Without going into the murky depths of any complete design, I believe we would all agree that a flatter rocker would make for a fast board.
I have heard that flat design lines resist the curves of a wave and therefore this resistance results in pressure, pushing the board away. That seems fair considering that highly rockered boards require greater rider input and appear to have less ‘run’.
I have tested 2 boards,
1 had 1" rocker in the front 25% and zero in the tail 75% and
the second had 3" in the front 25% and zero in the tail 75%. They were both “fast”, but maybe too flat !
Does anyone have any idea of what is the fastest rocker? Slight, nil or reverse even ??
It’s rates of curvature that count, not just overall rocker quantity . . … easy enough to measure but no one ever seems to bother, how about amount of rocker per foot as a standard for starters ?
It’s meaningless to measure rocker without a distance and a height
Actually, there’s one rocker measurement, (and only one), which is independent of the length over which it exists, that’s zero rocker.
Excellent point Bloke, although I am probably as guilty as anyone by using the “eyeball” technique for this more than anything. If the curve looks good to me, it probably is good for me. I aim to have one nice continuous flowing curve no matter how little or great it may be at any certain point over the entire length of the board. I measure at the tips and at foot increments (some times every 6”) to the apex of the curve for “ballpark” estimates, but rely heavily on what “looks” right to dial them in. I too am also very interested in your measuring technique and your theory behind your large rocker curves on what you claim to produce a very fast rocker contour for your boards. I know you have discussed this concept or something similar before so if you don’t feel like going into detail about it again I understand, but if you don’t mind commenting could you please incorporate your basis for using the tunnel fin design in your response as I would think this also plays a large role in your choice of rocker contours.
I am also very interested in what other people have to say on this subject. I personally don’t “know” what is the fastest and by no means am I an expert but I have to admit for the most part I prefer flatter boards and do feel they go faster in flatter surf. They perhaps would go faster in steeper surf as well, but personally I don’t care about fast then, I want make the drop and a flatter rocker isn’t helping my case. I would also like to think that in steeper surf generating speed isn’t and issue, making the drop is. Generally the flatter the surf the flatter I want my rocker, the steeper the surf the greater I would like my rocker curve to be. I also generally like a flatter rocker than my friends for the most part. They generally want exactly what ever is in the “shop”. I have been drifting away from that and have been experimenting with rocker, rail, and bottom contours, as well as foil to a certain extent. I haven’t been re-writing the book by any means, but just taking some basic “proven” or “contemporary” designs and changing on one element from one board to the next and seeing what results I could get. One recurring theme in my boards as of late being it is summer in my part of the world is flat rockered boards.
Lets hear it brothers, what’s your take on “the faster rocker this side of the Mississippi”.
since we don’t surf in straight lines on flat water, flatter is not always faster. the ideal amount of rocker varies based on the shape of the wave at that particular moment and what you happen to be doing on the wave. since all that varies instantaneously, there is no “best rocker”. It all depends on what you want to do and where you like to surf…and the wind, the tide, your ability, the swell characteristics, the sand deposits or anything else that affects the shape of the wave. another thing to consider is that you only need short bursts of speed for surfing. just enough to hit your next manuver. unchecked down-the-line speed on most waves will cause you to out run the curl and stall.
I was looking at widening the possible number of makeable waves by designing something for very fast straight tubes that are just too fast with standard equipment.
Design a purpose built board for really fast left or right tubes, no turning required. Like they already have speed skis, downhill snowboards, drag cars.
Just joking, top idea actually, you get a lifetime involuntary compulsory membership of the Global Association of Speed Surfers ( The G.A.S.S. )
The motto is ‘Indifferent to style’ and the battle cry is. . … . ‘Pax Vobiscum !’
All members get to be presidents we believe that in a true democracy everyone is president, current presidents include Laird Hamilton ( he may not be aware of this compulsory honorary presidency I haven’t checked )
I usually measure rocker in millimetres per foot, that is, get a one foot ruler, lay it on the bottom, and measure how much the rocker diverges from it at each end ( both measurements must be equal.)
:0
PS for a small compulsory fee we can extend you membership into the afterlife, plus a free bar of heavenly wax.
PPS measuring one foot of rocker only tells us how much rocker is in one foot of board ( excuse me for stating the obvious )
I don’t often measure rates of curvature either, you know how it is, once you’ve got a handle on where you are with a board of particular length then it’s easy to add a bit, subtract a bit and eyeball the curves, so it isn’t necessary very often. Really one reason why I mentioned actual rates of curvature is to compare boards of different length.
I so often hear about how my boards have a lot of rocker, but in terms of rates of curvature many of my tail rockers are really low, flattish curves. If an apparently flat rockered shortboard has it’s rocker extrapolated to 12 feet it looks ridiculously over rockered, but the rate of curvature ( which, after all, is what the wave relates to) hasn’t changed.
The theory behind those boards with low tail curve and loads of nose lift is the same as why that sort of curve is used for shortboards: a high lift high drag nose curve to lift the board onto the plane early, and a flat tail which is used when going faster, the nose is then clear of the water. . . much like a planing powerboat.
Tunnels tend to flatten the ‘effective’ rocker in the tail as the board goes faster.
I have noticed that it’s possible to use a much flatter rocker on boards with a lot of rail convergence or planshape curve in the tail, as then by going on rail the forward part of the rail can be released, it might be different for shorter boards which can be overpowered by the rider though. Do you find that to be the case ?
Thanks for the response. Thank you for pointing out that the rate of curvature in your boards can be quite low as they do tend to be quiet long. That is a very valid point, and I would concur with you that if you took a standard short board with the length drawn out it would look ridiculously “over rocked”, but yet the curvature remains the same. I believe it is a common misperception (at least from what I have perceived in previous threads) on this site that your boards have “exaggerated” rocker and your explanation about the length of the board and the curvature of the rocker in relation to your boards makes perfect sense to me now on why you choose the curves you do. I’m starting to see more of your viewpoint in the validity of the design, as your shapes do intrigue me.
Now if the tunnels are “flattening” the curve so to speak on your boards with your particular length and rocker curve, do you think perhaps a scaled down version of a tunnel would have the same effect in essence on a much shorter board with different design aspects such a “contemporary” short board, or are there to many other variables in play to effectively utilize the tunnel to its fullest potential?
I think you are right about the flatter rocker I boards with more rail convergence and plan shape curve as it is a fairly common design aspect in somewhat longer boards. I have found this experience to be true in riding these type of shapes as well. One thing I know for sure is that I personally can “overpower” a small board, particularly as I become a more powerful surfer and especially if the waves become more powerful. Generally the smaller the board, the more powerful the wave the easier it is to overpower the board… to a certain extent. There is a threshold in where I feel comfortable riding a certain size board in a certain size surf. It varies by swell, spot, conditions, etc. but generally there is a point where as the surf gets bigger so do my boards to the point where the board become s to big to effectively “overpower” in the given surf.
Heres a quick picture of Finian Maynard, the current speedsailing record holder at 48.? knots or ~25 metres a sec.
Faster than Yellow Pages,Rocketsail or Hydroptere.
Apart from his stealth wetsuit, the next most important thing is his low tech, skinny, flat low rockered board. I think the board is about 15 in across.
But its got a fin about 15 in deep.
No channels, no concaves.
Maybe thats the fastest hull design?
Absolute minimum area.
Lowest possible rocker and roll for the least ‘adhesive stick’ to the surface
and
One dirty big fin to direct lateral forces into forward movement.
And a similar lateral resistance vehicle.
Possibly fins arent big enough to utilise the available energy. Board design seems to have hit an impasse and previously ignored fin designs may be the way forward to new levels of performance.
It’s rates of curvature that count, not just overall rocker quantity . . … easy enough to measure but no one ever seems to bother, how about amount of rocker per foot as a standard for starters ?
Some surfboard design tools like shape3D and BoardCAD show the curvature of the board. Thus you can easily quantify and compare the curvature of the rocker of two boards. Also, it makes it easier to make sure your rocker is true to your intentions like when Greg Loehr says that the EPS blanks he designed have a slight flat spot in the rocker near the tail you can actually make sure this is how your boards rocker is as well. Or you can make a constant curvature rocker (like a circle sector).
So how is rocker measured today? And is it a worldwide technique ?
The most standardest technique is to
find the mid point between nose and tail
draw a tangent line in the fore-aft direction
measure displacement from the tangent line as a function
of distance from the nose or tail e.g. 5 inches at the nose and 3.5 inches 6 inches from the nose
Someone at Sways (Benny maybe) showed a picture of using a laser level and tripod to lay the tangent line. A most common technique is to have a standard long flat aluminum bar that you put on top of the hull. Of course, it is better if the bar is not so heavy it changes the rocker by itself.
HTH…this method of measurement is used industrywide worldwide, although I think you will find Roy doesn’t use it.
What is standard worldwide is a method which cannot measure rates of curvature, this means that the standard method is seriously flawed when comparing boards of different length.
Of course this matters not at all to the ‘industry worldwide’, which is, after all, happy to remain in the time honoured rut as long as it pays.
Surffoils specification is for a board for fast barrelling waves. Bearing this in mind maybe the function of rocker should define the means of measuring it.
Hypothesis 1: In keeping with staytrue’s statement that he prefers different rocker on different waves, I from experience would agree with this. The primary function of rocker is to fit into the shape of a wave.
Hypothesis 2: Rocker is an element of board design that defines it’s performance, and is universal across conditions.
I propose these two as starting points rather than personal beliefs. I wanted peoples ideas on them, it may be that nose rocker and tail rocker vary and conform with hypotheses to differing degrees.
My reasoning for this was the differing views of Roy and Blakestah.
In terms of tail rocker the same area of differing boards interacting with the same area of a wave would suggest absolute rather than relative methods of measurement.
What is standard worldwide is a method which cannot measure rates of curvature, this means that the standard method is seriously flawed when comparing boards of different length. …
Roy, I find that arguing people should not draw comparisons using the techniques used by 99% of the people in the world to be a little infantile and pedantic. There is nothing wrong with the standard method for measuring rocker. Defining the rocker measurement every 6 inches from the midpoint to the nose and tail will fully define the rocker for the purposes of making a surfboard and allow replication within tolerances that are undetectable to a surfer. If you don’t like it and prefer your methodology for making your boards that is fine, but I think you will find the world and easier place if you simply converse online using standard measuring techniques.
Haavard, how do they describe a rate of curvature on those programmes ?
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The rate of curvature is graphed as a function of the length of the board, ie. the curvature of every single point along the length of the boards is shown(almost true, in reality it’s using numerical methods so it breaks up the curve into discrete units, but it’s close enough).
I think both Blakestah and Roy is part right. You cannot use the common measurements of only nose and tail to describe the rocker, nor would the common 1’ off nose and tail be enough either. A bezier curve (the same that is used in APS/AKU/Shape3D) through four point can have extremely different shapes and thus extremely different curvature, so even measurement every foot will not suffice unless you add the constraint that it shall pass through those points with the least curvature possible (which in turn may or may not be what you want…). However given enough measurements (every 6" or so IMHO if you don’t consider the least curvature possible constraint) you can accurately reproduce a curve given the same boardlength. If you compare the rocker of a shortboard with a nine footer it’s like comparing apples and oranges unless you start looking at the curvature.
For the application suggested by the guy who started the thread, I think you need to consider outline together with the rocker. I guess conventional wisdoms says flat rocker in the tail, enough rocker in the nose not to pearl and spear like planshape for that kind of waves. I wouldn’t know the first thing about that tho, I try to stay away from those conditions.
I think some shapers really have the straight line speed down. Skip Fry would be one. Super flat rockers, super fast down the line, catch waves easy. He also has unique rails. Just about every board I have ever seen of his has this same idea behind it. from 5’6’’ to 12’.
It would be great to see some of his boards bottom pics posted.
I find the measuring rocker using std methods establishes a good baseline, but not much else.
Measuring rocker curvature I do with my EYES. To see ‘it’, requires that I stand about 15-20ft away from the board, side view of course. This ‘measurement’ is actually more meaningfull and a better predictor of how rocker curves influence performance. Curves are just as, if not more important than the numbers gathered at the tips.
Ive gotten to the point where I can eyeball the sideview of a board and tell you the numbers at the tips and be fairly accurate, within 1/8". Of course, I look at everything in between, thats where the truth really lies.
To answer the original question, speed/rocker relationship has a lot to do with the style of the rider, and fin setup. In a steep barreling wave with a very curved face, modern shortboard rockers work really well. Look towards typical Pipeline boards for guidance.
