Can anyone tell me the differences between a Thruster setup and a Single Fin setup. I have a 8ft. Funshape that can be setup either way . Thruster setup seems to work better for me but I wonder what the Technical differences are and what one should expect from each setup. Are there any reasons to use a single fin ? My Longboard does seem to work better with just the 1 larger fin and not the 3 smaller ones like I use on the smaller one… Thanks
good fin info from Greg Loehr: Smaller sides make rail to rail transition quicker. Conversly larger side fins slow rail to rail. This is a problem in hollow surf where quickness is more important and plus the sluggishness of a longboard can compound the problem. Mushy surf the larger side fins do add a bit of snap by giving a pivot point on the rail. Also they can add a bit of drive. The larger the back fin the more it pulls down and lifts the nose changing the balance of pitch aft. This provides better noseriding and better handling in hollow surf. In flat faced mush though your board may stall out and be be hard to get going especially around sections. My personal rule of thumb is larger sides and a smaller back fin for mush, a larger back fin and smaller sides for hollow days
more from Paul Jensen: Here are some of the basic concepts of fin set-ups on mid-length and longer boards, and how they affect performance. Shortboards are for someone else to explain… What I build are a “Thick Base - Fully Foiled Fin”. It is a smooth, loose-feeling fin, that turns tight and releases well. With a fully foiled fin you can use a deeper fin with out the drag you would feel with a conventional fin. The reason is that a foiled fin releases water efficiently and a “flat” fin creates turbulence drag. My personal favorite is: depth 10",rake 10.5",width of base 5",Thickness at base 1.125". It has an 1/8" glass core, laminated to that is 1/2" Baltic birch plywood on both sides, foiled, glassed. The theory behind the “Thick Base - Fully Foiled Fin”…George Greenough had perfected the high-aspect, laminar flow fin, a development, which made him literally the fastest man in the water. The key lay in constructing a fin which could harness the wave’s energy without generating drag-inducing turbulence along the trailing edge of the fin as it moved through the water…Laminar flow basically is over a very narrow range. Water only goes back an inch and a quarter or so before breaking into turbulent flow. So the fin must be narrow. Look at any high-performance fish and you’ll see my fin is basically the same - it’s the same plan and foil shape as a large tuna…you’ll notice their tail is very narrow and quite high. With that kind of fin by the time the turbulence shows up in the water the fin has already left it behind. Hence no turbulence to affect performance. Another great fin is a “Liddle Flex Fin”… Greg Liddle’s theory:“I cannot emphasize enough how important it is to have a flexible fin or fins. The fin allows the board to behave appropriately. To trim at high speed with little effort. To maneuver smoothly and particularly to release during down the line high speed turns. A rigid fin with the inappropriate foil will not make this happen with these boards. The board will pivot awkwardly and die out of a turn with no forward acceleration. It will feel wrong to the initiated.” “It is essential that the fin have this particular type of flex, not a soft bending over flex, but a high tension flex that bends concave and gradually into the base of the fin. It lets power on and off even and smoothly resulting in a high speed and flowing style of surfing.” Another good fin is the “Wingnut Long-Rake” fin made by Rainbow Fin Co. is a fairly deep (10") fin medium stiff with plenty of rake and not too much tip. It’s a good fin for longer, driving turns. I took a stock “Wingnut” and re-foiled it so that it had a lot of tip flex. I like it!!! Smooth sweeping turns and extended trim are more difficult with many of the contemporary multi-fin boards. These boards often have a “stage-y” feel that is more suited to those who prefer “triple-pump” bottom-turns. The tri-fin set-up is only “faster” if it is pumped or rapidly turned from rail to rail. In straight-line trim the tri-fins are just so much drag. Some of the more progressive tri-fins have other design features, such as accelerated rocker, thin volume or narrow planshape that adds more drag, and requires even more energy from the surfer’s to fully use the leverage and projection of the tri-fin design. A “2 + 1”, or a “single fin with training wheels”, is a larger single fin in a center box, supplemented with smaller, Thruster-like side fins set on the rails. The most common set-up is a center fin box holding a 6" to 8" single fin. Side fins are sometimes glassed-on, but FCS plugs are common. The center fin is sometimes placed further up in the box, serving to narrow the “wheelbase” of the combined fins to give the board a looser rail-to-rail feeling. To summarize, the single-fin seems best suited to those who want to trim, glide and perform smooth sweeping turns. A single fin is stable yet pivotal. If you enjoy more energetic surfing, go for a multi-fin, with the “2 + 1” being a reliable compromise. I hope this has been of some help, and that you enjoy experimenting… Paul Jensen
and even more from Tom@daum: Here’s an article I wrote a while back and is posted over at www.wetsand.com Surfboard Fins Get No Respect 1/27/01 Surfboard Fins get no respect! When you walk into your favorite surf shop and get all googley eyed over the masterpieces in the racks, its not the fins youre drooling over. Think about it for a minute though. What is a surfboard, but a summation of hydrodynamic surfaces. Just as an airplane generates lift from its wings and control from its tail; your boards bottom generates lift and affects speed. But, its your fins working together with rail and bottom contour that most influence the feel of your board when turning. And lets face it how many short boarders straight-line the waves they ride. Few surfers really understand how fins affect the way their board rides and leave all the specifics to someone else. Rail and bottom contour assist fins in performing their function. But, what really influences the way your board turns is the combination of several important fin factors. No wonder so few surfers pay attention to the “Fin Affect”. Its fn complicated! But, today, as the form shape of surfboards goes through finer and finer adjustments, the biggest gains you can make to your boards performance have to do with your fins. The predominant factors that influence your “Fin Affect” are: 1) Foil Shape- the curvature from leading edge to trailing edge as it changes from base to tip. 2) Template shape- The combination of depth, width, and rake that make up the profile outline of the fin. 3) Placement- which incorporates how far the fins are from the back of the board, how far apart they are from one another, toe and camber. 4) Stability and flex. Lets discuss each of these and how changing them will affect the way your board performs. Foils are surfaces that affect lift and drag. If you notice an airplane wing has a flat side on the bottom and curved side on the top. The path of least resistance is the bottom side. It takes more effort (drag) to flow around the curved top surface, so more air flows under the wing than over. This creates high pressure under the wing. The air that does flow over the wing separates from the wing at the apex of the leading edge of the wing and creates a low-pressure area. This difference in pressure forms the force (lift) that allows the wing to go up. The more curve a foil has the more drag it induces over the curved surface. Which means that a foil with greater curvature will have more lift at lower speeds. The problem is that at higher speeds that additional drag will develop turbulence and stall the flow across the foil. The exact same scenario occurs under water with side fins. The big difference is that instead of lifting your tail out under water; Side fins orient the curved surface so that they actually pull your boards fin and rail down into the water. This gives you hold when cranking a nasty slash. Consequently, thicker more curvy foils for slow waves and flatter more fine foils for high-speed waves. Template shape has to do with how the fin looks in profile. An over simplification would be deeper, rakier & wider fins provide more control. But, the more profile you have the more fin you drag around. So, you have to optimize the combination of the three so that it is loose enough for your conditions. Yet, tight enough to not get too squirrelly on you. Other factors that figure into requiring more or less of these three variables are: 1) Type of wave: steep and heavy or slopey and fun. 2) Surface conditions: Choppy and irregular or clean and smooth. 3) Rider Size: Big and heavy or small and featherweight. 4) Rider Style: Subtle and flowing or Extreme and radical. Each of the first considerations requires more fin template area and each of the second work better with less. Placement has traditionally been left to convention. Simon Anderson set a benchmark twenty years ago for approximate location. Each shaper has their own personal preference for each of the “models” they make. But, there are subtle differences in most boards and in all riders. Otherwise why would custom boards be in such demand. And remarkably as little as an 1/8" movement fore or aft in either or both the center fin or the side fins can have almost as much effect as going from a rakey 4 ¾" fin to a vertical 4 5/8" fin. If you move your fins closer together they act looser and if you spread them further apart they get tighter. Toe is the amount of angle the base of your side fins are pointed in towards the center of the board relative to the leading edge and trailing edge at the base. Camber is the amount of angle the body of your fin is set at relative to an imaginary horizontal plane perpendicular to your stringer. Both affect the angle of attack that your fin foils experience as they flow through the water. More angle forces more water flow around the outside plane at lower speeds. The net affect is that it becomes easier to initiate turns on slower waves. To much angle at higher speeds increases turbulence and drag. Finally, stability and flex are crucial to making this all click. If you have a deeper fin you can get away with more tip-flex and not wash out. The benefit of tip flex is that it dampens or smoothes out some of the bite in direction changes. The down side of tip flex is that if you get too much tip flex it will wash out. Base stability is crucial to a good set of fins. If a fin moves around at the base it will set up turbulence. Turbulence generates drag and disturbs the lift, which keeps you fins holding. So it is slow and out of control. If you like a more pivoty board you would do well to try a stiffer set of smaller more vertical fins. Prior to eight years ago the only options a surfer had to muck with all these variables was to grind his glass-on fins off and install a slightly different set in a slightly different location and record the differences until they found the optimum. Not very likely. So, with the exception of a few elite pros, we all lived with what we were given. Now with the advent of removable fins (i.e. FCS, Future, Lock Box, OAM and OFishl) you can at least muck with the first two “Fin affect factors”. But, if you want the ability to dial in your board with all four factors you have got to try the newest competitor to the fin system market Red X /Excel. Tom OKeefe
maybe something in there you can use maybe not. still great info that can always use a reread. hope there’s somthing in it for you.
Side bites are training wheels. Stick with a single. Ever see Dane & Ben ride a sigle fin short board?
If i were you id get a fin box and two side plugs so you can use either. singles work well only in certain types of waves, they tend not to like average conditions. trusters will work in anything. single fins are very restrictive as far as ease of turning and drawing modern lines are concerned if your feet are not in the exact right spot your board wont follow you as a thruster will, you are also restricted to a certain turning radius that the fin decides on. 3 fins have a far larger sweet spot to stand over when doing cutbacks etc. do not watch joel tudor on video and go out and get a single. you will only discover how gifted a surfer he acually is. i love singles on my 9’6’ log but many a time i have become frustrated with single fins on shorter surfboards. Most surfers will surf a single fin as an alternative when they need a bit of a change of pace.
Try it without any fins at all. That’s when you will notice the biggest difference. It makes it really easy to change directions. Kind of like mud wrestling on a sheet of glass.
For some reason, when I see 3 fins on 7’6" (or longer), I can’t help thinking the owner is a kook.
Thanks for the good responses . I printed it out and looked at it real good .Think I will try a different single fin one of the ones with flex that was designed for the “Retro” style boards . I read somewhere that fins were one of the last things that board makers have to really explore as far as changing the way boards handle. And as far as the last couple of guys who had the smart comments . Thats OK I still sometimes put someone else down too just to make myself feel better . Hope it worked for you .And also hope you really are able to get a life .ALOHA
My understanding is limited but the single fin creats less drag and can be faster down the line the thruster will hold the edge better in bttom turns and power moves. There are a lot variables the effect the way a board will handle but thats a good start for that question.
Because I have surfed many different fin combinations on mid-length boards I can assure you that rail fins give a positive advantage to boards with modern bottom and rail configurations. Hulls are another matter entirely. One that I have found to be very responsive and faster in moderate sized waves (It is not a standard set-up by any stretch of the imagination.) is 6" Liddle flex rail fins set with 3.5 degrees of cant and symmetrically foiled and a 3" center shape in imitation of an Dolphin dorsal set on very near the tail of the board. The rail fins don’t generate the lift in the turns that asymmetrical fins do you the board accelerates better on the drop and goes across the flats like it’s on oil and bottom turns are plenty strong as the rail fins seem to work in perfect unison with the rails. I will post a photo of set up on an 8’0” egg shape in the resource section soon. As wave size increases I find putting a vertical 5" cutaway of my own template in a similar position makes the board much more positive on steeper faces. I see master shaper/surfer Doug Haut out on something around 8’0” these days with the new Future vectors in it and he’s looks pretty smooth with a standard thruster set-up .The board wouldn’t surf with the same control or be as lively as it is with a single under it. When waves approach double overhead I have to agree with Greg Loerh when he says that for large pitching waves that the center fin needs to be a little larger than the rails. In the end size, foil, and position make all the difference. Some of the fastest boards I see are twin-fin fish around 6 feet in length. It is very hard to make general statements about fin performance simply because what brings one board to life will make a dog out of another. In the end speed and performance is more about the surfer than the board and fins IMHO. Gone Surfin’, Rich p.s. We reveal who we are and what we know by what we say.
In addition to the type of fins and their location, rocker and rail shape will have a huge impact on whether one kind of fin set up works or not. While they may not be mutually exclusive, a given rocker and rail will work better with the fin set up it was design for, regardless of the type of fin or fins. From about 8 foot up there is enough planing area to make up for incompatable rocker/rail/fin combos. With mid 7’s and smaller, you’re better off getting somthing designed specifically to be a multi-fin or single.
Just a tid bit…After making a turn on a single fin there seems to be a lag time before you get speed again (except with smooth pumping turns the n you can trim and get speed). Where a thruster is read to be pumped at just about any point on a wave and you are back in the game. I find singles to be vessels that need to be ridden carefully without to many radical turns…Justdon’t get Kelly Slater to disprove my last statement please…he is the exception…
Hey Steve, You hit the nail on the head and drove it home with one swing. Well said! Some waves aren’t so criritcal so that punch you need at just the right moment to drive through as section or around it isn’t so important. One thing clear to me is that boards with rail fins on them, twin finned boards included, seem to hold a high line on a steep face much better than an single. Less fin in the middle can often be a very good call when you have more time and you really want to snap a board around. The effective possiblities, when it comes to fin set-ups, are still being searched out. Mahalo, Rich
I beg to differ…Sounds like you are riding a single fin longboard or you are trying to ride a smaller single fin like a thruster. Pivoty turns from the tail will give you that exact feeling. A good single fin surfer uses the rail as much as the fin. The drive and acceration are there but it isn’t an instantaneous squirt like a thruster. Also you have to use completely different lines on a wave to get them to work right. Apples and oranges…one isn’t better than the other; just different.
Rich: I’ll bet my Liddle or Edge will hold a higher line longer (with speed) than most multi-fin set ups (the exception being a true fish)…The key is the rail; sand off the tucked edge and they’ll stay up there. With the multi-fin, you have to keep pumping or they’ll stall. A hard rail will slide down the face whether it’s a single or a multi-fin (I’m talking short to mid length boards).
Hey Lee, I could’nt agree with you more about rails being the key to surfboard performance. I surfed single for years and a board with the right kind of rails is dream. You have to be able to use them effectively or surfing single is a lost cause. I have an old 8’3"x21.5 single I have to send you a photo of. It’s the best single I’ve surfed. Because I surf lots of different fin combinations these days and have been working more on multiple set-ups these days I might get confused sometimes, so keep me on the straight and narrow Lee. I’m sure we agree that when you put different fins combinations or even different singles on a board you have to change the way you surf to get the most out of board. Obviously some set-ups work better in some situations than others, boards as well. I think Paul Jensen would say something like, when you surf single you surf the board. I would add that on modern thruster shortboards just about all you surf is the fins. Some rail designs just want to climb the face. Rocker can have a lot to do with it too. Relaxed tail rocker will hold a high line much better that exaggerated tail rocker will. So I guess when it all boils down, the old saying, There are horses for courses applies. Guess that’s why I’m keep switchin’ up. If I said multiple fin combinations are better I stand corrected. What’s better is what works better for each surfer. Good, better, best is pretty damn subjective when it comes to surfboards. Lee, Where do you think symmetrically foiled rail fins and a small central stabilizer fit into the picture? It sure blew my mind the first time I surfed a board set-up this way. It feels faster than anything I’ve ever ridden. but that could be my imagination. Sometimes mine gets me in trouble. Back to the fin shop, Rich
When I was a kneeboarder/shaper, it wasn`t very long before I discovered the advantages of a thin, soft rail, minus the tucked edge, in powerful conditions. Lee is right, such a rail design (I liked Fish/flextail shapes) will draw up the face until it finds the natural energy of a long, high pocket line. Also the outside rail was more forgiving (less catch in chop), and I rarely ever dropped to the bottom unless I wanted to.
perhaps its also that people are pre-dispositioned (i think thats the word im lookin fer) to riding a certain type of board. for example, i ride a standard thruster shortboard decently, and i can ride a longboard no problemo (2+1 or single), but what i really love is my twin fin fish. in the classic style by larry mabile. i really feel like i connect with this board better than the others, since i like to go fast, and on a high line, and i can surf it casually if id like to. i have yet to ride a singlefin surfboard, but im REALLY itching to try one of those new channel islands ones, or the surf RX’s. or any modernized single for that matter. style comes above manuvers for me. i would also like to try a five fin bonzer… but i dont think it would be a very good board for me, since im not much of a back foot surfer. so anyways. try everything. see what you like, and stick with it i suppose.