🔍 Key Concepts

• Boiler mounting and support and how mechanical looseness can transmit vibration • How combustion quality (air/fuel ratio and flame stability) affects smooth boiler operation • What is meant by combustion pulses and how pressure fluctuations feel as vibration

💭 Think About

• Think about which options relate to purely mechanical issues versus combustion/pressure issues. Could more than one realistically create noticeable vibration? • Ask yourself: if the boiler is shaking, could that come from how it is fastened to the ship, from the way the flame is burning, or from rapid pressure changes in the furnace? • Consider whether the final option is only correct if each of the specific causes listed before it is independently capable of creating excessive vibration.

✅ Before You Answer

• For each of A, B, and C, decide: Can this realistically make the boiler vibrate the hull or surrounding structure? • Visualize an auxiliary boiler in operation: What happens if the base bolts are loose? What if the flame does not burn smoothly? What if pressure pulses occur in the furnace? • Before choosing, confirm whether every single item listed would be a valid cause of excessive vibration, or if one (or more) would more likely cause another symptom (like poor combustion) rather than significant vibration.