Just finished shaping #009. I’m looking for some recommendations on quad fin placement.
Board is 6’1" x 14 7/8"N x 20 1/2" x 15 1/2"T x 2 5/8". Pretty wide diamond tail, 1/8" single concave through the belly of the board. Destined for waist-head high beach break. I am 5’10", 195lbs. It’s a PU US Blank going to be glassed with RR Kwik Kick.
Current placement of the dots is:
Front fins: 11.25" from tail, 1.25" off rail, 1/4" toe-in.
Rear fins: 5 5/8" from tail, 2" off rail. 3/16" toe in.
I am looking for this board to be well balanced: good drive and good pivot in the pocket. Don’t want it to be tracky. I have found McKee setups tracky in smaller waves, and with the rear fins too far up/out and close to the fronts, the board lacks drive and spins out unpredictably. So I am looking for a decent balance between the two extremes.
Any suggestions (or a pat on the back saying your numbers look fine) would be greatly appreciated. I am using pro-boxes so I can get some fore/aft adjustment.
Ah the Roberts White Diamond fever is hitting sways hard! I jumped and had to see what it was all about as well. Made a 6'2" x 20" x 2 5/8" and it has completely blown my mind. The design is a session saver. If you followed the rocker theory with your outline you should be equally stoked. Low entry with shortboard tail rocker equals magic!
I understand what your saying about the McKee formula. However I always found that it was pretty close and could be compensated by changing the fins. I found several rough constants that I'd apply to fin placement with the design. Moving the backs closer to the fronts made for a more pivoting feeling. Moving them away gave the opposite.
Moving the rears closer to the centerline gave more of a thruster feel. Board rode more off the front fins. Moving the rears closer to the rail made the board track on the rail. Same with fin foils, double foiled rears loose. Single foils more bite.
The toe of the rears would also affect the ride feel. Less toe more tracking, more toe equals more pivot.
With all that taken into account I'd say just by looking at the fin placement without knowing the rocker that that particular layout is going to make a loose pivoty ride. You've moved all the fins forward and the rears closer to the fronts and have moved the fronts away from the rail. That in conjunction with the reduced rail line of the diamond will make the board turn a short circle. Which for that design is what it's supposed to do. It just depends on what you are designing it to do. I'd guess that you might have to overfin the board to get it to project through turns.
For me I'd be a bit more conservative and move the rears somewhere around 1 3/4" from the rail and put the fronts at 1" off the rail. With those wide tails it offers more control. Also I never set any of my rears with more than 1/8" of toe 3/16" sounds a bit much. It will be interesting to see how it rides with that much toe in the rears. I'd like to hear how you like it.
With the Probox you should be able to dial in the front to back to get to ride like you want without having to try too many fin templates.
I found that the Futures FT1 fronts with the 3 1/4" trailer as a thruster worked best for me. Those wide tails need a big fin on the rail.
So yes good job! Shape looks clean. Develop your own theories and have fun with it!
Thanks DMP. Good stuff there. The rocker is about 4.5" in the nose and 2" in the tail. Funny because I really didn’t know much about the White Diamond until you brought it up. I just figured the diamond tail would complement the quad well to provide some centerline stability, wider tail block would give me some drive, and the shorter rail line would shorten up the turning radius. But now that I look at the White Diamond, I would say that’s pretty much what I’ve done.
As for fins, my two best quad sets are the Hynson Quads (big area fins with not alot of rake) and the PC5 Q (medium sized with more rake than the Hynsons). I have found that the Hynsons work better on wide tails and the PC5s work better on narrower tails. This board is wide-ish so my first instinct is to put the Hynsons on. I have always preferred single-foiled (or 80/20) rears as they seem looser. When I dried double-foiled rears (stretch) the board seemed kind of sluggish and locked in going straight.
set your fronts where you have them, 1 1/4" off the rail, toed how you want... set the rears 1 1/4" off the rail parrallel to the fronts so that the front edge of the rear fin is 1" from the rear edge of the front fins... parrallel and 1" apart is the bees knees or so i've heard from a few reliable sources. make the fins work together is the theory... i have a quad (Proboxes) with a setup that is similar to the one that you proposed above. liked it. but had some issues backside. i just dropped in 2 more boxes in the positions that i described and one more for a thruster setup. just sanded the boxes down yesterday and hope to get it in the water today. see how it goes.
I have done a few boards with front and rears 1 1/4" off the rail and pretty close to each other. My impression is that it worked “almost too efficiently”. IE, it was very loose and fast and pivoty. But if you pushed it hard on a cutback or during a whitewater rebound on a cutback, the tail would release in unpredictable ways. Nonetheless, please post up how your surf went today with the new setup.
i definitely will... i was wondering if the new setup would act like you say "very loose and fast and pivoty. But if you pushed it hard on a cutback or during a whitewater rebound on a cutback, the tail would release in unpredictable ways" ... because, even with the McKee-ish setup with the cluster moved tight together, i could sometimes overpower it in hard turns and spin out... hmmm i wonder if with the more effecient setup if i could afford to use bigger fins??? fun experimenting tho for sure
Anyway, for what it’s worth, I measured the distance between the two back fin dots and it’s 8" on the nose. That’s almost an inch wider than what McKee recommends for this board length/tail width (not that I want to do McKee on this one).
If anything, I am tempted to move the back fins back a little bit.
Perhaps a stupid question, but does anyone have a recommendation on how to remove pencil marks from a blank?
Big fins, wide tail, quad, definitely super fast accelleration.
I glassed the bottom today and after much deliberation, moved the rears 3/4" back to about 5" from tail. This gives about an inch or so space from the front of the rear fins to the rear of the fronts. Still kept the rears 2" from the rail, so now the rears are about 7 1/4" apart…
Here are some pics of the new layout. You can see the old dots just outside and forward the new ones. For whatever reason, I just like the look and feel of the new layout better. Hopefully my instinct is right.
I was thinking of using the Hynson Quad fins on this one, because they are the biggest ones I’ve got. But I am also thinking of trying out a pair of the Rusty Quad fins (green ones), because they look to be a nice happy medium between the Hynsons and the PC 5Qs.
Supposed to be good waves Wednesday, so I am going to try to hustle this one through. UPS man just delivered a new Milwaukee sander/polisher (thanks Ebay) so I am stoked to play with two new toys.
Just finished shaping #009. I'm looking for some recommendations on quad fin placement.
Board is 6'1" x 14 7/8"N x 20 1/2" x 15 1/2"T x 2 5/8". Pretty wide diamond tail, 1/8" single concave through the belly of the board. Destined for waist-head high beach break. I am 5'10", 195lbs. It's a PU US Blank going to be glassed with RR Kwik Kick.
Current placement of the dots is:
Front fins: 11.25" from tail, 1.25" off rail, 1/4" toe-in.
Rear fins: 5 5/8" from tail, 2" off rail. 3/16" toe in.
I am looking for this board to be well balanced: good drive and good pivot in the pocket. Don't want it to be tracky. I have found McKee setups tracky in smaller waves, and with the rear fins too far up/out and close to the fronts, the board lacks drive and spins out unpredictably. So I am looking for a decent balance between the two extremes.
Any suggestions (or a pat on the back saying your numbers look fine) would be greatly appreciated. I am using pro-boxes so I can get some fore/aft adjustment.
I have done a few boards with front and rears 1 1/4" off the rail and pretty close to each other. My impression is that it worked "almost too efficiently". IE, it was very loose and fast and pivoty. But if you pushed it hard on a cutback or during a whitewater rebound on a cutback, the tail would release in unpredictable ways. Nonetheless, please post up how your surf went today with the new setup.
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Spread the cluster of fins apart, your board is over taking the fins in this situation. Mahalo
what's the deal with that white diamond Larry? what's it getting under the hood?
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Hi Chris, This board was brought in to change out FCS to ProBox first. Then the customer wanted to go to Quad from Thruster. All this with the opt to go back to the original Thruster set-up by Roberts. Mahalo,Larry
Thanks for chiming in here. I have done several boards with your recommendations and they are all very loose and fast. I have also spread the cluster out to increase drive/stability, which works. Still, I find sometimes this setup gets a little weird finishing tight radius turns and in whitewater rebounds. It can slide out but not with any predictability.
I have seen three schools of thought on quad placement:
What you like: 11-12" front fins; 1.25 off rail; 6-7" rear fins; 1.25 off rail.
Then there is the McKee stuff, which has the fronts at 11-11.5" ish and also 1.25" off rail; with the rears further back and closer together: in the range of 5-5.5" from the tail and probably 3" from the rail.
Then there is the setup I am seeing on some of the big guys (Rusty, Lost, Roberts, Von Sol) where the front fins look in the 11-11.5 range, and the rears are somethere between your recommendations and the McKee recommentations off the tail, and about 2" off the rail (rusty describes this in detail in his blog on surfline).
So anyway, I was looking to find a happy medium between your setup (very loose and fast) and the McKee setup (very drivey but a bit tracky for me). This led me to option 3 above.
But before I take router to foam, I would love to know if this “compromise” position has any potential as a blend of looseness, drive, and a bit more predictability, or if I am making a big mistake.
