🔍 Key Concepts

• Lightweight condition vs. loaded condition for a vessel’s stability booklet • Meaning of longitudinal free surface moments and how tank contents contribute • Sign convention for positive vs. negative moments in naval architecture tables

💭 Think About

• Look at how free surface moments are typically listed in the trim and stability booklet: are lightweight free surface moments usually large, small, or zero? • Consider what is normally included in the lightweight definition – which tanks (if any) are assumed slack at lightweight? • Think about whether it is common to have a significant positive or negative longitudinal free surface moment in a carefully defined lightweight condition.

✅ Before You Answer

• Check the definition of lightweight for the DEEP DRILLER in the stability data – does it include any slack tanks? • Confirm whether the stability booklet shows ‘moments due to free surface’ as a separate column that is zeroed out in the lightweight condition. • Verify whether a negative sign is used in that booklet to indicate aft or forward moments, and whether such a sign would reasonably apply in a lightweight, no‑cargo, no‑ballast‑change condition.