discuss: quad v thruster quantified

I love my quad since we surf mushy waves a lot on the east coast. I love my thruster when the surf is actually good but thank god for my quad or I would not have as half as much fun surfing here! when I travel I leave the quads at home though of course

 

how did you get those pics of me from last weeks swell. weird

 

that's a very un-scientific approach...but how many shapers really know the physics behind what they're making? Surfboard science is still more trial and error than anything. As far as pivot, even a quad can turn on a dime, as long as you're using very upright fins...you just have to shift your weight to the tail during the turn. The center fin on a thruster gives more stability, at the cost of speed.

 

I mean, it may mean something different to various people. But When I say rail to rail, I am referring to a high volume of turns that completely transfer weight from one side to the other. For instance, to me, the "fish" as we know it, based on the rail volume, board volume and the wide tail do NOT go very well rail to rail, regardless of the fin setup. Many times, you will have a stall out effect or a "slide out" kind of deal. So yes, on a fish of any kind, with a more dramatic turning radius, yes you can perform a nice roundhouse figure 8 style cutback and go rail to rail. But if you look back in the 60's, 70's and "some" of the 80s, you will notice a lot of guys are "grabbing rail" to counteract the slide out and the volume of the board. Its like the only way to stabalize the board and make a quicker less dramatic turning radius is to grab the rail and force the issue. You see a lot of that on all the older boards. Single fins...

And this is also all relative to the board in question... So if you take your typical Channel Island's AM board... lets say a 6'1x18.5x2.25 or whatever and you take a head high reef break... You put your thurster fin setup on it and you paddle out. When you initiate that top turn (frontside) and you are cutting back to get into your figure 8 motion, that central pivot fin of the thruster helps you set that rail, with somewhat of a central balance in the back tail and get from one rail to the OTHER rail faster... That is the key to what I am saying, FASTER.... and when you get back towards the falling lip to finish your figure eight roundhouse, the pivot fin also helps you change directions QUICKLY and get back on the other rail....

I would assume, on the same board, on the same wave, with a quad fin setup, You could still accomplish the same turn, however it would have an exageratted bottom turn with a wider radius and your cutback would go further out on the face when you initiate it, and it would take you more distance and more time to get from your heel side rail at the peak of your top turn and all the way in the half-figure eight onto your toeside rail....

So, in a nutshell, any board can go "rail to rail" and mostly when I refer to "rail to rail" I am talking about someones style, the way they attack waves.... Rail to rail to me translates into shaper turns, and in modern days, more vertical ones, because taking a steep vertical angle with speed and flipping the tail around getting your other rail engaged is the fastest way to go rail to rail....

I am sure someone else could explain it better, or even give me a different idea of their "rail to rail" but its a broad term that I used for changing direction....

Occi is a "rail to rail" guy to me. His whole style is about smooth, fluid turns at sometimes radical angles, where other guys are barrel riders, or high flying aerialists.

 

And so everyone can form their own opinion, here is a link to the video...

This is Taylor Knox in Mainland Mexico on some sort of point break, riding a standard shortboard with a 5 fin bonzer setup... Make your own case. He is definitely making nice rail to rail turns, but for a professional surfer who we have all watched for years, who usually flips that tail right through the top and it releases into his landing spot as he whips the baord back under him. The same modern style that every single guy on the ASP has. They all release their tails through the top. Its the beginning of almost every trick in the book..

Does it, or does it not look like he is working SUPER hard to get through turns, sometimes having to lean over almost sideways and flail his arms back to get enough torque for the turn... I just watched it thinking, man I bet you his upper legs are gonna be plenty cramped after riding that board all day... Looks like its putting a lot of pressure on his legs and core, where usually they flip those shortboards around like its a piece of looseleaf with no fins on it.

http://bonzer5.com/film/contemporary/taylor-knox-5-fin-bonzer-mexico/

 

I like your spirit, Zach... Keep in mind that Bonzers are not just about the fin setups. They're about the combination of fin setups and bottom contours, which are very... VERY intricate and complicated. We're talking multiple concaves, channels and wings, along with a very fine tuned fin setup with specific cant and toe angles to work in conjunction with the bottom contours.

 

Yeah, no doubt. I can imagine what a mind **** it is trying to put together all of these variables to make the "perfect" craft. Thats why trial and error are so much fun...

An a side note, what ever happened to channel bottoms? I bought a sweet Peter Benjamin thurster with a 6 channel bottom on it. Deep, thick channels too. Glasses on fins. It was probably from the early 90s or late 80s from the design. I tooled around with it on the cliffs for a summer and it was SUPER fun...

Why don't we see any different bottom contour concepts like that these days?

 

I think channel bottoms are great but from what i understand are hard to do right. easier to put a single to double concave and they do pretty much the same thing

 

Yeah, I mean, I am no surf scientist, but I would think that the channel bottom could get your some serious speed when done properly, and wouldn't really have too much of an affect on turning. Maybe even help slow down the speed a bit with an abrupt direction change, but letting more water, pass by faster would make me think, speed speed speed.

And for you quad lovers, put channels all over the bottom of a speed quad and just take off to the racers.

And my shaper does some really interesting things and would always let me try out new boards he was making, but I have never seen him break out a channel bottom. God, the first Epoxy board he made almost a decade ago, we took it out on the cliffs and it was NOT cool. We were just running out of gas in the middle of a cutbacks and stuff. Fun to try new things though...

 

if you think that's what's happening in that picture, then you truly don't understand what is actually going on. taylor is basically sitting on his butt in the flat of the wave b/c of how hard he's turning that board. he wouldn't be able to do that turn on the thruster b/c the board would wash out & slide out. the big center fin & highly canted side fins (along w/ the rail) are what's allowing his to push the board so hard at such a high speed & actually hold his line to complete the natural arc of the turn. pushed that hard, a thruster would've washed out at the apex of the turn.

 

as i've said many, MANY times here before, bonzers don't lend themselves to flicky, slidey surfing. you have to actually use the rail. if sliding & flicking the board around is your thing, you're not going to like them.
& this is ONE video. there are dozens more out there...

like this one of rob machado in chile:
[video=vimeo;10661732]http://vimeo.com/10661732[/video]

 

or this one of knox & donovan frankenreiter from the film shelter:
[video=vimeo;10662321]http://vimeo.com/10662321[/video]

 

or the jones brothers:
[video=vimeo;10690939]http://vimeo.com/10690939[/video]


my point is, how can you judge a design from one video of one guy surfing it? sure, taylor knox is a known bonzer aficionado. but maybe that particular board wasn't suited to the wave very well or the center fin was positioned poorly (as LB mentioned, there's a lot going on w/ those boards & if you miss one element, you could make a magic board into a dud).

 

yes. taylor would've had to nurse that turn in order to avoid sliding out.

 

found some footage of taylor riding the green angel board. thought there'd be footage of that turn in particular in the video, but no such luck. stilll...

[video=youtube;rKNsCZV9CRI]https://www.youtube.com/watch?v=rKNsCZV9CRI[/video]

 

I did a 6 channel quad with glassed on fins a couple years ago. A guy bought it but I don't know who and haven't heard any feedback. But here's something I wrote on channel bottoms not too long ago, based on my experimentation with them over many years...

Like concaves, channel bottoms are designed, in theory, to direct water flow from nose to tail and in doing so, generate more drive and speed. They may also facilitate some ventilation or introduce some boundary layer turbulence, depending on their shape and length. But unlike concaves, channels do not alter rocker in any significant manner. Rather, channels are simply wedge shaped grooves shaped into the existing bottom of the board, whether it be flat, concave or (rarely) convex. The channels are most often toed in at the same angle as the rail fins, and may be uniform in width, or flared slightly from entry to exit. Typically 4 to 8 grooves are shaped into the bottom of the board through the tail section only, although some channel bottoms can begin to fade in at about the middle of the board. The longer and deeper the channels, the more their effects are felt. The channels may fade out behind the trailing fin, or may run right off the tail rails and out the tail block. The trailing fin most often sits on the peak created by the two centermost channels, and the rail fins may sit within a channel, or on the edge of a channel.

Most commonly used on boards for small to medium surf, channel bottoms are effective in creating more hold and drive, but at speed have a tendency to become tracky. To compensate for this trackiness would require accelerated rocker, smaller fins, or a narrower tail, all of which would effectively undo what small wave boards are designed to do – plane higher, flatter and faster in weak or small surf. Still, channels do provide excellent hold on steep sections, conserve speed through turns, and add heaps of drive, and so modest accommodations can be made: smaller fins and (because bottom channels, like rail channels, tend to stiffen a board) a touch more rocker are common combinations with this design.

 

...and on Bonzer bottoms, although with much less experimentation. One of the Campbell brothers... I think it was Malcom... read this and said I pretty much summed it up well.

Bonzer Bottoms: Around 1970, in Oxnard, California, two brothers, Malcolm and Duncan Campbell began to experiment with what they called the Bonzer. It may come as a surprise to many that the Bonzer was a predecessor to both the modern single to double concave and the three-finned thruster with toed and canted side fins. Years before either of those designs arose to popular status, the Campbell brothers were taking the short, wide-tailed, single fin boards of the era, and adding two more side fins, ahead of the center fin. The first Bonzers had flat-to-vee bottoms, but soon evolved into having a shallow single concave forward and two dramatically deep concaves through the tail. The single concave started in the entry rocker section of the board, and narrowed as it approached the wide point, where the double concaves began to fade in. The width of the double concaves did not run all the way out to the rail, but only gently flared from about 3½-4 inches wide along the stringer, to about 4½-5 inches wide through the tail. This gave the entire concave array an hourglass shape. Glassed onto the outside edges of the double concaves sat two long, low aspect, triangular shaped, highly canted fins (about 20 degrees), which essentially become an extension of the concave. These fins were commonly called “side runners.” Because the fins sat on the edge of the Bonzer concaves, they were toed in at the same angle as the concaves’ flared outer edges. The original three fin Bonzer’s triangular side runners had about a 10-inch base.

More than ten years later later, in the early 1980s, the Campbells introduced the Bonzer 5 Fin, which split the single side runners into two smaller, more elliptical or keel shaped fins, which were separated by a narrow channel, or “flute,” with the trailing edge of the outside lead fin slightly overlapping the leading edge of the inside trailing fin. Typically, the 5 Fin version used less cant on the side runners – about 18 degrees or less. The center fins were typically 6-7 inch center box fins. The side runners were about 4¾ and 5¼ inches along the base, with the rear set of fins being the larger of the two. This updated version met with great success for more than another ten years, when the addition of the elevated wing was introduced to the design. Part bottom design, part rail design, the wing began low on the rail, but as the tail slowly pulled in, the wing elevated off the bottom edge of the rail, becoming slightly fluted, ending around the trailing edge on the rear side runner. The wing added lift at low speed, bite and hold on steep sections, and pulled the tail template in when on a flatter, faster plane.

Although today’s Bonzers incorporate a number of finely tuned revision, and include a wide array of variations, the purpose of the design remains largely the same. By the Campbells’ own account, the Bonzer was, and remains, “a simple, low tech approach to getting high tech results.” The concaves manage the flow of water under the board very efficiently, channeling water out the back of the board in an effort to create greater speed and drive. The low aspect side runners dip in and out of the water easily, limiting turbulence and drag, while providing superior edge control, increased drive through turns, and blazing down-the-line speed. In addition, the designers contend, the side runners help harness wasted energy by deflecting water coming off the outside rail back, toward the tail, when the board is put on a rail. This rearward deflection water theoretically adds forward momentum to the board, helping the board hold speed through turns. The Campbell brothers contend that, overall, the design is geared toward minimizing entropy – loss of wasted energy that could potentially be conserved and changed into forward motion.

 

Average surfer on a bonzer perspective coming, get ready. Had 2. A 6'2" and a 6'6" in '88 and 89'. Both Campbell Bros. Maybe they work better in SoCal points but they always felt like I had to hold them too long on a turn and they always put me in the wrong place when I recovered. I surf crappy beachbreak. Never felt like they were on top of the water but dividing it. Destroyed a bunch of sessions for me. Guess they don't suit my timing? Rode an 8' Eaton bonzer with those lexan fins in a fun shape once in the '90s too. Meh. Knox can make any shape look great even if it is jinky, that's why we give him boards to play around with, right? So you will want to try one. I had to pay for mine. Bet he doesn't ride 'em when there is a paycheck on the line but I could never confirm that. Sorry to offend any of the Bonzer cult. I'll be waiting for the burning cross in my yard. I don't like Cher or ABBA either but I hear they have a huge following.

 

I get it. There are a lot of factors that contribute to that photo. Look at his enormous pivot fin. That thing looks like it dis-engaged about a milli-second before this photo was taken, so yeah, he was able to wind up some serious torque, which just released so his rails were already deep enough to avoid sliding out and he is going back up....

And I guess theoretically, yes a thruster would slide out more easily in a situation like that. But not always. I think you MIGHT actually have more speed and torque on standard shortboard thurster. Without that giant pivot fin dragging and having two less fins in general would lead me to believe you would have more speed and more torque built up just because of the dynamics of the fins....

SO its up for debate I guess. But your assesment of what is happening in that Knox photo is exactly what I said earlier in this post, that it seems that those fins just dig in more and allow him to get his body into crazy angle, almost exaggerated.

But normal thursters can dig plenty deep and get a lot of deep rail without sliding out. I think the worst slide out offenders would be the quad for sure. But the thruster fins don't dig as much as a 5 fin bonzer, especially with such a huge pivot fin... I think the same turning angles with your body can be achieved with both.

Guys do it all the time. Here are a couple making a similar turn on a thurster.





Depends on your preference. The only thing I gather about the bonzer setup that Knox rides in that video is that his board is moving slightly slower than normal, thus exaggerating all his moves.