Editing Kayak (section)

== Materials and construction ==
{{Multiple image
| total_width = 400
| header = Fiberglass kayaks
| image1=Kajak K1.jpg
| caption1=Carbon-fiber sprint kayak
| image2=Seekajak B.jpg
| caption2=Sea kayak, two-piece fiberglass
| image3=Siukkut tunusummillugu.jpg
| caption3=Custom-made fiberglass-on-frame kayak (kayaks in background are two-piece fiberglass and skin-on-frame)
}}

Today almost all kayaks are commercial products intended for sale rather than for the builder's personal use.

Fiberglass hulls are stiffer than [[polyethylene]] hulls, but they are more prone to damage from impact, including cracking. Most modern kayaks have steep V sections at the bow and stern, and a shallow V [[amidships]]. Fiberglass kayaks may be "laid-up" in a mold by hand, in which case they are usually more expensive than polyethylene kayaks, which are rotationally molded in a machine. The deck and hull are often made separately and then joined at a horizontal seam.

[[File:20190414 Spade Kayaks.jpg|thumb|Rotomoulded [[whitewater kayak]]]]
[[File:DuoWhitewaterKayak.jpg|thumb|Blow-Molded tandem whitewater kayak]]
Plastic kayaks are [[Rotational molding|rotationally molded]] ('rotomolded') from a various grades and types of polyethylene resins ranging from soft to hard. Such kayaks are seamless and particularly resistant to impact, but heavy.

[[File:Inflatable kayak.JPG|thumb|upright|Inflatable kayak]]
Inflatable kayaks are increasingly popular due to their ease of storage and transport, as well as the ability to be deflated for extended portage. Although slower than hardshell kayaks, many higher-end models often constructed of hypalon, as opposed to cheaper [[polyvinyl chloride|PVC]] designs, begin to approach the performance of traditional sea kayaks. Being inflatable they are virtually unsinkable and often more stable than hardshell designs. New drop-stitch technology means slab, rather than tube shapes are used in the designs with higher inflation pressures (up to {{cvt|10|psi|bar|1|order=flip}}), leading to considerably faster, though often less stable kayaks which rival hardshell boats in performance.

[[File:Kayak wood strip-built.jpg|thumb|Strip-built solid wooden kayak with fiberglass coat]]
Solid wooden hulls don't necessarily require significant skill and handiwork, depending on how they are made. Three main types are popular, especially for the home builder: plywood [[stitch & glue]] (S&G), [[strip-built]], and hybrids which have a stitch & glue hull and a strip-built deck. Kayaks made from wood sheathed in fiberglass have proven successful, especially as the price of [[epoxy resin]] has decreased in recent years.

Stitch & glue designs typically use modern, marine-grade [[plywood]] with a thickness of about {{cvt|3|to|5|mm|in}}. After cutting out the required pieces of hull and deck (kits often have these pre-cut), a series of small holes are drilled along the edges. [[Copper]] [[wire]] is then used to "stitch" the pieces together through the holes. After the pieces are temporarily stitched together, they are glued with [[epoxy]] and the seams reinforced with fiberglass. When the epoxy dries, the copper stitches are removed. Sometimes the entire boat is then covered in fiberglass for additional strength and waterproofing though this adds greatly to the weight and is unnecessary. Construction is fairly straightforward, but because plywood does not bend to form compound curves, design choices are limited. This is a good choice for the first-time kayak builder as the labor and skills required (especially for kit versions) is considerably less than for strip-built boats which can take three times as long to build.

Strip-built designs are similar in shape to rigid fiberglass kayaks but are generally both lighter and tougher. Like their fiberglass counterparts the shape and size of the boat determines performance and optimal uses. The hull and deck are built with thin strips of lightweight wood, often [[Thuja|thuja (Western Red cedar)]], [[pine]] or [[Cupressaceae|redwood]]. The strips are edge-glued together around a form, stapled or clamped in place, and allowed to dry. Structural strength comes from a layer of fiberglass cloth and epoxy resin, layered inside and outside the [[hull (watercraft)|hull]]. Strip–built kayaks are sold commercially by a few companies, priced US$4,000 and up. An experienced woodworker can build one for about US$400 in 200 hours, though the exact cost and time depend on the builder's skill, the materials and the size and design. As a second kayak project, or for the serious builder with some [[woodworking]] expertise, a strip–built boat can be an impressive piece of work. Kits with pre-cut and milled wood strips are commercially available.

[[File:070704 09 Seqqat-.jpg|thumb|Modern skin-on-frame kayak; the skin is cloth, sewn to fit over the wooden frame and then waterproofed]]

Skin-on-frame (SOF) boats are often more traditional in design, materials, and construction. They were traditionally made with [[driftwood]] frames, jointed, [[trunnel|pegged]], and lashed together, and covered with stretched seal skin, as those were the most readily available materials in the Arctic regions (other skins and baleen framing members were also used at need). A "poor man's kayak" might be frameless and stuffed with a snow "frame". Today, seal skin is usually replaced with [[canvas]] or [[nylon]] [[cloth]] covered with [[paint]], [[polyurethane]], or a [[hypalon]] [[rubber]] coating, on a wooden or [[aluminum]] frame. Modern skin-on-frame kayaks often possess greater impact resistance than their fiberglass counterparts, but are less durable against abrasion or sharp objects. They are often the lightest kayaks. Like the older skin-on-frame kayaks, they are often home-built to fit a specific paddler. Engineer [[Xyla Foxlin]] built a kayak out of transparent fibreglass as well as LEDs to create a floating vessel that lights up at night, which she calls the ''Rainbowt''.<ref name="twsBB887">{{cite web
| author= Jason Weisberger
| date= January 16, 2021
| publisher= Boing Boing magazine
| url= https://boingboing.net/2021/01/16/xyla-foxlin-makes-a-clear-kayak-with-led-lights.html
| title= Xyla Foxlin makes a clear kayak with LED lights
| access-date= July 8, 2021
| quote=...(she calls it the 'Rainbowt')...
}}</ref>

[[File:Kayak plegable.jpg|thumb|Folding kayak, partly-assembled]]
A special type of skin-on-frame kayak is the [[folding kayak]]. It has a collapsible frame, of wood, aluminum or plastic, or a combination thereof, and a skin of [[water-resistant]] and durable fabric. Many types have air [[sponson]]s built into the hull, making the kayak float even if flooded.