🔍 Key Concepts

• Think about basic ship construction terminology used for ALL vessels, not just MODUs (Mobile Offshore Drilling Units). • The term describes the PRIMARY longitudinal strength member that runs along the bottom centerline of a hull. • Consider what part of a vessel carries the main longitudinal bending stresses along its length.

💭 Think About

• Ask yourself: On a conventional ship, what is the main structural member running along the very bottom, from bow to stern? • Which of these choices is a standard shipbuilding term you would see in basic vessel construction diagrams? • Are any of these terms more likely to describe plates or local reinforcements rather than the main longitudinal strength member?

✅ Before You Answer

• Verify which term is commonly defined in basic seamanship or ship construction texts as the principal fore‑and‑aft strength member of the hull. • Eliminate any option that refers to a plate rather than a long, continuous structural member. • Confirm that your choice is something you would expect to find on ALL ships, not just on specialized MODUs.