🔍 Key Concepts

• semisubmersible operating modes: survival, transit, drilling (operating) drafts • how wave forces and motions (heave, pitch, roll, bending) change with draft and hull immersion • relationship between wave loading, buoyancy distribution, and structural stress on columns, braces, and pontoons

💭 Think About

• For each draft condition listed, ask yourself: how much of the structure is exposed to the most severe wave action, and where are the waves striking relative to the pontoons and braces? • Consider which draft typically has the largest motions and greatest wave‑induced bending on the columns and braces vs. which draft minimizes wave loading. • Think about the design purpose of each draft: which one is meant for maximum safety in storms, which for moving between locations, and which for normal drilling operations?

✅ Before You Answer

• Identify which draft is specifically intended to minimize wave loading and motions in severe storms. • Determine at which draft the pontoons are closest to the surface and most affected by wave action and slamming. • Verify which condition involves changing buoyancy and ballast distribution only temporarily, versus a steady‑state operating condition.