🔍 Key Concepts

• Ballast system operating limits on semi-submersibles like DEEP DRILLER • Effect of transverse list (inclination) on suction performance of ballast pumps • Why crossover operations can become unsafe or ineffective at higher lists

💭 Think About

• How does an increasing transverse inclination affect the ability of a high‑side pump to maintain suction from the low side? • Why would the manufacturer or operating manual specify a relatively small maximum angle for using crossovers, instead of allowing operation up to the damage stability or intact stability limits? • Among the choices, which angle seems most consistent with a conservative operating limit to prevent loss of suction and unintended heel changes during ballasting?

✅ Before You Answer

• Check what typical maximum list angles are for safe operation of ballast pumps and crossovers (not the vessel’s overall stability limit). • Confirm that at the chosen angle, the suction bell/sump for the high‑side pump is still reliably covered by water on the low side when using the crossover. • Verify that the selected angle reflects a conservative operational practice, not the extreme angle the rig could withstand structurally.