🔍 Key Concepts

• How the righting arm (GZ) relates to a vessel’s ability to return to upright • The meaning of positive, negative, and zero righting arms in terms of stability • What happens to the righting arm as the vessel is inclined from 0° to small angles when the vessel is initially stable

💭 Think About

• Think about a vessel that is upright and then given a small heel. Does it want to come back, stay where it is, or continue to roll over? How would the righting arm reflect that tendency? • Consider what the sign (positive, negative, zero) of the righting arm tells you about the direction of the righting moment relative to the heel. • For a vessel with positive initial stability, as you first begin to incline it from the upright, what is the expected behavior of the GZ curve at small angles of heel?

✅ Before You Answer

• Verify the definition: Righting arm (GZ) is the horizontal distance between the center of gravity (G) and the center of buoyancy (B1) when heeled. • Check whether a positive righting arm corresponds to a restoring moment or an overturning moment. • Consider the special conditions when GZ is zero (e.g., at 0° heel and at the angle of vanishing stability) and whether the question is talking about just any nonzero angle of list or a specific condition.