
A sea kayak or touring kayak is a kayak designed for open waters on lakes, bays and oceans. They are seaworthy human-powered watercraft with a covered deck and the ability to incorporate a spray deck, and trade off the manoeuvrability of whitewater kayaks for higher cruising speed, cargo capacity, ease of straight-line paddling (tracking), and comfort for long journeys.
Sea kayaks are used around the world for marine (sea) journeys from a few hours to many weeks, and can accommodate one to three paddlers along with their camping gear, food, water, and other supplies. Solo sea kayaks are 3.0–5.5 m (10–18 ft) long, while tandem craft can be up to 8 m (26 ft) long; beam widths range from 53 cm (21 in) to 91 cm (36 in).
The term "sea kayaking" may have been popularised by the 1981 book Sea Kayaking by John Dowd, who said, "It wasn't called sea kayaking until my book came out; it was called kayak touring or sea canoeing or canoe touring, blue-water paddling, coastal paddling, all those things".

Contemporary sea kayaks trace their origin to the native boats of Alaska, northern Canada, and Southwest Greenland. Inuit (formerly Eskimo) hunters developed a fast seagoing craft to hunt seals and walrus. The ancient Aleut name for an Aleutian kayak is Iqyak, and earliest models were constructed from a light wooden frame (tied together with sinew or baleen) and covered with sea mammal (sea lion or seal) hides. Archaeologists have found evidence indicating that kayaks are at least 4000 years old. Wooden kayaks and fabric kayaks on wooden frames (such as the Klepper) dominated the market up until the 1950s, when fiberglass boats were introduced. Rotomolded plastic kayaks first appeared in 1984.

Modern sea kayaks come in a wide array of materials, designs, and sizes to suit a variety of intended uses. In sea kayaking, where the designs continue along primarily traditional lines, the primary distinction is between rigid kayaks and Folding kayaks. Folding kayaks are in some ways more traditional boats, being similar in design to skin-on-frame kayaks used by native people. Modern folding kayaks use ash and birch or contemporary materials such as aluminum for the frame, and replace the sealskin covering with synthetic waterproof fabrics. Unlike rigid kayaks, folding kayaks can be easily disassembled and packed for transport. Many folding kayaks include inflatable sponsons that improve the secondary stability of the vessel, helping to prevent capsize. More recently, a class of inflatable folding kayaks has emerged, combining a more limited rigid frame with a tightly inflated skin to produce greater rigidity than an inflatable boat alone.
In recent years, there has been an increase in production of sit-on-top kayaks suitable for sea use.[citation needed]
Most rigid sea kayaks also derive from the external designs of native vessels, especially those from Greenland, but the strength of modern materials such as fiberglass, rotomolded plastic and carbon fiber eliminate the need for an internal frame, though significantly increasing weight. Modern skin-on-frame sea kayaks constructed with nylon skins represent an ultralight niche within the rigid sea kayak spectrum. Some recent design innovations include:
A different class of vessel emerged in the 1960s, the surf ski, a long, narrow boat with low inherent stability that is intended for use in surf and following waves.
Most production sea kayaks are between 3.7 and 7.3 m (12 and 24 ft) in length, the larger kayaks often built for two (or in rare cases, three) paddlers. The width (beam) of typical kayaks varies from 46 to 81 cm (18 to 32 in), though specialized boats such as surf skis may be narrower. The length of a kayak affects not only its cargo capacity (for both gear and paddlers) but may also affect its "tracking" ability—the ease with which the boat travels in a straight line. While other design features also impact tracking, very long kayaks are easier to paddle straight (and harder to turn). The width of a kayak affects the cargo capacity, the maximum size of the cockpit (and thus the size of the paddler in that cockpit), and (to a degree that depends on the design of the hull) the stability.

Most rigid production kayaks are now made out of fiberglass, rotomolded polyethylene, thermoformed plastic, blow moulded polyethylene or carbon-kevlar. More exotic materials include carbon fiber and foam core. Some kayaks are hand-built from plywood or wood strips covered with fiberglass. Skin-on-frame kayaks are built on wood or aluminum frames covered in canvas, dacron, or other fabrics, and may include inflatable tubes called sponsons.
Marine grade plywood available today provides a high strength to weight ratio for kayak construction. Inflatable kayaks may be made from cheaper polyvinyl chloride (PVC) with a nylon outer skin to resist abrasion, or more expensive single-skin designs made from hypalon which is very tough and easy to dry after use.

Sea kayaks have a wide range of hull designs, which greatly expands their range of performance. Designs can accommodate a wide range of physical fitness, or usage. Boats come in many lengths, whereby shorter boats are generally more maneuverable, and longer boats generally travel straighter and faster. Width of beam can affect a boat's stability, speed, and ability to bring to an edge. The amount of rocker (the curve from bow to stern) can greatly affect the ability of a boat to turn.
Many have steering gear or tracking aids in the form of rudders or skegs. In most cases, rudders are attached at the stern and operated by lines (wire or synthetics such as Spectra) from foot pedals in the cockpit. Rudders are typically retractable for beach landings. Skegs are typically retractable straight blades that drop from a well in the stern of the boat. Both devices assist in paddling when a strong wind or waves are coming from a direction other than directly in front. Some skegs may be more effective at countering pitch, roll and yaw.

Developed by kayak enthusiasts, Kayak sails can supplement or effectively eliminate the need for paddling. Using a sail can increase offshore range and allow longer expeditions. Use of a sail for touring has established a strong following with recreational sea kayakers, expedition paddlers, and adventure racers.

Weekend trips with overnight camping are popular among recreational kayakers and many combine kayaking with wildlife watching. Modern sea kayaks are designed to carry large amounts of equipment and unsupported expeditions of two weeks or more are conducted in environments ranging from the tropics to the Arctic. Expedition kayaks are designed to handle best when loaded, so it may be necessary to ballast them on shorter trips.
Closely related to surf boards and requiring a mix of surfing and kayaking skills, a wide range of sea kayaks are specifically designed for the sport of surf kayaking.
The sea kayak has long been a means of transportation and a means of accessing fishing grounds and kayak fishing has gained popularity due to the availability of purpose built stable designs. This technological development also solves some ergonomic problems that are associated with sitting for long hours without being able to change positions and special kayaks for fishing are accessorized for this sport, including specially designed hatches, built-in rod holders, catch bags and equipment mounts.
Many of the techniques used in kayak fishing are the same as those used on other fishing boats. The difference is in the set-up, how each piece of equipment is fitted to the kayak, and how each activity is carried out on such a small craft. Contemporary kayaks can be equipped with fishing aids such as rod holders, electronic fish-finders and live-bait containers. Kayak anglers target highly prized bottom feeders like halibut and cod and also pelagics like amberjacks, tuna, sailfish, wahoo, and even marlin.



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