🔍 Key Concepts

• Semisubmersible rig stability when under tow • Effect of ballasting down on motion and exposure of pontoons • Relationship between sea state, motions (heave/roll/pitch), and the rig’s draft

💭 Think About

• Which condition signals that the rig is riding too high for the sea state and could benefit from a deeper draft? • How does ballasting down affect both the motions of the rig and the amount of structure exposed to waves and wind? • Among the options, which one indicates an unsafe interaction between waves and the hull form near the waterline?

✅ Before You Answer

• Identify which option shows direct evidence of waves interacting with the lower structure of the rig (pontoons). • Ask whether ballasting down would reduce or increase the problem described in each choice. • Consider which condition is a clear operational trigger used by towing masters and rig movers, not just a general performance complaint.