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, 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 op ...
as applied to small watercraft
A watercraft or waterborne vessel is any vehicle designed for travel across or through water bodies, such as a boat, ship, hovercraft, submersible or submarine.
Types
Historically, watercraft have been divided into two main categories.
*Raf ...
(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 ...
concerning large ship
A ship is a large watercraft, vessel that travels the world's oceans and other Waterway, navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally disti ...
s).
A greater lateral width ( beam) 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
* Tertiary stability (also called inverse stabilitylimit 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 inverted, or turtled.
For example, if a boat with an ...
. For kayak rolling, the stability of an upside-down kayak is also important; lower tertiary stability makes rolling up easier.
See also
* 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 ...
*
* 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 inverted, or turtled.
For example, if a boat with an ...
— boats
References
Classical mechanics
Boats
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