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Design question: Can fins be too far back?
- Thread starter ghostshaper
- Start date
Either fin set up. As one of the quadfathers once told me: Think of the fins as a cluster and their placement as a whole (or something to that effect).
No way. You can put fins anywhere you want on a board. It doesn’t matter at all.
sure, but it’s also subjective to the rider. Loaned a twin that I like to someone and they didn’t click with it, thought it felt tracky and slow. Measured and the fins were further back than he was used to. I’ve liked how it surfs, but then we have different approaches and typically surf different kinds of breaks.
This is the type of question that I wish GG was still here to comment on
Definitely.
was always surprised by how convinced he seemed that each boar had one optimum fin position… given each rider’s different approach, style, stance, etc.
Just depends what you’re going for. I’m sure some must’ve thought his twins were too far back / not loose enough.
The fins in my GMM2 are further back than anything I've seen from other thruster set-ups. I love it!
The cluster is also a bit tighter, which definitely helps with as far back as they are.
The cluster is also a bit tighter, which definitely helps with as far back as they are.
not to get into this and I won't go beyond this post but I always though it was weird how he would make fins and placements for the board that would make it so you wouldn't have to experiment, yet they were designed to be moved within the boxes at the same time.
Yes, too far back equals hard to turn from anything but a foot-all-the-way-back position.
If you're able to set your rear foot in one (far back) spot only on a board for every type of section and
situation, then maybe not.
I wouldn't have asked this if he were b/c he'd get his feelings hurt.
I asked him this, and he said that it tracks up the face too much.
I've felt something else, though. I'm going to let more people chime in before I mention it. I'm becoming the new GG!
The one thing I’ve noticed is that the sweet spot narrows and misplaced front foot pressure can be like slamming a car brake. But have had some great boards with rearward placement from Greg and Tomo.
This has been my experience.
Further back needs less fin. Too far back can feel stiff like too much fin.
You mean like this?
although technically you could adjust them….
although technically you could adjust them….
The two turns (essentially the same turn) and criteria to judge boards: 1) do bottom turns/roundhouses hold in during deep turns; and 2) do the boards project coming out of them.
When I got GG's board back from the glasser, his g10 fins hadn't come, yet, so I tried it w MR78s, no canards. It felt lackluster by the criteria above, so I wrote it off as not having the canards.
When GG's fins came, I noticed that it felt better but still not as drivey through and out of turns like my previous 2 boards.
His rears were at 5.75" which is extremely aft for a twin(zer). After riding this board for a while, I realized that if you do a deep bottom turn in order to get some projection into the lip, fins too aft don't have the same drive as fins further forward. They feel almost like a twin w/o canards.
If you think of a fin cluster as a single unit, the removal of canards are essentially moving the cluster aft (I know there are other effects as well). Conversely, adding canards shifts the cluster forward.
I remember watching Shane Dorian surf the us open when I was young. In crap Huntington mush, he was doing huge drawn out bottom turns (backside) around crumbling sections and launching into the lip, throwing huge spray. It was incredible how he would keep his board buried at the bottom for so long and then have so much speed in such weak waves.
(Not Huntington)
As I improved, I tried to emulate this (and Tom Curren's frontside bottom turn) to get this projection.
In order to draw out the bottom turn (or roundhouse), you need to make an elongated turn, which means more rail/less tail.
TL;DR: If the fins are too far aft, the end result is no projection (drive) through/out of turns.
When I got GG's board back from the glasser, his g10 fins hadn't come, yet, so I tried it w MR78s, no canards. It felt lackluster by the criteria above, so I wrote it off as not having the canards.
When GG's fins came, I noticed that it felt better but still not as drivey through and out of turns like my previous 2 boards.
His rears were at 5.75" which is extremely aft for a twin(zer). After riding this board for a while, I realized that if you do a deep bottom turn in order to get some projection into the lip, fins too aft don't have the same drive as fins further forward. They feel almost like a twin w/o canards.
If you think of a fin cluster as a single unit, the removal of canards are essentially moving the cluster aft (I know there are other effects as well). Conversely, adding canards shifts the cluster forward.
I remember watching Shane Dorian surf the us open when I was young. In crap Huntington mush, he was doing huge drawn out bottom turns (backside) around crumbling sections and launching into the lip, throwing huge spray. It was incredible how he would keep his board buried at the bottom for so long and then have so much speed in such weak waves.
(Not Huntington)
As I improved, I tried to emulate this (and Tom Curren's frontside bottom turn) to get this projection.
In order to draw out the bottom turn (or roundhouse), you need to make an elongated turn, which means more rail/less tail.
TL;DR: If the fins are too far aft, the end result is no projection (drive) through/out of turns.
So what you're saying is the current anti orthodox erBB orthodoxy of pushing the fins further and further back (under the tutelage of the Great GG) has it's limits????
Fin cluster is akin to sail plan. Center of effort changes a lot when you have two engines instead one one. Think of eliminating one of the sails in this diagram.
I know sail dynamics don't translate neatly into surfboard design but they can give you a starting point for understanding.
Lengthening the fin cluster creates drive. In my experience, the board that best meets the criteria you describe, "1) do bottom turns/roundhouses hold in during deep turns; and 2) do the boards project coming out of them?" is the bonzer. Very elongated fin cluster. The main drawback of the bonzer, in my experience, was a lot of fin drag when going slow- not great in mush or fat waves and not quick out of the gate (twinzers seem, to me, very quick out of the gate). Also, not the best for short, tight arcs, although that is not the kind of turn I aspire to. On the other hand, the best long, drawn out, on rail cutback I ever did was on a bonzer on a big wave. I remember being blown away by how the board kept powering through the turn. I wish I had a board that would morph into a bonzer when the wave reached a critical steepness or the board a critical velocity.
Part of the "quick out of the gate" feel of my boards is also related to the full length hard edges (again
to GG). I also find the 2+1 has a quick out of the gate feel (due to the side bites forward position?). Canards have the same forward position. With so much going on with boards I find it hard to zero in on which element is making the board do what. There is a synergy of components that is intuitionally grasped. Sometimes I'm led to believe that things that look fast, go fast. Why do racing sailboats, formula one cars and fighter jets all assume a similar aesthetic?I am presently in the planning stages of another attempt at a Cove board. Now that I can surf mid week midday I am designing the board strictly for the wave, not for handling the crowd. Thinking of optimizing for head high to double overhead (basically the waves we had last week). Working on fin positions now. I want to use 4 FCSII boxes so I can use as twinzer or 2+1, and use g-10 fins so I can make the fin positions adjustable. This required me to open the slot up to 1-1/4". I've settled on 8" up which puts non overlapping canard at 12-1/2" which is also the optimum spot for widow maker side bites (according to Neil Purchase Jr.). *" is too far forward according to most twinzer doctors but this will be a 7-6. Also not at all a fishy board. Jobson's 80's high performance shapes (narrow tails), from what I have found , had mains at 8-1/2"+.
I love the design process!
Question- with this design, what difference would a swallow vs round pin make (second pic)? I'm kind of a swallow guy myself. I like the bite at the end of the board. These photos make the tail look wide. It is only 14". Last week, in DOH, the speed of the board made it resist going over onto the rail. Hence I'm keeping it kind of narrow, will introduce some vee and foil it pretty thin. I almost feel to make the round pin's curves fit, the tail would have to be even narrower which I'm not inclined to do.
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