🔍 Key Concepts

• Know what part of the ship the propeller shaft is and how it exits the hull • Understand which fittings are used specifically to seal moving shafts versus sealing static joints in the hull • Differentiate between valves on sea inlets and sealing devices around rotating machinery

💭 Think About

• Which option is designed to allow a rotating shaft to pass through a watertight boundary while keeping water out? • Which item on the list is more likely to be found on a sea inlet or discharge line rather than around a shaft? • Think about which item is associated with propeller assemblies outside the hull rather than the hull penetration itself.

✅ Before You Answer

• Identify which device is used where a moving shaft passes through a bulkhead or hull • Eliminate any option that is mainly a valve on a pipeline rather than a shaft seal • Confirm which option is typically packed with material (like flax or synthetic packing) that can be tightened to control leakage