Note: These excerpts are taken directly from ‘Board Design Theory - Shaper’s Journal’ 2004 by Steve Coletta - Natural Curves Surfboards
Useful definitions for surfboard design
Surfboard Design – Arranging or modifying the performance and durability of a surfboard to be functional and relevant to surfers and the waves they ride.
Design Variables – The elements of design describing the components of a surfboard. Template – The outline of the surfboard.
Rocker – Dimensional lines along the bottom, top, and rail of the surfboard usually referenced from nose to tail.
Bottom Rocker – Dimensional curve following a line along the bottom of a surfboard.
Deck Rocker – Dimensional curve following a line along the top of a surfboard. The area defined by plotting bottom and deck rocker defines the foil or thickness flow of a surfboard from nose to tail.
Rail Rocker – Dimensional curve along the rail of a surfboard. This line follows the outline and the bottom of a surfboard's rail(s). The relationship between a surfboard's bottom rocker and rail rocker helps define the bottom contours of a surfboard.
Bottom Contours – The nose to tail and rail to rail configuration of the bottom of a surfboard. Bottom contours may be flat, convex, concave, or a combination of these.
Deck Contours – The nose to tail and rail to rail configuration of the deck of a surfboard. Deck contours vary from flat to crowned.
Rails – Transition area between the bottom and deck of a surfboard configured for various performance options.
Rail Profiles – Section shape of the rail. Rail profiles vary in configuration and dimension. Configurations includes round, boxy or square, and crowned profiles. Dimensions vary from relatively thin, to medium, to thick and apply to all configurations.
Foil – Distribution of volume throughout a surfboard.
Foil (primary) – Thickness flow or distribution of volume along the center of a surfboard from nose to tail.
Deck Foil – Thickness flow or distribution of volume from side to side or rail to rail of a surf- board. The deck foil also varies from nose to tail.
Rail Foil – Thickness flow or distribution of volume along the rail of a surfboard from nose to tail.
Blank – Core of the surfboard. From ancient to contemporary surfboards cores have been solid wood, hollow (chambered), hollow (transverse braced), EPS foam, extruded styrofoam, and polyurethane foam (PU).
Stringer – Wood, foam, plastic, or reinforced plastic element glued into the center of a blank on a vertical axis. Stringers provide a crucial "I-beam" element to the "core" of a "foam sandwich." They reinforce the ultimate strength of a surfboard by holding the top and bottom "skins" of the "foam sandwich" apart.
Fiberglass – Fabrics of various weave, finish, and weight used as the reinforcement in a plastic matrix. When combined with a resin system the resulting composite forms the "skin" of a "foam sandwich" surfboard.
Resin – A material, generally a polymer, that has an indefinite and often high molecular weight. Resins are used as the matrix that binds together the reinforcement materials in composites.
Glassing Schedule – The arrangement of fabrics and resins included in the "skin" of a "foam sandwich" surfboard.
Curing – Time length of time a catalyzed thermosetting resin system retains a viscosity low enough for it to be suitable for processing.
Curing - Post Cure – Exposure of cured resin to higher temperatures to improve the mechanical properties of the resin system in the "skin" of a "foam sandwich."
Mechanical Properties – The properties of the "core" and "skin" materials that contribute to the ultimate strength and durability of a surfboard. These include bond, compression, flexural, impact, shear, tensile, and thermal strengths. These properties increase and decrease exponentially as a product of the surfboard's design.
Ultimate Strength – Measure of the ability of a surfboard to absorb energy. The maximum toughness and durability achieved by a surfboard's "design."
Fatigue – The failure of a composite's or a materials's mechanical properties as the result of repeated "stress." Strength to Weight Ratio – The relative relationship between the weight of a surfboard and the ultimate strength of a surfboard. "Custom" surfboard construction allows for the functional and relevant application of foam density, stringer, and glassing schedule. Surfboards may vary from a 4 1/2 pound high performance shortboard to a 20 pound tow in gun, from a light weight performance longboard to a classic heavy weight reproduction of a 50's - 60's era longboard, or may be the moderate and sensible strength and weight of a recreational oriented shortboard, hybrid or funboard.
Rocker is a dimensional curve along the bottom, top, and rail of the surfboard usually referenced from nose to tail.
Bottom Rocker - Dimensional curve following a straight line along the bottom of a surfboard. Bottom rocker is the backbone or foundation of a well designed surfboard.
Deck Rocker - Dimensional curve following a straight line along the top of a surfboard. The area defined by plotting bottom and deck rocker defines the foil or thickness flow of a surfboard from nose to tail.
Rail Rocker - Dimensional curve along the rail of a surfboard. This line follows the outline and the bottom of a surfboard's rail(s). The relationship between a surfboard's bottom rocker and rail rocker helps define the bottom contours of a surfboard.
Rocker is an extremely significant variable in the design of a surfboard.
Bottom rocker is (generally) the first design element a shaper puts into a surfboard. Once the bottom rocker is established the shaper will proceed to add bottom contours and foil the board from nose to tail and side to side, ALL in relation to the bottom rocker. It’s essential that these additional variables compliment the bottom rocker of the board. If these design variables are not in sync, they risk working against each other.
A well designed bottom rocker, functional – relevant – and well executed, is the foundation of a “magic” board.
The Bottom of the Board
There are several bottom contour configurations found in contemporary surfboard design. They may be divided into three primary groups: flat, convex, and concave. All may be applied to any type of surfboard, although most are relevant to specific types of boards.
FOILS / PROFILES
Foils / Profiles Overview
The foil / profile refers to the distribution of thickness of the surfboard. Surfboards are “foiled” nose to tail and rail to rail. The foils / profiles of surfboards vary with the many “classes” or types of surfboards. The foil / profile nose to tail facilitates several performance features of the surfboard – forward movement, momentum and inertia, initiating maneuvers, control of the rails and tail of the surfboard, and support of the surfer's displacement and technique. The foil / pro- file rail to rail facilitates many of the same performance features and others as well – transitions from rail to rail, initiating maneuvers, control and support of the surfer's displacement and technique through maneuvers.
The outline of a surfboard is the distribution and configuration of the surface area of the surf- board. This layout is referred to as the plan shape or the template of the surfboard.
Outlines are often referenced by the configuration of specific elements of the surfboard: the tail (roundtail, roundpin, pintail, squash tail, swallow tail) – the nose (shortboard nose, full nose, no nose, single fin nose, hybrid nose, longboard nose) – or the relative width of the surfboard (narrow board, wide board, narrow nose with wide tail, full nose with tear drop tail.)
Common to small wave boards where the design and performance preference is to maintain significant surface area without the “corner” typical to squash and swallow tails. A roundtail will release a bit easier off the top of a wave than a squash or swallow, but will not be as easy to “square off ” a turn in mid face or off the bottom of a wave.
The smooth curves and the reduced surface area allow this tail template to maintain more control than the roundtail when performing critical maneuvers. The roundpin template is common to a wide variety of short- boards, semi guns, hybrids, and longboards.
Absolutely minimizes the surface area in the tail of the surfboard’s outline. A great tail design where control is the primary design consideration – used exclusively by shapers and designers for large semi guns and big wave guns.
The most common tail template for shortboards, hybrids, and longboards. The squash tail combines maximum surface area (provides lift and generates speed) with a soft squared corner (for control.)
Thumbtails borrow the best of squash tails and round pin tails and morph them into a very functional tail design. They maintain the surface area of the squash and incorporate the smooth transitions of a round pin through maneuvers. The surface area provides lift and speed for a powerful feeling off the bottom. The soft thumb like corners are very forgiving and transition rail to rail with ease.
The swallow tail shares it’s fundamentals with the squash tail. The layout of the swallow tail maximizes surface area – from rail to rail or side to side – in short and mid range shortboards then reduces the surface area between the corners with a cut out area that provides a great deal of control into and out of turns.
Rails are the primary interface between surfboards and waves. The volume and configuration of rails facilitate control, maneuverability, power, and speed. In the same manner as the other primary variables of surfboard design, rail designs will vary according to the design goals of every surfer and the various wave they ride. Rail design is a function of the physical features and technique (board management skills) of the surfer, the various waves they ride, and the other design variables and features incorporated in any surfboard.
Note: These excerpts are taking directly from ‘Board Design Theory - Shaper’s Journal’ 2004 by Steve Coletta - Natural Curves Surfboards