ship's movements.

There are three special axes in any ship, called vertical, lateral and longitudinal axes. The movements around them are known as roll, pitch and yaw.

- The vertical axis, or yaw axis, is an imaginary line running vertically through the ship and through its center of gravity. A yaw motion is a side-to side movement of the bow of the ship.

yaw (n)
Definition: The turning of a boat off course caused by seas arriving at an angle. The motion of a ship when she deviates from the right or left.

- The lateral axis, transverse axis, or pitch axis is an imaginary line running horizontally across the ship and through the center of gravity. A pitch motion is an up-or-down movement of the bow of the ship.

pitch (n)
Definition: The rotation of a vessel around a lateral axis as it heads into heavy seas. The movement of a ship, by which she plunges her head and after-part alternately into the hollow of the sea.

- The longitudinal axis, or roll axis, is an imaginary line running horizontally through the length of the ship, through its center of gravity, and parallel to the waterline. A roll motion is a side-to-side motion of the superstructure around this axis.

roll (n)
Definition: The rotation of a vessel around the fore and aft axis. The motion by which a ship rocks from side to side like a cradle.