Hi Swaylockers,
I have never been a big fan of quad set ups because I feel that I lose too much pivot whilst surfing, but I do like the idea of the extra drive that it can give.
Its a fairly well known concept that if you place the rear fins closer to the stringer you can maintain more pivot.ques
My question is, how far can I push this concept before I get negative effects? And what negative effects would occur if I went too far
The answer to the question you didn’t ask in the first paragraph is the Griffin 5 fin.
I have read about griffins 5 fin placement and its certainly interesting stuff. But on the board in question there is no space to even consider that due to a deep angular swallowtail.
So its got to be a quad, I want to go as close to the stringer as possible but I dont want to ruin the board by doing something that won’t work.
If I knew what would happen to the board if I went really close to the stringer I could make a decision how close to go.
Gotcha…
I dunno the answer but, I have never seen McKee setup quad on a wide fishy tail…
Quads on wider tailed fishy boards tend to be right on the rail.
What about a twinzer setup?
I definitely don’t want to go down the road of a twinzer set up, definitely too down the line for me, I want to be able to surf as much top to bottom as possible so I will need good pivot.
Ron, Thanks, thats gold! It will certainly come in useful! Thanks for taking the time to post the link.
If anyone can chime in on how close together would be too much, and what negatives could be expected by doing so would really help me understand the whole quad placement logic
I think you have the theory a bit backwards - Thrusters drive quads skate - a quad is much like a twin fin - having the fins on the rails means they typically want to move in a pivoting fashion. Throwing a center fin in the mix is like adding the third leg to a tripod: it locks down the tail more and therefore eliminates some pivot and creates more drive.
What I think you’re experiencing isn’t actually a loss of pivot so much as not being used to having so much traction on your rails. At higher speeds too I find quads harder to throw a sharp turn with since they’re so loose it’s like slamming on the brakes sometimes. The three fins of the thruster allow it to change direction easier in a more gradual, proportional sense while the quad just lets you throw it sideways and wait for the fins to grab. One thing you might want to try to losen it up is putting the smaller fins in the back. That gives it a much skatier feel than having the larger fins in the back which tends to be more drivey. Also, the difference in size from front to back will (how drastic the change is) will dictate much of this
Mckee will work on a wider tail, but it won’t be the Mckee you’re used to seeing. Their formula places the rear fins based on tail width at 12" up from the tail. If you have a wide enough tail, the fins will still be closer to the rails than the stringer - I just put some on my batboard using that formula and I was kinda surprised how far from the stringer the fins ended up being.
Just remember if you have a wide fishy tail, you need the fins closer to the rail for them to perform properly. If you’ve ever seen a super wide fish with a thruster setup you can tell right off the back that the fins just don’t work for the shape. If you place them too close to the stringer you’re going to wind up with a board that doesn’t want to turn no matter how hard you crank it.
If you want closer to the rails I’d go mckee since they’ll give you a formula that works for your tail width - but even then… if the tail is over 14" I would ALWAYS place the fins on the rail. A fat ass needs strong legs if you know what I mean.
To give you an idea on how the mckee setup will work on a wider tail take a look at this. You’ll notice the fins aren’t nearly as close to the stringer as other boards using the mckee formula because of how wide my tail is at the 12" mark. I used this for my rear fin placement, then measured the tail from point to point (at the very rear), found that spot on the nose and toed my fins towards that point. Once I put them in and looked at them from the nose it was pretty clear why the formula placed them where they are.
Thanks guys, certainly some stuff to think about there.
If anyones interested the board is a 5 2 stub/diamond nose shaped down from a 6 4 that I was making. Unfortunately I sanded into a big cluster of bubbles in the blank in the nose area. Rather than try to spend ages trying to fix it I just tore up the rulebook and decided to shape myself something a bit different.
5 2 x 191/2 x 2 1/2
Swallow vector tail with slight hip at the front fins, Tail 16 inches. Loads of volume back at the tail to hopefully allow for being able to have weight back while paddling for waves (much easier pop up for smoother takeoffs) hopefully the vector swallow should still allow me to submerge enough rail at the tail for turning.
1 1/2 tail rocker 3 inches nose rocker. Channel concave to get up snd planing early rather than displacement. Raised stringer area at tail area.
Well thats the theory, theres only one way to find out if it will work or not
Don’t tease us, post a pic 
Whatever you choose, definitely post your results. I am curious what would work. I experimented with some longer boards, i.e. 6’3 and 6’9 putting rear fins closer to the stringer, and didn’t like it. Too many variables to really compare, but I have avoided close to the stringer, so would be neat to see it work.
For a bunch of my boards of similar size I have the rear fins close to the rail, i.e.( 1 1/8" , I think that sounds right?) I make them want to turn, by either putting in double foiled fins in the back, smaller more pivoty fins, or a fin in the center like sorta same idea as Chrisp mentioned. For what its worth, I have a 5’8 swallow tail, and depending on the surf, I get it to turn, with just big front fins, i.e. twin, or as mentioned above. Just takes a bunch of experimenting.
Thanks for chipping in melikefish, can you elaborate on why you didn’t like the board that you made with the fins closer together?
I’ll get a photo organised when its finished, its a bit of an ugly duckling but some of you might find it interesting.
Both boards with the configuration, were not the best shapes in the world… But, I could still get them surfing ok, with either a single fin or thruster setup.
Solely as a quad with that placement didn’t work for these boards. In some regards the tail felt more locked up. But this is comparing apples and oranges, with regards to your board shape and size.
I didn’t try to make it work on any other boards, because I had the quads on the rail dialed in for my other boards. The hard part is really getting any clue which fins work right for which board. I was using a Josh Mulcoy quad setup that was motivated from wakeboards( I think?) Those fins worked great on a 5’11 firewire unibrow I had at some point. Anymore back fin and the tail started to be harder to turn. I recently made a 6’ x 18 3/4"x 2 7/8" with super thin rails and squash tail. The mulcoy fins din’t lock the tail in enough, and it needed a little more. I had some future qd2 4.0’s put those in, and found I had a really good balance of speed, and maneuvarability.
On the other side, I don’t notice the extreme sensitivity to fins with my thruster setups. Maybe it is just because I surf quads more, and expect more from them.
Main point is that it takes me a bit of experimenting to get my four fin boards to work right( wide tail, fins on the rail), but they always end up working.
Basically, what Shushka said:)
Fins in and board tested.
I thought that with the quite straight rail outline it might have been a point and shoot board but it turns out to be the opposite.
Its way too squirrely, Im sure that it can be rectified by moving the fins because the general feel of the board was good, no sliding out, but just hyper reactive.
Perhaps Ill have to try a fit a rear fin in, or spread the fin cluster or move the rear fins further to the stringer, which I didn’t do before as I was worried that the board would be difficult to turn.
Shuska,.
I understand exactly what you were telling me now.
Thanks for the feedback on the configuration. Where did you end up placing the rear boxes?
I dont have the board with me to double check but I think i put them 3 inches in from the rail and 4 inches up from the tail.
The front fins as i recall were 10.75 inches up from the tail and 1 1/4 in from the rail.
Cant was 5 1/2 degrees for the front fins and 3 degrees for the rear fins.
Front fins were toed in 3 inches off the nose, rear fins toed in 1 1 1/2 off the nose .
Remember that the board is only a 5 2
If I was to start again with the fin placement (which I am planning on doing) I think I will probably spread the cluster a bit more. Fins further up and further back. And also bring the rear fins into the stringer a bit more.
I think the board really has potential so Im going to keep it as a work in progress.
You need a lot of fin area to control all that real estate. If you’re big enough to have originally been aiming at a 6-4 x 19.5 then you’re more than big enough to manhandle a 5-2 quad with the fins out at the rail. Preferably single-foiled rears, for that matter.
A twinzer with a big-ass twin fin as the main would be quicker off the line and more pivoty than most quads but (in my experience with them) they tend to max out on the top end. I dunno where you got the idea they are more down the line than any quad or thruster. You just can’t run the cants at 4 or 5*. Mattison runs a 5.5" MR-sized twin fin for his twinzers at a 7* cant, and I see him and his riders doing snaps with them on a regular basis.
You cut 14" of length off that 6-4, and it was all rocker and curve. Then you flattened your stringer line through the middle and added even more lift with the concaves. You may have tweaked the nose tip to get your 3" but everything else is probably super flat, and at 19.5" you’re 1" wider than the widest and most conventional shape Tomo does and almost 2" wider than most of his other designs. So what you’re doing is prolly more similar to a narrowed Simmons, which are not known for surfing top-to-bottom.
Tomo’s program involves taking a Slater-type board (with rocker) and chopping 8-10" off it, and then swimming the boards into the wave, then overpowering the template and rocker due to the low volume (23 liters @ 5’2" lengths) . I don’t see that happening with your width or with what I’m guessing you left in the foil and thickness from that 6-4 you started with.
Like they said above, I think you need to put your fins out at the rail and surf this shape for what it is rather than for what it isn’t. Your board will be fast but I don’t think any fin combo will make that template/rocker surf top-to-bottom.
Current setup on my single & dub wing Convertibles.
50/50 foil rear quads = loosest
Flat inside foil rear quads = driviest
Assymetrical Foils of 80/20, 70/30 = varying degrees of the aforementioned.
Depending upon fin choice(s) the boards ride equally well as twin, tri, quad, twin/keel or quad/keel.
