🔍 Key Concepts

• Difference between local structural vibration and overall ship motion such as pitching or rolling • Meanings of hogging and sagging in terms of how a ship’s hull bends • What happens to the hull structure when a single heavy sea impact causes rapid, shudder-like vibrations

💭 Think About

• Ask yourself: which term refers to the ship’s longitudinal motions in regular waves, and which term refers to a sudden shock impact? • Consider which options describe overall hull bending shape (middle up or middle down), and which describes a slamming or shuddering effect. • Focus on the phrase “rapid vibrations of the elastic portions of the ship’s hull” – which option is associated with that kind of vibration after a heavy blow from a sea?

✅ Before You Answer

• Identify which terms (from the choices) are normally used to describe global hull bending instead of local vibration. • Verify which option is specifically linked in seamanship texts to bottom or bow slamming in heavy seas. • Eliminate any term that mainly describes a fore‑and‑aft seesaw motion of the vessel rather than a structural vibration.