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A spraydeck (or spraycover or sprayskirt) is a flexible cover for a boat, in particular for a kayak or a canoe. It is used in whitewater, inclement weather or sport to prevent water from entering the boat while allowing one or more passengers to sit in the boat and propel the boat by paddling or rowing.
A spraydeck is a sheet made out of water-tight cloth (for example, rubberized or impregnated cloth) sized to fit over the opening, or cockpit, of the canoe or kayak.
A spraydeck has an opening for each passenger. Each opening likewise is encircled by a line or elastic string running in a hollow seam on the edge of the hole. This makes it possible to tighten the spraydeck around the body of the passenger.
Spraydecks are worn by kayakers in most conditions, but especially on rough water and in inclement weather, to prevent water entering the kayak's cockpit. On a kayak, the spraydeck is secured to a rim surrounding the cockpit with a line or elastic string called a rand. The line or string runs in a hollow seam along the edge of the spraydeck, alternatively elastic cord is attached directly to the edge of the spraydeck, and is tightened around the rim of the kayak's cockpit or stretched over it. The fastening may be pulled tight or held so by its elasticity, this prevents water infiltration while allowing passengers to quickly release it if the boat should capsize. To aid easy release during a capsize a grab loop is attached at the front of the spraydeck which the kayaker can use to pull the spraydeck free. A properly sealed spraydeck will allow a kayaker to perform an eskimo roll and continue paddling without having to bail out.
A kayaker's spraydeck is also known as a "sprayskirt", because it is donned like a skirt before entering the boat. "Sprayskirt" is the more common term in the US.
Spraydecks are commonly made from neoprene, nylon or a combination of both materials. The most appropriate material depends on the temperature/time of year and on the type of water being paddled. Whitewater spraydecks are made totally from neoprene, whereas flatwater touring/sea kayak spraydecks may be made from either material.
1. Neoprene:  These spraydecks are snug, tight, thick to keep in the warmth, and very tight fitting on the cockpit. They can usually withstand rolling, bracing and high wind and waves. They sometimes get uncomfortably warm during hot weather, but will keep the paddler very warm during colder conditions. On modern neoprene spraydecks, the rand is usually elastic cord attached directly to the rim of the spraydeck.
2. Nylon:  Nylon spraydecks are easy to attach, easy to remove, offer adequate seal to keep water out, comfortable, sometimes breathable, sometimes waterproof and are used during warmer conditions. They will either have neoprene or nylon for the torso. Nylon spraydecks are less commonly used during rough conditions as they are not as tighly fitted so are more likely to accidentally become free.
3. Other Materials: Whitewater spraydecks often have additional features to ensure the best seal and greatest robustness. Latex may be coated on the underside of the deck to grip the cockpit better and/or a protective material (e.g. Kevlar) added to the surface of the deck to provide abrasion resistance.
On a canoe, the spraydeck is secured to the outside of the hull with string or cords to a webbing specifically installed for this purpose. Modern designs have many features for safety and convenience such as map and paddle pockets, access openings, and tie-down straps.
Like a kayak, a spraydeck will allow a canoer to perform a kayak roll (provided he/she is strapped to the canoe) and continue paddling without having to bail out. But this manoeuvre is more difficult.
On a canoe, it is not only a safety item but may also be used for comfort. During rainy or cold weather, it keeps the lower body of the canoers dry and warm, and prevents rain from building up a puddle at the bottom of the boat.