Question for Fellow Hullers

As you know, finding the ultimate fin location on a hull can be a tedious exercise. May be you all can solve my dilema. My 7’5" Liddle ‘tweener is equipped with runners and a 8.5 flex fin. I found that setting the back of the fin 12.5 inches up from the tail give a smooth turn and nice a paddling feel. Easy to catch waves. The runners’ front edges line up with the leading edge of the flex fin. Now the problem: I moved the fins up to 13.5 inches from the tail and found that the planing speed was drastically reduced, like kelp grabbing the fins. I could barely drop-in on even very steep waves. Yet once I put the buggah on edge, it just flew! It turned easier and with more acceleration than at the setting closer to the tail. Have any of you hullers experienced this? The planing problem suddenly goes away once the fins are back at 12.5 inches. I’m asking this 'cause its a real pain in the ass to move the fins around and still surf (I keep the fins tight in the box so I’ve got to come into the beach every time to make adjustments). I’ve talked with Greg Liddle, and he is stumped too. Mahlo, Newbs

As you know, finding the ultimate fin location on a hull can be a tedious > exercise. May be you all can solve my dilema. My 7’5" Liddle ‘tweener > is equipped with runners and a 8.5 flex fin. I found that setting the back > of the fin 12.5 inches up from the tail give a smooth turn and nice a > paddling feel. Easy to catch waves. The runners’ front edges line up with > the leading edge of the flex fin.>>> Now the problem: I moved the fins up to 13.5 inches from the tail and > found that the planing speed was drastically reduced, like kelp grabbing > the fins. I could barely drop-in on even very steep waves. Yet once I put > the buggah on edge, it just flew! It turned easier and with more > acceleration than at the setting closer to the tail. Have any of you > hullers experienced this?>>> The planing problem suddenly goes away once the fins are back at 12.5 > inches. I’m asking this 'cause its a real pain in the ass to move the fins > around and still surf (I keep the fins tight in the box so I’ve got to > come into the beach every time to make adjustments). I’ve talked with Greg > Liddle, and he is stumped too.>>> Mahlo,>>> Newbs IMHO, I reckon the easiest thing to do is try another Liddle flex fin… slightly taller (an inch or so), with proportionally more rake, placed in the forward (13.5") position. See what Greg says about that… Dale

IMHO, I reckon the easiest thing to do is try another Liddle flex fin… > slightly taller (an inch or so), with proportionally more rake, placed in > the forward (13.5") position. See what Greg says about that… Yo Dale: I tried a 9.5er but it seemed worse or at any rate was the same…I’m going to push it up to the top of the box and work it back down but it’ll take several sessions to do. I thought some other opinions might speed the process. The feel of the turn is so good that I might just live with the ultra late take offs. Curious thing is, at the setting, when you do put it on edge, it draws you into the turn or pulls you up the face a lot like my mat… Newbs

Yo Dale:>>> I tried a 9.5er but it seemed worse or at any rate was the same…I’m > going to push it up to the top of the box and work it back down but it’ll > take several sessions to do. I thought some other opinions might speed the > process. The feel of the turn is so good that I might just live with the > ultra late take offs. Curious thing is, at the setting, when you do put it > on edge, it draws you into the turn or pulls you up the face a lot like my > mat…>>> Newbs … have you tried the 9.5" fin in the 13.5" forward position without the sidebites?

As you know, finding the ultimate fin location on a hull can be a tedious > exercise. May be you all can solve my dilema. My 7’5" Liddle ‘tweener > is equipped with runners and a 8.5 flex fin. I found that setting the back > of the fin 12.5 inches up from the tail give a smooth turn and nice a > paddling feel. Easy to catch waves. The runners’ front edges line up with > the leading edge of the flex fin.>>> Now the problem: I moved the fins up to 13.5 inches from the tail and > found that the planing speed was drastically reduced, like kelp grabbing > the fins. I could barely drop-in on even very steep waves. Yet once I put > the buggah on edge, it just flew! It turned easier and with more > acceleration than at the setting closer to the tail. Have any of you > hullers experienced this?>>> The planing problem suddenly goes away once the fins are back at 12.5 > inches. I’m asking this 'cause its a real pain in the ass to move the fins > around and still surf (I keep the fins tight in the box so I’ve got to > come into the beach every time to make adjustments). I’ve talked with Greg > Liddle, and he is stumped too.>>> Mahlo,>>> Newbs Newbs- have you tried an 8" fin?could be all that area that far up is pushing the hull down too much, not allowing it to function like it should… just a thought. Matt

Newbs- have you tried an 8" fin?could be all that area that far up is > pushing the hull down too much, not allowing it to function like it > should… just a thought. Matt That’s three votes for too much fin (Greg’s thought too). I’m going to try a 9.5 with no runners and see. Thanks Matt and Dale… Newbs

Newbs… I’m thinking that with the center fin up, perhaps the water flowing around the main fin is getting crossed up or compressed with water flowing around the side bites as you trim. When turning, the added water flow velocity through the fins overrides the turbulence. If it doesn’t seem to have as much drag when the main fin is back, I doubt if this issue is related to fin size alone. My vote is turbulence in the fin cluster area and agree that removing the side bites and installing a bigger center fin will eliminate the problem. A smaller (6" +/-) center moved way back may really surprise you if you want to maintain the advantages of side bites on a wide tail. I’ve ridden a 4 3/4" hanging over the back of the box on a 9’6" Eaton fun gun and it made a huge difference in small to medium sized waves.

Yo Dale:>>> I tried a 9.5er but it seemed worse or at any rate was the same…I’m > going to push it up to the top of the box and work it back down but it’ll > take several sessions to do. I thought some other opinions might speed the > process. The feel of the turn is so good that I might just live with the > ultra late take offs. Curious thing is, at the setting, when you do put it > on edge, it draws you into the turn or pulls you up the face a lot like my > mat…>>> Newbs o.k. I`ll bite the “bait”: why does a Greg Liddle hulled surfboard draw you into a turn and pull you up the face of a wave like an air mat?? This ought to be a good one…!!!

o.k. I`ll bite the “bait”: why does a Greg Liddle hulled > surfboard draw you into a turn and pull you up the face of a wave like an > air mat?? This ought to be a good one…!!! If I knew, I wouldn’t have asked the question, would I…

I’ve kept the relationship between the runners and the fin (leading edges even) the same regardless of the distance from the tailblock. So, I don’t think the amount of turbulence is going to change from one position to the next (the runners are parallel to the stringer so moving them up does not bring them closer to the center fin). The hull doen’t work like it is supposed to if the fin is too far back, so a small fin near the tailblock is not the answer (for me anyway). The runners don’t really work like “side bites” or outside fin thruster clusters either. For me, the runners reduce the tendancy for the tail to spin if you put too much weight behind the center of the board. In effect, they make the board easier to cut back or ride backside without sacrificing the rail turn on your forehand. When I’ve tried to vary the relationship with the leading edges of the fins, the result is a board that neither rail turns or pivot turns. More proof that the type and placement of fins on a surfboard affect the performance more than any other feature. Thanks for the input, John. Newbs

I’ve kept the relationship between the runners and the fin (leading edges > even) the same regardless of the distance from the tailblock. So, I don’t > think the amount of turbulence is going to change from one position to the > next (the runners are parallel to the stringer so moving them up does not > bring them closer to the center fin).>>> The hull doen’t work like it is supposed to if the fin is too far back, so > a small fin near the tailblock is not the answer (for me anyway). The > runners don’t really work like “side bites” or outside fin > thruster clusters either. For me, the runners reduce the tendancy for the > tail to spin if you put too much weight behind the center of the board. In > effect, they make the board easier to cut back or ride backside without > sacrificing the rail turn on your forehand.>>> When I’ve tried to vary the relationship with the leading edges of the > fins, the result is a board that neither rail turns or pivot turns. More > proof that the type and placement of fins on a surfboard affect the > performance more than any other feature. Thanks for the input, John.>>> Newbs hey Newbs! you may find the 9.5 might be too deep to allow full bank over.if so, try a 9 with more base.I recently sent Greg such a template, which is the one true ames currently sells as the l-flex,which of course is an earlier Liddle template.the current ones (g4’s)have less base, which is great for 2+1 set up and works in most single setups but Kp and I have found the wider base to provide more drive in the single situation.isn’t fine tuning fun?! Matt

isn’t > fine tuning fun?! Matt Yeah. What I need is a week at an empty point break with head-high surf. Know any place like that??? Newbalonie

I think it may have something to do with the thin rail on a hull type board set deep and the water coming up the face. Rather than a vertical turn up the face, your board is more parallel to the face as you glide through a turn and sort of get pulled up the face sideways. You can then bank it on the outside rail as you come off the top but again, more parallel. I know that doesn’t equate directly to the mat situation rail-wise, and that’s not to say a hull board can’t do a roundhouse. It does explain why a hull type board works best in a Malibu/Rincon type of wave. I also know that by modern contest oriented manuvers, this more parallel style of riding will not score as many points with the judges. I believe that water moving up the face will pull the mat into a parallel position right in the slot on a steeper wave in a similar fashion even if the two surfcraft aren’t similar in shape at all.

Well, that was pretty rude of me wasn’t it…As for why a mat does what it does, you’d have to ask Mr. Solomonson. A hull accelerates because you use the rail and just the tip of the fin to turn. There isn’t a whole lot of stuff dragging through the water. The radius of the turn is controlled by the rocker of the portion of the rail in the water and by how long you can keep in on edge with your body. Normally, the turn radius is very predictable and easy to control. Oh yes, you must stand in the middle or just ahead of the mid-point of the board to get the full effect. There is something about the curve of the rail and bottom that provides lift or “pull” like a jib allows a sailboat to point into the wind. The physics is beyond me or even Mr. Wizard Kevin. You can feel it as strongly as the squirt or acceleration through a turn on a thruster. With my fin too far up, the fin and rail are combining in a way that results in a tighter radius turn than normal. The board pulls in the direction of the turn like a car with bad tires. If you stand in trim the board pulls in the direction of the inside rail. It’s a good thing because, for me and the waves I usually surf, the hull’s natural radius is too long. If I can overcome the planing problem, I will have found the optimum placement for my fin(s). Is that “good” enough for ya? Newbs

…PNW …Coming this week…Shhhhh…>>> Yeah. What I need is a week at an empty point break with head-high surf. > Know any place like that???>>> Newbalonie

As one buries the rail in a turn water flows around the bottom and rail. The wave “grabs” the hull so to speak. If the wave being surfed is a point wave it will have both a lateral component, down the point, as well as a vertical component, lifting and breaking. Since the rail is buried and the wave has hold of it, the hull is lifted up the face of the wave and carried along at the same time. This doesn’t work with a flat bottomed surfboard with down rails and edge. Surfing a board with little or no displacement hull and flat or concave bottom is like driving a motor boat where the surfer is the motor. Because of the flats and edges, there is nowhere for the water to “grab”. Water runs or “sheets” off these surfaces. These boards IMHO seem to resist being turned up to a certain point, then turn all at once.

Newbs, I’m going to be receiving my Liddle Island template in a few days…it is a 7’8". Have you surfed the 'tweener as a single fin yet? Wonder if there would be a difference in Islande template and the 'tweener template as far as fin set-up. Alex>>> As you know, finding the ultimate fin location on a hull can be a tedious > exercise. May be you all can solve my dilema. My 7’5" Liddle ‘tweener > is equipped with runners and a 8.5 flex fin. I found that setting the back > of the fin 12.5 inches up from the tail give a smooth turn and nice a > paddling feel. Easy to catch waves. The runners’ front edges line up with > the leading edge of the flex fin.>>> Now the problem: I moved the fins up to 13.5 inches from the tail and > found that the planing speed was drastically reduced, like kelp grabbing > the fins. I could barely drop-in on even very steep waves. Yet once I put > the buggah on edge, it just flew! It turned easier and with more > acceleration than at the setting closer to the tail. Have any of you > hullers experienced this?>>> The planing problem suddenly goes away once the fins are back at 12.5 > inches. I’m asking this 'cause its a real pain in the ass to move the fins > around and still surf (I keep the fins tight in the box so I’ve got to > come into the beach every time to make adjustments). I’ve talked with Greg > Liddle, and he is stumped too.>>> Mahlo,>>> Newbs

In similarity to a displacement hulled surfboard, a mats turning radius is governed by the rocker and torque of the rails contact with the water, except that a surfmats rocker/torque are variable, continually being shaped by the curve and textures of the wave and modified by the rider. As with a displacement hull design, a mats turning radius is predictable, involving a minimum of effort to control, achieved through a balanced riding position, very slightly forward of mid-point. There are a number of reasons why a surfmat accelerates through a turn… reduced wetted area, constant adaptability of the mats running surface and rail contours to the waves surface and increases/decreases in its internal pressure via the riders grip, resulting in changes to its template, foil and rocker. As a surfmat rolls into a turn, the basic contact area between the waters surface and the rail contour remains substantial, not unlike the behavior of a radial tires "footprint" in cornering. Also, as a surfmat is banked farther over at speed, the more centrifical force contributes to generating acceleration out of the turns arc. On longer-walled waves, hulls and mats also share similar, sensations of acceleration, i.e. being “pulled and drawn” down the line, which are especially noticeable when approaching critical, inward-wrapping sections. Both designs tend to seek the fastest natural lines across a wave with a minimum of handling. Their unique, functional performance is optimized through a harmonious blend of planing, displacement and sensitive rider co-operation… One design being created through the hands of a skilled shaper… the other largely by the wave itself. Dale

Newbs,>>> I’m going to be receiving my Liddle Island template in a few days…it is > a 7’8". Have you surfed the 'tweener as a single fin yet? Wonder if > there would be a difference in Islande template and the 'tweener template > as far as fin set-up.>>> Alex I started my board as a single to fine tune the placement, then added the runners. The old hulls I used to ride were all singles…The board worked fine as a single. In fact, the runners do not affect the rail turn feel. They, to me anyway, keep the tail from spinning if you stand too far back or if you want to pivot turn for some reason (I use the tail slide for bringing the board back off the top as it is quicker than railing it around). Unfortunately, you’ll have to find your own sweetspot as it is affected by not just the shape and length of the board, but also by the waves you surf and the way you surf. Newbs.

Yeah. What I need is a week at an empty point break with head-high surf. > Know any place like that???>>> Newbalonie thirty years ago, sure!now?head high, point break not too much of a problem, but empty??where’s the time machine???by the way have you got that thing tuned in yet?if so, what did you use? Matt