🔍 Key Concepts

• Lightweight ship condition (no cargo, no fuel, no consumables) • How longitudinal moments are calculated from weight × longitudinal distance from a reference point • Typical order of magnitude for lightship longitudinal moments on a drillship or MODU (Mobile Offshore Drilling Unit)

💭 Think About

• Which answer choices look unrealistically large or small for a lightweight longitudinal moment on a vessel the size of DEEP DRILLER? • What sign (positive or negative) would you expect for the lightship longitudinal moment if the center of gravity is forward or aft of the chosen longitudinal reference (FP or AP)? • If you roughly estimate the total lightweight in long tons and multiply by a typical longitudinal lever arm, which answer choice seems in the right numerical range?

✅ Before You Answer

• Check the definition of lightweight and confirm you are using the correct condition (no variable loads). • Verify the reference point used for longitudinal moments in the hydrostatic/trim data (forward perpendicular, aft perpendicular, or midships). • Confirm the plausible magnitude of the moment by estimating: lightweight (LT) × a realistic longitudinal distance (ft) before choosing among the options.