Capsizing or keeling over occurs when a boat or ship is rolled on its side or further by wave action, instability or wind force beyond the angle of positive static stability or it is upside down in the water. The act of recovering a vessel from a capsize is called righting. Capsize may result from broaching, knockdown, loss of stability due to cargo shifting or flooding, or in high speed boats, from turning too fast.
Seawise University capsized after being gutted by fire in 1972
Righting a capsized Laser sailing dinghy by standing on the daggerboard
The Costa Concordia after sinking and running aground
A team at the 2005 ISAF Team Racing World Championship narrowly avoids capsizing.
A boat is said to be turtling or to turn turtle when it is fully inverted. The name stems from the appearance of the upside-down boat, similar to the carapace of a sea turtle. The term can be applied to any vessel; turning turtle is less frequent but more dangerous on ships than on smaller boats. It is rarer but more hazardous for multihulls than for monohulls, because multihulls are harder to flip in both directions. Measures can be taken to prevent a capsize from becoming a turtle.
Boat that has turned turtle (upside down)
Righting a capsized Hobie Cat.
A Hobie catamaran with a masthead float to prevent turtling
Righting a turtled sailing dinghy