Which statement correctly describes the relationship between Centre of Gravity and Centre of Buoyancy?

• A. The Centre of Gravity is the average location of body weight (hips), while the Centre of Buoyancy is the average center of upward lift (chest).
• B. The Centre of Gravity and Centre of Buoyancy refer to the same point in a swimmer.
• C. The Centre of Buoyancy is the weight location.
• D. The Centre of Gravity is the center of buoyant force and buoyancy.

Answer: (B)

The key idea is how weight and buoyancy act in the body. The weight of the swimmer acts at the centre of gravity, while the buoyant force acts at the centre of buoyancy. In many swimming analyses, these two forces are modeled as acting through the same point, meaning the centres coincide. When they align, there’s no rotational moment on the body, making it easier to maintain a stable, balanced position in the water. In reality the centres can be located at different spots depending on posture and submerged volume, but treating them as the same point is a common simplifying assumption for studying posture and stability. The other statements mix up the meanings (buoyancy is not the weight location, and the centre of gravity is not the center of buoyant force) or rely on fixed anatomical locations that aren’t universal descriptions.