🔍 Key Concepts

• Sagging vs. hogging longitudinal bending of a ship • Location of tensile vs. compressive stresses when a ship sags • Relationship between wave crest/trough position and hull bending

💭 Think About

• Picture the vessel on a long wave: where is the ship best supported in a sagging condition—at the ends or in the middle? • When the middle of the ship goes lower than the bow and stern, which part of the hull structure is being stretched (in tension) and which part is being squeezed (in compression)? • How would the stress distribution differ if the ship were on a crest amidships instead (hogging)?

✅ Before You Answer

• Be clear on the definition: sagging = middle lower than ends (opposite of hogging) • Identify which part of the hull (deck vs. bottom) is in tension when the ship is sagging • Check whether sagging is a longitudinal or transverse bending effect