🔍 Key Concepts

• Weight high in the vessel vs. weight low in the vessel and how this affects stability • Relationship between metacentric height (GM) and righting moment • What happens to roll period when a vessel becomes more or less stable

💭 Think About

• When drill pipe is laid down from the derrick, is weight moving higher or lower relative to the waterline? How does that affect stability? • If a vessel becomes ‘stiffer’ (more stable), what happens to its natural roll period—does it get longer or shorter? • Which of the listed options is a direct consequence of shifting weight down from high in the vessel: a change in GM, a change in waterplane area, or both?

✅ Before You Answer

• Be clear whether waterplane area depends on draft and hull shape at the surface, or on weight location high vs. low in the vessel • Recall the basic rule: increasing GM does what to the natural roll period? Verify that relationship before choosing • Confirm which quantity is the primary one that changes when weight is shifted vertically inside the vessel: GM, righting moment, waterplane area, or roll period