Secondary stability, also known as reserve stability, is a boat or ship's ability to right itself at large angles of heel (lateral tilt), as opposed to primary or

initial stability Initial stability or primary stability is the resistance of a boat to small changes in the difference between the vertical forces applied on its two sides. The study of initial stability and secondary stability are part of naval architecture as app ...

, the boat's tendency to stay laterally upright when tilted to low (<10°) angles.http://newboatbuilders.com/docs/stability.pdf /ref> The study of initial and secondary stability are part of

naval architecture Naval architecture, or naval engineering, is an engineering discipline incorporating elements of mechanical, electrical, electronic, software and safety engineering as applied to the engineering design process, shipbuilding, maintenance, and o ...

as applied to small

watercraft Any vehicle used in or on water as well as underwater, including boats, ships, hovercraft and submarines, is a watercraft, also known as a water vessel or waterborne vessel. A watercraft usually has a propulsive capability (whether by sail, ...

(as distinct from the study of

ship stability Ship stability is an area of naval architecture and ship design that deals with how a ship behaves at sea, both in still water and in waves, whether intact or damaged. Stability calculations focus on center of mass#center of gravity, centers of g ...

concerning large

ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...

s). A greater lateral width (

beam Beam may refer to: Streams of particles or energy *Light beam, or beam of light, a directional projection of light energy **Laser beam *Particle beam, a stream of charged or neutral particles **Charged particle beam, a spatially localized grou ...

) and more initial stability decrease the secondary stability- once tilted more than a certain angle the boat is conversely harder to restore to its stable upright position.

Other types of ship stability

Primary stability Initial stability or primary stability is the resistance of a boat to small changes in the difference between the vertical forces applied on its two sides. The study of initial stability and secondary stability are part of naval architecture as app ...

* Tertiary stability (also called

inverse stability Inverse or invert may refer to: Science and mathematics * Inverse (logic), a type of conditional sentence which is an immediate inference made from another conditional sentence * Additive inverse (negation), the inverse of a number that, when a ...

): Tertiary stability is undesirable as it causes a vessel to remain upside-down.

Self-righting watercraft 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 fro ...

have negative tertiary stability, and no

limit of positive stability In sailing, the limit of positive stability (LPS) or angle of vanishing stability (AVS) is the angle from the vertical at which a boat will no longer stay upright but will capsize, becoming :wikt:inverted, inverted, or Turtling (sailing), turtled. ...

. For kayak rolling, the stability of an upside-down kayak is also important; lower tertiary stability makes rolling up easier.

References

Classical mechanics Boats {{water-transport-stub

Other types of ship stability

See also

References