Aux 1 Unit 11 Q12

1 / 10

What is the primary function of the aft seal in an oil-lubricated stern tube bearing?

B) To prevent the ingress of seawater into the stern tube and the leakage of lubricating oil into the sea

D) To reduce the weight of the propeller shaft

C) To increase the speed of the vessel

A) To cool the propeller shaft

2 / 10

How is the aft seal typically arranged in relation to the propeller shaft?

D) The aft seal is located on the rudder.

A) The aft seal is mounted directly on the propeller shaft and housed within the stern tube seal assembly.

C) The aft seal is positioned inside the engine room.

B) The aft seal is placed at the bow of the vessel.

3 / 10

What additional component might be included in the aft seal arrangement to protect the seal from damage caused by debris or fishing lines?

D) A plastic cap

A) A metal guard ring or rope guard

C) A wooden cover

B) A rubber washer

4 / 10

How is the aft seal assembly typically lubricated?

D) With engine oil

B) With a dedicated supply of lubricating oil from the stern tube lubrication system

A) With seawater

C) With grease applied manually

5 / 10

What is the purpose of the water cooling system often found in conjunction with the aft seal arrangement?

A) To cool the engine

B) To reduce the temperature of the lubricating oil and prevent overheating of the seal assembly

C) To increase the speed of the vessel

D) To heat the propeller shaft

6 / 10

What type of seal is commonly used for the aft seal in an oil-lubricated stern tube bearing?

A) A rubber O-ring

B) A lip seal or face seal

D) A cork seal

C) A metallic gasket

7 / 10

What could be a potential consequence of a failed aft seal in an oil-lubricated stern tube bearing?

B) Seawater ingress into the stern tube, leading to contamination of the lubricating oil, and potential damage to the bearings and shaft

C) Reduced fuel consumption

A) Increased vessel speed

D) Improved propulsion efficiency

8 / 10

What maintenance procedure is typically performed to ensure the aft seal remains effective?

B) Regular inspection and replacement of the seals if wear or degradation is observed

D) Tightening the propeller shaft bolts

C) Painting the seal assembly

A) Heating the seal assembly

9 / 10

Why is it important to monitor the condition of the aft seal in an oil-lubricated stern tube bearing?

B) To detect any signs of wear or damage that could lead to leaks, ensuring the seal continues to protect the stern tube from seawater ingress and oil leakage

A) To increase the vessel's speed

C) To reduce the vessel's draft

D) To increase the weight of the vessel

10 / 10

What material is commonly used for the lip seals in an aft seal arrangement?

C) Synthetic rubber or a composite material resistant to oil and seawater

D) Wood

B) Metal

A) Plastic

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