SEED Science

Floating and Stability: Stability in Sailboats

Find out more about
Floating and Stability

Center of Gravity 
General Stability
Buoyant Force
Floating and Sinking
Archimedes’ Principle
Center of Buoyancy
Stability and Center of Buoyancy
Stability in Sailboats

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Stability in Sailboats

So, how do sailboats stay upright? The secret is in the location of the center of gravity. A sailboat has a long, thin, heavy board that sticks out from the bottom of the hull of the boat. This board, called the keel, locates the center of gravity below the center of buoyancy and keeps the boat from tipping over.

Because the center of gravity is below the center of buoyancy, the downward force of the weight and the upward buoyant force are represented by arrows that point away from each other.

When the boat tilts, both the center of buoyancy and the center of gravity move in the direction of the tilt. The center of buoyancy moves a greater distance than the center of gravity does.

The upward buoyant force and the downward weight of the boat rotate the boat back to its equilibrium position.

The boat is stable in the water.

Note: When sailboats tilt (or heel over) in a strong wind, sometimes the crew members will move to the opposite side of the boat. This adjusts the center of gravity so that it helps to stabilize the boat. When the boat tilts so much that the center of buoyancy and the center of gravity are on the same level, the boat capsizes.

buoyant
force
Opposing forces
boat
weight
Inverted triangle
   
buoyant
force
Opposing forces
boat
weight
Inverted triangle