🔍 Key Concepts

• Hogging vs. sagging: how the hull bends and what happens to the deck vs. the bottom • Types of structural stress: tension, compression, shear, racking • Where the hull is being stretched vs. squeezed when the ship is hogging and not moving

💭 Think About

• In a hogging condition, does the middle of the ship tend to be higher or lower than the ends? Visualize the ship’s shape from the side. • If the hull bends so that the bow and stern droop relative to the midship, is the deck being stretched or squeezed along its length? • Which stress acts along the length of a member to shorten it, and which one acts to lengthen it?

✅ Before You Answer

• Be clear on the definition of hogging (middle up, ends down) and sagging (middle down, ends up). • Identify whether the deck (top) and the keel/bottom are in opposite types of longitudinal stress in hogging. • Verify the basic definitions: tension = pulling apart (lengthening); compression = pushing together (shortening).