.
Hmmm -
There seem to be two things going on:
One - How do most people talk about rocker? From the center.
Two - Where is the apex of a curve? (Given the bottom up view.) The “high” point with both ends the same distance “down,” i.e., from the apex the nose and tail “rocker” are the same - but will certainly have different curve profiles.
I use “two” because I make my own blanks, and I also measure every three inches for two feet from each end, and six inches in between.
[quote="$1"]
I assume the apex would be that point on the bottom of the board from which tail and nose rocker are equal. Roughly, lay the board on the floor deck down and the place where the bottom of the board is highest is the apex....???
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Lie dat?:
Isn’t the apex of a curve the position with the sharpest curve (lowest radius ark).
There can be several on boards old and new.
before after feet
between feet (MP used to do this) weight forward= speed. weight back = stall. I supose thats how he rode the tube so well at kirra. And out turned everyone.
…etc
Huckelberry, that board had better not have tail pad on it, the arch bar would through it out a bit. 
Aloha Silverback
I am a bit late to this “apex” party… But hopefully you will find some value in the graphic below. The main thing to consider is that Apex and the way most people think about it, is irrelevant. Various bottom curves can surely make a big difference in how a board rides. But the term “Apex” doesn’t really work very well to describe those curves. It is a flawed term when applied to a surfboard rocker. It will lead you into meaningless and confusing territory with little reward for the trouble.
[img_assist|nid=1050927|title=Surfboard Apex|desc=|link=none|align=left|width=640|height=206]
Brilliant, Bill. And I am not surprised. I just clipped the graphic and am saving it for future use. Thx
OK, everyone, move along. Our work is finished here.
I agree … was a place we left many years ago. Nice post Bill.
Aloha Greg and Greg
Kind of amazing how much life and diversity, things like the APEX, can have. Why is that? Is it that they are catchy terms, with the promise of containing mysterious and profound design revelations?
I realize the magazines and media like to present the mysterious, elusive and magical world of surfboard design and construction as the way it really is. It’s good for business after all and from a marketing standpoint, it is much more advantageous to have these powerful fantasies to springboard off of, to make products appear more magical and attractive. We are all victims of it to some degree. And we are all guilty to some degree also. The myths and fantasies are mostly kind of fun as long as we don’t come to believe too deeply in them.
So glad we’re not slaves to the mags anymore. The internet has it’s issues too but at least communication doesn’t have to go through a third party. To me it’s not mysterious, it’s quantifiable. You know this too. We have been given the ability to understand the world around us. But it’s a long way between knowing and a broader acceptance. Too many want it to remain magic.
Agreed Greg
I like knowing I can figure it out and replicate it. But I also like the mystery and magic. Even if it is over marketed way too often.
Very nice graphic Bill.
As you pointed out long ago - we talk about rocker from the center in large part because it is an easy and obvious place to work from, and then we are all using the same language.
Sorry to confuse the discussion based on my personal quirks.
Aloha TaylorO
Yes, simplicity and commonality are important factors in good techniques.
Surfboard making, tends to attract a lot of us gizmo guys. Gizmo guys like to create gizmos… but they also like their gizmos to be “accepted”.
To justify their gizmos and efforts to create them, they work from the standpoint that their “NEW or DIFFERENT” creations are “BETTER” then the old things. This spurs creativity and is a good thing. But it also leads to the flawed belief that all existing things are bad and need to be changed. If the gizmo guy can do something differently, they will have automatically improved the thing and made it better. Taken too far then… Any CHANGE, becomes more important then what the actual change is or how well it will actually function.
To prove their change to others, (and themselves) they often have to develop complicated theories and explanations to confirm the value of the CHANGE and establish it as a true improvement. This is where a lot of the mythology enters into surfboard building. It is also the basis for 90% of the marketing that is done and because surfers are a fairly gullible bunch, it easily justifies the huge expenditures on team riders and full page ads in the magazines.
Occasionally there are times when dramatic changes in products, can be made for the better. But they are very rare and far between. Even less often can the techniques to make products be improved significantly. When one is starting out making boards, their knowledge and skill is severely limited. So the first couple of years requires a lot of learning and change and allows for a lot of experimentation. This is way fun and exciting but easily sets up a belief that this is what surfboard making is all about and makes it seem very attractive, especially to gizmo guys. It is also why many stop after only a few years or less. This early attraction draws in far too many who want to be players in this exciting scene at any cost This drives surfboard prices downward and creates a flawed employee pool. Later when the realization comes that, it is just a job, and isn’t as much fun as they thought, they leave to get a real job.
Eventually, one comes to realize that there are well established tools and techniques for building good surfboards. And 99% of them have been around for a very long time. The fastest way to be successful is to learn them as quickly as possible and use them regularly! It will primarily be the personal skill of the user of these tried and true techniques, that will make good surfboards.
Its about time someone covered this term being bandied about–Apex. As usual Bill B has the goods.
SilverBack wrote:
2) JC in 101 says “bigger waves, rocker further forward; smaller waves
rocker further back” but G loehr says “hollow waves further back, mushy
waves further forward” - who’s right?
I dont think this was addressed.
Maybe its all : bigger waves and/or hollow: more rocker smaller waves and/or mushy: less rocker
Aloha Otis
This is going to be straying into pretty subjective territory… but…
It is very hard to set rigid guide lines regarding rockers, riders and waves. The “right” combo of things just doesn’t like to be nailed down that easily or tight. Still there are generalities that one can rely on with reasonable safety, especially when designing average boards for average surfers. So assuming similar distributions of curvature along the rocker then… Generally…
Longer boards will require more rocker the shorter boards.
Shorter boards will require less rocker then longer boards.
Hollow waves, big or small, can handle and may even prefer more rocker.
Flatter waves, big or small, may prefer less rocker.
Of course, these statements clearly ask… "What are the base amounts of rocker that, more or less rocker is calculated from? The base or average amounts of rocker will vary by the wave, rider and style of surfing to be done. Each shaper will have to arrive at their own sense of “average” to start from; by guessing, trial and error, asking others, or copying someone else’s design. From there you begin modifying to determine what seems to be the best average or base to work from.
As to more rocker pushed forward or back. That depends on a whole bunch of other stuff. First some clarification…
Are we referring to moving curvature forward by adding more nose rocker and reducing tail rocker? In other words, are we changing the measurable amounts of rocker at the nose and tail?
Or are we maintaining the same amount of measurable rocker at each end and just changing where and how the curve is concentrated in the back half of the board or the front half of the board, or both halves?
Wow Bill!!!
That should be mandatory reading for anyone who thinks they want to get into “the industry.”
Thanks for taking the time to share.
By the way - In case I forgot to mention it - my friends had a great time in your neighborhood… and all I got was a few t-shirts… Ha! Thanks again -
Right on............. from someone who has religiously used a rocker stick for decades. The 10" back shaping 101 thing is bullshit. Or at least misunderstood by the interpreters? Accelerated and flattened curves are determined by measurements taken off my rocker stick relative to center and to the nose and tail measurements relative to each end. On shorter boards I know what numbers I need at 12", 18" 24" for paddling ease and early entry into waves. I also know how the tail rocker curve contributes to the previous consideration, and those numbers change depending on whether it is a HPSB or a noserider or something else.
To quote Bill Barnifeld....... but not exactly...... I, too look at surfboards as lines that have relationships to one another to deliver a desired effect.
To think that knowing where the apex of the rocker is could be more relative to what I would call Pitch. It starts to become more complicated from there.
Why? Because the high point or crown of a curve and ow it performs is working in conjunction with many (other) compounding curves on the given design.
Here is a simple example bringing foil into the fray. Let's say you give me a bottom rocker curve and tell me if the apex is at a given point, any board with that EXACT bottom apex/curve will ride the same.
Well, I would deliver to you a contemporary shortboard, let's say 2-1/4" think with 1-1/2" tail thickness 1ft. up and a nose @ 12" of 1-1/4".............. then I would also give you your bottom rocker/apex with a thinkness flow aka foil that looked like a surf ski.
They would begin to ride the same even though they had identically apex/bottom rocker. Foil is all encompassing.
My point is even far more subtle changes in all the COMPOUNDING CURVES deliver a different experience to an overall completed design..
If you prescribe to what Barnfield and I, and many experienced shapers do....... which is to realize that the rocker curve is as personalized as any give planshape aka outline on a surfboard, then you are on your way to a heightened awareness of what surfboard design is really about.
Have fun.
P.S. I didn't read the whole thread before posting, then came back and saw that Bill had chimed in. I should have known he would make time for a subject like this....... a lot of the stuff on Sway's is rhetorical and not worth the time answering (sorry). I'm sure a LOT of what BB states is my same mind set and I will come back and read it later after shaping............. sorry about that.
my head is smoking....
so you mean , by changing the foil, you change the rocker apex?
hey horsemouth
what DS means is that how your board goes through the water is influenced by not only the rocker, but all the curves together, called compounding curves.
if you have 2 identical rockers, but different volume, say, one super thick, and one super thin, they ride differently.
the way the board goes through the water, or the angle that is uses relative to the water it goes through [called pitch] changes with different volumes/foils
In DS his example he uses two identical boards but the 2nd one is ultra thin, it will want to bury itself in the water. the one with more volume will tend to float on top, plane better.
greg loehr wrote a long essay on it "Theory of Pitch" it is here on sways, do a search because i dont have the link for it.
is it still smoking now?
delete double post
Ah…paddling ease and early entry…summer is here and I’m thinking of those qualities in a 6-0 twin fin groveller (modern fish). I’m thinking 4-1/2" nose and 2" tail rocker but those 12", 18" and 24" are unknown to me. I usually just go by eye. Care to share concrete numbers?