Rocker - The basics
Rocker can be defined as the curve or profile from nose to tail of a surfboard when viewed from the side. It is generally accepted and considered to be the single most important feature in the design of a surfboard as it is the primary profile that governs the fluid flow from its entry point to its release.
Through my research into the feasibility or application of an appropriate rocker profile, I have come to understand that a complex balance of curves and/or straight lines are blended together to create a well designed surfboard; some to enhance speed, others to increase manoeuvrability, maybe even a focus on flexibility. These curves include but are not limited to such things as Rocker lines (nose, tail, entry, deck, bottom, and rail), bottom profiles (such as concaves, V’s or rolls), rail form (up, down, 50/50, boxy, knife, soft, etc. etc.), foil thickness right through to the basic plan shape or template. So, rocker may just be “the single most important feature in the design of a surfboard”, but the art or manner in which these curves are blended, merged or conjugated is of equally high importance. In considering the points above, I feel that it is better to state that a well designed bottom rocker that is both functional and in tune with the design parameters on a whole is the foundation in the search for that “magic board”.
In my search I have identified three basic Bottom Rocker forms categorised as: (1) Continuous curve, (2) Staged and (3) hybrid. I have designed my rocker around the continuous rocker concept and hence will explain very little, if anything about the other two forms.
As the name implies, continuous curve rocker is a bottom profile with no flat areas that commences with tighter curves through the nose and entry area of the surfboard and in turn are developed to flow into curves of a larger arc in the mid and tail section of the board. The primary design concept in the application of a continuous curve rocker is to enhance or create a smooth transition in and out of a turn. As for all three rocker types, many governing factors such as the length, cord thickness and other relevant curves that exist as previously outlined above must also be considered in order to develop a functional profile that benefits the overall design.
My understanding is that when continuous curves are applied to the design of a bottom rocker for a Longboard it’s done in such a way to produce a curve that is flatter through out. The flatter rocker inherent in the design of the nose and mid sections of a Longboard helps to develop the trimming area of the board. The curves positioned behind the peak of the rocker curvature are primarily for turning purposes although often adjusted to influence the riding performance or characteristics; ie. Symmetrically centred boards diverge and ascend about the central point or centroid of length, where as boards designed with nose riding as a primary function generally have the maximum width or wide point shifted behind the centroid of the length and conversely exiting rocker curves are initiated beyond this point. In the case of a nose rider, tighter curves are generally utilised in the tail (referred to as tail rocker or tail lift) to encourages such things as water flow over and around the rails (highly dependent on rail rocker and profile) and in doing so induces a drag force that impairs maximum velocity and in part causes the tail to be sucked into the wall. In turn this aids or in some instances enables a board to be ridden closer to the curl. Cutting it short, this addition of tail rocker benefits nose riding for a number of reasons and therefore should be considered and applied if nose riding is a functional aspect of your design.
Some basic rules to rocker, by Dave Parmenter, February 2001 (taken from: SURFLINE)
Some basic 'rules' concerning rocker are as follows: The more rocker or bottom curve that a board has, the looser (but slower) it will be. Water flow has to follow the excess curve, ends up pushing water, and drag is the result. Flatter rocker brings more speed but brings a decrease in manoeuvrability. Generally, boards with more rocker work better in larger, hollow waves where the added curve and drag can contribute to more control for the rider. Flatter bottoms are normally used on small-wave boards designed for slower, mushier surf, where the speed (and added leverage) helps keep the board planning.
As with every other aspect of surfboard design, the best option lies in the happy medium of compromise. The better-designed surfboard steers clear of extremes and finds that an even, neutral rocker serves best: flat enough to be fast and efficient, but with enough curve to let the surfboard fit into the curved face of the wave and allow for the tight turns that are the mainstay of performance surfing.
A section taken from SCSURFERS site, entitled: What rocker does, one by one, comments geared towards longboards:
Nose rocker - more here makes a board resistant to nose diving or pearling. Less rocker here makes a board go faster and stall less, easier paddling as the board glides through the water, not pushing the water. Less rocker here is better for nose riding, rocker all the way through; generally slows it all down some, but makes a board turn well.
Tail rocker - makes a board turn real well, easier drops into the wave for a speedier entry, and also aids in nose riding... but pays a large speed penalty due to drag both while riding and paddling.
The best is a combination of all. Modern boards need to be able to turn to get speed, so tail rocker is important, and it's not exactly true that "flatter is faster" on a wave, maybe on flat water with a sailboard, but not on a wave.
Through my research into the feasibility or application of an appropriate rocker profile, I have come to understand that a complex balance of curves and/or straight lines are blended together to create a well designed surfboard; some to enhance speed, others to increase manoeuvrability, maybe even a focus on flexibility. These curves include but are not limited to such things as Rocker lines (nose, tail, entry, deck, bottom, and rail), bottom profiles (such as concaves, V’s or rolls), rail form (up, down, 50/50, boxy, knife, soft, etc. etc.), foil thickness right through to the basic plan shape or template. So, rocker may just be “the single most important feature in the design of a surfboard”, but the art or manner in which these curves are blended, merged or conjugated is of equally high importance. In considering the points above, I feel that it is better to state that a well designed bottom rocker that is both functional and in tune with the design parameters on a whole is the foundation in the search for that “magic board”.
In my search I have identified three basic Bottom Rocker forms categorised as: (1) Continuous curve, (2) Staged and (3) hybrid. I have designed my rocker around the continuous rocker concept and hence will explain very little, if anything about the other two forms.
As the name implies, continuous curve rocker is a bottom profile with no flat areas that commences with tighter curves through the nose and entry area of the surfboard and in turn are developed to flow into curves of a larger arc in the mid and tail section of the board. The primary design concept in the application of a continuous curve rocker is to enhance or create a smooth transition in and out of a turn. As for all three rocker types, many governing factors such as the length, cord thickness and other relevant curves that exist as previously outlined above must also be considered in order to develop a functional profile that benefits the overall design.
My understanding is that when continuous curves are applied to the design of a bottom rocker for a Longboard it’s done in such a way to produce a curve that is flatter through out. The flatter rocker inherent in the design of the nose and mid sections of a Longboard helps to develop the trimming area of the board. The curves positioned behind the peak of the rocker curvature are primarily for turning purposes although often adjusted to influence the riding performance or characteristics; ie. Symmetrically centred boards diverge and ascend about the central point or centroid of length, where as boards designed with nose riding as a primary function generally have the maximum width or wide point shifted behind the centroid of the length and conversely exiting rocker curves are initiated beyond this point. In the case of a nose rider, tighter curves are generally utilised in the tail (referred to as tail rocker or tail lift) to encourages such things as water flow over and around the rails (highly dependent on rail rocker and profile) and in doing so induces a drag force that impairs maximum velocity and in part causes the tail to be sucked into the wall. In turn this aids or in some instances enables a board to be ridden closer to the curl. Cutting it short, this addition of tail rocker benefits nose riding for a number of reasons and therefore should be considered and applied if nose riding is a functional aspect of your design.
Some basic rules to rocker, by Dave Parmenter, February 2001 (taken from: SURFLINE)
Some basic 'rules' concerning rocker are as follows: The more rocker or bottom curve that a board has, the looser (but slower) it will be. Water flow has to follow the excess curve, ends up pushing water, and drag is the result. Flatter rocker brings more speed but brings a decrease in manoeuvrability. Generally, boards with more rocker work better in larger, hollow waves where the added curve and drag can contribute to more control for the rider. Flatter bottoms are normally used on small-wave boards designed for slower, mushier surf, where the speed (and added leverage) helps keep the board planning.
As with every other aspect of surfboard design, the best option lies in the happy medium of compromise. The better-designed surfboard steers clear of extremes and finds that an even, neutral rocker serves best: flat enough to be fast and efficient, but with enough curve to let the surfboard fit into the curved face of the wave and allow for the tight turns that are the mainstay of performance surfing.
A section taken from SCSURFERS site, entitled: What rocker does, one by one, comments geared towards longboards:
Nose rocker - more here makes a board resistant to nose diving or pearling. Less rocker here makes a board go faster and stall less, easier paddling as the board glides through the water, not pushing the water. Less rocker here is better for nose riding, rocker all the way through; generally slows it all down some, but makes a board turn well.
Tail rocker - makes a board turn real well, easier drops into the wave for a speedier entry, and also aids in nose riding... but pays a large speed penalty due to drag both while riding and paddling.
The best is a combination of all. Modern boards need to be able to turn to get speed, so tail rocker is important, and it's not exactly true that "flatter is faster" on a wave, maybe on flat water with a sailboard, but not on a wave.
posted by GRUB at 12:41 pm
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