Definition

1. Noun:
   • The point at which the buoyant force on a floating or submerged object can be considered to act: In physics and naval architecture, the "centre of buoyancy" is the geometric centre of the volume of fluid displaced by an object. It is the point through which the total buoyant force (the upward force) is directed.

Usage

• The "centre of buoyancy" is a critical concept for understanding the stability of ships, boats, and other floating structures.
• It is used when calculating or describing the righting moment that returns a tilted vessel to an upright position.
• Its position changes as the shape of the immersed part of the object changes (e.g., when a ship rolls or pitches).

Examples

• Noun:
  • A ship's stability depends on the relative positions of its centre of buoyancy and its centre of gravity.
  • When the vessel heeled, the centre of buoyancy shifted to the side, creating a restoring force.
  • Naval architects must carefully calculate the centre of buoyancy for every new hull design.

Advanced Usage

• Metacentre: A key related concept is the . It is the intersection point of the vertical line through the centre of buoyancy of a tilted vessel and the original vertical centreline. The distance between the centre of gravity and the metacentre (metacentric height) is a direct measure of initial stability.
• Righting Arm: The horizontal distance between the vertical line through the centre of gravity and the vertical line through the centre of buoyancy. This distance, multiplied by the buoyant force, gives the righting moment that corrects a tilt.

Variants and Related Words

• Center of buoyancy: The American English spelling variant.
• Centroid of the displaced volume: A more technical, geometric synonym.
• Buoyancy: (n) The upward force exerted by a fluid that opposes the weight of an immersed object.
• Centre of gravity: (n) The point where the total weight of an object is considered to act.

Synonyms

• Centroid of displacement
• Buoyancy centre

Notes

• The "centre of buoyancy" is not a fixed point on a ship; it moves as the ship's orientation in the water changes.
• For an object to be stable when floating, its centre of gravity must be vertically aligned with, and typically below, its centre of buoyancy when in the upright position.

Noun

1. (physics) the center of mass of the immersed part of ship or other floating object