🔍 Key Concepts

• Angle of loll – what it means about a ship’s initial stability when upright • Relationship between GZ (righting arm) and the ship’s tendency to heel or return upright • How the GZ curve behaves when the vessel passes through the neutral stability point (GM = 0)

💭 Think About

• Ask yourself: at an angle of loll, is the vessel in stable, unstable, or neutral equilibrium? How does that affect the sign of GZ? • Think about what the ship is doing at the angle of loll: is it trying to roll back upright, stay where it is, or heel even further? What does that imply for the righting moment? • On a GZ curve, imagine moving from small angles of heel through the point where GM changes sign. What happens to GZ exactly at that critical angle?

✅ Before You Answer

• Be clear on the definition: an angle of loll occurs when the ship with negative GM when upright comes to rest at some angle of heel where it is in neutral equilibrium. • Remember that GZ = 0 indicates no righting or upsetting lever at that exact angle; positive GZ gives a righting tendency; negative GZ gives a capsizing tendency. • Visualize or sketch a GZ vs. heel angle graph for a ship with negative GM when upright and identify what GZ must be at the actual angle of loll.