In nautical terms, "capsize" means a vessel has tipped over so far that it has become disabled in the water. A boat can capsize for a variety of reasons, and in some cases a boat may be intentionally capsized. Larger vessels will often be completely disabled by this condition, leading to the destruction of the boat. Smaller vessels, however, can usually be recovered and restored to an upright position, a practice known as righting. Small dinghies and other small boats such as kayaks are routinely capsized and easily righted thereafter.
Kayakers often learn early on how to capsize the boat and then right it quickly. The process of capsizing and then returning to the upright position is sometimes known as a kayak roll or Eskimo roll; if the kayaker upends the boat so it is upside down and then rights it by returning in the same direction as the capsize, this practice is often called a half roll. Owners of smaller dinghies may purposely tip the boat over in order to drain water from it, as this is often much quicker and easier than baling water from the vessel. Sailing yachts and racing yachts are susceptible to capsizing as well, though it is much more difficult to right these ships and damage to the mainstays and sails is likely.
A full capsize results in a turtle, or turtling, in which the hull of the boat is facing upward and the deck of the vessel is facing downward in the water. On larger vessels, it can be extremely difficult or even impossible to right from turtling. Smaller vessels will usually be impaired by turtling but not totally incapacitated. Small vessels can usually be righted with some effort. Even when a boat is turtled, it is still buoyant and can act as a life vessel for stranded boaters left in the water. This is especially useful in stormy conditions or life-threatening conditions in which other rescue boats are not in the vicinity.
Some boats are self-righting, which means they will return to the upright position after capsizing or before a capsize can occur. Most modern life rafts are self-righting; they must feature a solid hull rather than an inflatable one in most cases to be designated as self-righting. Such vessels can often self-right without any intervention at all, thereby eliminating the need for humans to attempt a righting maneuver or for other ships to do this job.