Crafty, the rocker on your board looks great, but I too, am confused by what you mean.
Hi Bill,
How do you insure that your laser line is tangent to the rocker curve at center? Do you have pads at each end on the bottom of the laser unit and then locate the laser's center over the boards center?
- The laser is mounted on small u shaped feet, one on each end. I position the laser center over blank or board center.
If the laser beam projects out of only one end of the unit, do you just spin it around to do the other end of the board. If so, does it always stay accurate to the tangent when doing so?
- The laser unit is only 6 inches long and I turn it to point at nose or tail. Because it stradles such a short distance I find no noticable discrepencies.
Assuming the laser unit sits on the blank, then the light source is above the blank and the beam/line it projects is also above the blank. So, do you just deduct that amount above the blank, from all your measurements along the rocker?
- I've calibrated my ruler to the height of the laser so no deduction is needed.
Lastly, is the lasers light beam small enough to put a fine enough line on the ruler so you can easily measure down to 1/16" on the ruler?
- The light beam is about 1/8". I use the top of the beam reading.
I've been pleased with the ease of use and good results. Blanks that come to me that I know have been measured with a rocker stick I get the same mesurements consistantly. Intially I tested the thing by measuring boards with my rocker stick then with the laser to see if I was getting the same reading.
Nice blog on Foils.... Thanks
BTW, did you ever get your Penetrator in the water?
D.R.
Sadly no. I got it all finished and polished out. Then finally got around to taking photos of it before the big launching. My friend was helping me set it in place in my little light box photo studio. It was sitting up on a 2 x 4 to put it above the cement floor. Apparently it wasn’t centered but too much out on the edge. The 2 x 4 rolled over and dropped the tail on the cement. It shattered the glass over the wood tail block pretty bad. So… it is back in the glass room awaiting the time when I have an extra moment to fix it. Probably will be surfed in July if we get a swell out here or I will launch it in Waikiki.
Your answers about the laser were all good. I have a small one that sits less then 1" off the board. Maybe I will give it a try again someday. If I am duplicating a previous rocker I use the stick and measure often. The numbers are like using a rocker template for me, without having to make a real one. If I could get used to setting the laser and measuring the numbers, I would be happy to get rid of the stick. The portability of the laser would be nice. And never worrying about a bent rocker stick would be an extra bonus. I will report later if I get it working in a way that works for me.
This laser shoots both ways and self levels.
A little pricey, but I have found tons of other uses too.
http://www.cstsurvey.com/products/LaserMark/LM_ILM.htm.
Rob
The interesting thing about design theory is that no one is right or wrong. I just think that the transition between entry and exit rocker is really important, especially relative to the rider's position (theoretical pivot point) is located. Just an opinion.
I also think that the "magnitude" (insert nebulous term here) of entry and exit rockers is also critical. Theoretically, the area near B is not providing much lift and possibly responding in the opposite.
EDIT: forgot to draw and mention the tangent line at C parallel to the red dashed line.
Seems to me, as has been pointed out. If one uses a standard of reference for measurements - most commonly the center line - and takes and keeps record of accurate measurements, then one’ll be able to track, compare, and recreate any curve.
What one “believes” about the importance of the rocker in some given area is irrelevant to the numbers which represent a given curve. If we start from the same place, we should be able to replicate one an others rockers by the use good data.
For fun, and self horn playing practice, I’ll say I was glad to read Bill B. pointing out the utility of the whole curve geometric apex in relation to making ones own stringers/rocker foil templates. (Helps it fit in the smallest possible rectilinear shape/board.)
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Seems to me, as has been pointed out. If one uses a standard of reference for measurements - most commonly the center line - and takes and keeps record of accurate measurements, then one'll be able to track, compare, and recreate any curve.
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Agreed.
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What one "believes" about the importance of the rocker in some given area is irrelevant to the numbers which represent a given curve.
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Can't agree with that one. The "belief" you reference refers to one's idea of design theory. The numbers you value so much are just a means to an end. But the beginning starts with a "belief". If you dont have "beliefs" you are just mindlessly either throwing darts or copying/targeting raw numbers.
The problem here is that APEX is a belief, and the center point is just a convinient reference tool everyone uses. A well stablished point of reference that allows people to do things without much thought.
I for one, am very glad beliefs exist. Makes the world much more interesting......and dangerous!
Aloha Crafty
I understand your focus on the part of the rocker that you think matters most. And I agree that that area of the curve is seemingly more important than other parts. Especially when the goal is function alone.
I don’t think I am disagreeing with you really. Or not much anyway. I just think that all the parts are pretty much equal in importance. So while the nose rocker isn’t as important to you, it is to me. For example, while it can vary a tad bit at the tip without drastically effecting function, this curve quickly defines the entry rocker and has a huge effect on the esthetics of the boards overall look. Few would dispute the importance of fashion in the the business of selling surfboards.
Where I would disagree with you is in your idea that the last part of the tail rocker doesn’t provide lift or is doing the opposite. If there was no lift from this area of the board, there would be no reason for the surfers foot to be located over that area to counter balance the upward lift, with his downward force. It is hard to tell in your drawing where you think this exit rocker begins but most fins are around 11" or more up and there is still a tremendous amount of lift being generated in that fin area of the board.
As to the entry rocker, most any photo will show that the surfers front foot is located, 99% of the time (short boards), right where the water is primarily entering the boards bottom. So in that I think we agree.
The rocker area you are focusing on is an Apex of sorts depending on the boards “trim” in the water. But I like to describe it rather as a fulcrum point. And maybe you would agree. The boards width, thickness and rocker apex, all converge in this area (to varying degrees) making this general area of the board into a sort of swivel point around which most surfing activity stems from. It isn’t just the rocker alone. The width bulge in the template is also a fulcrum point of equal importance as the board is rolled up on a rail. And the thickness or volume of foam in the rail also creates a fulcrum point. There is, for lack of a better description, a convergence of force here that the surfer manipulates as he sees fit. It isn’t just lift, nor gravity, it is a fairly ambiguous convergence of all forces that for the most part has never been talked about or dissected, and for many (if not most) ever been recognized. But it is there all the same. And all areas of the board have to be designed properly to feed into this area to satisfy the needs of the surfer and the waves he rides.
At the risk of sounding like the arrogant old guy talking to the young guy… As we grow in our knowledge of surfboards we continually hit plateaus were it seems like we have had the ultimate revelation regarding how boards work. But it soon passes… as we stumble onto the next revelation that is equally amazing and consequential to us at that time. This sets in motion an expectation that we will eventually discover the TRULY ultimate but elusive and profound KEY to making magical surfboards. Everyone in the industry has been launched off onto this mystical quest. It is way fun and is the primary reason that Swaylocks exists!
But once you have made boards long enough to have passed through all the previous “ultimate revelations” and have discovered a few zillion little ones on your own You (meaning everyone) will eventually realize that the ultimate KEY doesn’t exist. But that doesn’t mean this wonderful quest for the revelations ever ends.
Crafty - All I meant by “beliefs” v. numbers is: “beliefs” won’t change numbers, nor what curve, in this instance, they represent.
To be sure, what one believes about the function of the compound curves in a surfboard make all the difference in how one applies their understanding and applies the interaction of the different curves different functions.
As Bill said, and it sounded a lot like a life philosophy, there probably is not “an” answer/key to everything - surf board design included.
It’s skills and experience.
Hitting specific rocker numbers is fine, but doesn’t do you much good if you don’t also get the outline, rails, and foil right. Sometimes an experienced eye is better at feeling the flow of a rocker for a given foil than hitting specific numbers, at least that’s my opinion. Like Mike Daniels was talking about, it’s the whole ball of wax, not just one side of it.
Thanks Bill, Taylor, Ozzy and the rest. There are some good points being made, but also some tangential points that don't help to answer the original question.
I took the time to read the thread (yeah its pretty old) and I agree with some others that the concept of rocker "apex" is pretty much WORTHLESS.
I was just simply trying to add to the discussion of what I think is more relevant than some meaningless term who's origins is unknown.
Where do terms like "rocker apex" come from anyway? Do the spring up like summer weeds hydroponically out of bong water?
Hey Bill - I like nose rocker a lot! Sexy plexy!
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As Bill said, and it sounded a lot like a life philosophy, there probably is not "an" answer/key to everything - surf board design included.
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And to be sure, there IS no answer to the original question posted in this thread.
Maybe there is a conspiracy on Sways to bring back old frustrating threads??
I don’t know if it’s worthless. As Bill would say it’s a moving target. It represents the crown in the bottom rocker but there’s no way to make it an absolute measurement and therefore hard to define it’s position and relationship. I too am curious to hear everyone’s thought on the original post if we could get back on track.
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[quote="$1"] A few questions gentlemen:
1) What's the generally accepted method for finding its position ( I put mine on the stands right way up so it looks as though it's in trim and just sight the lowest point)
SNIP
Silverback
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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=0|height=0]
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Taking the time to go back at look at this bit of WISDOM, it really illustrates the point why both BB and I (and other high level guys) envison surfboards as lines....... purely stripped down to LINES and the relationship they have to one another.
I talked about foil, and if you look at Bill's diagram here you see "draft". If you are a DESIGNER you look at surfboards differently than Joe Average shaper. Esp. when it comes to the relationship of Tangent Base Line and Chord Base Line. Loehr made the case regarding pitch which is related to those terms. Draft reminds us of the board in how it moves through its medium just as a sail moves through air and the effect it delivers depending upon the shape and location of the draft (forward or aft, flat or deep, etc.) We see the term "chord"...... where else do we use that term in surfing: FINS. Depending upon the position of the chord we affect the amount of lift, drag, etc. much as we do the foil, draft, pitch of the surfboard. YOU CAN LEARN A TON FROM THIS ONE DIAGRAM (ALONE) AND ADVANCE YOUR ABILITY TENFOLD MERELY BY STUDYING AND GROKING IT.
Crafty, the problem I have with your approach using an ideal, simply put, is that it cannot be used like a given known or constant. It is simply that: "ideal" is abstract and subjective. Let me illustrate, I will only address "ideal entry point" in the case of paddling ease and catching waves. Someone wrote earlier in this thread requesting some dims when I menitoned entry point at 12", 18", and 24". He was doing around a 6 ft. fish for summer and said his nose was something like 4-1/4". So I might give him numbers like 1-7/8", 11/16", and 3/8" per his request. But as far as ideal entry rocker, I have seen variance depending on whether the board I'm making is made from EPS or PU.
And more importantly, we are considering a huge variable. LOAD. Is the board I'm making with 5/16" rocker at 24" on a 6'3" being paddled by a guy weighing 160 lbs, or is he 195 lb? See the dilemma? IMHO, the boards I have built in EPS have a bouyancy that allows a bit more leeway in the "ideal entry dims" over a denser less bouyant material. That "ideal" entry rocker on my 6'3" PU might demand no more than 1/2" at 24: wheras the EPS version in the same design would not indicate a compromise in peformance by having 5/8" at the same 24: point. By using given measuring methods, versus abstracts, I avoid unforseen (and in this case, forseen) variables that can make or break me as a designer.
(Dennis........ cool tool of the month! :)
I would like to agree with you, but for one thing, I have no idea BB's use of the word "level" in his diagram. It is used several times in a confusing way.
I would tend to agree that having a baseline is a good thing. But I don't agree with the term "apex". The two concepts are mutually exclusive, or a least one of the two is meaningless.
Aloha Crafty
I have included my Diagram again in this post for reference.[img_assist|nid=1050926|title=Rocker Apex|desc=|link=none|align=left|width=640|height=206]
There is only one “Level” in my diagram. It is based on gravity or horizon.
There are 4 lines, 2 are BLUE. 2 are PINK.
They represent the 2 possible Base Lines, derived from the 2 possible ways of measuring rocker, on a each board.
#1 Tangent Base Line.
#2 Tip to Tip Base Line.
Of the 4 lines then, only 1 PINK and 1 BLUE, are oriented to “Level” in my diagram.
The PINK “Level” Line, is the Base Line, derived from the (#1) Tangent at center, and tilted till it is “Level” along with the whole PINK board associated with it. This skews the other PINK line well off of Level.
The BLUE “Level” Line, is the Base Line, derived from the (#2) Tip to Tip line that is then tilted until it is “Level” along with the whole BLUE board. This skews the other BLUE line well off of Level.
The two base lines are only leveled for the purpose of comparing how the two different Base Line Methods, create two different Apex points in the exact same exact rocker curve.
The purpose of my diagram was to establish that the APEX or highest point in a curve, is directly dependent on how that curve and therefore, the highest point in the curve, is actually oriented in space.
The use of, “Level” Base Lines, is necessary simply for the purpose of communication clarity. There is no particular magic or influence on the design as rocker curves are actually identical.
The main points being…
APEX is the high point in a curve. But the high point cannot be arrived at unless there is an agreed Base Line to reference the high point from.
There are only 2 “practical” Base Line Methods that can be used. And they produce vastly different APEXES, so it is Imperative to decide and agree on which Base Line Method, is going to be used as the the “Industry Standard” from which common communication can take place.
Once that Base Line Method is agreed on. The Base Line it creates, must be oriented to “Level” to further insure that we are communicating from common ground.
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There is only one "Level" in my diagram. It is based on gravity or horizon.
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Bill, as you might guess by now, I'm not the type that is easily confused. And I appreciate you taking the time and all, but there is no "level" or "horizon" in your drawing.
If it were up to me and I was trying to communicate this concept in a drawing, I would seperate it out, using a level reference line in each. But hey thats just me.
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Crafty, the problem I have with your approach using an ideal, simply put, is that it cannot be used like a given known or constant. [/quote]
Fair enough.
But how do YOU determine where you're entry rocker finishes and your exit rocker begins?
Seems as if there are two camps.
1. One camp sees it as an interaction between the blank and the shaper.
2. The other camp sees it as an interaction between the board and the water.
#1 is infinitely easier for shapers to digest and use to make better boards.
But I prefer #2 myself. Just my opinion. Whatever floats your board.