🔍 Key Concepts

• Hard iron vs. soft iron magnetism on a ship • When and where in a ship’s life permanent magnetism is mainly acquired • The role of the earth’s magnetic field during shipbuilding and major repairs

💭 Think About

• Ask yourself: Which type of iron (hard or soft) keeps its magnetism for a long time, even after the original magnetic influence is removed? • Think about when the ship’s structure is most exposed, in one fixed orientation, to the earth’s magnetic field (for example, during construction or major overhaul). • Which options describe effects that would be more temporary (induced) rather than long‑lasting (permanent) magnetism?

✅ Before You Answer

• Identify which answer choices are clearly referring to soft iron (more associated with induced, changeable magnetism). • Identify which answer choice involves hard iron and a long, continuous exposure to the earth’s field. • Before choosing, ask: "Does this cause a lasting magnetic field in the hull, or only while the influencing field/equipment is operating?"