I’ve been following and posting on the History of Belly thread, and this came up. But i think it’s worthy of a thread of its own.
I’m listening to the hull vets explaining how they adjust their fin placement by 1/4" or so, and how that can yield performance benefits. GL or someone here advised i start at 12" from tail (trailing edge of fin) and work up in 1/2" increments up to 14" and back until you find the spot. And i’ve pretty much been doing that - but i don’t know for sure if i’ve ever really found the optimum positioning. So far the board has worked in nearly all the positions i’ve had it in. (However know that i’ve only had my hull in two sessions on a right proper point ) Will it be THAT evident? In all the positions so far she comes up on a rail easily, and the speed is good.
so typically how many waves do you ride or how much time to you try the fin at any one position until you adjust the fin trying to find the best position? Once you find that position, is that it? or do you keep adjusting everytime the wave changes or you change waves? Some waves i’ll ride further back on the board, and others i’ll scoot up - or on the same wave moving around. Where i surf there is an average rise/fall of 16ft tides every six hrs, so quite literally the waves change before your eyes. as mentioned before, i keep a washer on a cord round my neck, so adjusts aren’t really all that difficult. (but that o’fishl fin box system i see on Dennis’ site would be the cats’ ass i think)
I usually like to get in at least a half dozen waves before I make any changes… unless you get a “whoa! what the *&%#! was that!?” moment.
So I can usually get it dialed in during one good session.
I know it hurts, but try to sacrafice a few rides to just doing the same move as consistently as you can to really feel the difference. By the end of the session you’ll have it wired.
If the board paddles straight (no tail wagging) and doesn’t feel like there is seaweed on the fin when you take off then it is not too far forward.
If the rail engages easily and predictably and you have drive out of the turn then it is not too far back.
The rest is kinda personal preference. The farther the fin is back from the optimum spot, the more walking you can do as the sweet spot gets a little bigger. But you will sacrifice drive and that special “down the line pull” feeling.
My experience has been that the optimum fin location results in a really narrow sweetspot. But that spot is the optimum trim location as well as the turning sweet spot. You will know because as soon as your center of gravity is on it, the board will just fly! As you move forward or back the board just doesn’t respond as well.
When you have more powerful surf (bigger or hollower) I move the fin back to widen the sweetspot and make the board more user friendly (a plus in tricky conditions). You need less rail/fin interaction when the surf is powerfull enough to push the board.
After riding a thruster the past week or two, I have reaffirmed my opinion that hulls are all about the feel. Where you can put the board on a wave or the manouvers you can pull are really inconsequential to the regular hull rider (the Malloy’s and Gamboa don’t count because they really aren’t human)…it is all about that feedback you get through your feet. And that is what keeps me coming back to this quirky design.
Neither of my boards with fin boxes are hulls, but I did spend time dialing in their fin positions this summer. I’m slower than the rest of you. I started with the fin centered in the box and would surf on it for a session, then tweak it when I got home for the next session. I stayed committed to riding the same board for a week or so and made pretty small changes to the position each time. 1/2" the first position change, then 1/4" or so afterward.
I couldn’t believe how big a difference such subtle changes would make. Some fin positions turned the board into a complete dog… 1/2" later… something would just ‘pop’ and the thing became magical. Especially on my egg… it’s a 7’4" rounded-pin egg with a 9" velzy flex fin in it… The fin position turned out to be extremely important on that board.
For the 7’4" I rode it in a variety of conditions and liked the one position for everything. For my 6’2" single, I’m still playing with positioning in different surf… but I’ve been thinking maybe the position should stay the same, but I should get a slightly different fin for bigger surf… Dunno. It’s fun to experiment with.
I have a suspicion that the 12’’ to 14’’ up, was referring to the leading edge of the fin. A fin with a 6’’ base would have the leading edge up a bit too far, from my experience.
Rightly or wrongly, it has been a Liddle tradition to measure the placement from the back of the fin. On Liddle boards, the fins can easily be up 14 inches (measured from the trailing edge). My optimum spots have ranged from 12.75 inches to 13.5 inches depending on the fin and board combination.
Remember that the finboxes on these boards are generally around 9" up from the tail. With that in mind, my fin’s trailing edge is set at 12 5/8" up from the tail.
Was trying for clarity on placement. I’m going to assume a deeper fin, or more swept back fin is being used. For a fin of 7 1/2’’ to 8’‘, with a fairly high angle of attack,I have found the optimum placement to range between 11’’ to 14’’ to the leading edge base. Tail width comes into play, and will dictate either a change in position, or fin depth. My current 23’’ wide twinfin has the fins 16’’ up from the tail to the leading edge. Since fin bases vary, I have always felt that the measurement to the leading edge to be the more relevent indicator of fin performance.
Regarding the swell down south… Can’t say much as I haven’t been to the beach in the last two weeks. I will be this weekend.
measure from trailing edge like lee said.currently tuning a 7’9" liddle blade.i started out at 13" then up to 13.5-at the latter position it jumped into waves a little better but didn’t do much else like i wanted.then i went back to 12.75".was pretty good but sweet trim spot seemed to be slower.went out today in some clean surf.got about 4 waves but really wasn’t comin’ off the bottom quite right and seemed to bog on cutbacks.went back to 13 and that was it!this has been over a two week period and about 6 or 7 sessions. by the way that liddle danny boy has is a 7’4" liddle roundtail i gave them to try for the hull experience.i dunno why, but they always refer to it as a 7’2". nonetheless, they really dig that board and are now having boards made with some subtle changes and chris had one made that is completely radical. on most my boards paul gross made me the fin was usually at 14" up, but his hulls are a little different than liddles so that was were the balance point was…
another tip in tning is the sniffing dog syndrome.if fin too far back the nose will waver side to side like a dog does with his nose when sniffing along the ground in search of something.as you move the fin up the nose will start to settle down and when right it will feel like you are almost on the verge of pearling-but it will go straight instead of wagging side to side.like the dog, when he finally catches that scent he’s looking for his nose will point straight out and stop wavering side to side. hope this makes sense and helps!
Fin size, shape, flex and placement though almost completely overlooked is extremely important to board performance. It’s also very specific to the individual.
For hull riders the moveable, removable fin system is about the greatest thing since peanut butter. In the old days with glass on fins tune ups were limited to flex and fin shape… unless you ground off the fin and repositioned it. I can remember fussing over flex plenty. Got one just right then over time the fin became more and more flex stressed until it actually broke. Back to the drawing board… what a pain.
The cool thing now is you can take your time and dial your board in. It’s a learning thing that develops a personal knowledge base about waves and your surfing experience. There are a few approaches. Put the fin as far back as possible, note performance. Then put the fin as far forward as possible, note performance. Then go find that magic spot, and keep in mind there could be a few, dependent and wave conditions or even mood for that matter. All along the way take notes. Then over time don’t be surprised when your surfing takes on a whole new dynamic both physically and mentally.
It’s all about the joy of the ride.
D.R.
P.S. There is a winged head screw available for water based fin placement changes, no need tools.
both of you mention a side-to-side motion when you have wrong fin placement - but one of you says its when fin is too forward and the other says that it’s when fin too far back.
Are you both talking about when the board is being paddled? (not riding a wave, and not paddling onto a wave)
i’m referring to when riding the wave in particular.the tendency is for the nose to be sucked back up over the top of the wave.the fin keeps it from doing so by driving it back down.too far back and it won’t properly balance the nose which allows for it to wander side ti side. too far forward and it will want to push it down too far almost out of the wave towards the beach.somewher in between the two is the “sweet” location. as dennis alluded to, fin shape,size, foil and flex all play a roleas well as wave conditions , mood etc.
I don’t think anybody could tune a hull like Tommy Trim. He used to dial in my boards and they would go from great to magic with a bit of fin fiddling. He could tell with a few paddle strokes sometimes if the fin was right and come back on the beach at Malibu and change or move fin…then after maybe a half dozen adjustments down to a 16th of an inch…mark the box with a razor blade. He would sometimes then have the fin glassed in over the box.
I think he rode first point Malibu better than anyone…past or present…at least from a perspective of trim and speed. His collaborrations with Paul Gross through the 90’s paid off hugely…he would always make waves from the top of first to the beach. Few guys had the equiptment to come from so far back…sometimes we felt we were surfing alone.
He got to where on long hulls, he would use thicker foiled non flex fins that he would have custom made. As Thrailkil has noted in the past, available fins are not thick enough… therefore the foils are not right.
Hope Tom gets those old hips fixed and back at the top of First Point where i can give him hell since that has been my job since we were freshman in high school together.
I don’t think anybody could tune a hull like Tommy Trim. He used to dial in my boards and they would go from great to magic with a bit of fin fiddling.
I think he rode first point Malibu better than anyone…past or present…
Hope Tom gets those old hips fixed and back at the top of First Point where i can give him hell since that has been my job since we were freshman in high school together.
Be finicky with your fins!
Aloha,
Roger
So the lesson is to be as finicky w/ your hips and get a tune up.
l miss tommy trim/like to see him back again. agree on what he did, especially with the longer hulls.i also mis PG and some of the magic he produced for me. i kinda held back on how intricate fin placement can be, but indeed a razor blade swath can make all the difference in board perfomance. some folks may not believe it but it’s true. whooya to the extreme fanatics-long may they ride!