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NATURAL CURVES SURFBOARDS |
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| Bottom Contours 2024 version | Bottom Contours 2012 version |
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BOTTOM CONTOURS |
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November 3, 2024 |
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There are several bottom contour configurations found in contemporary
surfboard design. They may be divided into three primary groups - flat, convex,
and concave bottoms. All may be incorporated in any type of surfboard, although
most are relevant to specific types of boards.
FLAT BOTTOMS Some shapers employ flat bottoms in their designs, but a flat bottom is hard pressed to add any performance features to a surfboard - shortboards, step ups, semi guns, XXL guns, mid lengths and eggs, or longboards. Although fast, flat bottoms provide no lateral stability, lift, or leverage. Bottom contours with flat areas combined with other bottom contours can be an exception. Combined with vees, tri planes, soft rolled surfaces, and concaves, bottoms with flat features move beyond their safe, neutral, vanilla performance features and contribute to developing acceleration, projection, speed, maneuverability, and control. CONVEX BOTTOMS are any combination of rail to rail planes and curves that descend below the rail line of the surfboard. Convex bottoms generate lift and reduce drag by reducing wet surface and maximizing laminar flow. Tri plane entry and wide point to panel vee is a very basic and simple bottom design. Tri planes create lift and reduce drag. It's a very fast bottom, as it planes in the face of a wave with less wet surface, it's very forgiving as it lifts the forward rails out of the water in critical sections, and it initiates turns with ease as the tri plane entry transitions from rail to rail with minimum effort. Panel and spiral vees from wide point to tail also offer fluid rail to rail transitions as well as acceleration, projection, speed, and maneuverability. The combination of tri plane and vee feels like a ball bearing under a surfer. Convex designs provide great lateral stability and control, smooth transitions from rail to rail, and are very forgiving. They handle well at a full range of speeds. They are an excellent design for XXL guns. They are very functional in mid lengths, eggs, and longboards. And, they are functional, although somewhat conservative, in shortboards and specialty shortboards. CONCAVE BOTTOMS are combinations of curves nose to tail and rail to rail that ascend above the rail line. Rail rocker drops below bottom rocker creating concaves. Variations of single and single to double concaves are the primary bottom contour configurations in the modern shortboard. Concaves are one of the most complicated and contradictory design components in surfboard design. Consideration of other design variables of the board is essential to decisions about the arrangement, depth, and placement of concaves. Imagination and experimentation, trial and error, testing and observation yield efficient multiple concave bottoms. When a surfboard moves over water concaves produce lift with laminar flow channeling water under the board. Concaves produce additional lift when water runs under the bottom of a surfboard through the tail. Here the board's outline curves into the tail reducing surface area. The water flowing through the tail under the board is compressed into less surface area creating additional lift. Try placing both sides of a spoon under a faucet of flowing water. The concave side of the spoon pushes away from the flow of water. The convex side of the spoon sucks into the flow of water. It's a classic example of water moving over a surface and creating either lift or drag ! Working effectively with lift and drag is key to designing concaves into the bottom of a surfboard. Efficient multiple concaves feed water under a surfboard then release water through the fins and tail of a surfboard. When a surfer weights the rail and bottom of a surfboard he compresses the water, channeling it through the concave array. The rocker, template, rail, and fin arrangement provides this compressed water with an avenue of escape - out through the tail section of the board. This phenomena excentuates the power, acceleration, projection, and speed of the surfboard through it's turns. Tuning each variable and their interaction with the other variables determines the performance characteristics of the surfboard. Most concave bottoms are one of two primary concave designs single concave or single to double concave. Single concave features shallow concave or vee in the entry, shallow single concave from entry to wide point increasing in depth to maximum depth just in front of the fins, with concave decreasing in depth through the fins to the tail. The single concave may transition to vee behind the fins. A single to double concave features shallow concave or vee in the entry, shallow single concave from entry to wide point increasing in depth to maximum depth just in front of the fins, and double concave from this point through the tail. The double concave may also transition to vee behind the fins. Holding the other primary surfboard design variables constant, single concaves tend to be looser than single to double concaves and have the potential for greater variation in turning radius. They have more control and predictability. The spine of a double concave offers more lift to the center of the bottom of a board. Single to double concaves have a consistent predictable turning radius. REVERSE VEE BOTTOM designs feature vee in the nose and entry - even optionally to the wide point - that transitions to very shallow vee, flat, or concave bottom contours from the wide point through the fins to the tail. The vee in the front half of the board is deeper than the bottom contours in the back half of the board. Early shortboard designs often featured these or similar bottom contours. The "mini gun" designs of the late 60s that became prototypical shortboards throughout the 70s and 80s often featured vee in the entry, flat or shallow concave from the wide point to near the fins, and panel vee or alternatively spiral vee through the fins and tail. As the down rail shortboard designs of the 70s and 80s evolved it was common for the vee in the nose and entry to be reduced or eliminated entirely and the vee from wide point to tail or in the area of the fin or fins increased in depth. The multiple concave shortboards that evolved from the glass slippers of the early 90s also rarely if ever featured vee in the nose and entry. Reverse vee designs reintroduce convex entry to laminar flow in bottom contours. Bottom contours coupled with rocker, profile, and rails create the laminar flow of water along the bottom of a board. Correct laminar flow maximizes lift and minimizes drag. In reverse vee designs the vee forward transitions to flat or concave contours aft. The vee forward in the design settles a board into the water and the transition to reduced vee, flat, or concave feeds the water under a board from the wide point to the tail maximizing lift, acceleration, and speed. Vee or double concave from the fins to the tail coupled with nuanced rocker and rails releases the water flowing under the bottom of the board reducing friction and minimizing any drag. The performance features of reverse vee bottoms come from the juxtopisiton of the curve of bottom rocker with straighter rail rocker. This combination creates a board that goes rail to rail with ease and provides speed and power through turns. The vee forward in the design creates easy rail to rail transitions and the flat or concave bottom from wide point to tail or between the fins provides controlled and predictable acceleration, projection, speed, and maneuverability. Nuanced tail rocker and rails release water off the tail of the board. Credit to Maurice Cole and Tom Curren for the emergence of reverse vee in contemporary surfboard design. Surf history and culture found both of them living and surfing in Southwest France in the 80s. In 1990 they collaborated on a reverse vee design that was at the core of Curren's trials to title World Championship run in 1991 and became an iconic functional design |
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BOTTOM CONTOUR IMAGES |
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CONVEX BOTTOMS offer more momentum than any bottom contour. By their design and nature they maintain their speed, trim, and glide better than any bottom design. Tri plane contours in the entry and wide point engage waves with less wet surface, create lift, and reduce drag. They initiate fluid rail to rail transitions off the front foot. Panel and spiral vees from wide point to tail also offer fluid rail to rail transitions as well as acceleration, projection, speed, and maneuverability. |
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CONVEX TRI PLANE to PANEL VEE |
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Convex tri plane to vee designs maximize laminar flow and minimize drag. They offer excellent turn and trim features. They are the ultimate bottom design for maintaining and controlling speed. |
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CONCAVE BOTTOMS are the primary bottom design for contemporary high
performance shortboards, step ups, and semi guns. They are created by the
juxtaposition of bottom rocker and rail rocker. They feature more curve in the
rail rocker than in the bottom rocker. Concave bottoms are generally single
concave nose to tail with the concave getting progressively deeper until the
just in front of the fins before fading through the tail, or single to double
concaves featuring the same progressively deeper single concave into the fins
with double concave fading through the tail. Some double concaves feature the
double concave further into the bottom from the tail. When tuned correctly in a
design concaves amplify laminar flow and create lift acceleration, projection,
speed, and maneuverability.
Single concave and single to double concave performance varies moderately. Water flows in a smooth arc from rail to rail in single concaves enabling powerful, stable, and predictable turns. The smooth rail to rail water flow enables maximum controlled power through turns and nuanced turning radii for a wide variety of turns and barrels in different waves. The way water flows from the rail the peak of the double concave at the stringer creates additional lift at the center of the bottom of the board and with it's spine offers directional stability through turns. |
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CONCAVE VEE to SINGLE CONCAVE |
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Concave designs have significant curves and fit into and source energy in critical sections and waves. They offer an exciting and powerful blend of acceleration, projection, speed, and maneuverability. |
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LINK Single and Single to Double Concave Designs Design Topics essay |
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REVERSE VEE BOTTOM designs feature vee in the nose and entry - even common, optionally, to the wide point - that transitions to very shallow vee, flat, or concave bottom contours from the wide point through the fins to the tail. The vee in the front half of the board is deeper than the bottom contours in the back half of the board. Early shortboard designs often featured these or similar bottom contours. The "mini gun" designs of the late 60s that became prototypical shortboards throughout the 70s and 80s often featured vee in the entry, flat or shallow concave from the wide point to near the fins, and panel vee or alternatively spiral vee through the fins and tail. As the down rail shortboard designs of the 70s and 80s evolved it was common for the vee in the nose and entry to be reduced or eliminated entirely and the vee from wide point to tail or in the area of the fin or fins increased in depth. The multiple concave shortboards that evolved from the glass slippers of the early 90s also rarely if ever featured vee in the nose and entry. Reverse vee designs reintroduce convex entry to laminar flow in bottom contours. |
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REVERSE VEE VEE to SPIRAL VEE to SINGLE CONCAVE |
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Reverse vee designs offer generous portions of power, projection, and acceleration. They are most relevant for step ups, semi guns, and XXL guns. Reverse vee designs offer the most power of all bottom contours. |
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LINK Reverse Vee Designs Design Topics essay |
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BOTTOM CONTOURS
November 19,2012 This essay is from 2012. The various flat, concave, and convex bottom contour designs remain fundamental options today. Nuanced variations in bottom contours continue to evolve. |
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There are several bottom contour configurations found in contemporary
surfboard design. They may be divided into three primary groups - flat, convex,
and concave bottoms. All may be incorporated in any type of surfboard, although
most are relevant to specific types of boards.
FLAT BOTTOMS Some shapers employ flat bottoms in their designs, but a flat bottom is hard pressed to add any performance features to a surfboard - shortboards, step ups, semi guns, XXL guns, mid lengths and eggs, or longboards. Although fast, flat bottoms provide no lateral stability, lift, or leverage. Bottom contours with flat areas combined with other bottom contours can be an exception. Combined with vees, tri planes, soft rolled surfaces, and concaves, bottoms with flat features move beyond their safe, neutral, vanilla performance features and contribute to developing acceleration, projection, speed, maneuverability, and control. CONVEX BOTTOMS are any combination of rail to rail planes and curves that descend below the rail line of the surfboard. Convex bottoms generate lift and reduce drag by reducing wet surface and maximizing laminar flow. Tri plane entry and wide point to panel vee is a very basic and simple bottom design. Tri planes create lift and reduce drag. It's a very fast bottom, as it planes in the face of a wave with less wet surface, it's very forgiving as it lifts the forward rails out of the water in critical sections, and it initiates turns with ease as the tri plane entry transitions from rail to rail with minimum effort. Panel and spiral vees from wide point to tail also offer fluid rail to rail transitions as well as acceleration, projection, speed, and maneuverability. The combination of tri plane and vee feels like a ball bearing under a surfer. Convex designs provide great lateral stability and control, smooth transitions from rail to rail, and are very forgiving. They handle well at a full range of speeds. They are an excellent design for XXL guns. They are very functional in mid lengths, eggs, and longboards. And, they are functional, although somewhat conservative, in shortboards and specialty shortboards. The following illustrations show two convex bottom configurations, flat to vee and tri plane to vee. Flat to vee is very simple and common to mid lengths, eggs, and longboards. The flat entry is fast enough and forgiving enough for surfers of all skills. The depth and length of the vee is varied to determine turning radius and provide control at higher speeds or in critical sections. When employed in mid lengths and longboards, surfboards with lots of surface area and volume, the vee helps manage and control the boards' mass. Tri plane to vee is also a very simple bottom, and arguably a more versatile and effecient configuration than flat to vee. The tri plane creates lift and reduces drag. The feature in front of the vee is faster than flat, as it planes in the face of a wave with less wet surface, it's very forgiving as it lifts the forward rails out of the water in critical sections, and it initiates turns with less effort as the surfer leads the surfboard onto rail or from rail to rail. |
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CONCAVE BOTTOMS are combinations of curves nose to tail and rail to rail
that ascend above the rail line. Rail rocker drops below bottom rocker creating
concaves. Variations of single and single to double concaves are the primary
bottom contour configurations in the modern shortboard. Concaves are one of the
most complicated and contradictory design components in surfboard design.
Consideration of other design variables of the board is essential to decisions
about the arrangement, depth, and placement of concaves. Imagination and
experimentation, trial and error, testing and observation yield efficient
multiple concave bottoms.
When a surfboard moves over water concaves produce lift with laminar flow channeling water under the board. Concaves produce additional lift when water runs under the bottom of a surfboard through the tail. Here the board's outline curves into the tail reducing surface area. The water flowing through the tail under the board is compressed into less surface area creating additional lift. Try placing both sides of a spoon under a faucet of flowing water. The concave side of the spoon pushes away from the flow of water. The convex side of the spoon sucks into the flow of water. It's a classic example of water moving over a surface and creating either lift or drag ! Working effectively with lift and drag is key to designing concaves into the bottom of a surfboard. Efficient multiple concaves feed water under a surfboard then release water through the fins and tail of a surfboard. When a surfer weights the rail and bottom of a surfboard he compresses the water, channeling it through the concave array. The rocker, template, rail, and fin arrangement provides this compressed water with an avenue of escape - out through the tail section of the board. This phenomena excentuates the power, acceleration, projection, and speed of the surfboard through it's turns. Tuning each variable and their interaction with the other variables determines the performance characteristics of the surfboard. Most concave bottoms are one of two primary concave designs single concave or single to double concave. Single concave features shallow concave or vee in the entry, shallow single concave from entry to wide point increasing in depth to maximum depth just in front of the fins, with concave decreasing in depth through the fins to the tail. The single concave may transition to vee behind the fins. A single to double concave features shallow concave or vee in the entry, shallow single concave from entry to wide point increasing in depth to maximum depth just in front of the fins, and double concave from this point through the tail. The double concave may also transition to vee behind the fins. Holding the other primary surfboard design variables constant, single concaves tend to be looser than single to double concaves and have the potential for greater variation in turning radius. They have more control and predictability. The spine of a double concave offers more lift to the center of the bottom of a board. Single to double concaves have a consistent predictable turning radius. |
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| DESIGN SPECIFIC BOTTOM CONTOURS |
| SHOTBOARDS and STEP UPS feature concave bottoms. These boards are designed to perform in a wide variety of conditions. Vee or very shallow conacave in the entry transitions to shallow concave at the wide point and deeper single or single to double concave in the tail. The vee in entry settles the board into the water and helps rail to rail transitions. The single concave in leading from entry to mid board creates lift. The deeper concaves from the wide point to tail create more lift and channel and accelerate water under and through the board creating acceleration, projection, planning speed, and maneuverability. |
| SEMI GUNS can feature a convex or a concave bottoms. Surfers will prefer convex or concave bottom contours depending on the power, size, and conditions of the surf. In larger more extreme waves convex bottoms will promote extra control. In more moderate yet still powerful and extreme waves concave bottoms will promote common shortboard perfromance features. Both bottom designs offer a surfer excellent performance in heavy water. |
| Shortboard, Step Up, and Semi Gun Concave Bottom Contours |
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| Semi Gun Convex Bottom Contours |
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| XXL GUNS feature convex bottoms. These boards are designed to be functional and effecient in extreme conditions. Vee in the entry transitions to tri plane in the mid section to panel vee from the mid section to the tail. The vee in entry can cut through the chop and turbulence of wind blown or riptide surfaces or slice into a glassy surface at the speeds developed dropping into XXL waves. The tri plane mid section keeps the board at speed and accelerates the board into the panel vee in the tail. The panel vee in the tail steers the board from rail to rail and holds the board on rail with control and stability. |
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| MID LENGTH and EGG DESIGNS can feature convex or concave bottoms. The Convex versions feature the sublime Natural Curves tri plane to panel vee bottom contours. Tri plane to vee is a very simple bottom. It is versatile and efficient. The tri plane in entry and wide point is faster than flat, as it planes on the face of a wave with less wet surface. It is very forgiving as it lifts the forward rails out of the water in critical sections, and it initiates turns with less effort as the surfer leads the surfboard onto rail or from rail to rail. The panel vee from wide point to tail performs like a ball bering freeing the board for rail to rail transitions and accelerating and projecting a board out of turns. The Concave versions feature subtle concave bottom configuration. These boards are designed to perform very much like a shortboard. Vee or very shallow conacave in the entry transitions to shallow concave at the wide point and deeper single or double concave in the tail. The vee in entry settles the board into the water and helps rail to rail transitions. The single concave from entry to mid board creates lift. The deeper concaves from the wide point to tail channel and accelerate water under and through the board creating acceleration, projection, planning speed, and maneuverability. |
| Mid length and Egg Bottom Contours |
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CONTEMPORARY PERFORMANCE LONGBOARDS feature a convex bottom. Unlike the
rolled bottom nose to tail of traditional classic LBs, contemporary LB's convex
bottom generally feature a tri plane to rolled or panel vee design. Tri plane
to panel vee is very simple, versatile, and efficient bottom. It provides lift,
acceleration, projection, planning speed, and maneuverability. The tri plane
offers the opportunity to introduce concave in the center plane in the nose to
enhance nose riding.
CLASSIC LONGBOARDS and reproductions of the classic surfboards of the '50s and '60s, feature a convex bottom. The longboard bottom design is a displacement hull, moderately rolled from rail to rail and from nose to tail. These boards are designed to glide, trim, and roll from side to side to turn and adjust trim. The convex features hold the board firmly in the face of a wave. |
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LINK
Design Topics - Single & Single to Double Concaves |
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