🔍 Key Concepts

• Line shaft bearings function and location in the propulsion train • Difference between misalignment due to hull/shaft movement vs. torque, thrust, or vibration effects • What a spherical / self-aligning seat allows the bearing to do physically

💭 Think About

• Ask yourself: Which of these four choices would actually change the alignment angle between shaft and bearing as the ship operates? • Think about what happens to a long shaft line when a steel hull hogs/sags or changes trim with different loading conditions—what happens to bearing alignment then? • Which listed effect (torsion, thrust, hull flexing, vibration) mainly needs a bearing that can tilt and follow the shaft, rather than just be stronger or more heavily built?

✅ Before You Answer

• Verify which condition causes gradual changes in shaft line alignment along the ship’s length. • Check which option involves angular misalignment that a spherical seat can follow by rocking/tilting. • Eliminate any options that deal mostly with twisting, pushing, or shaking forces rather than alignment between bearing and shaft.