How to Build Your First Surfboard
by Stephen Pirsch

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It seems there has never been sportsmen more image driven, or immersed in confusion than surfers.  This section will attempt to provide clarity to surfboard design subjects, submerged in controversy.


Contrary to popular belief, (all other things being equal) lighter materials will not usually add enough floatation to justify a smaller surfboard.  It is misleading to think of the floatation of a surfboard with no one on it.  A surfboard that is 10% lighter will float 10% better, but this is only when no one is on the board.  The 10% increase is reduced to less than 1% when anyone over 100 lbs. is put on the surfboard.  Example:

10 lb. board minus 10% = 9 lb. board.
10 lb. board plus 100 lb rider = 110 lb
9 lb. board plus 100 lb rider = 109 lb
1 lb.= less than 1% buoyancy increase

The failure to think of the surfer and board as one unit, causes the unhappy case of the missing floatation.

Although many have stated otherwise, two surfboards of the same size and weight will float exactly the same, no matter what they are made of.  This can be proved by weighing the water displaced (Archimedes' principle – Law of Buoyancy).  Numerous people claim that a board made with a lighter core material (usually 2 lb./cu.ft. polystyrene foam) will always float better (board dimensions being equal) than a polyurethane blank (about 3 lb./cu.ft.).  This is only true if the shell material (usually fiberglass cloth and resin) is about the same weight.  If the shell is heavier, (which should be the case, in a well made polystyrene board) the total board weight could be more.  Building with lighter materials does not usually justify using a smaller board (all other things being equal).

Increasing buoyancy in a meaningful, practical way is simple;  lose body weight, or use a bigger board.  Advertisers know no one wants to hear this.


Followers of flex energy transfer state "some boards flex in a hard turn and release this stored energy coming out of a turn, thereby increasing speed."  Most of the arguements about flex are based on personal feeling and are completely subjective (cannot be proved or disproved).  Nevertheless, this is an emotionally charged subject with believers devoting pages of text defending their view.  The importance of flex is convenient for the custom builder, as he can claim to create more or less flex as the customer wishes.  The actual amount of flex in inches is never stated, but measurements on racks indicate it is very unlikely to be more than 1/2".  Everyone appreciates responsiveness, but a custom surfboard that is constructed so lightly as to have notceable flex also has negative characteristics - it will be relatively weak and prone to dinging, denting, delaminating, and breaking.

Competitive snow boarders and skiiers have discovered a shorter, stiffer board/ ski are faster in a timed slalom course than longer more flexible boards/skiis. All surfers who have ridden a comparable hard surfboard, and a soft surfboard (body board construction) agree the soft surfboard is noticeably slower. Most surfers agree a stiff fin is more responsive than a flexible fin. Most other sports have adopted stiffer, stronger materials with a resulting gain in durability, and performance - not so for surfers mired in the flex energy transfer debate.

Recommendation:  Ignor the flexibility debate and make a relatively stiff, durable surfboard (minimum 1-6oz. "E".top and bot.w/ 6oz. deck patch)  If you insist on a lighter board, please read the GLASSING, EPOXY and TIPS chapters, or research boards constructed using "S" cloth, divinycell, vacumn bagging, or injection molding.  A board with the same lightness as a weak, flexible board can be created which is stiff and durable, but it will probably cost more.  Using the forementioned construction methods, your board can be light and reasonably strong, but the flexibility debate will never end. 

Although many will continue to extole the virtues of flex energy transfer, and it could be argued that a durable board with usable flex can be made, the evidence suggests that boards claimed to be flexible are also weak and disposable.


The surfboard building industry is a tough, low profit business.  The big companies need to feature new innovations to boost sales. Sometimes this creates a trend. In 2012 the trend is;  concaves, V bottoms, and quad fins.

Surfing seems more prone to fads than any other sport. First, sharp rails and shallow fins resulted in very loose, snappy turns. To add more control, concaves were added. To compensate for the stiffer turning of concaves, V bottoms were added. To compensate for the loosness of V bottoms, quad fins were added. This seems sily as, a simpler, better solution is to use a flat bottom with slightly deeper fins, but this is not new, and it does not increase board sales. This is not to say a concave, V bottom, quad is no good, only that, perhaps we are lost in small details and are missing the bigger picture. 

Concentrate on finding the length, width, and thickness which is best suited to your weight and waves, then fine tune the rocker and fin set up.  After that, experiment with every new idea you fancy.


It is now accepted that surfboards are going to ding, dent, delaminate, and break.  If a new tennis racket, bicycle, or kayak breaks in normal usage, it will very likely be returned - not so for surfboards.  Almost every surfer loves the responsive feel of a light board, but now it has gone too far.   Although custom builders are simply supplying what customers want, it is more than coincidence that it also gives them more business.  We should demand durable surfboards from custom builders.  This can be done by simply asking for heavier cloth or denser foam, and accepting that there is merit to a slightly heavier board.  

SPEED (in general)

If a surfboard does not have enough surface area (is too small) to flatten out (plane) in the fast part of a wave, it will drag water, and never perform as it was designed to.  On a small, slow wave a bigger board is usually a faster board.  As the size and steepness of the wave increases the surface area of the board needed to reach full plane is reduced.  As a general rule, chest high waves are needed to get a thruster to plane properly.  Although we have all heard that certain boards are faster than others, if a longboard and a thruster achieve full planning speed in the same part of the same wave, (without any maneuvering) they will usually appear to be traveling at the same speed - this can be seen on many films. Although a short board may be seen in a film, passing or accellerating towards a long board this is usually after the short board has accellerated out of a hard turn or steep drop - he quickly decellerates as he aproaches the flater part of the wave.

Yes...speed can be increased through maneuvering in the steep part of the wave.  This increased speed can be demonstrated by skateboarders who use a weighting and un-weighting motion on the sides of empty swimming pool walls.  They can glide for as long as they have energy this way, without ever putting a foot down.  Many thruster riders are well aware of this same weighting and un-weighting, although many longboarders are skeptical.

If we could achieve the speed that a water skier does (or a tow boarder), flotation would become insignificant, and the needed surface area would be similar to a slalom ski (due to hydroplaning).  Tow boards are now aproaching the look of slalom skiis, and surely someone will design a board for paddling into large waves that has a raised ski like platform on the bottom rear (for hydroplanning at high speed) - this has already been done on sail boards.

One reason a small board sometimes feels fast is because it will only ride in the fast part of the wave.  A bigger board will catch a wave before it gets steep, and build up speed more gradually, (as the wave gets steeper) thereby feeling slower.  Most of the design features which are associated with a fast board are actually for control at high speed (narrow outline, more rocker, etc.).  These features may actually slow the board down (this is often not apparent because there may be so much wave energy, only a very small part of the board is contacting the water).

Speed is almost totally dictated by the wave. Although many surfers will swear one board is much faster than another, in the size waves most frequently ridden by recreational surfers, there is very little straight line speed differences in surfboards at full plane. It will be more advantageous to design for maneuverability than speed.


Thrusters are great for a very fit, lightweight surfer who surfs mostly chest high plus, hollow surf.  Consider that thrusters do not have enough planning surface and flotation for the average surfer, in average wave conditions, to be able to effectively utilize the design.

Longboards are great for a surfer who moves around a lot on his board and surfs relatively small, glassy surf.  Consider that a surfer needs to step forward at least two full steps after standing or turning to achieve full plane on a longboard.  Few surfers do this. Most longboards are noseriders, and are very flat.  The lack of curvature, causes the nose to go under water when planing in moderately choppy surfing conditions or when dropping down a steep wave.


Surfboards with sharp downturned rails sink into the wave and hold in better in fast, steep conditions. Sounds reasonable does'nt it? All surfers have heard this repeated so much it has now become conventional wisdom. Exactly the opposite is true. Round rails cause water to wrap around the rail, sucking the rail into the wave face - this tends to stabilize the round rail board in steep surf. Yes, round rails suck. This has been tested in wave tanks with strain guages and photography. Sharp rails release more easily, this is why they turn faster. Sharp rails tend to slide out in big, fast, steep conditions. When designing exclusively for big, hollow conditions, make the rails round or eliptical, the bottom convex, and the fins deep - the trend is sharp rails, concave bottom with added V, and three, or four shallow fins.

Round rails have other advantages. Chops and other uneven surface water tend to slide under the rail, where a sharp railed design tends to cut into the chop, sometimes causing a fall. Also; round rails make it easier to tilt the rail into the water, which wide tails tend to resist. Although sharp, downturned rails are much better for ripping and carving, for the type of surfing the small wave design was made for, a round rail is preferable.

Do curved fins suck? Yes, they do. A fin with straight lines releases water easier than fins with a conventional curved shape. This has been tested in wave tanks with strain gauges and photography. When designing for easier turning in mostly chest high or less surf, make a fin that is more upright, (rake - 20 degrees from perpendicular) with straight lines (a parallelogram). See SMALL WAVE DESIGN.


Is the idea of progressive surfing actually causing the general surfing public to regress? Probably never in surfing history have such a high percentage of surfers rode such a low percentage of waves. This is often due to surfboard choice, but it is more than that. The problem stems from a state of mind. Although a comparitively short, thin, narrow board will generally perform better in chest high plus, hollow surf, this is also generally all it is good for. It has now become normal to see shortboards completely submerged and progressive longboards half submerged. The high performance surfer has, whether he knows it or not, decided to sacrifice most of the waves in the world, and even most of the parts of the best waves. He must stay in a very tight area, on a very specific type of wave - the best area, yes, but if the wave significantly slows down, or speeds up, he is, compared to a surfer with a larger board, out of luck.
Not only does the progressive surfer use retrictive equipment, but he restricts himself in the length of ride, often opting for some vertical manuever that reduces his forward speed, and leaves the surrounding surfers looking at another unridden wave. Simply riding the wave seems unthinkable.

Some say, "It is all just for fun. What does it matter?" Yes, but what the surfing public thinks is surfing, is highly influenced by the media, which portrays surfing as riding big, hollow waves, doing tail slides and aerials.

Be one of the few who discard the media enhanced notion of progressive surfing. There is a wonderful world of uncrowded, and easy to ride waves waiting for those who do.


My friends and I believe that the vast majority of surfboards made today are nowhere close to the optimum design for the average surfer.  Much of this is due to the (passive) influence of pro surfers on surfboard design, and the desire of surfers to have a pro surfer replica board.  This is unfortunate.  Pro surfers are generally smaller than average, surf mostly hollow waves, and surf mostly for points (almost totally maneuver oriented).  Maybe something made specifically for a surfers weight, waves, and style would be more suitable than a pro replica board?  Could it be that something other than a thruster or a nose rider would be a better choice?  What design might be a better choice for the small, choppy waves so common world wide?  What design might be a better choice for less than hollow chest high plus waves?

We believe a design with the surface area and flotation of a longboard which is compressed into a shorter, wider, thicker shape is better suited to the average surfer.  This design allows for easy paddling, yet can be more easily turned and planed from one position on the board.

There is no one optimum board.  The optimum design will be different for each person and each type of wave.  Allow a suggestion however;  a generally wider, thicker shape.  Although the small wave design is not optimum for fast, powerful surf, the average surfer may derive some benefit from a modification of the design.  With an open mind, the average surfer will find a compromise of the measurements from the SMALL WAVE DESIGN chapter useful.  A surfer used to a 9' longboard could transition to an 8'6" x 25.5" x 3.25" small wave design for a 170 lb. rider.  If this is too extreme to accept, consider using the measurements from a favorite longboard shape, changing the length to 8' 6" and the thickness to 3.25" for a 160 lb. rider).  For each 15 lbs. of body weight change, add or subtract 1/4" in total board thickness (through most of the entire board - not just the middle).  A thruster could be designed 1/4" thicker and/or 1&1/2" wider.  Note:  the small wave design measurements (same length and thickness) support a heavier surfer (use 20 lbs. per 1/4" change) because the board (especially the tail) is much wider.  Please refer to the DESIGN chapter for more information on how to adjust measurements.

A surfer can make, or have something made, which is more suitable than what is pre-made in a shop.  This is especially true for surfers over 160 lbs.

Depending on pro's to help guide you to good equipment is not a good idea in surfing.  You could ride Armstrongs' bike.  You could hit a tennis ball with Federers' racket.  You could hit a baseball with Bonds' bat.  However, many surfers would not catch one wave with Slaters' surfboard.

Surfboard design is a fascinating subject.  If you have any design ideas, would like to discuss design, or need some help, email


2003 by Stephen Pirsch, All Rights Reserved.

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