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Surfboard Design

Surfboard Design


Welcome to the Extremehorizon surf shop guide to essential surfboard design.   You should find all the information you need to gain a better understanding of surfboard design, surfboard construction and dynamics.   Surfboard design and construction can be a complex area to cover and one that is continually developing.   Here we have gathered information from various sources to provide you with a concise guide to the main elements which should give you a better understanding of the surfboard you are riding and how its shape and design effects the way it handles.

Surfboard Construction

Shaping a Surfboard We are going to concentrate on "traditional" custom PU foam surfboards, which are surfboards shaped by hand using materials and methods originating from 1958 when Hobie and Clarke began using foam blanks.

Essentially a surfboard is made by taking a foam blank, which is shaped to the desired design and covered with a fibreglass fabric, which is sealed with an epoxy resin:


Foam Blanks

The foam is a lightweight, cellular plastic material containing gas-filled voids.   Surfboard foams used by surfboard makers include, polyurethane (most common) expanded polystyrene, extruded polystyrene and styrofoam.   Surfboard blanks can be ordered in any number of shapes, thicknesses, densities, with preset or custom rockers.   A blank is usually strengthened by the addition of one or more stringers.

A Stringer is one or more strips of strengthening material, typically wood, glued vertically into the foam of a surfboard blank, typically basswood, spruce, balsa, red cedar though it may also be a glue line stringer of paper plus coloured adhesive.
Surfboard Foam Blanks


Fiberglass Cloth

Fiberglass Fabric and Epoxy resins

This is a cloth woven from glass strands gathered into yarns, available in various weights, patterns and finishes.   The fibres are similar to wool or cotton fibres, but made from glass; sometimes called fibrous glass.   When making a surfboard there are a range of glassing options as different types of glass having different strengths and weights/densities.   A typical longboard will come with a 6 oz bottom and one 6 oz and one 4 or 6 oz top and maybe another 4oz or 6 oz deck patch (extending 2/3 of the board) to cover the tail area where you spend most of your time on the board.   The less glassing used the lighter your board will be, but this will make it more prone to dings, delamination and breakage.
Epoxy Resins are used to coat and seal the fiberglass cover.


Surfboard Shape

Outline/template

The template or planshape is the outline of a surfboard viewed from overhead, with the nose at the front, rails down the side, and tail at the back.   Templates are used for the initial outlining of a foam blank by marking out the desired outline, which is then sawed out of the blank.

Surfboard Outline

Rails

Rails are the edge of a surfboard, where the deck and the bottom meet.   Rails are a critical part of surfboard design as the shape affects how water flows over the rails.   The softer the rail the more the surfboard will hold its "track" in the wave and reduce turning ability- you'll find softer rails on more traditional longboards.   The harder the rail will produce a board that produces quicker, tighter turns and increased acceleration.

Soft rails are relatively round and without defined edges.   Hard rails have a corner and a distinct edge.   Rails can be described proportionately, e.g. 50/50 rails, which means that the widest point of the rail is 50% up from the bottom, or 70/30 rails, in which the apex is 70% down the rail, or 30% up from the bottom:
  • Round Rail - Round, semi-circle
  • Egg Rails - Like round rails, except drawn out a bit so they bite in and help hold an edge on a wave
  • 50/50 Rails - Drawn out even more, with the 'point' in the middle of the rail, about halfway from deck to bottom
  • 60/40 Rails - Same as 50/50s, but the 'point is just a little lower down towards the bottom
  • Down Rails - The 'edge' of the board, is right at the bottom.  The rest of the board eases over to it
  • Rolled Rails - They are down rails, but rolled under
  • Soft Rails - Has a radius of at least half an inch
  • Hard rail - May have a radius of 1/8 inch or less

Rocker

Basically, rocker is the curve along the bottom of the board.   Some of the newer foam blanks have natural rocker built into the boards and generally the board doesn't need to be shaped down as much.   Rocker is placed in a blank when the stringer is glued in.   The blank is cut in half, insert the stringer and glue it back together.

Rocker can be differentiated between nose rocker, midsection rocker, and tail kick.   They all contribute to tuning your surfboard for particular wave types and styles of surfing as they are blended together.   The shape of the rail and vee also add into this equation.

Surfboard Rocker

Tail Kick

Tail kick is crucial as it has the biggest lever arm.   More tail kick brings the front of the board out of the water when you stand on the tail and makes a board turn well and produce easier drops into the wave for a speedier entry....but it also pays a large speed penalty due to drag both while riding and paddling.

Mid-section rocker

The mid-section rocker is where your accelerator is placed, if it has one.   Flat being faster.   Most shortboards don't have flat speed sections because speed is generated by turning and pumping.   They have much tighter turning radius for top to bottom, slash and burn surfing.   You will find less mid-section rocker in boards designed for fast, down the line, point break waves.

Nose Rocker

For longboards more rocker here makes a board resistant to nosediving or pearling.   Less rocker makes a board go faster and stall less and provides easier paddling as the board glides through the water, not pushing the water.   Less rocker here is better for noseriding.&nsbp;  For shortboards extra nose flip will allow you to surf steeper waves and drop in late.   Having soft rails in the "catch zone" in conjunction with a fair amount of nose flip makes a board more forgiving in these situations.

Fins (skegs)

Surfboard Fin Bolt Fins provide lots of potential to change surfboard performance and evolution.   The increased use of removable fin systems like FCS and Futures has led to a lot of the innovation in fin design.   With these systems, fins can be easily swapped in and out with a screw or snap allowing surfers to try lots of different fin combinations whereas traditionally you would have to reglass the fins on the board.

Longboards have traditionally been single fins, but many modern boards are tri-fins with a large middle fin and two small side fins.   When ordering a board, the most versatile setup is two side plugs for the small fins and a large box in the middle.   This way you can switch around if need be to a smaller or larger middle fin with or without sidefins, or switch to only a single centre fin.

An ideal longboard fin accessory is the Northcore Bolt which allows easy adjustment and removal of your centre fin with the need for a screwdriver.


For longboarding a long fin helps keep the board from spinning out or side slipping as well, but it will also affect the looseness during turns.   8-10" will probably do fine for a single fin and tri-fin can go from 4-8" centre fins with 3-4" side fins.

Cutaway fins are relatively narrow at the base compared to the tip of the fin and are far looser than full fins.   The shorter the fin, the less drag in turns.

The placement of the fins will effect turns a lot.   It has a lot to do with the idea of a "sweet spot".   There will be a spot where you place your back foot that gives you the best turning responses.   A big spot is best because you don't have to be in the perfect spot to get the responsiveness you want to have.   Subtle changes (1/4") in fin position can make a big difference.   Moving the middle fin forward in the box will help with trim speed and help loosen up the board.   Unless you put it so far forward that you must do more rail turns (on the softer part of the rail) than fin turns and the board may also spin out more often.   Moving the fin back will increase stability to help with nose riding.

Most single fins are placed a little farther back than the middle fin on a tri-fin setup.   The reason being it's the only fin you've got and if it is spinning out on turns or while you're on the nose you generally lose control.   On three fin longboards, the more you move the fin towards the side fins, the looser the board will be (for small waves), towards the back the more it will hold in and draw out your turn (for bigger waves).   Using a big retro fin with side fins may be counterproductive, as you would have too much total fin area, more than you need, and thus causing needless drag.

If your into nose-riding, go with a big middle fin only.   Side fins create wobble when you're up on the nose, and this is even more the case when you have a low-aspect centre fin like in a standard thruster setup with three fins of equal size.   The longer and higher-aspect ratio and farther back in the box your centre fin is, the more it will anchor the tail of your board in the curl of the wave.

The side fins work because they are toed-in which causes drag, which causes tail lift getting you into the wave earlier.   They also loosen up a board by putting higher pressure on the outside edge of the fin and helps keep the board from heading straight in and makes boards react quickly and appropriately to direction changes.

Tail Shape

The major difference in tails is the width or volume.   A wider tail with rocker catches waves easier, because it lifts up with the wave, and provides a quicker plane and start.   Narrower tails give more control and holding power especially in steeper waves, but can drag in smaller weaker surf.

The two basic tail shapes are pintails and square tails.   Everything else is a variation on these.   Round tails, rounded pins, swallow tails, fish and diamond tails are just designs that go in between.
Surfboard Tail

Pintails are pointed and you will see guns that are extreme examples of this design but you will also see them on longboards.   People who prefer them claim that they get very smooth turns and cutbacks and also much more hold in steeper/hollower and bigger waves.   Again pin tails will get in the way on smaller, mushier surf.

Square or squash tails are flat at the back.   The squash tail design is related to shortboard design, and refers to the widest part of the board being near the tail.   The more volume and planing surface you have at the tail, the more there is to push against to do fast, precision flicky turns.   Vice-versa, the less you've got, the more you'll need to turn from the rails.

Bottom Shape

The shape of the base of your surfboard also affects the way it rides.   The variation in bottom shapes is almost limitless.   Essentially a surfboard can have "V" in the tail, textured bottoms, concaves or channels but these tend to be high performance features that shouldn't come into the equation if learning to surf.

Nose concaves are designed to provide lift so that you can nose ride longer.   Single or double concaves towards the tail of the surfboard also generates lift, but in the tail it helps the board plane earlier thus getting up and riding earlier on the wave.   Concaves add surface area to the part of the board that is in constant contact with the water for early planing.   Besides lift, concaves also create some drag.   Channels towards the tail of boards basically attempt to increase the speed of the board.   Lots of "V" in the tail will help cut through chop especially on big wave boards and it may affect turning ability.

Essentially, if you find something that works for you, go with it, otherwise stay with a basic bottom.

Board Thickness

In general terms the thicker a surfboard, the more float it has and will be easier to paddle.   A surfboard can be shaped with a combination of thicknesses to best suit the rider.   A thicker board will of course add weight which will add strength but reduce manoeuvrabilty.

Width

Wider boards are more stable but a narrow board will be quicker to turn.   The width in the centre of the surfboard is the most critical.

Length

Length influences the board as a longer board provides a greater surface area which in turn equates to more "glide", more sustainable momentum, faster to paddling and faster wave pick up.

Leash Plug

Plastic inserts set into the deck of a board at the tail, usually with a plastic or stainless steel crossbar. A number of different varieties are available. There's also an innovative product available called the Lockjaw Surfboard Lock to lock your board when leaving it or travelling, which locks using the leash plug.

Surfboards Types

In the most basic terms there are five main types of surfboard: The shortboard/thruster, a longboard/mal, a gun, Stand up paddle board and a fish.

Shortboard

The Thruster was invented by Simon Anderson, of Australia and is a smaller, performance surfboard generally in the 5 to 7 foot range, designed for maximum speed through turns.

Fish

Developed by Steve Lis in San Diego, CA, the fish was a short, thick, wide board with a deep and rounded swallow tail, keel fins, little rocker, and a stubby outline.

Longboard/Malibu

A surfboard distinctly longer and broader at the nose and tail than a conventional "short" board; usually over nine feet in length and 22" or more in width, often with a rounded nose, based on surfboard designs pre-1968.   Longboards were replaced by shorter boards in the late 60's but became more popular again in the late 80's and 90's.

Gun

A special surfboard designed to ride big waves.   Generally longer than normal surfboards so the surfer can paddle faster to catch the bigger, faster moving waves, with a pulled-in tail to handle the high speeds.

The next chapter

Following the demise of Clark foam in Dec 2005 there were many in the industry predicting a disaster of mass proportions- Clark foam was producing a 1000 blanks per day and pretty much supplied the foam for most of the shapers on the planet so what was going to happen when the supply dried up overnight?

Luckily there were some people out there that realised that the release of the Clark grip on the surfboard industry was just what it needed to trigger a much needed change.   Foam board technology is years behind other watersports in terms of materials used.   It's a production method that the industry has used for so long that no one could really break the habit despite the fact modern foam/glass boards are an environmental nightmare and shortboards are often more akin to toothpicks and have a tendency to snap way too easily.   It may be cool in a kind of macho way to show off a snapped board, but when it happens to a brand new board after a couple of sessions it gets to be an expensive boast.

So the overnight disappearance of Clark foam left the door wide open for others to step in and the likes of Surftech and NSP have done just that.   Surftech is owned by Randy French of Santa Cruz who earned a great deal of respect in the development of windsurfing boards in the 1980's which he has continued into the production of his "Tuflite" surfboards.   The boards are manufactured from one off master blanks which are copied using a fused high tolerance core, then hand laminated and vacuum bagged with epoxy and PVC.   French has succeeded in reducing one of the primary problems of foam boards, that of dings and breaks as the Tuflite boards are much tougher and with shapers like Dale Velzy, Donald Takayama, Robert August, Micky Munoz and Reynolds Yater producing shapes for Surftech he is onto a winner.

However the one essential element that composite surfboards have not improved upon is the environmental problem.   All current mass produced and hand shaped boards are toxic, non-biodegradable disaster areas, which is the ultimate irony as we surfers often try to live our lives in an environmentally low impact way.   So the void left by Clark foam has yet to be filled by a mass produced tough, inexpensive, environmentally friendly, recyclable board.   There are plenty of smaller companies working on solutions like bio-foam blanks (Homeblown), back to basics wood (Grain)...sustainable, recyclable boards are the ideal future but when it'll be an everyday reality is anyone's guess?
 
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