皮艇

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.

Plastic kayaks are 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.

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 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 0.7 bar（10 psi）), leading to considerably faster, though often less stable kayaks which rival hardshell boats in performance.

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 3至5 mm（0.12至0.20英寸）. 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 3 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 (Western Red cedar), pine or 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. 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.

Skin-on-frame (SOF) boats are often more traditional in design, materials, and construction. They were traditionally made with driftwood frames, jointed, 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 wood as well as LEDs to create a floating vessel that lights up at night, which she calls the Rainbowt.^[33]

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 sponsons built into the hull, making the kayak float even if flooded.

Most modern kayaks differ greatly from native kayaks in design, manufacturing and usage. They are often designed with computer-aided design (CAD) software, often in combination with CAD customized for naval design.

Modern kayaks serve diverse purposes, ranging from slow and easy touring on placid water, to racing and complex maneuvering in fast-moving whitewater, to fishing and long-distance ocean excursions. Modern forms, materials and construction techniques make it possible to effectively serve these needs while continuing to leverage the insights of the original Arctic inventors.

Kayaks are long—5.8米（19英尺）, short—1.8米（6英尺）, wide—110 cm（42英寸）, or as narrow as the paddler's hips—for example 35 cm（14英寸）. They may attach one or two stabilizing hulls (outriggers), have twin hulls like catamarans, inflate or fold. They move via paddles, pedals that turn propellers or underwater flippers, under sail, or motor. They're made of wood/canvas, wood, carbon fiber, fiberglass, Kevlar, polyethylene, polyester, rubberized fabric, neoprene, nitrylon, polyvinyl chloride (PVC), polyurethane, and aluminum. They may sport rudders, fins, bulkheads, seats, eyelets, foot braces and cargo hatches. They accommodate 1-3 or more paddlers/riders.

Modern kayaks have evolved into specialized types that may be broadly categorized according to their application as sea or touring kayaks, whitewater (or river) kayaks, surf kayaks, racing kayaks, fishing kayaks, and recreational kayaks. The broader kayak categories today are 'sit-in' (SI), which is inspired mainly by traditional kayak forms, 'sit-on-top' (SOT), which evolved from paddle boards that were outfitted with footrests and a backrest, 'hybrid', which are essentially canoes featuring a narrower beam and a reduced free board enabling the paddler to propel them from the middle of the boat, using a double blade paddle (i.e. 'kayak paddle'), and twin hull kayaks offering each of the paddler's legs a narrow hull of its own. In recent decades, kayaks design have proliferated to a point where the only broadly accepted denominator for them is their being designed mainly for paddling using a kayak paddle featuring two blades i.e. 'kayak paddle'. However, even this inclusive definition is being challenged by other means of human powered propulsion, such as foot activated pedal drives combined with rotating or sideways moving propellers, electric motors, and even outboard motors.

Recreational kayaks are designed for the casual paddler interested in fishing, photography, or a peaceful paddle on a lake, flatwater stream or protected salt water away from strong ocean waves. These boats presently make up the largest segment of kayak sales. Compared to other kayaks, recreational kayaks have a larger cockpit for easier entry and exit and a wider beam (69—91 cm（27—36英寸）) for more stability. They are generally less than 3.7米（12英尺） in length and have limited cargo capacity. Less expensive materials like polyethylene and fewer options keep these boats relatively inexpensive. Most canoe/kayak clubs offer introductory instruction in recreational boats. They do not perform as well in the sea. The recreational kayak is usually a type of touring kayak.

Sea kayaks are typically designed for travel by one, two or even three paddlers on open water and in many cases trade maneuverability for seaworthiness, stability, and cargo capacity. Sea-kayak sub-types include "skin-on-frame" kayaks with traditionally constructed frames, open-deck "sit-on-top" kayaks, and recreational kayaks.

The sea kayak, though descended directly from traditional types, is implemented in a variety of materials. Sea kayaks typically have a longer waterline, and provisions for below-deck storage of cargo. Sea kayaks may also have rudders or skegs (fixed rudder) and upturned bow or stern profiles for wave shedding. Modern sea kayaks usually have two or more internal bulkheads. Some models can accommodate two or sometimes three paddlers.

Sealed-hull ("unsinkable") craft were developed for leisure use, as derivatives of surfboards (e.g. paddle or wave skis), or for surf conditions. Variants include planing surf craft, touring kayaks, and sea marathon kayaks. Increasingly, manufacturers build leisure 'sit-on-top' variants of extreme sports craft, typically using polyethylene to ensure strength and affordability, often with a skeg for directional stability.

Sit-on-top kayaks come in 1-4 paddler configurations. Sit-on-top kayaks are particularly popular for fishing and SCUBA diving, since participants need to easily enter and exit the water, change seating positions, and access hatches and storage wells. Ordinarily the seat of a sit-on-top is slightly above water level, so the center of gravity for the paddler is higher than in a traditional kayak. To compensate for the higher center of gravity, sit-on-tops are often wider and slower than a traditional kayak of the same length.

Water that enters the cockpit of a sit-on-top kayak drains out through scupper holes—tubes that run from the cockpit to the bottom of the hull. The cockpit is thus self-bailing. The hull may be sealed, or perforated by hatches and deck fixtures. Contrary to popular belief, the sit-on-top kayak hull is not self-bailing, since water penetrating it does not drain out automatically, as it does in bigger boats equipped with self-bailing systems. Furthermore, the sit-on-top hull cannot be molded in a way that would assure water tightness, and water may get in through various holes in its hull, usually around hatches and deck accessories. If the sit-on-top kayak is loaded to a point where such perforations are covered with water, or if the water paddled is rough enough that such perforations often go under water, the sit-on-top hull may fill with water without the paddler noticing it in time. If a sealed hull develops a split or hole, it will also fill and sink.

Specialty surf boats typically have flat bottoms, and hard edges, similar to surf boards. The design of a surf kayak promotes the use of an ocean surf wave (moving wave) as opposed to a river or feature wave (moving water). They are typically made from rotomolded plastic, or fiberglass.

Surf kayaking comes in two main varieties, High Performance (HP) and International Class (IC). High Performance boats tend to have a lot of nose rocker, little to no tail rocker, flat hulls, sharp rails and up to four fins set up as either a three fin thruster or a quad finTemplate:According to whom. This enables them to move at high speed and maneuver dynamically. International Class boats have to be at least 3米（9.8英尺） long and until a recent rule change^[何时？] had to have a convex hull; now flat and slightly concave hulls are also allowed, although fins are not. Surfing on international boats tends to be smoother and more flowing, and they are thought of as kayaking's long boarding. Surf boats come in a variety of materials ranging from tough but heavy plastics to super light, super stiff but fragile foam–cored carbon fiber. Surf kayaking has become popular in traditional surfing locations, as well as new locations such as the Great Lakes.

A variation on the closed-cockpit surf kayak is called a waveski. Although the waveski offers dynamics similar to a sit–on–top, its paddling technique and surfing performance and construction can be similar to surfboard designs.

Whitewater kayaks are rotomolded in a semi-rigid, high impact plastic, usually polyethylene. Careful construction ensures that the boat remains structurally sound when subjected to fast-moving water. The plastic hull allows these kayaks to bounce off rocks without leaking, although they scratch and eventually puncture with enough use. Whitewater kayaks range from 1.2至3.0米（4至10英尺） long. There are two main types of whitewater kayak, playboats and river-running boats. Creekboats (for small rivers) and squirt boats are more specialized.

One type, the playboat, is short, with a scooped bow and blunt stern. These trade speed and stability for high maneuverability. Their primary use is performing tricks in individual water features or short stretches of river. In playboating or freestyle competition (also known as rodeo boating), kayakers exploit the complex currents of rapids to execute a series of tricks, which are scored for skill and style.

The other primary type is the creek boat, which gets its name from its purpose: running narrow, low-volume waterways. Creekboats are longer and have far more volume than playboats, which makes them more stable, faster and higher-floating. Many paddlers use creekboats in "short boat" downriver races, and they are often seen on large rivers where their extra stability and speed may be necessary to get through rapids.

Between the creekboat and playboat extremes is a category called river–running kayaks. These medium–sized boats are designed for rivers of moderate to high volume, and some, known as river running playboats, are capable of basic playboating moves. They are typically owned by paddlers who do not have enough whitewater involvement to warrant the purchase of more–specialized boats.

Squirt boating involves paddling both on the surface of the river and underwater. Squirt boats must be custom-fitted to the paddler to ensure comfort while maintaining the low interior volume necessary to allow the paddler to submerge completely in the river.

White water racers combine a fast, unstable lower hull portion with a flared upper hull portion to combine flat water racing speed with extra stability in open water: they are not fitted with rudders and have similar maneuverability to flat water racers. They usually require substantial skill to achieve stability, due to extremely narrow hulls. Whitewater racing kayaks, like all racing kayaks, are made to regulation lengths, usually of fiber reinforced resin (usually epoxy or polyester reinforced with Kevlar, glass fiber, carbon fiber, or some combination). This form of construction is stiffer and has a harder skin than non-reinforced plastic construction such as rotomolded polyethylene: stiffer means faster, and harder means fewer scratches and therefore also faster.

Sprint kayak is a sport held on calm water. Crews or individuals race over 200 m, 500 m, 1000 m or 5000 m with the winning boat being the first to cross the finish line. The paddler is seated, facing forward, and uses a double-bladed paddle pulling the blade through the water on alternate sides to propel the boat forward. In competition the number of paddlers within a boat is indicated by a figure besides the type of boat; K1 signifies an individual kayak race, K2 pairs, and K4 four-person crews. Kayak sprint has been in every summer olympics since it debuted at the 1936 summer olympics.^[34] Racing is governed by the International Canoe Federation.

Slalom kayaks are flat–hulled, and—since the early 1970s—feature low profile decks. They are highly maneuverable, and stable but not fast in a straight line.

A specialized variant of racing craft called a surf ski has an open cockpit and can be up to 6.4米（21英尺） long but only 46 cm（18英寸） wide, requiring expert balance and paddling skill. Surf skis were originally created for surf and are still used in races in New Zealand, Australia, and South Africa. They have become popular in the United States for ocean races, lake races and even downriver races.

Marathon races vary in distances from ten kilometres to over 1000 kilometres for multi-day stage races.