Editing Surfboard (section)

==Construction==
To achieve positive buoyancy and a stiff deck, shapers have always reached for a foam, often hardened with a tensile skin, using [[toucan]] beak engineering concepts.<ref>{{Cite web |url=http://jacobsschool.ucsd.edu/news_events/releases/release.sfe?id=417 |title=Engineers Discover Why Toucan Beaks Are Models of Lightweight Strength |access-date=2020-03-19 |archive-date=2019-11-14 |archive-url=https://web.archive.org/web/20191114052920/http://jacobsschool.ucsd.edu/news_events/releases/release.sfe?id=417 |url-status=dead }}</ref>

Delamination is a problem where the skin of the board (i.e. fiberglass) separates from the foam core. All surfboards made of foam and resin can face the problem of delamination. A common reason for delamination is excessive heat.<ref>[https://surfngear.com/a-surfboards-big-summertime-enemy-surfboard-delamination/ A Surfboard's Big Summertime Enemy - Surfboard Delamination!]</ref> Delamination often first appears around dents.

Modern surfboards are usually made of foam using one of the following construction materials:
* [[Polyurethane]] (PU foam) with [[polyester resin]] have been used in surfboards since the 1950s, and is, therefore, the oldest of the modern construction methods. Many hand-shaped boards are made of PU since it is a brittle material, making it easy to form by hand using sandpaper, shortening the build time. Both PU boards made by hand or by machines are usually more affordable compared to other foam materials. Some drawbacks are the toxicity of the material, that it is non-recyclable and that the PU foam is more flexible than some alternatives, making the board less stiff so that it can bend and twist more during use. PU foam can also absorb water and yellow over time.<ref name="thoughtco.com">[https://www.thoughtco.com/polyurethane-or-polystyrene-foam-3154881 Surfboard Foam: Polyurethane or Polystyrene Core?]</ref> It is also possible to build PU boards using [[epoxy|epoxy resin]].<ref>[https://www.boardcave.com/the-surfers-corner/pu-or-epoxy-which-one-is-best/ The Surfers Corner - PU or Epoxy: Which one is best?] "As most of us can’t afford a large quiver of boards, one really solid option you can consider is looking at having your board made with PU foam and Epoxy resin. This will give you the trusty feel and performance of your standard board, but with the added strength of epoxy resin instead of polyester"</ref> PU is still the most used material in surf board construction today.
* [[Polystyrene]] (PS foam) with [[epoxy|epoxy resin]] has a lower weight, but is not as strong as the more traditional PU foam. The PS foam core is therefore enclosed with a layer of epoxy to increase strength. Within polystyrene, mainly two types are used in surfboard construction; EPS and XPS. The reason epoxy resin is used exclusively instead of polyester resin on these boards, is that the polystyrene foam reacts chemically upon contact with polyester resin, causing the PS foam to melt. EPS and XPS have the advantages that they are more environmentally friendly, can last longer{{citation needed|date=April 2019}} and are recyclable. However, they are more time consuming to shape by hand, taking for example 2 to 4 times as long to build.<ref>{{Cite web |url=http://www.surfscience.com/topics/surfboard-anatomy/materials/know-your-foam |title=Surf Science {{!}} Know Your Foam |access-date=2019-04-27 |archive-date=2019-05-13 |archive-url=https://web.archive.org/web/20190513214323/http://www.surfscience.com/topics/surfboard-anatomy/materials/know-your-foam/ |url-status=dead }}</ref> Often PS boards are not as stiff as PU boards, which may be the reason most professional surfers still prefer PU.
** [[Polystyrene#Expanded polystyrene (EPS)|Expanded polystyrene]] is the lightest foam material commonly used to produce surfboards today, being lighter than both PU and XPS. A drawback to EPS is that it is difficult to shape by hand, and EPS boards are therefore typically made using machines where the shaping of the foam is near completed after the molding itself. It is possible to buy such semi-finished EPS boards (known as "pop out boards") to which the buyer can add glassfiber and resin themselves. Another drawback with EPS foam is that it absorbs water more easily. EPS has a structure consisting of individually closed cells, but there are air gaps between the cells themselves where water can enter. This gives EPS a higher [[Permeability (earth sciences)|permeability]]. EPS boards typically don't delaminate easily, but should be constructed using a vent to prevent delamination due to [[outgassing]].<ref>[https://www.soulrsurfboards.com/help/why-do-stand-up-paddle-boards-have-air-vents Why Do SUPs have Air Vents? Difference between Hassle Free Air Vents & Screw Type Air Vents on Stand Up Paddle Boards]</ref>
** [[Polystyrene#Extruded polystyrene (XPS)|Extruded polystyrene]] (XPS foam) is somewhat heavier than EPS, and usually weighs as much as PU or more.<ref>[https://www.sanded.com.au/pages/core-basics Surfboard blanks types of EPS PU and XPS cores and blank – Sanded Australia]</ref> XPS has a homogenous structure consisting of several layers of continuously extruded closed cells. XPS therefore resists water absorption very well, since there are no air gaps between the beads. Depending on construction, XPS boards may however be more prone delamination due to the closed structure preventing the epoxy resin getting a good grip on the foam.<ref>[http://epoxysurfboards.com/epoxy-101/ EPOXY 101 - Epoxy Surfboards]</ref> Improvements in manufacturing has alleviated some of these problems.<ref name="thoughtco.com"/> XPS boards typically don't have a vent.{{citation needed|date=April 2019}}

Fiberglass is the most common skin regardless of foam type. Other skin materials used are [[bamboo]], [[carbon fiber]], [[hemp]] [[kevlar]] and [[Innegra S|innegra]].<ref>[https://www.sanded.com.au/pages/skin-basics Skin Basics – Sanded Australia]</ref>

EPS and XPS boards are sometimes erroneously referred to as "epoxy boards", while PU boards sometimes are erroneously referred to as "fiberglass boards". These designations are not correct. Firstly, fiberglass is the most common skin for all the mentioned foam types. Secondly, PU foam boards can also be constructed using epoxy resin.<ref>[https://www.sanded.com.au/pages/surfboard-resin-basics Resin Basics – Sanded Australia] "Cores: Epoxy can be used on PU, EPS and XPS cores"</ref>

===Polyurethane (PU) boards===
Surfboards have traditionally been constructed using [[polyurethane foam]] and it remains a popular choice. They are made stronger with one or more stringers going down the middle of the board. The foam is molded into a "blank", in the rough shape of a surfboard.<ref>Recently, the largest producer of these blanks, [[Clark Foam]] announced its [http://surfline.com/surfnews/article.cfm?id=1618 Surfline.com closure]. This move drastically affected surfboard production and has become known to surfers as Blank Monday or Black Monday.</ref> Once the blanks have been made they are given to shapers. Shapers then cut, plane, and sand the board to its specifications. Finally, the board is covered in one or more layers of [[fiberglass]] cloth and resin. It is during this stage that the fins or boxes for removable fins are attached and the leash plug installed. Another method of making boards is using epoxy resin and prolapse [[polystyrene]] foam, instead of polyester resin and polyurethane foam. In recent years, surfboards made out of [[balsa]] and a polystyrene core are becoming more popular. Even solid balsa surfboards are available.

Although foam boards are usually shaped by hand, the use of machines to shape them has become increasingly popular. Vacuum forming and modern sandwich construction techniques borrowed from other industries have also become common. Many surfers have switched to riding sandwich-construction epoxy boards which have become especially popular with beginner surfers as they provide a durable, inexpensive, entry-level board.<ref>{{Cite web|url=http://www.westcoastsurfmag.com/equipment/10507_surfboards_foam_feature.php|author=Ben Perreira|website=westcoastsurfmag.com|title=Apocalypse to epoxy, from Clark Foam to the New Standards of Surfboard Production |access-date=2008-11-04}}</ref>

===Balsa boards===
[[Image:Riley-MiniMal-Allrounder2.jpg|right|thumb| Balsa MiniMal.]]
The [[Ochroma pyramidale]] wood's surfboard history originates in the Hawaiians, and the wood lead surfing's landfall on the US west coast in the 1940s. Being light and strong, balsa wood was long considered a perfect material for surfboards. Shapers could not use this fragile wood to make entire surfboards until after WWII, when fiberglass skins were invented.

Balsa wood boards are lighter, more buoyant and easier to handle than other boards. These boards have some disadvantages, however: they are not as sturdy as solid redwood boards.

===Hollow wooden boards===
Hollow wooden surfboards are made of wood and [[epoxy]] or oil (as a sustainable alternative to epoxy), and are a reversion to using wood after the foam became dominant in the 1950s. Hollow wooden surfboards specifically have no foam in their construction. (Boards made with foam and wood are commonly known as ''compsands'' or ''veneer boards''.) Various construction methods are used to hollow the inside of the surfboard and lighten the weight of the completed board. Generally, a hollow wood surfboard is 30% to 300% heavier than a standard foam and resin surfboard. The main inspiration, apart from beauty, is that this is a more environmentally friendly method of construction (compared to epoxy and polyurethane methods) which uses fast-growing plantation wood such as [[paulownia]], [[Cedrus|cedar]], [[spruce]], [[redwood]], and, of course, balsa.

The current construction methods descend from the 1930s Tom Blake [[paddleboarding]] method, which favors a central stringer with individually shaped transverse ribs covered with a skin and rails. A modern interpretation of Tom Blake's work is the perimeter stringer method used by some manufacturers, utilizing laminated rails as stringers connected with a series of plywood ribs. This skeleton is then sheathed with 5mm-thick wood strips, creating a fast hollow board with good flex properties.

The parallel profile system was developed from cold molded (double diagonal) boat building, and uses at least four layers of material laminated over a male mold into a curved blank, including enough wood for rails, which are then shaped.

The chambering method follows a system in which planks of paulownia wood are selected and the rocker of the board is cut into each. The planks are then chambered to reduce weight, and then bonded together to form a hollow or "chambered" blank.

===CUSH - skinned surfboards===
One of the most recent modern advancements in surfboard technology is the creation of high performance boards which are wrapped in a stretchable soft skin which does not absorb water.  The internal structure of Cush (cushion) boards is an epoxy surfboard with an EPS (extruded polystyrene) shaped foam core. The "skin", made of a gloss coated foam, is stretched and adhered while vacuumed over the  surface of the entire epoxy surfboard. The purpose of the cush is for dampening of chatter, absorption of impact landings, airs, grip, and overall added protection for a light epoxy board.  Jim Richardson, 25-year veteran shaper on the North Shore of Oahu, first pioneered this technology in the mid 1990s. And recently a few company's including Spacestick, Radiowake and CUSH (brand) have begun to market the advancements to the surfing community. Spacestick and CUSH surfboards are the current manufacturer for the various brands as of 2018.

=== Composite Sandwich Construction ===
The Composite Sandwich type of board construction became popular among garage shapers and later, major manufacturers, during the 1990s and 2000s. This construction method entails hand- or machine-shaping a foam blank from EPS foam and then vacuum-bagging or hand-laminating a more dense layer of foam, wood, or carbon onto the bottom and deck of the EPS foam core, usually separating the two layers with lightweight fiberglass cloth (2&nbsp;oz&nbsp;pr.&nbsp;sq.yd, or 70&nbsp;g/m<sup>2</sup>) or other composites cloths. This can also be accompanied with parabolic rails made of balsa or other buoyant woods, carbon, or other high-density materials. This blank construction is then laminated with epoxy resin and fiberglass or other composite cloth as any other surfboard would be, by hand or via vacuum bag.

The construction is referred to as a sandwich as it consists of the top skin, fiberglass or other composite cloth, the EPS core, fiberglass or other composite cloth, and the bottom skin, the cross section of which appears as a sandwich with the different layers. Firewire Surfboards pioneered this technology for the mass-produced surfboard market beginning in 2006.

Soft skin construction, such as Cush or Spacestick boards, adds an additional soft shell skin to the outside of a sandwich construction board.  The soft skin is vacuumed to the cloth and epoxy so that the soft shell is exposed--- meaning the hard glass and resin are protected inside, and under, the soft cush skin.