of you without Pro Box's; no worries, the Halo's fit right into your FCS fin boxes! - Aloha and Happy Holidays! Can't wait to see you in the water!

[coldsup]

Thanks Larry - appreciated.

[SUP-poser]

Having very limited personal experience with thrusters and other multi-fin setups, I still find myself wondering how these configurations overcome the increased tip vortice flow problems that are well known in aviation engineering circles:

http://nattomatto.blogspot.com/2008/04/wingtip-vortices.html

Modern airplanes are designed with long and narrow, short chord (leading to trailing edge length) "high aspect" ratio wings to minimize flow from the underside (high pressure) to the top (low pressure) of the wind at the wingtip. Long, narrow wings are considered vastly more efficient for generation of lift with minimal drag because this flow is minimized. (Winglets [the bent up tip extensions] on many modern airplanes are intended to utilize this flow to minimize drag and increase lift.) Because they have four wingtips where lift is lost as air flows to the upper wing surface, biplanes, for example, with say a 20 foot wingspan (20' times 2 wings) are slower and less efficient aerodynamically than monoplanes with a 40' wingspan and the same chord, and not just because of the drag "N" struts and flying wires biplanes generally utilize cause. That being said, the long monoplane wing may be heavier due to the required strength such a long, unbraced wing requires.

Not an engineer, but I suspect that during turns, flow from the high pressure side of fins to the low pressure side is far higher with a multi-fin board and would reduce the effective side force the fins can generate per unit drag/area.

I'm sure there are advantages to multi-fin configurations that may compensate for this hydrodynamic inefficiency, just as a biplane may enjoy the benefits of added strength/reduced weight. I understand a lot of quad enthusiasts like to do tail-slide 360's etc. that are facilitated with that setup. Also, the shorter fins don't encounter reefs as often! As a previous poster mentions, they do look cool.

[ninja tuna]

hey sup-poser,

my edit
**
speaking in terms of fins for surfing

**

Just an observation before any conversations about this take five left turns out of control.  I have seen these battles over the internet boards about how many fins are better than this many fins, and this size is better than this other size and vice versa.  My first surfboard was a single fin.  I have had a few tri fins, but life really took off when I started riding Malcolm Campbell five fin bonzers in 1990.  I love em.  I own quite a few of them.  When I bought my first one, it was from someone who had a few of them and some experience and he told me not to get frustrated becasue you will fall off the back when you start making turns.  He was right.  They don't slow down in turns, no matter how hard the turn.  I now have a few quad fin fish that I have been also riding for the past few years and they are a blast too.  I have owned and ridden some tri fins since riding my bonzers and quads, but they do not give me the excitement of my bonzers and quads. 

Basically my point is who gives a crap about what resistance your are having put on or getting as long it works for you and you are smiling when you get out of the water.  I try and read to see what other people have gone with and experimented to help narrow down choices. I have bought some fins that made my board feel like I was pulling a five gallon bucket. Switched fins and now my bucket pulling wagon is a lively rocketship. 

To me there are tooooooo many variables to bother with, and I am an engineer, but not in the field of aerofoils.  I am not the type that sits in a cubicle all day either.  Boards are not moving that fast, you are not riding on a perfectly flat surface, your angle, speed, direction, and surface are constantly changing.  I have found arguments for both sides that seemed logical and well explained.  But did it ever change anything? 

[Larry Allison]

Don't mean to jack things up. Bob the Greek actually makes a double ender 10 fin.

Quote from Greek:
BobtheGreek Bolen Nose rider one way and a beach break the other. We sold a lot of them through out the earl y70s But then they only had one fin box on each end.

[SUP-poser]

I have no strong position on fin configuration. As I mentioned, my experience with multi-fin setups is limited. That being said, I think debating the issues and mysteries is sensible, interesting, and need not be contentious (I don't intend to be a multi-fin detractor, at least not yet). Surfboards are distinct from many other foil-using craft (for lack of a better word) in that they operate largely on the boundary between air and water, generally fully immersed in neither of these fluids, often on a curved liquid surface.

One thing which seems clear is that boards with any width at the tail may have more fin in the water during a hard bottom turn with "sidebites" installed when compared with a single-fin board. I'm aware of no other craft that uses toed-in fins which are not mounted parallel to the direction of "flight" like a thruster, though I think winglets may be toed-out slightly to take aerodynamic advantage of the flow around wingtips. An first glance the drag sidebites which are not parallel to the stringer induce would appear to diminish performance/speed. Imagine increasing the toe-in to say, something beyond twenty degrees on the sidebites and you will likely see drag soar to a point where it becomes obviously detrimental. I have heard thruster advocates describe a surge of accelleration they feel during turns that they attribute to the fin config. It occurred to me that they may actually be experiencing a decrease in drag when the outside fin breaks out of the water, not an increase in thrust. However, I suppose it may actually be beneficial to have increased drag during the drop in some circumstances (surfers more skilled than I am appear to routinely stall their boards by sinking the tail or using their hands in the face to slow down for positioning, especially in hollow waves). The turning moment a toed-in side fin produces (which presumably yaws the nose toward the side of the immersed sidebite) may also be a benefit.

[banzai]

I have found that there are different strokes for different folks. What are you looking to do on the wave, big bottom turn off the lip, mellow cruising, blow the tail, rad 360? What type of wave do you ride, steep barrel, mellow slow building, or sloppy mush and/or how big? Each fin set up/design has a purpose and works better in different applications from each situations. Fin size also plays an important role and feels different in different situations. I change fin set up and size according to wave size and conditions. I've SUP surfed with twin, thruster, and quad set ups with different sized fins, each has its advantages...just depends on what you want to do on the wave.

[Fanman]

I like the keels w a nubster so far the best for loosening up the board in waves below head high! I have tried these configurations, quad, thruster, twin, keels w twenzers etc.
Give um a try!