How does a positive GM affect initial stability?

• A. It reduces stability at small angles.
• B. It provides a righting moment to return the ship to upright for small angles.
• C. It has no effect on stability.
• D. It makes the vessel more likely to capsize at small angles.

Answer: (B)

Positive GM means the metacenter is above the center of gravity. When the ship tilts a little, buoyancy shifts and a couple is created between weight and buoyancy that tends to push the vessel back upright. The righting lever, GZ, becomes positive for small angles, so the righting moment (weight times GZ) restores the ship toward vertical. In other words, larger positive GM gives a stronger restoring moment for small heel angles, enhancing initial stability. The other ideas would imply the vessel would tilt further or not respond at all, which isn’t the case when GM is positive.